ALBERT

Description: In the southern winter of 1970, a phreatomagmatic eruption occurred in the northern part of Deception Island (South Shetland Archipelago, Antarctic Peninsula). The eruption, with no eye-witnesses to the event, occurred in the same general area as the 1967 eruption, but with new, more widely distributed vents. Two contrasting groups of craters were formed in the 1970 eruption, showing that different active fissures and eruptive dynamics were operating. One group consists of ‘maar-like’ craters, whereas the other comprises conical edifices. The 1970 eruption can be classified as volcanic explosivity index (VEI) 3, with mainly phreatomagmatic phases that generated a bulk volume of about 0.1 km 3 of pyroclastic material and an eruptive column at least 10 km high, from which fallout deposits are recognized more than 100 km to the NE. The 1970 eruption was similar to that of 1967 and together these two eruptive events show how eruption dynamics can be controlled by the uppermost part of the volcano substrate and the width and orientation of the eruptive fissure. These influence magma–water interaction and hence may imply different eruptive phases and associated volcanic hazards. Supplementary material: Granulometric and component histograms of the samples that are not shown in Figure 4 are available at http://www.geolsoc.org.uk/SUP18761 .

Description: Neoproterozoic oceans provided the setting for the rise of animals, yet little is known of their chemical composition. Marine carbonates from the Cryogenian Oodnaminta Reef Complex, South Australia, reveal the chemical structure of a Neoproterozoic ocean. Pseudo-depth profiles from shallow- to deep-water reef facies have been constructed from geochemical and sedimentological analysis of marine cements. Evidence suggests that under a peritidal oxic–anoxic chemocline, the water column was largely anoxic, strongly ferruginous and had a chemistry profoundly different from that of modern seawater. These geochemical data suggest early Archaean-like conditions for this late Cryogenian ocean, posing problems for metazoan evolution in extremely anoxic conditions. Supplementary material: Detailed methods and data tables are available at www.geolsoc.org.uk/SUP18764 .

Description: U–Pb ages and Hf isotope data were obtained for zircon from amphibole-rich mafic to ultramafic rocks from the Adamello batholith and the Bergell pluton, the largest Palaeogene intrusions of the Alpine Orogen. The 206 Pb/ 238 U age pattern of U–Pb concordant dates from the Adamello mafic rock shows a major crystallization event at c . 41 Ma and older age peaks at c . 50 and c . 45 Ma. Hornblendite and amphibole gabbro samples of the Adamello batholith have zircon with initial Hf of c . +9.0 and c . +7.0, respectively. Amphibole gabbro and diorite samples of the Bergell pluton yield a younger age of c . 31 Ma and have zircon with lower initial Hf ( c . +4.0). We propose that the amphibole-rich rocks from the Adamello batholith originated from a depleted mantle source activated by the subduction of the Ligurian–Piedmontese Basin. The amphibole-rich rocks from the Bergell pluton formed 10–15 Ma later than the Adamello counterparts by melts derived from a mantle sector metasomatized by the subduction of the Valais Basin. The enriched Hf isotopic signature of the amphibole-rich rocks from the Bergell pluton is therefore interpreted to reflect the peculiar lithostratigraphy of the Valais Basin or a primary feature of the newly activated mantle source. Supplementary material: (1) A map showing the location of analysed samples and table with GPS coordinates of the samples, (2) data tables for U–Pb in zircon determined by LA-ICP-MS, (3) data tables for Hf isotopes in zircon, (4) U–Pb and Hf isotope analytical methods, (5) cathodoluminescence images of analysed zircon from the amphibole-rich mafic rocks of the Adamello and Bergell intrusions, and (6) a U–Pb concordia diagram for zircon of the Adamello amphibole gabbro are available at www.geolsoc.org.uk/SUP18763 .

Description: The only place where Neogene–Quaternary rocks crop out for the entire Tuscan Archipelago in the Northern Tyrrhenian Sea is the island of Pianosa. In particular, the Miocene deposits record the depositional and tectonic evolution of the Northern Tyrrhenian region during this time period. These deposits are subdivided into two successions separated by a low-angle unconformity. The older, middle Burdigalian succession represents a calciturbidite shallow marine system, whereas the younger late Tortonian–early Messinian succession comprises a continental alluvial system that evolves upwards into a lagoonal–marginal marine environment. Here we present sedimentological, palaeontological and petrographical data that support a new stratigraphic and palaeogeographical framework for reconstructing the opening of the Northern Tyrrhenian back-arc basin. The early Miocene succession records a pre-rift marine depositional phase followed by a late Burdigalian–Langhian erosional phase. This was followed by a period of synrift continental-marginal deposition, as recorded by the late Miocene succession, terminated by an important phase of uplift, probably induced by the start of magmatic activity in the Tuscan Archipelago area.

Description: Microbial carbonates contain valuable chemical, isotopic and molecular information regarding the Precambrian Earth. They record shallow-water information complementary to deep ocean proxies, such as banded iron formation and black shale. Six groups of well-preserved stromatolites illustrate how the rare earth elements (REE) are used for chemical investigation. The first task is to test whether the REE inventory of carbonate is compromised by clastic, volcanic, or diagenetic contaminants. Once the cleanliness has been verified, the shale-normalized REE pattern can be used to distinguish between marine and lacustrine settings. For marine carbonates, it is possible to distinguish between restricted basin and open marine settings and for thick platform limestones the relative water depth can be inferred from REE systematics. The studied shallow-water stromatolites range in age from 2.52 to 3.45 Ga. They contain no evidence from the behaviour of the redox-sensitive element cerium that free oxygen levels in the shallow sea approached concentrations beyond a trace gas by 2.52 Ga. Compared with abiotic early diagenetic marine carbonate cements, microbial carbonate is strongly enriched in REE. This may itself not yet serve as a biomarker, but it is regarded as a necessary prerequisite for a sample to qualify for biomarker studies.

Description: For over 200 km along strike the Shuilikeng fault of Taiwan separates Miocene rocks of the Western Foothills from the largely Eocene and Oligocene rocks of the Hsuehshan Range to the east. Despite its importance in the Taiwan mountain belt, the structure and kinematics of the Shuilikeng fault are not well known. Here, we present results from new geological mapping along 100 km of its strike length. At the surface, the Shuilikeng fault is a steeply east-dipping brittle fault with a series of splays and bifurcations. Along its southern part, it cuts an earlier fold and fault system. Outcrop kinematic data vary widely, from thrusting to strike-slip. The surface data are integrated with a relocated and collapsed seismicity database to interpret the fault location at depth. These data indicate that the Shuilikeng fault can be traced to greater than 20 km depth. Some 260 focal mechanisms from this dataset indicate that its kinematics is overall transpressive. From a regional perspective, we interpret the Shuilikeng fault to reactivate a pre-existing rift-related basin-bounding fault to the east of which rocks in the Hsuehshan Range are being exhumed.

Description: The Nile drains a large basin covering various source-rock terrains of different age, mineralogical and isotopic characteristics. Its sediments are stored within the Nile delta but significant volumes are swept eastwards in the SE Mediterranean, onto the Sinai–Israeli coasts. Alongside wave transport, aeolian transport plays an important role in recycling the Nile-derived sands. We present new laser ablation inductively coupled plasma mass spectrometry, 882 U–Pb and 586 Lu–Hf analyses of detrital zircons from Quaternary to Recent sands of the Israeli coast and shelf to decipher their provenance. The detrital populations are dominated by 0.56–1.15 Ga zircons with Hf(t) of +13 to –27, implying a mixture of juvenile and non-juvenile latest Mesoproterozoic to Neoproterozoic sources. Small populations of Archaean–Palaeoproterozoic and Palaeozoic zircons are also distinguished. The detrital zircon U–Pb–Hf pattern indicates that rather than being sourced from the Arabian–Nubian Shield or older basement terranes in the Nile drainage basin, the sands are dominantly recycling products of older sediments. The detrital zircon U–Pb–Hf spectra resemble those of Cambro-Ordovician sandstones that blanket much of North Africa. These sediments were recycled into younger sand reservoirs that were in turn eroded into the Nile and transported to the coast of Israel. Supplementary material: Details of analytical methods and detrital zircon U–Pb–Hf data are available at www.geolsoc.org.uk/SUP18677 .

Description: Detrital zircon U–Pb age data from the Moldanubian part of the Bohemian Massif obtained by laser ablation inductively coupled plasma mass spectrometry show variations between the lithotectonic units and point to their formation in spatially close but separated basins that were supplied by detritus from somewhat different source areas, possibly over different periods of time. The youngest detrital zircon component in metasediments of the Monotonous and Varied Units is Early Ordovician and Mid- to Late Devonian in age, respectively, suggesting their deposition in Palaeozoic times. Reliable interpretation of the Mid- to Late Devonian zircons recovered from metasediments of the Gföhl Unit is precluded by their high metamorphic grade and presence of anatectic melt. The Early Carboniferous zircons from the Gföhl Unit are interpreted as being of metamorphic origin. Comparison of detrital zircon age spectra from the Moldanubian, Teplá–Barrandian and Moravo-Silesian metasediments suggests that these were deposited in separate basins but the overall similarity of the Neoproterozoic and Palaeoproterozoic age maxima and sparse Neo- and Mesoarchaean ages suggest that the three crustal segments must have been spatially related prior to the Variscan orogeny. Future tectonic models of the Variscan assembly of the Bohemian Massif must account for nearly synchronous evolution of the Moldanubian, Teplá–Barrandian and Moravo-Silesian Palaeozoic sedimentary basins that shared a common crust and most of their sedimentary sources, as well as for a rapid burial of the Moldanubian sediments to mid- and lower crustal levels that was followed by their rapid exhumation to the upper crust in Mid-Devonian to Early Carboniferous times. Supplementary material: Results of LA-ICP-MS U–Pb analyses of zircons extracted from the Moldanubian and Moravo-Silesian metasediments are available at www.geolsoc.org.uk/SUP18676 .

Description: We use 3D seismic data to image a series of enigmatic, SW-dipping reflection packets within pre-Mesozoic crystalline basement offshore western Norway. Based on their low-angle dip and complex reflection wave-train our preferred interpretation is that the reflection packets are the seismic expression of mylonitic zones generated by nappe emplacement during the Caledonian orogeny. Late Jurassic faults truncate and offset these reflection packets by several hundred metres, suggesting that these faults did not exploit pre-existing basement weaknesses. Our observations suggest that older basement fabrics may not always play a significant role in determining the geometry of later fault systems. Supplementary materials: Details of the time-depth relationships from wells that have been used to depth-convert interpretations (S1), a supplementary figure showing an uninterpreted version of the seismic profile presented in Fig. 2 (S2) and a throw v. distance plot for fault F1 at the structural levels of the basement reflection and intra-basement reflection 1 are available at www.geolsoc.org.uk/SUP18683 .

Description: The study of the foraminiferal fauna in the Ogmore section in south Wales produced a detailed late Chadian–early Arundian biostratigraphy and sequence stratigraphy with a higher resolution than in the Arundian stratotype in Hobbyhorse Bay. The earliest Visean (late Chadian) pedogenic horizon close to the Gully Oolite and Caswell Bay Mudstone boundary (MFZ9) corresponds to the mid-Avonian unconformity. The entry of primitive archaediscids of MFZ10 within the Caswell Bay Mudstone is followed by more advanced archaediscids of MFZ11 at the base of the High Tor Limestone. The mid-Avonian unconformity at the Chadian–Arundian boundary is not confined to the London–Brabant Massif, but is also present in central Europe, the East European Platform, the Urals, west Siberia and probably also in Kuzbass and North America. The global extent of the the mid-Avonian unconformity suggests that it is a consequence of early to mid-Visean glacioeustacy.

Description: The structure of the Neogene–Quaternary Ptolemais sedimentary basin exemplifies the importance of deformation partitioning in the kinematic history of basin formation. Structural analyses were carried out at outcrop from the metre to kilometre scale on basin marginal faults, and on structures reflecting deformation of the interior of the basin. Deformation is partitioned into three spatially separated, but kinematically linked domains. Two transtensional-dominated domains in the northern and in the southern parts are separated by a transpressional-dominated domain in the central part of the basin. Intense synsedimentary deformation of Pliocene–Quaternary deposits occurred in all three domains. Dominant structures that affected pre-Neogene lithologies and the basin-fill include (E)NE–(W)SW- and NW–SE-trending basin kilometre-scale marginal faults. We propose that the structures of the three domains were active simultaneously during progressive deformation reflecting an overall transtensional-dominated regime. The deformation is imposed by boundary conditions and is consistent with the Pliocene–Quaternary large-scale deformation in northern Greece that includes clockwise (dextral) rotations of crustal blocks and gravity-driven NNW–SSE extension. Strong partitioning of deformation produced contrasting structures, which do not reflect a sequence of events related to a regional stress fields that changed with time.

Description: A multidisciplinary study (U–Pb sensitive high-resolution ion microprobe geochronology, Hf and O isotopes in zircon, Sr and Nd isotopes in whole-rocks, as well as major and trace element geochemistry) has been carried out on granitoid samples from the area west of Valcheta, North Patagonian Massif, Argentina. These confirm the Cambrian age of the Tardugno Granodiorite (528 ± 4 Ma) and the Late Permian age of granites in the central part of the Yaminué complex (250 Ma). Together with petrological and structural information for the area, we consider a previously suggested idea that the Cambrian and Ordovician granites of northeastern Patagonia represent continuation of the Pampean and Famatinian orogenic belts of the Sierras Pampeanas, respectively. Our interpretation does not support the hypothesis that Patagonia was accreted in Late Palaeozoic times as a far-travelled terrane, originating in the Central Transantarctic Mountains, and the arguments for and against this idea are reviewed. A parautochthonous origin is preferred with no major ocean closure between the North Patagonian Massif and the Sierra de la Ventana fold belt. Supplementary material: U–Pb SHRIMP analytical data, geochemical analyses and sample global positioning system locations are available at www.geolsoc.org.uk/SUP18722 .

