ALBERT

Description: This paper successfully applied the geoengineering workflow for integrated well-test analysis to characterise fluid flow in a newly discovered fractured reservoir in the Barents Sea. A reservoir model containing fractures and matrix was built and calibrated using this workflow to match complex pressure transients measured in the field. We outline different geological scenarios that could potentially reproduce the pressure response observed in the field, highlighting the challenge of non-uniqueness when analysing well-test data. However, integrating other field data into the analysis allowed us to narrow the range of uncertainty, enabling the most plausible geological scenario to be taken forward for more detailed reservoir characterisation and history matching. The results provide new insights into the reservoir geology and the key flow processes that generate the pressure response observed in the field. This paper demonstrates that the geoengineering workflow used here can be applied to better characterise naturally fractured reservoirs. We also provide reference solutions for interpreting well-tests in fractured reservoirs where troughs in the pressure derivative are recognisable in the data.

Description: The high fluxes of iron minerals associated with aeolian dry deposition may result in an anomalously high reactive iron content and the rapid reoxidation of hydrogen sulfide in sediments. This will prevent the formation of pyrite and result in a ‘cryptic’ sulfur cycle. We studied the cycling of iron and sulfur in deep water (〉800 m water depth) sediments of the Red Sea and its northern extension, the Gulf of Aqaba. We found that the reactive iron content in the surface sediments of the Gulf of Aqaba and the Red Sea is high, whereas the amount of sulfur-bound iron is very low and decreases with the water depth. The presence of trace amounts of pyrite and zero-valent sulfur, as well as the isotopic compositions of sulfate and pyrite, which are consistent with sulfate reduction under substrate-limiting conditions, suggest that cryptic sulfur cycling is likely to be a result of the rapid reoxidation of hydrogen sulfide rather than the suppression of microbial sulfate reduction. The low amount of reactive iron and high organic carbon content in the sediments of the Shaban Deep, which are overlain by hypersaline hydrothermal brines, result in a non-cryptic sulfur cycle characterized by the preservation of pyrite in the sediments.Supplementary material: Data for sulfur speciation, iron speciation and sulfur isotope composition are available at https://doi.org/10.6084/m9.figshare.c.5508155Thematic collection: This article is part of the Sulfur in the Earth system collection available at: https://www.lyellcollection.org/cc/sulfur-in-the-earth-system

Description: Recent ichnological analysis conducted in two sections (Rodiles and Lastres) of the Asturian Basin revealed the presence of Halimedides Lorenz von Liburnau 1902, which occurs just above the black shales related to the end of the T-OAE. Halimedides is associated with the recovery of the tracemaker community after the reestablishment of favourable, oxic, conditions. The appearance of Halimedides after the T-OAE event, previously not registered, supports the close relationship of the tracemaker with oxygen conditions, as occurs in other anoxic events including the Cretaceous OAE-1a and OAE-2. Also a relation between morphometric and paleoenvironmental parameters is observed, occurring larger and densely chambered specimens in darker, weakly oxygenated facies, while smaller and sparsely chambered forms are registered in lighter, better oxygenated sediments.

Description: The geometry, distribution, and rock properties (i.e. porosity and permeability) of turbidite reservoirs, and the processes associated with turbidity current deposition, are relatively well known. However, less attention has been given to the equivalent properties resulting from laminar sediment gravity-flow deposition, with most research limited to cogenetic turbidite-debrites (i.e. transitional flow deposits) or subsurface studies that focus predominantly on seismic-scale mass-transport deposits (MTDs). Thus, we have a limited understanding of the ability of sub-seismic MTDs to act as hydraulic seals and their effect on hydrocarbon production, and/or carbon storage. We investigate the gap between seismically resolvable and sub-seismic MTDs, and transitional flow deposits on long-term reservoir performance in this analysis of a small (

