ALBERT

Beschreibung: In most hot deserts Quaternary environmental changes have left their imprint on ground conditions, creating a legacy of materials that often reflect past as well as contemporary processes, and can appear unusual to geologists trained in temperate environments. Attention is drawn in this article to three near-surface features (duricrusts, palaeolakes and sulphate-rich soils) that reflect changing environmental conditions and that are of potential significance to engineering investigation, design and construction.

Beschreibung: The results of 61 in situ UK thermal response tests, derived from three commercial test-rigs, have been analysed. Derived values of thermal conductivity yield a median of 2.25 W m K –1 , with 25th and 75th percentiles of 1.86 and 3.0 W m K –1 . The lowest single values are derived from Northern Irish basalt (1.1 W m K -1 ) and from Mesozoic and Tertiary argillites (often in the range 1.43–2 W m K –1 ), whereas the highest (〉5 W m K –1 ) are from Sherwood Sandstone and Coal Measures strata where advective heat transport with groundwater flow may have led to an elevated apparent conductivity. Borehole thermal resistance exhibits 25th percentile, median and 75th percentile values of 0.09, 0.11 and 0.14 K m W –1 and correlates with borehole heat exchanger diameter and configuration. Undisturbed ground temperature exhibits 25th percentile, median and 75th percentile values of 11.7, 12.3 and 13.2 °C and exhibits a latitude dependence.

Beschreibung: The Whitby Mudstone Formation has one of the highest landslide densities in the UK with 42 landslides per 100 km 2 . Landsliding at Hollin Hill in North Yorkshire, UK is complex and continuing, and includes shallow, retrogressive rotational failure on the upper slope, translation, and flow from the base of the Whitby Mudstone Formation over the scarp slope of the Staithes Sandstone Formation. Surface observations augmented by information relating to lithological, moisture and strength variation with depth allowed rapid initial interpretation of the masses affected by movement. These were provided by a single person operating portable probes providing depth logs of cone penetration resistance and soil moisture based upon dielectric property measurements in conjunction with a sampling auger. The gathered information was used to guide the design of further invasive site investigation and the configuration of permanent systems to monitor changes in dynamic moisture distribution and direct movement. At Hollin Hill, the near-surface materials in the upper 5 m interval are distinctly weathered or destructured, predominantly comprising silty clay in the Whitby Mudstone Formation, and fine silty, clayey sand and silty clay in the Staithes Sandstone Formation. Direct and secondary evidence was observed showing high moisture variation to be related to narrow intervals within the upper 5 m. Cyclic variation in moisture has played a key role in the movement and break-up of sliding materials, especially within the prograding lobes resulting from flow over the Staithes Sandstone Formation. Since these observations, permanent monitoring systems have been installed, including electrical resistivity tomography (ERT) arrays, which have successfully mapped the distribution of the Whitby Mudstone and the Staithes Sandstone, but will also be used in time lapse mode to image the near-surface moisture movement driving the landsliding processes. ERT array installations included a large area, low spatial resolution grid designed to investigate the potential coupling between the upper and lower slope hydrogeological processes and a small area, high spatial resolution grid designed to investigate the hydrogeological processes driving the earth flow.

Beschreibung: Atmosphere-Ocean, Volume 0, Issue 0, Page 1-5, Ahead of Print.

Beschreibung: The thermal springs of Bath, England, produce 1.25 Ml day –1 of water at 46.5 °C. The spring at Hotwells, Bristol, England, 15 km to the west, is estimated to produce between 0.17 and 0.39 Ml day –1 of water at a temperature between 22.8 and 24.4 °C. Published research suggests that the waters originate in the Mendip Hills, SW of Bath and Bristol, and are heated by geothermal energy within the Carboniferous Limestone basin (‘The Mendips Model’). The exact paths of the waters to the springs have not been established. We interpreted seismic reflection data for the urban district of Bath and for the Radstock Basin to the south of Bath. By combining the geophysical interpretations with published geological data we have established a potential route through the Carboniferous Limestone reaching sufficient depths for the waters to attain the required temperatures. We imaged a steeply dipping, fractured region of Carboniferous Limestone coincident with the valley of the River Avon and propose that this is the feature by which the thermal waters can rise rapidly to the surface, providing an explanation for the existence of these unique springs. We have incorporated these new aspects of the Mendip Model into the ‘Mendip–Avon Fracture Zone Model’.

Beschreibung: Atmosphere-Ocean, Volume 0, Issue 0, Page 1-18, Ahead of Print.

Beschreibung: Remote Sensing Letters, Volume 4, Issue 11, Page 1049-1056, November 2013.

Beschreibung: Remote Sensing Letters, Volume 4, Issue 11, Page 1039-1048, November 2013.

Beschreibung: Remote Sensing Letters, Volume 4, Issue 11, Page 1067-1076, November 2013.