Description: An integrated stratigraphic study was conducted on the shallow water carbonate platforms of the Guadeloupe archipelago to refine the tectonic evolution of the Lesser Antilles forearc. The carbonate platforms are now dated to the Zanclean–Calabrian interval, and their demise occurred between 1.5 and 1.07 Ma. The precise chronostratigraphy allows dating of the main extensional tectonic events since the late Miocene. An initial episode occurred during the late Miocene, related to the reactivation of inherited N130°E-trending shear zones, and led to the emergence of most parts of the forearc. Subsequently, Zanclean to early Piacenzian carbonate platforms developed in association with a general subsidence of the forearc. During the late Piacenzan, a second extensional episode occurred. At this time La Désirade underwent major uplift and emergence whereas most of the forearc remained submerged. Prior to 1.07 Ma, a third north–south extensional episode occurred and led to the final demise of the carbonate platforms. Thus the forearc was characterized by general subsidence since the early Pliocene interrupted by three main extensional episodes and related differential uplifts. This suggests that the Lesser Antilles subduction is probably erosive north of latitude 15°N since c . 5 Ma, related to aseismic ridge subduction. Supplementary data: Planktonic foraminiferal assemblages, calcareous nannofossil taxa associations, 40 Ar/ 39 Ar geochronological data and palaeomagnetic data are available at www.geolsoc.org.uk/SUP18724 .

Description: The Triassic sedimentary succession in the Central North Sea has been investigated to establish a broader understanding of the Triassic Period, from the combined interpretation of seismic reflection data and well data. The Triassic succession has been subdivided into four seismic units, where unit boundaries are characterized by regional seismic amplitude anomalies, reflecting changes in gross sedimentary facies or rock properties. A successful correlation between sedimentary facies, interpreted within the well sections and distinct seismic reflection patterns, allowed a thorough mapping of the gross palaeoenvironment throughout the Triassic. The method presented of subdividing a continental sedimentary succession into seismic units should be applicable elsewhere in other basins. The main source area during the Triassic was Scandinavia to the north, and sediment transportation was mainly along north–south- and NE–SW-trending lineaments, which are at present located onshore southern Norway, and in the Åsta Graben and the Varnes Graben offshore. An uplifted Skagerrak Graben area acted as source area in the Early and early Middle Triassic, with sediment dispersal to the south and SW. High relief existed for a longer period in western Scandinavia than in eastern Scandinavia, which supports an asymmetric shape of the Scandinavian mountains during the Triassic. Accommodation space in the Early Triassic was mainly controlled by the relief inherited from a Late Carboniferous–Permian rift phase. Although thermally induced regional subsidence continued in the Middle and Late Triassic, creation of local accommodation space was mainly limited to halokinesis, including redistribution and withdrawal of salt from the subsurface. The Upper Triassic succession is eroded across the western and central parts of the study area, although the Upper Triassic unit is preserved in synforms adjacent to salt structures. In the western part of the study area, dry, playa conditions prevailed during the Early Triassic, although fluvial systems supplied long-transported sandy detritus southeastwards in the late Early Triassic. More sandy detritus was transported into the sedimentary basin in the Middle and Late Triassic, concurrently with a gradually wetter climate. Supplementary material: Uninterpreted seismic sections are available at www.geolsoc.org.uk/SUP18726 .

Description: Teide and Pico Viejo (TPV) are twin stratovolcanoes that form one of the largest alkaline volcanic complexes in the world. They began forming inside the caldera of Las Cañadas about 200 ka ago and are largely made up of an accumulation of mafic, intermediate and more recent felsic products that form lava flows. However, a significant number of Holocene pyroclastic deposits are also present. To quantify the explosive contribution to the construction of TPV, we re-examined its stratigraphy and identified several Holocene phonolitic explosive episodes ranging from Strombolian to sub-Plinian styles that are represented by fallout and pyroclastic density current deposits. Although some of the pumice deposits have been related to known sources, a few have not been linked to a specific vent. The use of field data as well as geochemical and mineralogical analysis helped to provide reliable criteria for robust correlations and to establish the relative stratigraphy of the deposits. The presence of these pyroclastic deposits in the recent history of the TPV complex suggests that these stratovolcanoes are entering a more explosive stage that represents a non-avoidable hazard for the island of Tenerife.

Description: Dykes feed laccoliths and sills; however, the link between feeder and intrusion is rarely observed. The felsic San Martino laccolith displays a clear feeder–intrusion link, allowing reconstruction of the influence of the size and location of feeder dykes on magma flow during formation of subhorizontal intrusions. This work uses anisotropy of magnetic susceptibility (AMS) combined with mineral shape-preferred orientations of sanidine megacrysts to examine magma flow pathways through feeders into a laccolith. Strong correlation between AMS and K-feldspar datasets indicates that alteration affecting the paramagnetic mineralogy did not influence AMS results. The well-established field relationships between feeder and laccolith provided a robust ‘geo-logical’ model for flow pathways that we have used as a framework to aid interpretation of AMS data. The position and size of the main feeder dyke helped to predict the flow paths in the overlying laccolith. Our results show that magma spread laterally from the feeding system and built the laccolith layers with propagating and inflating divergent flow where tabular particles became aligned perpendicular to the magma displacement direction. The lack of internal discontinuities indicates that the magma was injected as a single pulse or a series of quickly coalescing pulses. Supplementary material: AMS methods, AMS data and detailed fabric maps are available at www.geolsoc.org.uk/SUP18717 .

Description: New 40 Ar/ 39 Ar geochronological data from the Buchan and Barrovian metamorphic sequences on the NE coast of Scotland have been obtained from in vacuo step-heating experiments conducted on white mica extracted from seven samples. The results confirm the synchronous formation of the Barrovian and Buchan metamorphic sequences, with the 40 Ar/ 39 Ar apparent age spectra obtained for samples of andalusite grade and higher recording a range of ages between 470.4 ± 1.8 and 464.6 ± 1.3 Ma. These ages are close to the accepted age for peak metamorphism during the Grampian Orogeny, c. 470 Ma, whereas 40 Ar/ 39 Ar apparent age spectra of white mica from the lower grade cordierite zone near Banff preserve pre-Grampian detrital ages. In these spectra an age of c. 560 Ma is recorded. This indicates that a tectonothermal event occurred at c. 560 Ma and may provide further insight into the timing of sedimentation. These samples also preserve evidence of ages older than 750 Ma. Supplementary material: 40 Ar/ 39 Ar step-heating data tables for all samples, data from analyses of flux monitors, determination of correction factors and mass discrimination used for data reduction and 40 Ar/ 39 Ar step-heating spectra and inverse isochron plots from each sample are available at www.geolsoc.org.uk/SUP18723 .

Description: The Bunter Sandstone Formation (BSF) in the UK sector of the Southern North Sea is thought to have a significant potential for the injection and storage of anthropogenic CO 2 within periclines that lie above salt domes and pillows formed by halokinesis in underlying Zechstein strata. During the formation of the periclines, the BSF and its overlying top seals were subjected to extensional stresses and, in consequence, are commonly cut by seismically resolvable faults that present a risk to the containment of gas and buoyant fluids such as supercritical CO 2 . Although most of the closed structures in the BSF are saline water-bearing, eight gas fields (total gas initially-in-place 〉72 bcm (billion cubic metres)) have been discovered to date. The seismically resolved structure of these gas fields demonstrates that two different top seals, the Haisborough Group and the Speeton Clay, can seal gas columns of up to 128 and 104 m respectively, despite the presence of faults with small displacements above the field gas–water contacts. The observed gas columns are equivalent to CO 2 columns of up to around 100 m in height. Simple geomechanical modelling suggests that existing optimally orientated faults may dilate or be reactivated if the pore-fluid pressure increase as a result of CO 2 injection exceeds a gradient of about 13.4 MPa km –1 , potentially resulting in loss of storage integrity.

Description: Pore-lining chlorites are often associated with a low-resistivity contrast between corresponding reservoir units, making the identification and quantitation of hydrocarbon-bearing intervals difficult. In many low-resistivity situations, the traditional approach of using Archie’s equation to determine saturation from electrical resistivity fails, and modified Archie equations derived specifically for ‘shaly sands’ have been developed. In chlorite-bearing intervals, however, the effect of chlorite can be such that both Archie and the so-called shaly-sand models are inappropriate. Under these circumstances, calculating saturation from electrical resistivity can be circumvented by detailed analysis of the sedimentology and petrophysics, enabling the construction of a saturation height model based on core data. In this novel study we integrate a detailed core-based sedimentological facies scheme with wireline log data and petrophysical core data to demonstrate a clear link between chlorite occurrence, petrophysical characteristics and saturation height. Through this innovative approach, saturation is estimated without recourse to resistivity logs and improves hydrocarbon saturation estimates in chlorite-bearing reservoirs.

Description: Preliminary dynamic modelling, using TOUGH2/ECO2N, has been carried out to assess the suitability of a site in the UK North Sea for sequestering CO 2 . The potential storage site is a previously unused saline formation within the Permian Rotliegend sandstone. Data regarding the site are limited. Therefore, additional input parameters for the model have been taken from the literature and nearby analogues. The sensitivity of the model to a range of parameters has been tested. Results indicate that the site can sustain an injection rate of around 2.5 Mt a –1 of CO 2 for 20 years. The main control on pressure build-up in the model is the permeability of the unit directly beneath the Rotliegend in the location of the proposed storage site. The plume diameter is primarily controlled by the porosity and permeability of the site. A comparison between static, analytical and dynamic modelling highlights the advantages of dynamic modelling for a study such as this. Further data collection and modelling are required to improve predictions of pressure build-up and CO 2 migration. Despite uncertainties in the input data, the use of a full three-dimensional (3D) numerical simulation has been extremely useful for identifying and prioritizing factors that need further investigation.

Description: Natural gas hydrate (NGH) is a solid crystalline material composed of water and natural gas (primarily methane) that is stable under conditions of moderately high pressure and moderately low temperature found in permafrost and continental margin sediments. A NGH petroleum system is different in a number of important ways from conventional petroleum systems related to large concentrations of gas and petroleum. The critical elements of the NGH petroleum system are: (1) a gas hydrate stability zone (GHSZ) in which pressure and temperature lie within the field of hydrate stability, creating a thermodynamic trap of suitable thickness for NGH concentrations to form; (2) recent and modern gas flux into the GHSZ along migration pathways; and (3) suitable sediment host sands within the GHSZ. These elements have to be active now and in the recent geological past. Exploration in continental margin sediments includes basin analysis to identify source and host sediment likelihood and disposition, potential reservoir localization using existing seismic analysis tools for locating turbidite sands and estimating NGH saturation, and deposit characterization using drilling and logging. Drilling has validated first-order seismic analysis techniques for identifying and quantifying NGH using rock physics mechanical models.

Description: Understanding the controls on the size and shape of sandstone bodies deposited by fluvial systems is important in the reconstruction of ancient fluvial deposits and construction of quantitative reservoir models. Measurements and analyses of sandbodies from remotely sensed imagery have allowed quantification of width and length ratios of barforms in modern fluvial systems. For bank-attached bars the width:length ratios range between 0.12 and 0.47 (arithmetic mean: 0.25), for lateral bars between 0.19 and 0.42 (arithmetic mean: 0.30), for mid-channel bars between 0.09 and 0.49 (arithmetic mean: 0.28), and for point bars between 0.14 and 0.50 (arithmetic mean: 0.30). The majority of width:length ratios for all bar types range between 0.15 and 0.35. Examination of other parameters such as basin type, planform geometry, apparent stream width, river length, gradient over the investigated area, aggradational or degradational system, tectonic setting and climate do not significantly affect the width:length ratio. Therefore, the bar planform shape, the width:length ratio, can be considered to be scale invariant. The recognition that bar planform shape in fluvial systems is scale invariant will be useful in the construction of subsurface three-dimensional models of fluvial deposits with variable dimensions. Supplementary material: Data tables with information obtained for all of the rivers studied are available at http://www.geolsoc.org.uk/SUP18745 .

Description: Calculation of the total depositional volume of an ancient source-to-sink system, combined with estimates of the area of catchments acting as source regions using provenance methods, is used to evaluate average catchment erosion rates on a million year time scale. These rates are compared with values derived from thermochronological methods. Using the mid- to late Eocene (33.9–41.6 Ma) Escanilla palaeo-sediment routing system from the south–central Pyrenean orogenic wedge-top zone as an example, c . 3500 ± 300 km 3 of solid particulate sediment was derived from two catchments in the south–central Pyrenees over a 7.7 myr period, equivalent to a mean erosion rate of c . 0.15–0.18 mm a –1 . Average exhumation rates in contributing catchments over the same time interval are estimated at 0.2–0.3 mm a –1 based on apatite fission-track analysis of pebbles in proximal conglomerates, and 0.23–0.34 mm a –1 from fission-track analysis of detrital apatites sampling a wider range of grain size. Sediment supply progressively increased during the mid- to late Eocene time period, at least in part driven by catchment expansion deep into the Pyrenean Axial Zone at c . 39 Ma. The consistency of the rates of catchment-averaged erosion calculated from different methods builds confidence that source areas have been connected to depositional sinks correctly. Supplementary materials: A description of the provenance methods used to link sources and sinks of the Escanilla palaeo-sediment routing system, including the analysis of clast lithologies, palaeocurrents, heavy minerals and geochronology of detrital zircons, are available at http://www.geolsoc.org.uk/SUP18727 .