Description: Micritic sediments containing dark, discrete, organic-rich burrows, situated in a light grey background carbonate mud, were deposited over a broad geographic area in deep-shelf, bathyal, and basinal environments in the western margin of the Tethys Ocean during the Early and Middle Jurassic. These hemipelagic deposits represent a distinct depositional regime marked by low-energy, soft-bottom and only locally dysoxic environments. Still, it is unclear whether the trace fossil assemblages occurring in these deposits pertain to a network of several community types -the ichnotaxa differing from basin to basin- or else a single community of environmentally broad-ranging, burrow-producing species. Lower Jurassic trace-fossil assemblages are found in the Western Carpathians and in the Subbetic, Betic Cordillera, i.e. in basins separated by more than 2,000 km in their original palaeogeographic areas. The stereotypical Chondrites and Zoophycos trace-fossil assemblages that occur in the analysed deposits share two ichnogenera of distinctive morphology (Lamellaeichnus, Teichichnus). Agglutinated foraminifera Bathysiphon occurs together with the described trace fossil assemblage and determines epibenthic palaeoenvironmental conditions. In the Western Carpathians, a Lamellaeichnus-dominated assemblage alternates with a Zoophycos-dominated assemblage in small, metre-scale cycles in the upper Pliensbachian, and the proportion of the Zoophycos assemblage increases stratigraphically upwards, probably owing to reduced basin ventilation during the early Toarcian. Within the southern Iberian Palaeomargin, represented by the Betic Cordillera, Zoophycos is scarce in the facies.

Description: Recently, time-lapse seismic (4D seismic) has been steadily used to demonstrate the relation between field depletion and 4D seismic response, subsequently to have more efficient field management. A key component of the reservoir monitoring is the knowledge of fluid movement and pressure variations. This information is vital to assist infill drillings and a trustworthy source to update reservoir models, consequently improving model-based reservoir management and decision-making process. However, in practice the 4D seismic interpretation of reservoirs with multipart production regime possesses ambiguities through different levels of uncertainty. Complex nature of some 4D seismic signals emphasizes the roles of competing effects, geology, rock and fluid interactions. Hence, a reliable 4D interpretation requires an interdisciplinary approach entailing data analysis and insights from geophysics, engineering and geology. In this research, a step-wise workflow was introduced to reduce uncertainties in the 4D seismic interpretation and provide diagnoses to perform better reservoir surveillance. In parallel, the workflow expresses the use of engineering data analysis to conduct a consistent interpretation and encompasses the 3D and 4D seismic attributes with engineering data analysis. This study is implemented in a Brazilian heavy-oil offshore field where production started in 2013. The field experienced intense production activity up to 2016, making the deep-water field an ideal candidate to explore the challenges in interpreting complex 4D signals. Beyond these challenges, significant understanding of reservoir behavior is obtained and suggestions are made to improve the reservoir simulation model, which could support reservoir engineers with data assimilation applications.

Description: Early Paleozoic trondhjemites, gneissic granites and alkali granites in southern Yunnan preserve important records of the tectonic evolution of the Prototethyan Ocean and regional correlations. Zircon ages suggest that these granitoids were emplaced from 476 to 436 Ma. The trondhjemites are characterized by high Na2O and low K2O contents, with εNd(t) values of −1.9 to −3.5 and εHf(t) values of −2.8 to +3.9. The trondhjemites were derived from an amphibolite source with a juvenile mafic component. The gneissic granites belong to the metaluminous low-K calc-alkaline series with an εNd(t) value of −6.2 and εHf(t) values of −5.0 to −0.4. The alkali granites belong to the high-K calc-alkaline series and yield εNd(t) values of −10.1 to −10.7 and εHf(t) values of −7.9 to −2.3. The gneissic granites were derived from an ‘ancient' lower mafic crust, whereas the alkali granites were derived from a meta-sedimentary source. These granitoids were formed during the subduction of the Prototethyan Ocean beneath the Simao Block and can be compared with similar igneous rocks from the Truong Son and Tam Ky-Phuoc Son zones in southern Laos. Our study, along with Early Paleozoic igneous suites from southern Laos, central Vietnam and the Malay Peninsula, suggests an arc–back-arc system along the northern margin of Gondwana.Supplementary material: Tables of zircon U–Pb and in-situ Hf and geochemical data are available at https://doi.org/10.6084/m9.figshare.c.5322386

Description: Observation of basin-scale networks of sandstone intrusions are described from subsurface studies and outcrop locations. Regional scale studies are prevalent in the volume and two new regionally significant subsurface sand injection complexes are described. Higher resolution studies, both outcrop and subsurface, show the small-scale complexity but high level of connectedness of sandstone intrusions. Discordance with bedding at all scales is diagnostic of sandstone intrusions. The propensity of hydraulic fractures to develop and fill with fluidised sand in a broad range of host rocks is demonstrated by examples from metamorphic and magmatic basement, and lignite. Terminology used to describe sandstone intrusions and other elements of sand injection complexes is diverse.