Beschreibung: Remote Sensing Letters, Volume 4, Issue 11, Page 1057-1066, November 2013.

Beschreibung: Adverse reactions between specific aggregate particles and the pore fluids in cement pastes have been widely reported, and have been regarded as responsible for the failure of the structures into which the resulting concrete had been emplaced. The reactivity of aggregates containing various forms of silica has been well understood but similar reactions, apparently taking place between aggregates of limestone, dolostone and ‘dedolomites’, although widely recognized, remain controversial. Here we review the evidence bearing on the latter reactions and suggest a new view of their implications.

Beschreibung: Air at high pressure has recently been encountered during ground investigation borehole drilling for the Thames Tideway project in London. The air was released from within the Upnor Formation (at the base of the Lambeth Group beds), which is at the top of the Lower Aquifer. Cavitation within the granular beds of the Lower Aquifer would have occurred as a consequence of drawdown from the extensive water extraction that began at the start of the nineteenth century, resulting in the water table dropping by almost 70 m. Estimated historical pore pressure profiles are postulated and the cavitation process that occurred, along with the subsequent pressurization of the air during recharge that has occurred in recent years, are discussed using behavioural concepts from unsaturated soil mechanics. The hypotheses are corroborated by a series of simple column experiments where the processes are modelled using analogous soils. Engineering implications of the presence of the pressurized air are discussed: besides the potential for borehole blow-out, another serious consideration is the depletion of oxygen from the trapped air by chemical reaction with the soil, increasing the risk of confined space hypoxia.

Beschreibung: Predictions from laboratory tests of the compression behaviour of peat from 14 sites are compared with full-scale field loading at five sites. Data presented confirm the heterogeneous nature of the deposits. However, for typical engineering works, calculations based on laboratory test data are likely to give reasonable predictions of the magnitude of immediate and primary compression. Standard (20 mm thickness) samples may give misleading data on time for primary consolidation. Thicker samples (e.g. 50 mm) should be used. Sampling by conventional samplers, as used for mineral soils, can cause densification of the peat, resulting in underestimation of actual settlement. Block samples or sample tubes with serrated cutting edges are recommended for peat soils. It was found that the data presented follow the C α / C c law of compressibility. There is also is some evidence to suggest that the H 2 scaling law may be applicable. Good correlations were found between vertical yield stress ( p vy ') and compression index ( C c ) and index parameters such as water content ( w i ). Conventional staged construction with surcharge loading may be successfully applied to peat soils as long as adequate drainage exists to permit consolidation over reasonable time intervals.

Beschreibung: This paper discusses the interpretation of the pore water dissipation curves obtained during a piezocone test with the prime objective of determining the seismic behaviour of fine-grained soil. The pore pressure dissipation approach was attempted to perform a faster diagnosis of liquefiability of fine-grained soils where the ground water table is almost at the surface. Furthermore, because non-plastic silts are very difficult to sample for laboratory testing, such an in situ measurement appears to be the only realistic method for the purpose. Most of the dissipation tests were conducted by using the u 2 filter on the neck of the probe, and the others were performed by using the u 1 filter where the piezometer is located on the cone tip. Penetration was arrested at depths where the presence of silts had been detected by previous sounding and drilling, and t 50 , t 90 and t 100 were determined analytically. The results indicate that t 90 values have a notable potential for diagnosing a potential for liquefaction. This was demonstrated by a t 90 of 300 s or less for liquefiable layers, whereas considerably longer periods are required for non-liquefiable silts similar to clays. This feature is illustrated by the presentation of several types of dissipation curves.

Beschreibung: 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 .

Beschreibung: 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 .

Beschreibung: 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 .

Beschreibung: 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.

Beschreibung: 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.

Beschreibung: There is a basic assumption that the upper crustal point of magma emplacement overlies the point where magma was generated. This contribution discusses the concept of lateral magma movement in the upper crust based on the Mourne Granite Centres, Northern Ireland. We report anisotropy of magnetic susceptibility fabric data from the Western Mourne Centre that indicate SSW to NNE inflow in this centre, parallel to the Eastern Centre. This suggests that these two centres share a common feeder zone outside the Mourne area c. 20 km to the south, coincident with a c. 50 mGal gravity anomaly that may be caused by an unexposed mafic pluton. The links between mafic and felsic magmas in this region, and the coincidence of the projected Mourne granite feeder zone and the possible buried mafic pluton lead to a model in which the Mourne granites were emplaced in a NNE direction as two gently dipping sheets from this unexposed mafic body. From this we develop a model that incorporates existing geophysics and known tectonic framework and involves an interconnected upper crustal network of Early Palaeogene igneous intrusion pathways fed from a common tectonically controlled, and probably long-lived, deeply penetrating feeder zone.Supplementary material: Anisotropy of magnetic susceptibility data, thermomagnetic analyses and a thin section showing magnetite in biotite cleavage are available at http://www.geolsoc.org.uk/SUP18458.