Description: The Cryogenian record of South Australia includes the type region of the Sturtian glaciation, the oldest of three pan-global icehouse intervals during the Neoproterozoic. Data are presented from previously little described sections at Holowilena Creek, Oladdie Creek and Hillpara Creek in the central and southern Flinders Ranges, where five facies associations are recognized. These are (1) diamictite and conglomerate, (2) interbedded heterolithic deposits, (3) hummocky cross-stratified sandstone, (4) lonestone-bearing siltstone, and (5) ferruginous siltstone and sandstone. The succession reveals significant lateral and vertical facies variation, which is linked to a complex inherited palaeotopography and distance from the sediment source. Repeated stratigraphic occurrences of striated clasts and abundant ice-rafted debris strongly support recurrent glacial influence on sedimentation. The intercalation of gravitationally reworked diamictites, dropstone-bearing siltstone and dropstone-free siltstone testifies to dynamic sedimentation within a periodically glacially influenced subaqueous environment. Sequence stratigraphic analysis identifies four glacial advance systems tracts, separated by three glacial retreat systems tracts, wherein hummocky cross-stratified sandstones attest to open water conditions. These findings support dynamic ice sheet behaviour in South Australia, and provide clear evidence for repeated intra-Sturtian ice sheet recession.

Description: The stable isotope composition of planktic and benthic foraminifera and the distribution of selected benthic foraminiferal species from a Messinian record of the lower Guadalquivir Basin, northeastern Atlantic Ocean, show that regional productivity changes were linked to glacioeustatic fluctuations. Glacial periods were characterized by poorly ventilated bottom waters as a result of weak Atlantic Meridional Overturning Circulation (AMOC), and by phases of high productivity related to intensified upwelling. In contrast, well-ventilated bottom waters owing to strong AMOC, the presence of degraded organic matter in the upper slope, and high input of degraded terrestrial organic matter derived from fluvial discharge to the outer shelf were recorded during interglacial periods. Before closure of the adjacent Guadalhorce Corridor at 6.18 Ma, which was the final active Betic Atlantic–Mediterranean gateway, the study area was alternately influenced by well-ventilated Mediterranean Outflow Water (MOW) and poorly ventilated Atlantic Upwelled Water (AUW). Following closure of the corridor, cessation of the MOW reduced the AMOC and promoted glacial conditions in the northern hemisphere, resulting in the establishment of local upwelling cells.

Description: In recent decades various interpretations have been proposed to explain the evolution of fissure-ridge-type travertine deposits. In this paper, we discuss the relationships between fissure-ridges and brittle structures affecting their substratum, through a detailed analysis of an inactive fissure-ridge (near Çukurbağ) located in the Pamukkale geothermal area (western Turkey). The Çukurbağ fissure-ridge can be taken as a model as it offers an opportunity to examine its internal structure on the walls of a Roman quarry; in addition, this ridge has been studied by several researchers who have discussed the processes promoting the fissure-ridge evolution. The Çukurbağ fissure-ridge is composed of irregularly alternating travertine laminated facies (bedded travertine) crosscut into rather large lithons by subvertical crystalline veins (banded travertine). The relationships between bedded and banded travertine indicate that the banded veins are diachronous and migrated through time, suggesting a progressive fault zone enlargement in the footwall. Such a fault zone was characterized by polycyclic activity, with normal to transtensional kinematics, and was active during the latest Quaternary. We demonstrate that formation of banded veins is coeval with bedded travertine deposition and strictly depends on fault activity, therefore highlighting the fundamental role of travertine fissure-ridges in reconstructing palaeotectonic activity in a region.

Description: The use of lightweight cemented clay has wide applications in infrastructure rehabilitation and in the construction of new facilities. Effects of water content, cement content, air content and fly ash (FA) on the unit weight and strength of lightweight cemented clay are presented and analysed. FA decreases the liquid limit and the plasticity index of the lightweight cemented clay. Consequently, it improves the unit weight, strength and workability of the lightweight cemented clay. For the same generalized stress state, w / w L (ratio of water content to the liquid limit), lightweight cemented clay with a higher replacement ratio has a higher strength for the same input of cement owing to a higher cement/clay-water ratio, C / w . The FA fixation point is a practical indicator to obtain a minimum FA replacement because it is simply obtained from an index test. The prediction of unit weight of the lightweight cemented clay for different water contents, air contents, FA replacement ratios and cement contents is performed and verified. From the critical analysis of test results, a mix design method to attain the target strength and unit weight is suggested. This method is useful from both engineering and economic viewpoints.

Description: We evaluate the hydrogeology of the area around the Soğuksu spring in the Aydıncık district, Mersin, Turkey, with a focus on the groundwater and aquifer systems. An increasing population and the expansion of agricultural land have resulted in increasing demand for water in the Aydıncık area. The Soğuksu spring, discharging from the Aydıncık aquifer, is the major source of water for Aydıncık and the surrounding area. To establish a sustainable water management plan for the region it is essential to determine the characteristics of the hydrogeological structure of the area. Water samples taken from the Soğuksu spring and other small springs in the Aydıncık area were analysed and the spring recession curve, hydrochemistry, stable isotopes ( 18 O, 2 H), and tritium isotopes ( 3 H) were used to characterize the aquifer. The master recession coefficient obtained from analysis of the spring discharge data for 1999–2012 indicates one exponential term. Analysis of the groundwater composition identified two groups, the Ca–HCO 3 and Ca–Mg–HCO 3 groups, based on the major cation and major anion in the sampled water, as expected from karstic carbonate aquifers. The stable isotopes demonstrate the predominance of low-elevation precipitation. High tritium concentrations between 2.32 and 4.25 TU suggest recent recharge of groundwater from rainfall.

Description: Stabilization/solidification has been found to be a relatively sustainable and economical method for managing risks associated with contaminated land. The technology has been employed extensively over the last three decades, particularly for the containment of heavy metals. However, because contaminants are not removed, there is a need to validate the long-term effectiveness of the technique. This requires knowledge of the containment mechanisms, the kinetics of contaminant release (equilibrium and disequilibrium conditions), and identification of the reactive surfaces that induce containment. In the present study, cement-stabilized zinc-contaminated kaolin clay containing 1% humic acid was tested to evaluate chemical performance in the long term. Time-dependent (chemical kinetics) and pH-dependent (equilibrium conditions) and equilibrium porewater leaching were evaluated, using LeachXS and geochemical speciation modelling using ORCHESTRA (embedded in LeachXS). Results showed that zinc was effectively contained within the waste form matrix under the prevailing chemical conditions, with immobilization increasing with hydration. Presence of humic acid increased the availability of zinc at an early stage, but this decreased at later stages and was comparable with results for organic-free matrices.

Description: Hydrogeology has traditionally been regarded as the province of the water industry, but it is increasingly finding novel applications in the energy sector. Hydrogeology has a longstanding role in geothermal energy exploration and management. Although aquifer management methods can be directly applied to most high-enthalpy geothermal reservoirs, hydrogeochemical inference techniques differ somewhat owing to peculiarities of high-temperature processes. Hydrogeological involvement in the development of ground-coupled heating and cooling systems using heat pumps has led to the emergence of the sub-discipline now known as thermogeology. The patterns of groundwater flow and heat transport are closely analogous and can thus be analysed using very similar techniques. Without resort to heat pumps, groundwater is increasingly being pumped to provide cooling for large buildings; the renewability of such systems relies on accurate prediction and management of thermal breakthrough from reinjection to production boreholes. Hydrogeological analysis can contribute to quantification of accidental carbon emissions arising from disturbance of groundwater-fed peatland ecosystems during wind farm construction. Beyond renewables, key applications of hydrogeology are to be found in the nuclear sector, and in the sunrise industries of unconventional gas and carbon capture and storage, with high temperatures attained during underground coal gasification requiring geothermal technology transfer.

Description: A stagnation point is any point in the aquifer where the fluid velocity is equal to zero. Stagnation points can occur where the flow encounters impermeable surfaces or where the potentiometric surface is nearly horizontal. The presence of stagnation points is useful to locate groundwater bodies characterized by a very long renewal time.

Description: Understanding the 3D geometry and evolution of extension-related folds is important because they may document the geometry and evolution of the associated faults, influence sediment routing and accommodation development, and may represent targets for hydrocarbon exploration or CO 2 storage. Previous work on extension-related folds has largely been restricted to a 2D plane of observation; in this study we use 3D seismic reflection data from the Gulf of Suez, Egypt to determine the 3D geometry and evolution of fault-parallel folds during dip linkage of a vertically segmented extensional fault array that is locally decoupled across a salt-bearing interval. The 3D geometry of individual faults in the array and adjacent hanging-wall folds varies along strike; rollover structures occur above listric faults, whereas fault-bend folds occur above faults that have a ramp–flat–ramp geometry. Quantitative analysis of fault–fold attributes (e.g. fold amplitude) and the growth history of the fault array indicate that fault shape is controlled by the style of dip linkage, which in turn is controlled by the lateral separation of sub- and supra-salt segments prior to linkage. Small lateral separation yields a relatively subtle change in the overall convexity of the listric fault, whereas larger lateral separation results in a ramp–flat–ramp fault geometry, with the layer-parallel detachment lying within the salt. This study provides a link between fault spacing, style of dip linkage, final fault shape and, ultimately, the style of hanging-wall folding in mechanically layered stratigraphy. Our study indicates that 3D seismic reflection data have the ability to provide us with new 3D insights into the variability of, and controls on, the geometry and evolution of fault-related folds.

Description: Palaeozoic–Mesozoic brittle normal faults onshore along the SW Barents Sea passive margin off northern Norway give valuable insight into fault and fluid flow processes from the lower brittle crust. Microstructural evidence suggests that Late Permian–Early Triassic faulting took place during multiple phases, with initial fault movement at minimum P–T conditions of c . 300 °C and c . 240 MPa ( c . 10 km depth), followed by later fault movement at minimum P–T conditions of c . 275 °C and c . 220 MPa ( c . 8.5 km depth). The study shows that pore pressures locally reached lithostatic levels (240 MPa) during faulting and that faulting came to a halt during early (deep) stages of rifting along the margin. Fault permeability has been controlled by healing and precipitation processes through time, which have sealed off the core zone and eventually the damage zones after faulting. A minimum average exhumation rate of c . 40 m Ma –1 since the Late Permian is estimated. It implies that the debated Late Cenozoic uplift of the margin may be explained by increased erosion rates in the coastal regions owing to climate detoriation, which caused subsequent isostatic recalibration and uplift of the marginal crust. The studied faults may be used as analogues of basement-involved fault complexes offshore, revealing details about the offshore nature of faulting, including past and present basement and fault zone permeability.

Description: There is a strong genetic relationship between the petrogenesis of I-type granitoids and the evolution of continental crust in orogenic belts. This study of I-type granitoids in the East Kunlun orogen, Northern Tibetan Plateau, shows that reworking of old continental lithosphere is an important key to this genetic relationship. The East Kunlun has numerous Triassic granitic plutons that are related to subduction of the Palaeo-Tethyan ocean and terrane collision in the early Mesozoic. U–Pb analysis of zircons from these Triassic granitoids indicates that the granitic magmatism lasted from 249 to 223 Ma. Based on elemental and isotopic compositions and their petrogenesis, the magmatism can be divided into three groups. (1) Group 1 consists of quartz diorites and granodiorites (241–249 Ma), which are metaluminous high-K calc-alkaline I-type granitoids and exhibit typical subduction-related chemical characteristics. They were derived from lower crust mainly composed of Precambrian metabasaltic basement rocks with different degrees of involvement of mantle material. (2) Group 2 consists of granitic porphyries and syenogranites (231–238 Ma), which are high Rb/Sr, metaluminous to weakly peraluminous high-K alkali-calcic I-type granitoids, showing characteristics of typical pure crustal-derived granitoids. They were derived from partial melting of a Mesoproterozoic metagreywacke source in the lower crust. (3) Group 3 consists of porphyry granodiorites ( c . 223 Ma), which are metaluminous high-K calc-alkaline I-type granitoids and exhibit the typical geochemical characteristics of adakites (e.g. high La/Yb and Sr/Y ratios and low Y and Yb contents). Their high K 2 O and low Mg# with evolved Sr–Nd–Hf isotopic compositions indicate that they were most probably derived from thickened mafic lower continental crust, which underwent partial melting induced by underplated hot mafic magma. Combining the present work with previous studies, we propose that the subduction of the Palaeo-Tethyan ocean lasted from 278 to 241 Ma, and the collision between the Bayan Har terrane and the East Kunlun occurred at 231–238 Ma, whereas the group 3 granitoids most probably formed in a post-collisional setting. Overall, all the studied I-type granitoids were derived from partial melting of old continental lower crust with minor addition of lithospheric mantle material; thus reworking of old continental lithosphere is an important mechanism for the evolution of orogenic crust. Supplementary materials: Analytical methods, zircon U–Pb data, geochemical data, and Sr–Nd–Hf isotope data for the granitoids are available at www.geolsoc.org.uk/SUP18758 .

Description: We present here a low-temperature thermochronological study that combines the apatite fission-track and (U + Th)/He dating methods with a pseudo-vertical sampling approach to generate continuous and well-constrained temperature–time histories from the onshore Irish Atlantic margin. The apatite fission-track and (U + Th)/He ages range from the Late Jurassic to Early Cretaceous and the mean track lengths are relatively short. Thermal histories derived from inverse modelling show that following post-orogenic exhumation the sample profiles cooled to c . 75 °C. A rapid cooling event to surface temperatures occurred during the Late Jurassic to Early Cretaceous and was diachronous from north to south. It was most probably caused by c . 2.5 km of rift-shoulder related exhumation and can be temporally linked to the main stage of Mesozoic rifting in the offshore basins. A slow phase of reheating during the Late Cretaceous and Early Cenozoic is attributed to the deposition of a thick sedimentary sequence that resulted in c . 1.5 km of burial. Our data imply a final pulse of exhumation in Neogene times, probably related to compression of the margin. However, it is possible that an Early Cenozoic cooling event, compatible with our data but not seen in our inverse models, accounts for part of the Cenozoic exhumation. Supplementary material: Details on the apatite fission-track and (U + Th)/He methods are available at www.geolsoc.org.uk/SUP18765 .

Description: A large submarine slope failure, the Baiyun Slide Complex, has been discovered in the northern South China Sea. We describe the slide complex morphology, the seismic character of its structural elements and the slide evolution based on high-quality seismic reflection and multi-beam bathymetry data. The Baiyun Slide Complex has three major slide scars that show differences in headwall and sidewall geometry, the nature of the basal shear surfaces and the internal architecture of the deposits. From these observations, we propose a four-phase emplacement model. An extrapolation of the post-slide drape thickness (60 m) gives a rough age estimate for the mass transport events of 0.3 Ma. Pore pressure models for the unfailed continental slope in the vicinity of the Baiyun Slide are based on porosity measurements at nearby Ocean Drilling Program Site 1146. They show that excess pore pressure in slope sediments is anomalously high at a depth around 93 m, most probably as a consequence of a dramatic increase in sedimentation rates over the past 1.8 Ma. This excess pore pressure is proposed to be the major preconditioning factor for the slide initiation, possibly aided by volcano-tectonic activity and gas hydrate dissociation. The unfailed slope is stable under static conditions. However, a near-field earthquake of Mw 5 would suffice to induce a slope instability at c . 93 m depth.

Description: The Wudongde dam is located in the mountainous region of southwestern China. Debris flows form a serious threat to the safety of this site and appropriate hazard assessments need to be carried out. However, the results of such assessments may be erroneous, especially when certain influencing factors are not properly considered. In this study, a stepwise discriminant analysis is used to investigate which factors influence debris-flow occurrence. A total of 27 debris flows, identified through field investigation, are analysed and this resulted in the selection of 17 influence factors. By employing a stepwise discriminant analysis it is possible to reduce these to just five major influencing factors, thus simplifying the calculation of debris-flow hazard assessment. Extension theory has been used to further identify the role of the influencing factors in debris-flow hazard assessment. Thus, reasonable and objective results of hazard degree assessment are expected. Once the criteria for debris-flow hazard assessment are established, the hazard degree of each debris flow is determined. Of the 27 debris flows analysed in this study, four are categorized as ‘extremely hazardous’, 10 as ‘very hazardous’, 10 as ‘moderately hazardous’, and three as ‘slightly hazardous’. The results are consistent with current expert knowledge of these debris flows, thereby providing an indication that the methods used in this study adequately replicate the expert assessments.

Description: Controls on the basin-scale distribution of hydraulic conductivity of superficial deposits are assessed in the context of hydrological setting and basin evolution and are investigated using a case study from the Thames Basin, UK. A conceptual model of superficial deposits across the Thames Basin is used to define six lithostratigraphic classes of superficial deposits: pre-Anglian Clay-with-Flint deposits; pre-Anglian River Terrace Deposits associated with the ancestral River Thames and its tributaries; Tills formed during the Anglian glaciations; glacio-fluvial sand and gravel deposits formed during the Anglian; post-Anglian River Terrace Deposits associated with the modern-day River Thames and tributaries; post-Anglian alluvium associated with the modern-day River Thames and tributaries. Hydraulic conductivity of the superficial deposits has been estimated from grain-size distribution data, originally collected for mineral resource assessments, using the Kozeny–Carman method. Based on 6411 samples from 1416 boreholes, estimated hydraulic conductivity ranges from 0.2 to 5942 m day –1 , median and mean hydraulic conductivities are 1.67 and 26.72 m day –1 respectively, and the overall distribution of hydraulic conductivity values has a strong positive skew An apparent reduction in mean hydraulic conductivity with increasing age of the deposit is observed, particularly for the River Terrace Deposits. A reduction in maximum hydraulic conductivity at depths 〉10 m is also observed and the relationship between hydraulic conductivity and depth is controlled by the type of superficial deposit. At the catchment to basin scale, variation in hydraulic conductivity with depth may be explained with reference to both the deposit types and the age of the deposits. Where hydraulic conductivity is found to be intimately linked to the Quaternary evolution of the basin, through contrasts in age and deposit type, permeability variations at the basin scale may be constrained by applying a suitably refined conceptual model of the superficial deposits.

Description: Large suffusion and cover-collapse sinkholes, of up to 100 m in diameter, developed in the Lar valley in Iran. The sinkholes formed through overburden several hundred metres thick comprising coarse- and fine-grained deposits. The formation mechanism for these large sinkholes was studied based on the topography of the bedrock and on deep borehole log data. It could be determined that the large cover-collapse sinkholes are located above permeable bedrock berms and that they formed through a layer of fine-grained, cohesive soil that was both underlain and overlain by coarse-grained soil layers. The data analysis showed that suffusion from the coarse-grained layer at the bedrock and subsequent erosion of these particles through permeable zones in the bedrock to the karst channels caused settlement of these coarse-grained layers and the formation of open caverns above them, at the interface with the fine-grained layer. With continuing erosion, the caverns widened until the limit equilibrium of the fine-grained layer was reached and then collapsed to form a depression with a horizontal bottom surface, termed a cover-collapse sinkhole. An analytical model was developed for this mechanism, considering cohesive and non-cohesive soil layers. This analytical model confirmed that, for the given composition of the overburden, cover-collapse sinkholes of 80–100 m in diameter can be expected. The paper also analysed the formation mechanism of the suffusion sinkholes and it was shown that their formation took place through coarse-grained, non-cohesive formations, in this case alluvium and slope talus. Finally, it was analysed whether the formation of new cover-collapse and suffusion sinkholes after the rehabilitation of the reservoir leakage is likely.

Description: In this paper we describe an improved sample-preparation technique for applying confocal laser scanning microscopy to image the void space of porous geological media, particularly various kinds of carbonate rocks with significant microporosity. We have improved the existing sample-preparation technique for confocal imaging by introducing a positive-pressure application step. This additional step helps to force the fluorescent-doped epoxy mixture inside the submicron pores (the microporosity) which make up a significant fraction of the total porosity of the carbonate rocks being characterized using confocal laser scanning microscopy. We also provide additional technical details and discuss practical aspects important to consider when imaging carbonate rock samples using this technique.

Description: Analytical well-test solutions are mainly derived for simplified and idealized reservoir models and therefore cannot always honour the true complexity of real reservoir heterogeneities. Pressure transients in the reservoir average out heterogeneities, and therefore some interpretations may not be relevant and could be misleading. Geological well testing refers to the numerical simulation of transient tests by setting up detailed geological models, within which different scales of heterogeneity are present. The concept of geological well testing described in this paper assists in selecting from multiple equi-probable static models. This approach is used to understand which heterogeneities can influence the pressure transients. In this paper, a low-energy multi-facies fluvial reservoir is studied, for which data from a well test of exceptionally long duration are available. The pervasive low reservoir quality facies and restricted macro cross-flow between the reservoir layers give rise to an effective commingled system of flow into the wellbore (i.e. zero or very low vertical cross-flow between the reservoir units). In our model, facies transitions produce lateral cross-flow transients that result in a ‘double-ramp-effect’ signature in the test response. A sophisticated multi-point statistical (MPS) facies modelling approach is utilized to simulate complex geological heterogeneities and to represent facies spatial connectivity within a set of generated static models. The geological well-test model responses to a real well-testing cycle are then evaluated using dynamic simulation. The pressure match between simulated and recorded data is improved by generating multiple facies and petrophysical realizations, and by applying an engineering-based hybridization algorithm to combine different models that match particular portions of the real well-test response. In this example, the reservoir dynamics are controlled by subtle interaction between high-permeability channels and low-permeability floodplain deposits. Effective integration of geology and dynamic data using modern methods can lead to better reservoir characterization and modelling of such complex reservoir systems.

Description: Many diverse challenges – political, economic, legal and technical – face the continued development and deployment of geological storage of anthropogenic CO 2 . Among the technical challenges will be the satisfactory proof of storage site security and efficacy. Evidence from many past geotechnical projects has shown the investigations and analyses that are required to demonstrate safe and satisfactory performance will be site specific. This will hold for the geomechanical assessment of saline aquifer storage site integrity where, compared to depleted hydrocarbon fields, there will be no previous pressure response history or rock property characterization data available. The work presented was carried out as part of a project investigating the improvement in levels of confidence in all aspects of saline aquifer site selection and characterization that could be expected with increasing data availability and in-depth analysis. Attention focused on the geomechanical modelling and the rock mechanics data used to populate models of two storage sites in geological settings analogous to those where CO 2 storage might be considered. Coupled geomechanical models were developed from reservoir simulation models initially incorporating generic rock mechanical properties and then laboratory-derived site-specific properties. The models were run in various configurations to investigate the effect of changing the rock mechanical properties on the geomechanical response of the storage systems. Modelling results showed that the pressure response at one site due to low injectivity caused significant potential for fault reactivation. Increasing the number of injection wells, thereby reducing the individual rates needed to deliver the target capacity, reduced the injection pressures and ameliorated, but did not eliminate, this adverse response.

Description: When petroleum-based vehicle fuels are released to the subsurface environment, only a small number of chemical constituents typically account for a large majority of human health risks associated with potential exposures to affected soil, soil gas or groundwater. In other words, the risk ‘footprint’ of most fuel constituents is most often contained within the footprint of key risk-driving constituents of potential concern (COPCs). Therefore, assessment and management of an appropriate set of COPCs can support robust management of all potential risks and eliminate unnecessary chemical analyses and evaluation of constituents that rarely (or never) give rise to unacceptable human health risks. This paper presents an approach for identifying COPCs for petroleum fuel releases, based on internationally adopted human health risk assessment practices and available information on fuel composition and chemical toxicity. COPCs are identified as all constituents that could potentially give rise to unacceptable human health risks, based on theoretical upper-bound exposure estimates for exposure pathways. COPC lists are presented to guide the investigation and evaluation of risks at sites where releases of petrol, diesel, and kerosene/jet fuel have occurred. Such lists are generically applicable and may underpin site-specific evaluation of environmental conditions and associated risks. Supplementary materials: Risk equations, input definitions and values, the physical–chemical properties of the fuel components, human health criteria, complete results and rankings of the calculated risk values are available at http://www.geolsoc.org.uk/SUP18789 .

Description: The UK Government expects that, by 2020, 12% of the UK’s heat demand will come from renewable sources, and is providing incentives to help achieve this. Open-loop ground source heat pumps (GSHP) could make a substantial contribution. A web-based screening tool has been developed that highlights areas where conditions may be suitable for installing commercial-scale (〉100 kW heating or cooling demand) open-loop GSHP systems in England and Wales. In addition to the basic requirements for open-loop GSHP (i.e. the availability of a sufficiently productive aquifer within a reasonable depth beneath the surface) the tool provides information on existing abstractions, water chemistry and the location of protected areas. Validation and tool application show that it produces reliable results and provides an effective method for the initial assessment of subsurface conditions and suitability for GSHP installations. Hence, the tool can help to reduce uncertainty at the early planning stage, and also to promote GSHP technology to a variety of audiences.

Description: The furore that has arisen in the UK over induced microseismicity from ‘fracking’ for shale gas development, which has resulted in ground vibrations strong enough to be felt, requires the urgent development of an appropriate regulatory framework. We suggest that the existing regulatory limits applicable to quarry blasting (i.e. peak ground velocities (PGV) in the seismic wavefield incident on any residential property of 10 mm s –1 during the working day, 2 mm s –1 at night, and 4.5 mm s –1 at other times) can be readily applied to cover such induced seismicity. Levels of vibration of this order do not constitute a hazard: they are similar in magnitude to the ‘nuisance’ vibrations that may be caused by activities such as walking on wooden floors, or by large vehicles passing on a road outside a building. Using a simple technique based on analysis of the spectra of seismic S-waves, we show that this proposed daytime regulatory limit for PGV is likely to be satisfied directly above the source of a magnitude 3 induced earthquake at a depth of 2.5 km, and illustrate how the proposed limits scale in terms of magnitudes of induced earthquakes at other distances. Previous experience indicates that the length of the fracture networks that are produced by ‘fracking’ cannot exceed 600 m; the development of a fracture network of this size in one single rupture would correspond to an induced earthquake c . magnitude 3.6. Events of that magnitude would result in PGV above our proposed regulatory limit and might be sufficient to cause minor damage to property, such as cracked plaster; we propose that any such rare occurrences could readily be covered by a system of compensation similar to that used over many decades for damage caused by coal mining. However, it is highly unlikely that future ‘fracking’ in the UK would cause even this minor damage, because the amount of ‘force’ applied in ‘fracking’ tends to be strictly limited by operators: this is because there is an inherent disincentive to fracture sterile overburden, especially where this may contain groundwater that could flood-out the underlying gas-producing zones just developed. For the same reason, seismic monitoring of ‘fracking’ is routine; the data that it generates could be used directly to police compliance with any regulatory framework. Although inspired by UK conditions and debates, our proposals might also be useful for other regulatory jurisdictions.