Beschreibung: Combined U–Pb and Lu–Hf isotope analyses of zircons from 16 tonalite–trondjemite–granodiorite (TTG) gneiss and granite samples from Swaziland reveal that the oldest rocks of the Ancient Gneiss Complex in southern Africa formed by reworking of Early Archaean or perhaps Late Hadean crust at 3.66 Ga, and that new crust was extracted from a depleted mantle source during Palaeoarchaean events between 3.54 and 3.32 Ga. This interpretation is supported by eHft of -1.6 ± 2.0 obtained from 3.66 Ga TTG gneisses, corresponding to hafnium model ages between 3.77 ± 0.18 Ga, for a presumed Hadean–Early Archaean chondritic mantle, and 4.08 ± 0.18 Ga, for a presumed Hadean depleted mantle reservoir, with the first model age being the most likely in the light of recent data from worldwide sources. Furthermore, it is reflected by superchondritic eHft up to +2.2 ± 2.0 for TTGs formed at 3.54, 3.45 and 3.32 Ga. The new datasets additionally show that the Palaeoarchaean crust formed between 3.54 and 3.32 Ga was intensely reworked afterwards, without significant addition of depleted mantle derived material, during orogenic and intracratonic melting processes at 3.23, 3.1 and 2.7 Ga. This is well reflected by an array of decreasing eHft from +2.2 to -7.2 between 3.3 and 2.7 Ga, which can be forced by 176Lu/177Hf of 0.0113, which is similar to that of present-day average continental crust, and might result from lower crust zircon fractionation during Archaean crust reworking.Supplementary material: Results of in situ U–Pb and Lu–Hf isotope zircon analyses and concordia diagrams are available at www.geolsoc.org.uk/SUP18465.

Beschreibung: Dyke thickness datasets offer new insights into the detailed 3D geometry of dyke swarms and an exceptional opportunity to evaluate theoretical emplacement models. The Swartruggens kimberlite dyke swarm extends over 7 km along strike and intrudes a dolerite, quartzite, shale and andesitic lava succession. The Star kimberlite dykes cut shales and sandstones, intersect a large dolerite sill and extend 15 km along strike. Both dyke swarms comprise anastomosing en echelon segments, each several hundred metres long. In total 1532 Swartruggens dyke thickness measurements were taken, to 750 m below the surface over a 250 m depth range, and 3354 Star dyke thickness measurements were taken over a 520 m depth range. The Swartruggens dyke thicknesses are 0.05–1.95 m (mean 0.64 m), whereas the Star kimberlites range from

Beschreibung: The present-day Zagros mountain belt of SW Iran corresponds to the former Arabian passive continental margin of the southern Neo-Tethyan basin, which existed since a Permian–Triassic rifting episode and underwent later collisional deformation in mid- to late Cenozoic time. In West Zagros, the Kermanshah Radiolarian Trough, separated from the Neo-Tethyan basin by the narrow continental platform of the Bisotun Limestone, resulted from the Triassic–Jurassic rifting of the passive margin. Brittle tectonic analyses of syndepositional normal fault slip data have been undertaken to study the extensional history of the passive margin in terms of palaeostress reconstruction. Dominant east–west trends of the inherited rift-related normal faults in West Zagros indicate an approximately north–south trend of extension that prevailed during the entire Mesozoic syn- to post-rift evolution of the radiolarian trough. This extension characterizes a stretched continental margin similar to the present-day passive margin of the British Isles. Considering the structural pattern of the inherited basement faults, as revealed by the present-day earthquake focal mechanisms, an oblique crustal stretching model is proposed for the rifting process.

Beschreibung: Numerous structures and textures, which can be related to magma flow, were observed in felsic dykes intruding late Mesozoic granitoid plutons in the Jiaodong peninsula, in eastern Shandong province, eastern China. These flow structures may be classified into two categories, interior and peripheral. The former group includes magmatic bands, various types of folds (e.g. injection, sheath, similar and disharmonic folds), rotation of phenocrysts, magmatic foliation or lineation, and crenulation, whereas the latter includes hot tool marks and quarrying structures. Magmatic banding resulted from shearing of mingled magma during magma flow in the dykes. The magma seemed to flow rapidly, probably triggering turbulence in some thick dykes. Interaction at the contact between the hot, moving magma and the cold, stationary wallrock sometimes produced the peripheral structures. A few measurements of hot tool marks and of magmatic lineation reveal a roughly horizontal flow of magma within these dykes. For the dominant NE–SW-striking dyke set in the Laoshan granitoid pluton, the felsic magma probably ascended on or to the SW of the pluton to feed the dyke swarm, and then flowed laterally to drive the horizontal propagation of dykes.