Description: Core samples from seven wells in Lower Cretaceous limestones of the Upper Shu’aiba Member were characterized by conventional core analyses, petrography, bulk chemistry and mercury-injection capillary pressure data to define reservoir rock types (RRT). In the main oilfield studied, lithofacies are arranged in three main belts corresponding to ramp crest, upper slope and lower slope, with bioclast content and size decreasing down depositional dip. Rock typing is based on the observation of distinct, but overlapping, porosity–permeability transforms for each lithofacies, although most samples plot in or below the class 3 field of Lucia, reflecting the presence of abundant lime-mud matrix. Because of the wide range of porosity in each of the main lithofacies, an arbitrary division at 20% porosity is used in combination with lithofacies to define RRT with both three-dimensional (3D) geological significance and distinct ranges of permeability and capillary pressure characteristics. The use of total porosity as a rock-typing criterion is based on the interpretation that porosity is controlled on the reservoir scale by the depositional clay content of the local stratigraphic environment. The seaward and uppermost parts of the clinoforms a have low clay, and, thus, highest porosity. Because both lithofacies and porosity are linked to the sedimentological and stratigraphic organization of the Upper Shu’aiba clinoforms, the RRT can potentially be implemented in a reservoir model for assigning distinct ranges of petrophysical properties to the different architectural elements comprising each clinoform. Two additional grain-dominated RRT have also been defined in a single core that was available from a second oilfield.

Description: One of the main objectives of nanotechnology in the oil industry is to identify applications that could bring significant benefits to enhanced oil recovery. Therefore, it has attracted the attention of many researchers over the last decade. This paper experimentally investigates the efficiency of surface-modified silica nanoparticles in enhanced oil recovery. These nanoparticles improve oil recovery through two main mechanisms: oil–water interfacial tension reduction; and wettability alteration. Various concentrations of nanofluid were made, and their effect on wettability and interfacial tension were investigated to determine the optimum concentration for injection into core samples. The results indicate that a concentration of 4 g l –1 is the optimum concentration. Moreover, this paper reports the nanofluids’ potential in enhanced oil recovery of water-wet core plugs. The results of coreflood experiments reveal that oil recovery increases by 26.2% and total oil recovery considerably improves after the injection of nanofluid. In addition, filtration of the nanofluid before injection into the core was very effective in reducing the risk of possible permeability damage that occurred due to the deposition of large nanoparticle aggregates onto the rock surface.

Description: The wireline gamma-ray log is sensitive to open-hole conditions and, in particular, the diameter. This means that the log can jump at casing points. Although environmental corrections exist, they can fail at these points. We present a Bayesian method for deriving a new quantity – the shifted gamma–ray index – that takes these shifts into account by fitting a piecewise linear function to open-hole data in a depth window around the casing point. Because it is Bayesian, the method enables us to assess our uncertainty about its performance. This method requires very little knowledge of the borehole or drilling conditions but relies on the assumption that the lithology is consistent. Investigating the other wireline logs enables us to assess whether this assumption is valid. We demonstrate our method using well data from offshore mid-Norway.

Description: It is important to compare different methods and apply combined models for landslide susceptibility zonation on a regional scale for land-use planning and hazard mitigation. The purpose of this study is attempt to obtain an optimal landslide susceptibility zonation in a severely landslide affected region where the available data are very limited. Six single models (analytical hierarchy process (AHP), logistic regression (LR), fuzzy logic (FL), weight of evidence integrated logistic regression (WL), artificial neural network (ANN) and support vector machine (SVM)), were applied to obtain the single landslide susceptibility zonations along the middle reaches of the Bailong River from Zhouqu to Wudu, southern Gansu, China, then these single models were compared, after which the three single models that performed better (LR, ANN and SVM) were selected to prepare the combined zonations. Six conditional independent environmental factors were selected as the explanatory variables that contribute to landslide occurrence (elevation, slope, aspect, distance from fault, lithology and settlement density). The mapped landslides in this region were randomly partitioned into two sets: 80% of the landslides were used for the model training and the remaining 20% were used for validation of the models. Receiver operating characteristic and cost curves were plotted as means of evaluating the quality of the susceptibility zonations for the single and combined models. Results show that the single LR, ANN and SVM are models with superior prediction performance and are more suitable for constructing the combined models in this study. Compared with single models, the combined models provided an improved prediction capability and reduced uncertainties.

Description: This paper reports on the application of radar satellite data and Persistent Scatterer Interferometry (PS-InSAR) techniques for the detection of ground deformation in the semi-arid loess region of Lanzhou, northwestern China. Compared with Synthetic Aperture Radar Interferometry (InSAR), PS-InSAR overcomes the problems of temporal and geometric de-correlation and atmospheric heterogeneities by identifying persistent radar targets (PS) in a series of interferograms. The SPINUA algorithm was used to process 40 ENVISAT ASAR images for the study period 2003–2010. The analysis resulted in the identification of over 140000 PS in the greater Lanzhou area covering some 300 km 2 . The spatial distribution of moving radar targets was checked during a field campaign and highlights the range of ground instability problems that the Lanzhou area faces as urban expansion continues to accelerate. The PS-InSAR application detected ground deformations with rates up to 10 mm a –1 ; it resulted in the detection of previously unknown unstable slopes and two areas of subsidence.

Description: Catchment management is favoured by the Water Framework Directive as a solution to the problem of rising nitrate levels in groundwater. The directive requires that member countries achieve a good, or improving, status in all water bodies by 2015. Currently, Cambridge Water relies on treatment or blending to reduce end-of-pipe nitrate concentrations to below the drinking water standard. The effectiveness of catchment management measures at 21 boreholes in Cambridgeshire was assessed with a combination of models, representing groundwater and soil zone processes. These sources are in predominantly arable catchments; they abstract from the Chalk aquifer, which is covered by Glacial Till in the south and east. Only seven sources showed a response to the catchment management scenarios within 40 years when compared with the current practice scenario. However, nitrate concentrations were not reduced at any sources by 2015 with the simulated catchment management measures. The seven sources that are most responsive to changes in land use or land management are those already affected by high nitrate levels. Catchment management may need to be used in conjunction with treatment and/or blending in the short to medium term so that Cambridge Water can continue to provide compliant drinking water to customers.

Description: We test the integration of ground-penetrating radar (GPR) borehole investigation and electromagnetic flowmeter surveys to characterize fissured or complex aquifers. Borehole GPR investigation allows assessment of the lateral continuity of the porous and permeable zones between closely spaced boreholes, whereas flowmeter tests are adopted to identify the inflow–outflow zones in the boreholes. We apply the coupled approach in a portion (between 10 and 20 m below ground surface) of a complex aquifer hosted in a calcareous–gypsiferous formation. The hydro-geophysical characterization was aimed to detect the most conductive levels and to estimate the hydrodynamic properties of the aquifer. The integration of single-hole flowmeters and GPR measurements accurately distinguished different productive levels of high porosity and permeability in the aquifer. Two aquifer systems characterized by a complex geometry of fissures and permeable layers have been recognized, establishing the role of the drilled boreholes in the short-circuiting of the two systems. Interpretation of the GPR survey in cross-hole configuration gave values of total porosity of the order of 0.35 and 0.5 in the two more productive levels, which were detected by the flowmeter investigation.

Description: Hydrocarbon leakage is a major exploration challenge in the western Hammerfest Basin. Most exploration failures in the area have been attributed to leakage; hydrocarbon-bearing traps are rarely filled to their structural capacity, and almost all traps have hydrocarbon shows down to their structural spillpoint or below. We have investigated to what extent the hydrocarbon column heights can be explained by vertical leakage along faults or at fault intersections. For the fields that we evaluated we observe that: (a) all dry structures have fault intersections at top reservoir level up dip of the well position: (b) the only structure where no faults intersect at top reservoir level is the only structure that is clearly filled to structural spillpoint; and (c) all fluid contacts in underfilled structures broadly coincide with the position of intersecting faults. The underfilled structures have less than two fault intersections up dip and above the gas-bearing reservoir. We suggest that vertical leakage at fault intersections has exerted a main control on the position of the gas–water contacts in the western Hammerfest Basin, and therefore that hydrocarbon column-height predictions can be improved by addressing the positions of such intersections at the top reservoir surface.

Description: Future geological CO 2 sequestration in the Gippsland Basin is contingent upon an effective regional top seal; potentially provided by the late Oligocene–early Miocene Lakes Entrance Formation. This study integrates various top-seal assessment methodologies into a workflow to estimate the efficiency of the Lakes Entrance Formation as a top seal. Factors related to, for example, top-seal lithology, shale volume, carbonate content and fracture density, and factors relating to the faults that cut the top seal, fault-zone shale content, strain, slip-tendency, etc., are compared to hydrocarbon leakage and seepage indicators reported in the study area. The factors that best correlate with reported leakage indicators are combined to map the spatial risk variation. While the study indicated that the ultimate control on top-seal efficiency is the formation’s membrane seal capacity; it also highlighted the spatial correlation between leakage indicators and some fault-related factors, suggesting that faults are key to top-seal bypass in much of the Gippsland Basin. Fault-zone shale content proved the dominant fault-related factor; as such, it can be concluded in the Gippsland Basin, at least, that a fault-zone shale content of less than 0.3 is the dominant factor with regard to faults enabling fluids to bypass top seals.

Description: The initialization of a reservoir simulator calls for the populating of a three-dimensional dynamic grid-cell model using subsurface data and interrelational algorithms that have been synthesized to be fit for purpose. These prerequisites are rarely fully satisfied in practice. This paper sets out to strengthen initialization through four key thrusts, all of which seek to optimize the bridgehead between reservoir geoscience and reservoir engineering, and thereby maximize value from reservoir simulation. The first addresses representative data acquisition, which includes the key-well concept as a framework for the cost-effective incorporation of free-fluid porosity and permeability within an initialization database. The second concerns the preparation of these data and their products for populating the static and dynamic models. Important elements are dynamically conditioned net-reservoir cut-offs, recognition of primary flow units, and establishing interpretative algorithms at the simulator grid-cell scale for application over net-reservoir zones. The third thrust is directed at the internal consistency of capillary character, relative permeability properties and petrophysically-derived hydrocarbon saturations over net reservoir. This exercise is central to the simulation function and it is an integral component of hydraulic data partitioning. The fourth concerns the handling of formation heterogeneity and anisotropy, especially from the standpoint of directional parametric averaging and interpretative algorithms. These matters have been synthesized into a workflow for optimizing the initialization of reservoir simulators. In so doing, a further important consideration is the selection of the appropriate procedures that are available within and specific to different software packages. It is the authors’ experience that implementation of these thrusts has demonstrably enhanced the authentication of reservoir simulators through more readily attainable history matches with less required tuning. This outcome is attributed to a more systematic initialization process with a lower risk of artefacts. Of course, these benefits feed through to more assured estimates of ultimate recovery and, thence, hydrocarbon reserves.

Description: The Fjerritslev Formation in the Norwegian–Danish Basin forms the main seal to Upper Triassic–Lower Jurassic sandstone reservoirs. In order to estimate the sealing potential and rock properties, samples from the deep wells Vedsted-1 in Jylland, and Stenlille-2 and Stenlille-5 on Sjælland, were studied and compared to samples from Skjold Flank-1in the Central North Sea. Mineralogical analyses based on X-ray diffractometry (XRD) show that onshore shales from the Norwegian–Danish Basin are siltier than offshore shales from the Central Graben. Illite and kaolinite dominate the clay fraction. Porosity measurements obtained using helium porosimetry–mercury immersion (HPMI), mercury injection capillary pressure (MICP) and nuclear magnetic resonance (NMR) techniques on the shale samples show that MICP porosity is 6–10% lower than HPMI or NMR porosity. Compressibility, from uniaxial loading, and elastic wave velocities were measured simultaneously on saturated samples under drained conditions at room temperature. Uniaxial loading tests indicate that shale is significantly stiffer in situ than is normally assumed in geotechnical modelling. Permeability can be predicted from elastic moduli, and from combined MICP and NMR data. The permeability predicted from Brunauer–Emmett–Teller (BET)-specific surface-area measurements using Kozeny’s formulation for these shales, being rich in silt and kaolinite, falls in the same order of magnitude as permeability measured from constant rate of strain (CRS) experiments but is two–three orders of magnitude higher than the permeability predicted from the 1998 model of Yang & Aplin, which is based on clay fraction and average pore radius. When interpreting CRS data, Biot’s coefficient has a significant and systematic influence on the resulting permeability of deeply buried shale.

Description: This study examines the four-dimensional (4D) seismic signatures from multiple seismic surveys shot during gas exsolution and dissolution in a producing hydrocarbon reservoir, and focuses in particular on what reservoir information may be extracted from their analysis. To aid in this process, hydrocarbon gas properties and behaviour are studied, and their relationship to the fluid-flow physics is understood using numerical simulation. This knowledge is then applied to interpret the seismic response of a turbidite field in the UK Continental Shelf (UKCS). It is concluded that for a repeat seismic survey shot 6 months or more after a pressure change above or below bubble point (as in our field case), the gas-saturation distribution during either exsolution or dissolution exists in two fixed saturation conditions defined by the critical and the maximum possible gas saturation. Awareness of this condition facilitates an interpretation of the data from our field example, which has surveys repeated at intervals of 12–24 months, to obtain an estimate of the critical gas saturation of between 0.6 and 4.0%. These low values are consistent with a range of measurements from laboratory and numerical studies in the open literature. Our critical gas-saturation estimate is also in qualitative agreement with the solution gas–oil ratios estimated in a material balance exercise using our data. It is not found possible to quantify the maximum gas saturation using the 4D seismic data alone, despite the advantage of having multiple surveys, owing to the insensitivity of the seismic amplitudes to the magnitude of this gas saturation. Assessment of the residual gas saturation left behind after secondary gas-cap contraction during the dissolution phase suggests that small values of less than a few per cent may be appropriate. The results are masked to some extent by an underlying water flood. It is believed that the methodology and approach used in this study may be readily generalized to other moderate- to high-permeability oil reservoirs, and used as input in simulation model updating.

Description: Multivariate statistical methods can be applied to analyse a complete set of multidimensional geochemical data and to identify latent relationships among these data. In this paper, we used multivariate statistical analysis, including k-means clustering, principal component analysis (PCA) and factor analysis (FA), to study the similarity of the sampling points and the relationships between metal mineralization and geological environment in the Nanling metallogenic belt, South China. The dataset consists of 1617 sediment samples analysed for 39 elements. The dataset was divided into three clusters by k-means clustering which were strongly associated with the distribution of lithostratigraphic units and the level of metal mineralization. Each cluster was analysed by PCA to identified principal components. Three factors extracted by the factor analysis explained c. 62% of the total variance and allow identification of the dominant ore-forming environment. Factor 1 describes c. 30% of the common variance and is highly loaded by Zn, Cu, Cr, Co, Ni, Mn, P, Ti, V, Mg and Fe. Factor 2 includes rare metals, rare earth elements (REE) and radioactive elements with Y, La, Nb, Zr and U, explaining c. 19% of the common variance. Factor 3 describes c. 14% of the common variance and is highly loaded by W, Sn, Mo, Pb, Be and Bi, representing tungsten polymetallic mineralization. In this paper, the Student’s t-test derived from weights-of-evidence modeling was used to measure the significance of spatial correlation between factor scores and mineral deposits.

Description: Geoscientists undertaking mineral exploration sometimes are provided with historic geological and geochemical information about a prospective mineral deposit that they would like to use in a modern mineral resource assessment. Unfortunately, these historic datasets may lack critical information describing the quality of the data, such as duplicate samples, that are required under today’s disclosure regulations. As a result, geoscientists sometimes need to generate such data quality information after the fact ( a posteriori ). This contribution describes how duplicate samples can be obtained from historic drill-core to provide an unbiased assessment of grade and measurement error, as well as ensuring equivalent geostatistical ‘support’ in all samples, while at the same time retaining at least one quarter of the drill-core in archive for all sample intervals. It also describes an alternative method that can be applied to unsampled drill-core ( a priori ) to acquire unbiased grade and measurement error estimates, ensure equal sample support, while at the same time retaining half of the drill-core in archive.

Description: A fast method for the direct analysis of soils, namely solid sampling (SS) electrothermal vapourization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES), was validated through the accurate analysis of a soil standard reference material (SRM) using another soil SRM as a calibration standard and an Ar emission line as internal standard to compensate for sample loading effects on the plasma. Good agreement was obtained between the measured concentrations and certified values according to a Student’s t-test. The validated method was applied to the determination of the distribution of elements in depth profile soil samples from across the Talbot Lake VMS Cu-Zn prospect, in the Flin Flon-Snow Lake terrane, Manitoba, Canada. These profiles revealed that: Zn, P and Ag had anomalously high concentrations at 20–50 cm depth at 400 m, above where the easternmost part of the ore deposit is located along a 0–1000 m sampling line; Cu, Al, Ba, Pb and Hg were concentrated on the surface and at 40-cm depth mostly between 500 and 600 m; and Cl, Br and I were concentrated at depth at 400 m and over all depths at 600 m. As the geochemical anomaly is known to lie from 400 to 600 m, all these elements could be used to locate the ore. Good agreement was obtained with results by ICP mass spectrometry (ICP-MS) following aqua regia (AR) digestion, for those elements that could be determined by ICP-MS. In fact, not only is sample dissolution unnecessary but qualitative analysis by SS-ETV-ICP-AES is sufficient to obtain depth profiles, including for elements like Cl, which cannot be determined when AR is used for digestion.

Description: Delineation of vertical distribution patterns of elements in overburden over a concealed deposit is essential for determining potential upward migration mechanism of elements and for predicting undiscovered mineral deposits. The aim of this study is to identify the vertical distribution features of elements in the regolith over the Jinwozi gold field, NW China by using factor analysis (FA) and concentration-volume (C-V) fractal modeling based on the data-set generated from 70 overburden drilling boreholes. Firstly, the zones of different gold enrichment states were obtained by the C-V fractal method. Secondly, FA was utilized to define the mineralization-related element association. Finally, the C-V method was applied to the relevant association defined by FA. The results showed that: (1) the C-V fractal method distinguished four enrichment states determined by Au thresholds of 1.6, 7.9 and 39.9 ng/g and by factor scores of –1.14, 0.33 and 1.45; (2) the first factor that describes 41.5% of the common variance has positive loadings in Au, As, Sb and Mo; (3) the zones of both high Au contents and factor scores generally showed horizontally northeasterly distribution along the ductile-shearing alteration belt and vertically top-bottom symmetric distribution in the regolith over the deposit; (4) the rest of the zones determined by the C-V fractal model properly delineated the zones of low and high backgrounds and moderate Au enrichment; and (5) the moderately-enriched zones of the raw Au data are better than those of the factor scores, and the rest of the zones have the similar distributions. These results indicate that: (1) the distribution of elements in the regolith was the product of nonlinear natural processes resulting in an enrichment pattern at the surface over the deposit; and (2) the integration of FA and C-V fractal model is effective for the delineation of 3D geochemical patterns.

Description: Iron oxides are minerals resistant to chemical alteration and mechanical abrasion, and which have ferromagnetic properties and a range of chemical compositions. These characteristics are useful as indicator minerals in exploration, for example using till in glaciated terrains. Iron oxide proportions, grain size, and chemical composition of till samples collected near the Sue-Dianne Cu-Au-Ag IOCG deposit in the Great Bear magmatic zone (Northwest Territories, Canada) and magmatic Ni-Cu deposits in the Thompson Nickel Belt (Manitoba, Canada) show that subsamples containing c. 100 grains from the 0.25–1.0 mm grain size ferromagnetic fraction yield a representative mineralogical and compositional range of oxide grains from a till sample. Subsamples with less than 100 grains yield statistically less representative data. The 1–2 mm grain size fraction typically contains too few iron oxide grains and thus using this fraction is not statistically representative. The composition of iron oxides from eight till and five bedrock samples was determined along transects up- and down-ice of the Cu-Au-Ag Sue-Dianne IOCG deposit. At, and immediately down-ice of, the deposit, hematite is the principal oxide and shows dominant BIF and IOCG chemical signatures in the Ca+Al+Mn v. Ti+V discriminant diagram. Up-ice and farther down-ice of the deposit, magnetite and titanomagnetite are the dominant oxides and magnetite shows dominant Kiruna and IOCG signatures. The composition of iron oxides from six till samples along a north–south transect and 11 till samples from a 180 km-long east–west transect, along the older and younger directions of ice-flow, respectively, was determined in the Thompson Nickel Belt (Manitoba, Canada). The proportion of magnetite in till with the signature of Ni-Cu deposits increases for at least 1 km south of the Pipe Ni-Cu deposit along the direction of the older southward ice flow, whereas the glacial dispersal of magnetite with a chemical signature typical of Ni-Cu deposits was limited during the younger westerly ice flow.

Description: The area-concentration multifractal modelling of a soil geochemical survey performed in the Alfarrobeira–Chança region (covering the Pulo do Lobo Terrane, PLT, and the Iberian Pyrite Belt, IPB) shows that the upper limit of Cu, Zn and Pb background concentrations in soils over PLT metasediments are c . 20, 55 and 20–30 ppm, respectively. In soils derived from the Volcano-Sedimentary Complex of IPB, the Cu, Zn and Pb regional threshold values are within the 25–45, 40–60 and 20–90 ppm intervals, respectively. The lower limit of Cu, Zn and Pb soil anomalies overlying metasediments are within the 30–50, 90–115 and 45–60 ppm intervals, respectively; over soils with abundant volcanic-derived components those lower limits are scattered in the 30–70, 70–90 and 33–100 ppm intervals. Proximity to mineralized rocks is indicated by Cu, Pb and Zn soil contents above c . 100, 120–150 and 250 ppm, respectively. Most of the anomalies display strong anisotropy. Separation of Cu, Zn and Pb soil anomalies reflects mostly the existence of distinct metal sources related to original compositional differences or to chemical changes developed during Variscan times. Metavolcanics represent the prevailing sources of Cu and, to a lesser extent, Pb; the prevalent sources of Zn are metasediments of the Phyllite-Quartzite (IPB) and Chança (PLT) Groups.

Description: Liberia is recovering from a 14 year civil war and only 51% of the rural population has access to safe drinking water. Little hydrogeological knowledge survives in Liberia, increasing the difficulty in successfully siting new boreholes. An understanding of the local hydrogeological environment is therefore needed to improve borehole site selection and increase success rates. This research provides a semi-quantitative characterization of the hydrogeological environment of the basement aquifer in Lofa county, Liberia. Based on literature review and analysis of borehole logs, the study has developed a conceptual hydrogeological model for the local conditions, which is further characterized using 2D geoelectrical sections. Groundwater is predominantly obtained from the saprolite and underlying fractured bedrock, but specific capacities (median 281 l h –1 m –1 ; 25th and 75th percentile of 179 and 490 l h –1 m –1 , respectively) are constrained by the limited thickness of the saturated saprolite. This study has shown that the groundwater resources in the crystalline basement in this part of Liberia conform to the general conceptual model, allowing standard techniques used elsewhere for siting and developing groundwater to be used.

Description: An increase in moisture accelerates the deterioration of a pavement and this is especially so for unbound granular materials below the pavement surface. One of the possible reasons for this accelerated deterioration can be the mineralogical makeup of the aggregates, which can include clays. This research paper discusses the effect of the relative proportions of clay minerals on the performance of different base course materials in repeated load triaxial (RLT) tests considering moisture variation. The materials selected for this study were sourced from greywacke sedimentary rocks from both the North and South Islands of New Zealand. The mineralogical makeup of the clay content present in the base course materials was determined by X-ray powder diffraction (XRD). The performance of these materials was further tested in RLT tests at different moisture and drainage conditions. The results of the XRD and RLT tests showed that aggregates with high relative proportions of smectite clay minerals can decrease the load-bearing capacity of the base course material when moisture is introduced into the pavement materials.

Description: The presence and activity of microorganisms in aquifers can affect, amongst other things, nutrient cycling, contaminant degradation and water flow. The introduction of a pollutant or other changes in water chemistry can alter the microbial community composition and affect aquifer functioning. To understand the microbial response to anthropogenically induced changes, a better knowledge of baseline microbial communities in uncontaminated aquifers is needed. Here, we review the information on microorganisms in UK aquifers together with examples of research from other countries on this topic, and discuss how these communities might respond to disturbance. Research into microbial communities in UK aquifers has mostly been limited to bacteria and often reveals a community dominated by Proteobacteria. The community composition is influenced by factors such as mineralogy and water chemistry, and the natural baseline community may be altered by aquifer contamination. A UK-wide survey of aquifer microbes, similar to one recently carried out in New Zealand, would provide valuable information about the current state of UK aquifer microbiology. This would lead to a greatly improved understanding of the ecosystem services provided by the microbial communities present in aquifers, allow future monitoring and assessment of the effects of pollution, and assist in groundwater resource management.

Description: Water is known to be the main deteriorating agent of building geomaterials. Owing to the presence of water, the alteration phenomena observed particularly on limestones are transportation of soluble salts, dissolution of calcite and development of micro-organisms. In restoration works, several chemical treatments can be used, such as biocides to remove existing biofouling and water-repellents to prevent the ingress of water and its deteriorating effects. The aim here was to combine these two properties in one treatment that could be applied at the end of the restoration work and to develop treatments based on natural products and that are safer for the users and the environment. Products with water-repellent and/or anti-colonization properties were developed and tested on a bioclastic limestone both in laboratory and outdoor conditions. They were compared with commercial water-repellents and a preventive anti-colonization treatment. Samples were exposed for 2 years in a forest environment, where the hydrophobicity and the colonization were evaluated every 6 months. In the laboratory, anti-colonization effects were determined through algae growth measurements. The product that confirmed an efficient hydrophobicity and anti-colonization effect will be applied on a restored site to test it under real conditions.

Description: Engineering geology has a long and rich heritage and the UK has been in the vanguard of the development of the subject as a distinct discipline, with the first book on the subject being published in London in 1880. Since then, engineering geology has been applied to projects around the world and engineering geologists have become core members of planning, investigation, design and construction teams in the civil engineering and mining industries. However, in the past few decades we have seen numerical analyses increasingly being accepted as the answer to all geotechnical design questions, although as engineering geologists we are used to dealing with natural materials and processes and recognize that their inherent variability cannot always be reduced to a simple numerical value. Consequently, how do we ensure that any proposed construction works in civil engineering or mining take full account of this variability and the uncertainties that result? To enable engineering geologists to understand and describe these uncertainties are there fundamental skills that define an engineering geologist and, if so, how can these skills be taught or acquired? Also, in a world dominated by readily accessible data that can be downloaded and analysed for so many planned development sites, how important are the field techniques of observation and mapping that an older generation of engineering geologists, including the author, considered their defining skill? Concentrating on the role of engineering geology in relation to civil engineering, these are amongst the questions explored in this paper, leading to observations as to how the profession might develop in the future in order to meet the needs of society.

Description: Portable XRF instruments are effective tools to provide ‘fit for purpose’ qualitative chemical data that are precise but typically very inaccurate. Under standardized test conditions, the analytical performance of portable XRF instruments varies significantly between individual instruments from the same manufacturer, and between manufacturers using similar instruments. The precision of the instruments to repeat a constant element concentration from a single sample is typically very good (〈5 % RSD); however, the accuracy is generally poor to very poor with huge concentration differences in some elements. For example, Al measured from the same NIST standard reference material (NIST 2709a, an agricultural soil) by six Olympus-Innov-X Delta Premium instruments ranged from 2.56 to 7.93 % Al whilst two Thermo-Niton XL3t GOLD+ instruments gave values of 2.14 and 2.33 % Al against the certified value of 7.37 % Al. After two to five months, repeat analysis by the same instruments under the same conditions shows a measurable deterioration in element concentration, with elements of lower atomic number, Al and Si, the worst affected; for example, the Si response from the Olympus-Innov-X Delta Premium and Thermo-Niton XL3t GOLDD+ instruments deteriorated up to 43 % and 40 %, respectively. This deterioration in the instruments’ performance was observed in all instruments evaluated. Lithium-ion battery packs, a key to the instruments’ portability, can have a measurable effect on the precision and accuracy of the data with an instant 0.05 % concentration change in Fe (from 3.39 to 3.44 % Fe) during a routine battery pack change. Batteries’ serial numbers should be recorded to monitor these effects and corrections applied. Each instrument provides uniquely individual data that should not be combined with data from any other units without appropriate post-processing or recalibration. To significantly improve the quality and value of the pXRF data, a calibration procedure appropriate to the material(s) being evaluated should be implemented with regular baseline data collected to ensure instrument and data stability. Over time, matrix calibrations need to be verified with the instrument undergoing a manufacturer’s recalibration when control limits deteriorate significantly.

Description: Powdered international reference materials and samples with previously obtained conventional geochemical data were analysed using a benchtop portable X-ray fluorescence (pXRF) spectrometer to test the abilities of pXRF in silicate rock lithogeochemistry. Results from international reference materials illustrate that pXRF can provide very precise data for many major, minor, and trace elements, generally with RSD values of 〈7.5 % and many 〈5 %, except at very low concentrations (i.e. approaching the limit of detection). Despite good precision, accuracy is highly variable and ranges from excellent to reasonable for many major and minor elements (±15–20 % relative difference, RD, for Al 2 O 3 , SiO 2 , K 2 O, CaO, Fe 2 O 3 , TiO 2 , and MnO±S), base metals (±20 % for Cu, Zn), the low field strength (LFSE) and high field strength elements (HFSE) (±15 % RD for Rb, Ba, Zr; ±20 % RD for Nb). Poor accuracy was obtained for MgO, P 2 O 5 , and the transition elements (V, Cr, Ni); Sr shows variable accuracy. Comparison of pXRF results to independent samples with data from conventional analyses illustrates very poor correlation for MgO, P 2 O 5 , V, Cr, and Ni, suggesting they have poor accuracy by pXRF. Aluminum (Al 2 O 3 ), SiO 2 , and Zn have r 2 values of c . 0.6–0.7 illustrating reasonable correlation, whereas most other elements (S, K 2 O, CaO, TiO 2 , MnO, Fe 2 O 3 , Co, Cu, Pb, Rb, Sr, Ba, Zr, Nb, U, As, and Mo) have very good to excellent correlation between pXRF data and conventional analysis (i.e. r 2 〉0.80). In addition, many of the elements with r 2 〉0.8 have slopes that are close to 1 or within 20 % of ideal, indicating that pXRF is replicating the results of conventional analyses and likely within ±20 % of what can be obtained by conventional methods. Down-hole profiles of pXRF data and element ratios replicate the geometry of the profiles from conventional analyses and illustrate the ability of the pXRF to discriminate rock type, alteration, and mineralization in unknown samples. Portable XRF can provide fit-for-purpose data that is useful in discriminating lithogeochemical variations related to lithology, alteration, and mineralization. However, pXRF should be considered a preliminary screening tool for sample selection and not a substitute for conventional lithogeochemical methods (e.g. XRF, fusion ICP-ES and ICP-MS), particularly when important economic decisions are to be made using such data (e.g. NI-43-101 resource calculations). Supplementary Material: Collated data for repeat analyses of reference materials in Mining Plus (Table 1) and Soil 3 Beam (Table 2) modes. Tables 3-9 contain plots comparing results from pXRF to accepted values for various reference materials. All tables are available at at www.geolsoc.org.uk/SUP18735

Description: This paper responds to the expanding interest in archaeology in the use of portable X-Ray fluorescence (pXRF) technologies. Accurate analysis using pXRF requires correction for absorbance and secondary enhancement of the excited element X-rays by the other elements present. Several correction methods are widely used, including fundamental parameters, influence coefficients, Compton ratioing, multi-variate statistical analysis, and dilution. Most pXRF calibrations use either fundamental parameters or multi-variate statistics. However, influence coefficients are known to be the most certain calibration method for XRF analysis of geological materials. Portable XRF calibrations using influence coefficients in the analysis of obsidian, flint, mudbrick, and sediment have far less bias and include a wider range of elements (Mg through Ce) than multi-variate statistical or fundamental parameter calibrations using beam filtered spectra. Bias v. wavelength dispersive XRF data using influence coefficients is mostly less than 1 % for obsidian and flint, and less than 2 % for mudbrick and sediment, in contrast with the large biases (up to 36 %) found using fundamental parameters or multi-variate statistical methods.

Description: An economic Cu-Zn volcanogenic massive sulphide (VMS) deposit was modeled in flow-through columns to examine the microbial controls on ore weathering and soil anomaly development. The presence of microorganisms, especially S- and Fe-oxidizing bacteria, increased the rate of weathering and metal release from ore. To examine the development of soil metal anomalies overlying the VMS deposit, flow-through experiments modeling the full overburden profile were completed. Selective extractions on the soil demonstrated that enhanced metal anomalies in the biotic column were developing in the reactive Fe- and Mn- oxide phases. These experimental results are linked to in situ biogeochemical processes through the use of Fe-oxidizing bacteria isolated from the deep subsurface of Triple 7 Cu-Zn VMS mine in Flin Flon, Manitoba, Canada, in direct proximity to where the ore material was collected. These results demonstrate that the rates of metal mobility in the subsurface and soil metal anomaly development at the surface are increased by the presence and activity of microorganisms when compared to control experiments.

Description: Eureka, Nevada, was once a boom-mining town with peak production of Pb, Ag, and Au between the 1870s and 1890s. Most of the ores from the area were processed in two smelters located at the north and south edges of the town. Smelter effluent was exhausted in the vicinity of the smelter furnaces with little regard to potential health concerns. For this study, 186 soil samples from sites in the area surrounding Eureka were analysed for 43 elements. Factor analysis and element plots identified 16 smelter-related elements: Ag, As, Bi, Cd, Cu, Hg, In, Mo, Pb, S, Sb, Sn, Te, Tl, W, and Zn. Eight other elements (Ba, Be, Co, Cr, Mn, Ni, U, and V), whose distributions are controlled by the chemical composition of the underlying substrate material, were also evaluated. Of these 24 elements, only six (As, Cd, Pb, Tl, Sb, and Mn) had concentrations that exceeded U.S. Environmental Protection Agency (EPA) estimated residential soil screening levels considered to represent possible health risks. For some analysed elements (In, S, Te, and W) no screening levels have been established. Whether these elements, or any of the others determined, constitute a health risk in the local population is not known. Supplementary Material: Analyses for 43 elements in 186 soil samples are available at www.geolsoc.org.uk/SUP18673

Description: Stream sediment geochemical data are usually subjected to methods of multivariate analysis (e.g. factor analysis) in order to extract an anomalous geochemical signature (factor) of the mineral deposit-type sought. A map of anomalous geochemical signature can be used as evidence, in combination with other layers of evidence, for mineral prospectivity mapping (MPM). Because factor analysis may yield more than one factor in a stream sediment dataset, it raises the challenge of how to recognize the factor that best indicates presence of the mineral deposit-type sought. In addition, MPM is faced with the challenge of how to assign weights to classes in a geochemical evidence map. Accordingly, a new approach is discussed in this paper for the extraction of significant anomalous geochemical signature of the mineral deposit-type sought and for assigning weights to anomaly classes in a geochemical evidence map. In this approach, we used a staged factor analysis and then applied a logistic function to transform factor scores representing an anomalous geochemical signature in order to derive a map of geochemical mineralisation prospectivity indices (GMPI) as a spatial evidence layer for MPM based on the theory of fuzzy sets and fuzzy logic. The GMPI is a fuzzy weight in the [0,1] range. We demonstrate the application of the GMPI for mapping prospectivity for Mississippi valley-type fluorite deposits in the Mazandaran province, north of Iran, which is a greenfield area.

Description: The results from exploration geochemical stream sediment surveys of the central Wales lead-zinc orefield by undergraduates from the University of Portsmouth between 1979 and 2003 are now available on open access at www.geologis.com for further investigation. Details are given here of the procedures of collection, preparation and chemical analysis of the samples together with an estimate of analytical precision. Log-probability plots for different sub-areas give different results depending on the proportion of anomalous to background values. Important details are lost when undivided data for the whole study area are used. Comparison of repeat surveys of the same area shows that the findings obtained are consistent even though sampling sites differ. The Portsmouth results are compared with those of the British Geological Survey’s G-BASE survey for the area. The two sets of data are compatible and the Portsmouth data enhance the utility of the G-BASE survey. The value of the Portsmouth database for environmental studies and for mineral exploration is illustrated with examples, demonstrating that undergraduate training can, over a period of time, provide an important source of data.

Description: Ages retrieved from accessory minerals in high-grade metamorphic rocks place important constraints on the timing of events and the rates of tectonometamorphic processes operating in the deep crust. In suprasolidus rocks, the dissolution and growth of zircon and monazite are strongly dependent on the P–T conditions of metamorphism and the chemistry and quantity of anatectic melt present. Along a clockwise P–T path, prograde heating above the solidus leads to episodic melt loss and changes in melt chemistry that have important implications for the dissolution and growth of zircon and monazite. In this study, phase equilibria modelling of open-system melting is coupled with experimental data on zircon and monazite solubility to evaluate the stability of these minerals at suprasolidus conditions along several schematic clockwise P–T paths. In migmatite melanosomes and residual granulites, some zircon is expected to survive heating to peak temperature and subsequent isothermal decompression, whereas monazite may be completely consumed, consistent with the observation that inherited cores are less common in monazite than in zircon. After decompression, during cooling to the solidus, new zircon and monazite growth from melt trapped along grain boundaries in melanosomes and residual granulites is expected to be limited. By contrast, leucosomes in migmatites and anatectic granites are predicted to contain mostly newly formed zircon and monazite with minimal inherited components, unless significant entrainment of these minerals from the source occurs. The preservation of cores inside newly formed zircon, as observed in many anatectic granites, demonstrates that segregation, ascent and emplacement is commonly fast enough to limit dissolution of these inherited grains.

Description: The influence of effective stress history on reservoir stability and the response to hydraulic fracturing are simulated for two hypothetical shale reservoirs. It is numerically demonstrated that the effective stress history influences the present-day stability of faults and natural fractures. Any assumption of a homogeneous stress state is shown to be unrealistic in the majority of fractured shale reservoirs. The simulations demonstrate that, depending upon the effective stress history, shear displacements can be induced by stress changes associated with stimulation without a change of fluid pressure in the destabilized fractures. Elastoplastic shale and other fractured reservoirs are shown to have a memory of past geomechanical states. These numerical findings demonstrate the value of interpreting reservoir effective stress history when planning fluid injection. A previous case history is summarized to illustrate the overwhelming dependence of stress history analyses on a wide spectrum of earth science disciplines. It also illustrates the application of stress history analyses to activities other than hydraulic fracturing. The current inexperience of effective stress history description means that new approaches must be identified to optimize the necessary multidisciplinary investigations. Supplementary material: Details of the simulations are available at www.geolsoc.org.uk/SUP18743 .

Description: The leaf longevity of trees, deciduous or evergreen, plays an important role in climate feedbacks and plant ecology. In modern forests of the high latitudes, evergreen trees dominate; however, the fossil record indicates that deciduous vegetation dominated during some previous warm intervals. We show, through an integration of palaeobotanical techniques and isotope geochemistry of trees in one of the earliest polar forests (Late Permian, c . 260 Ma, Antarctica), that the arborescent glossopterid taxa were both deciduous and evergreen, with a greater abundance of evergreen trees occurring in the studied forests. These new findings suggest the possibility that deciduousness was a plastic trait in ancient polar plants, and that deciduous plants, migrating poleward from lower latitudes, were probably better adapted to high-disturbance areas in environments that were light-limited. Supplementary material: Wood anatomy descriptions (supplemental file 1), stable carbon isotope data for tree rings (supplemental files 2–4), and method and parameters for modelled 13 C (supplemental file 5) are available at www.geolsoc.org.uk/SUP18744 .

Description: Marine evaporites such as the Zechstein (Permian, NW Europe) consist of thinning-upward sulphate–halite–potash cycles whose origin is poorly understood. An intra-basinal mechanism presented here explains well their mineral composition and cycle development. It involves the progressive obstruction of ocean connections by sulphate-platform progradation, causing a chain reaction of outflow reduction and subsequent accelerated sulphate precipitation. Numerical modelling shows this to be a self-accelerating process that ultimately triggers halite and potash precipitation. Isostatic compensation of the salt load explains the formation of accommodation space for subsequent cycles, each about half the thickness of the previous cycle.

Description: Radiometric dating by the 40 Ar– 39 Ar incremental heating method was carried out on lavas, sills, dykes, and a central intrusion from NE Greenland. Eighteen samples gave acceptable crystallization ages. Lavas of both Lower and Upper Plateau Lava Series gave ages in the range 55.5–53.5 Ma and cannot be constrained to better than 56–53 Ma. Sills and dykes from Traill Ø to Shannon, with compositions fairly similar to those of the lavas, gave ages of 55.1–51.3 Ma, contemporaneous with and slightly younger than the lavas. Alkaline lavas on inland nunataks have ages of 53–50 Ma, and the Kap Broer Ruys intrusive centre has an age of 48.7 ± 0.5 Ma. An alkaline sill on Hvalrosø is much younger at 20.3 ± 0.1 Ma. There are no pre-breakup lavas onshore NE Greenland. We surmise that the hot mantle of the Iceland plume arrived and melted extensively beneath the northern basins only at the time of breakup around 55 Ma. Post-breakup intrusive events in NE Greenland coincided with plate-tectonic events such as reorganization, uplift and opening in the north. The Hvalrosø sill represents a local small melting event that may be related to coeval opening of the Lena Trough. Supplementary materials: Details of the source data, results, and the compositions and locations of the dated samples, are available at www.geolsoc.org.uk/SUP18738 .

Description: In thrust belts, low-angle tectonic contacts are common, and are associated with the stacking of tectonic units and the resulting regional shortening. The Southern Apennines of Italy, where basin and platform sediments are stacked along low-angle regional thrusts caused by the shortening of the Adria passive margin, are no exception. We studied a portion of a north–south-trending, low-angle regional thrust that separates Apennine platform sediments from Lagonegro basin rocks. To the east of the thrust, klippen composed of platform sediments overlying Lagonegro rocks along a low-angle tectonic contact are present. The klippen were first interpreted as remnants of the regional thrust. We performed a detailed structural analysis of the regional thrust, and we examined the structural setting of the klippen. Field evidence and analysis of map patterns revealed that emplacement of low-angle, foreland-propagating thrusts was followed by extensional deformation accommodated by regional east-dipping, low-angle normal faults. At the base of the klippen, we identified low-angle tectonic contacts with an extensional kinematics. We conclude that the klippen were the result of movements of platform sediments and Lagonegro rocks along low-angle normal faults, and not thrusts as previously interpreted. These faults are cut by more recent, high-angle normal faults associated with the opening of the Agri basin. Collectively, we show that evidence of changes in the tectonostratigraphic architecture, fault geometry and kinematics, and fabrics in the thrusts can reveal the presence of low-angle normal faults, the result of an extensional regime. We expect that our findings will contribute to the understanding of the deformation history of part of the Southern Apennines, and of other mountain belts. The results are also important to understand the transition from compression to extension in the Southern Apennines and in similar orogenic belts.

Description: Host rock mechanical heterogeneities influence the spatial distribution of deformation structures and hence predictions of fault architecture and fluid flow. A critical factor, commonly overlooked, is how rock mechanical properties can vary over time, and how this will alter deformation processes and resultant structures. We present field data from an area in the Borborema Province, NE Brazil, that demonstrate how temporal changes in deformation conditions, and consequently processes, exert a primary control on the spatial distribution and geometric attributes of evolving deformation structures. Furthermore, each temporal deformation phase imparted different hydraulic architecture. The earliest flowing structures are localized upon subtle ductile heterogeneities. Following fault formation, both fault core and damage zone were flow conduits. In later stages of faulting pseudotachylyte welding created a low-permeability fault core and annealed high-permeability fractures within the fault damage zone. Modern flow occurs along a zone of later open shear fractures, defined by the mechanical strength contrast between the host rock and annealed fault. This second hydraulically conductive zone extends hundreds of metres from the edge of the annealed fault damage zone, creating a flow zone far wider than would be predicted using traditional fault scaling relationships. Our results demonstrate the importance of understanding successive deformation events for predicting the temporal and spatial evolution of hydraulically active fractures.

Description: The Late Bronze Age ‘Minoan’ eruption of Santorini, Greece occurred from within an existing caldera. Low-temperature pyroclastic flow emplacement on shallow slopes outside the caldera can only be consistent with the caldera being filled with eruption products that are not preserved. Field observations and seismic reflection surveys suggest that this missing material has been downfaulted. The volume of the caldera infill is estimated as 18–26 km 3 dense rock equivalent (DRE), increasing the total of the Minoan eruption deposits to 78–86 km 3 DRE and making it the largest known Holocene eruption. This study highlights a general mechanism whereby caldera eruption volumes could be significantly underestimated.

Description: The late Mesozoic Yanshanian volcanic arc affected an extensive region of SE China, but the conclusion of magmatism and later evolution are not fully understood. Widespread Yanshanian ignimbrites and their contemporaneous granites exposed in Hong Kong represent a microcosm of this magmatic arc. To constrain the post-magmatic thermal history of the region, we present zircon and apatite fission-track analyses from these rocks. Double dating using laser ablation inductively coupled plasma mass spectrometry U–Pb and fission-track techniques on detrital zircons from post-volcanic Cretaceous sediments is used to further constrain the tectonothermal evolution. The resulting dataset and thermal modelling suggest that the igneous rocks and Cretaceous sediments together experienced post-emplacement or post-depositional heating to 〉250 °C, subsequently cooling through 120–60 °C after c . 80 Ma. The heating reflects the combined effects of an enhanced geothermal gradient and burial. We interpret the enhanced gradient to represent continuing Yanshanian magmatic activity until c . 100–80 Ma, much later than previously considered. Our data also indicate a long-term, slow cooling ( c . 1 °C myr –1 ) since the early Cenozoic, linked to c . 2–3 km of erosion-driven exhumation. The thermotectonic history of Hong Kong reflects the mid-Cretaceous transition of SE China from an active to a passive margin bordered by marginal basins that formed in the early Cenozoic. Supplementary material: Descriptions of samples, operating conditions of the laser ablation inductively coupled plasma mass spectrometry system and the full dataset of U–Pb dating of detrital zircons are available at www.geolsoc.org.uk/SUP18750 .

Description: A seismic sequence offshore the Marche region sheds new light on the active tectonic setting of the outer northern Apennines, revealing the existence of a previously unknown transcurrent seismogenic structure. In contrast to the Po Plain area, where vigorous seismicity testifies to active frontal thrusting, the seismotectonic setting of the Adriatic domain is characterized by the occurrence of active crustal strike-slip faults dissecting the thrust belt. As recent studies suggest that thrust faults represent the unique seismogenic sources characterizing the Adriatic sector of the outer northern Apennines, our results pose new challenges to the identification of seismogenic structures in the region.

Description: During terrane convergence, an influx of clastic sediment from an upper plate onto a lower plate is an early indication of terrane juxtaposition. In the Caledonides of Great Britain and Ireland, units accreted to Laurentia during the early Palaeozoic Era include peri-Gondwanan terrane assemblages that earlier separated from West Gondwana. However, the Southern Uplands Terrane contains detrital zircon populations apparently derived entirely from Laurentia, characterized by a large, asymmetric Mesoproterozoic peak and a scarcity of zircon at 600 Ma and 2.1 Ga. In contrast, Cambrian and Ordovician rocks from the Lake District and the Leinster Massif of Ireland show abundant grains with these ages, together with a range of Mesoproterozoic zircon. These characteristics are shared with the Monian terrane of Anglesey and with Ganderia in the Appalachians, indicating probable derivation from Amazonia in West Gondwana. Silurian sandstones from the Lake District show an influx of Laurentia-derived zircon, and lack the peri-Gondwanan signal. This indicates that in the Caledonides, Ganderia was not accreted to the Laurentian margin until c . 430 Ma, in contrast to the Ordovician accretion of Ganderian fragments recorded in the Appalachians, suggesting that the configuration of the closing Iapetus Ocean varied significantly along the strike of the orogen. Supplementary material: Details of sample coordinates, analytical procedure and U/Pb detrital zircon analytical data are available at www.geolsoc.org.uk/SUP18739 .

Description: The Kingston Peak Formation is a diamictite-bearing succession that crops out in the Death Valley region, California, USA. An exceptionally thick (〉1.5 km) outcrop belt in its type area (the Kingston Range) provides clear insights into the dynamics of mid-Cryogenian (‘Sturtian’) ice sheets in Laurentia. Seven detailed logs allow the lateral and vertical distribution of facies associations to be assessed. We recognize (1) diamictite facies association (ice-proximal glacigenic debris flows), (2) lonestone-bearing facies association (ice-marginal hemipelagic deposits and low-density gravity flows with iceberg rafting), (3) pebble to boulder conglomerate facies association (ice-proximal cogenetic glacigenic debris flows and high-density turbidites), (4) megaclast facies association (olistostrome and hemipelagic sediments subject to ice-rafting), and (5) interbedded heterolithics facies association (low-density turbidites and hemipelagic deposits). The stratigraphic motif allows three glacial cycles to be inferred across the range. Ice-minimum conditions interrupting the Kingston Peak succession are associated with the development of an olistostrome complex, succeeded by a thick accumulation of boulder conglomerates deposited during ice readvance. The data testify to a strong glacial influence on sedimentation within this ancient subaqueous succession, and to highly dynamic ice sheet behaviour with clear glacial cycles during the Sturtian glaciation.

Description: The Globigerina Limestone of the Maltese Islands, widely used in construction and for restoration purposes, comes in a variety of types, with the Franka and Soll types (local terms) being the end members. The Soll type manifests widespread and often serious problems of durability and weathering resistance. The Franka type tends to be more durable. The selection of these materials is generally entrusted to quarry workers and builders, who primarily use visual criteria. This can lead to unsuitable stone being used. The current study uses ultrasonic and thermographic methods to distinguish between the two types at the extreme ends of the range, and to determine how their water absorption characteristics (fundamental when durability is being considered) can be evaluated. Results show that the Franka and Soll types behave very differently; ultrasonic testing showed that the Franka type possesses a significantly higher velocity compared with the Soll type; the thermographic technique verified that the Soll type absorbs less water by capillarity. Having an objective test to distinguish between stone types can lead to fewer errors in the choice of stone; such errors at present are possible because of the subjectivity of the methods used, with ensuing grave economic and practical consequences.

Description: Complex environmental controls have influenced deposition of the Gråklint Beds, a prospective oil- and gas-prone Late Triassic (Mid-Carnian) source rock in the Jameson Land Basin, East Greenland. The identification of a Late Triassic source rock is significant for hydrocarbon exploration in the North Atlantic region. Detailed sedimentological analysis, biostratigraphy and geochemical analysis provide insights into the controls on source rock development and have wider implications for palaeoclimatic trends and palaeogeographical reconstructions of the North Atlantic at this time. The Gråklint Beds were deposited in a predominantly lacustrine setting during a phase of climatic cooling that can be ascribed to the ‘Mid-Carnian Pluvial Event’. This further extends the evidence for the global effect of such climatic perturbations and furthermore highlights the potential for the use of climatic events for global and regional correlation between varying environmental settings. Evidence is also recorded for marine ingression, which resulted in the precipitation of magadiite (NaSi 7 (OH) 3 .3H 2 O) and the brief influx of a marine fauna. This provides the most southerly record of marine influence from the Boreal Ocean at this time and has important implications for palaeoenvironmental reconstructions and correlation in the region.

Description: The Pentland Formation of the UK Central North Sea is a quartzite in a sequence of more arkosic sandstones. Provenance-sensitive heavy mineral indices are interpreted to indicate that it was probably derived by erosion of arkosic sediments, which also supplied the arkosic marine sandstones of the contemporaneous Fulmar Formation. A lack of apatite within the Pentland Formation suggests that the feldspars could have dissolved during exposure to groundwaters during very shallow burial. However, petrographic and geochemical evidence supports survival of at least some of the feldspar to burial depths in excess of at least 2 km, when the sandstones had been stabilized against compaction by quartz cements or overpressure. Abundant kaolin, which has not reacted to form illite, is preserved at burial depths in excess of 4000 m, suggesting an unusual lack of available potassium. There is a strong contrast in diagenetic pathways with the overlying marine Fulmar Formation, which most probably had the same initial composition but in which kaolin is absent and fibrous illite is present. It is suggested that a lower concentration of potassium (and aluminium) within the Pentland Formation compared with the probable source and the comparably sourced Fulmar Formation represents export of K from the sands on a metre scale.