Description: This study discusses the petrological and geochemical features of two monogenetic Miocene volcanoes, Mount Early and Sheridan Bluff, which are the above-ice expressions of Earth's southernmost volcanic field located at c. 87° S on the East Antarctic Craton. Their geochemistry is compared to basalts from the West Antarctic Rift System to test affiliation and resolve mantle sources and cause of melting beneath East Antarctica. Basaltic lavas and dykes are olivine-phyric and comprise alkaline (hawaiite and mugearite) and subalkaline (tholeiite) types. Trace element abundances and ratios (e.g. La/Yb, Nb/Y, Zr/Y) of alkaline compositions resemble basalts from the West Antarctic rift and ocean islands (OIB), while tholeiites are relatively depleted and approach the concentrations levels of enriched mid-ocean ridge basalt (E-MORB). The magmas evolved by fractional crystallization with contamination by crust; however, neither process can adequately explain the contemporaneous eruption of hawaiite and tholeiite at Sheridan Bluff. Our preferred scenario is that primary magmas of each type were produced by different degrees of partial melting from a compositionally similar mantle source. The nearly simultaneous generation of lower degrees of melting to produce alkaline types and higher degrees of melting forming tholeiite was most likely to have been facilitated by the detachment and dehydration of metasomatized mantle lithosphere.

Description: Two small monogenetic volcanoes are exposed at Mount Early and Sheridan Bluff, in the upper reaches of Scott Glacier. In addition, the presence of abundant fresh volcanic detritus in moraines at two other localities suggests further associated volcanism, now obscured by the modern Antarctic ice sheet. One of those occurrences has been attributed to a small subglacial volcano only c. 200 km from South Pole, making it the southernmost volcano in the world. All of the volcanic outcrops in the Scott Glacier region are grouped in a newly defined Upper Scott Glacier Volcanic Field, which is part of the McMurdo Volcanic Group (Western Ross Supergroup). The volcanism is early Miocene in age (c. 25–16 Ma), and the combination of tholeiitic and alkaline mafic compositions differs from the more voluminous alkaline volcanism in the West Antarctic Rift System. The Mount Early volcano was erupted subglacially, when the contemporary ice was considerably thicker than present. By contrast, lithologies associated with the southernmost volcano, currently covered by 1.5 km of modern ice, indicate that it was erupted when any associated ice was either much thinner or absent. The eruptive setting for Sheridan Bluff is uncertain and is still being investigated.

Description: The Erebus Volcanic Province is the largest Neogene volcanic province in Antarctica, extending c. 450 km north–south and 170 km wide east–west. It is dominated by large central volcanoes, principally Mount Erebus, Mount Bird, Mount Terror, Mount Discovery and Mount Morning, which have sunk more than 2 km into underlying sedimentary strata. Small submarine volcanoes are also common, as islands and seamounts in the Ross Sea (Terror Rift), and there are many mafic scoria cones (Southern Local Suite) in the Royal Society Range foothills and Dry Valleys. The age of the volcanism ranges between c. 19 Ma and present but most of the volcanism is

Description: The Hudson Strait Platform and basins Tectono-Sedimentary Element (HSPB TSE) is part of a major topographic feature that connects Hudson Bay and Foxe Basin with the Labrador Sea in the Canadian Arctic. The Paleozoic succession (Ordovician to Silurian) unconformably overlies the Precambrian basement and reaches a maximum preserved thickness of less than 600 m on the islands. High-resolution marine seismic data indicate that the offshore part of the Hudson Strait is underlain by several fault-controlled sub-basins with a half-graben geometry. The sedimentary succession in the sub-basins is thicker than the one preserved in nearby islands and includes an upper sedimentary package for which the nature and age remain poorly constrained. Upper Ordovician source rocks have been mapped onshore. Known potential reservoir rocks consist of Ordovician clastics and Ordovician-Silurian reefs and dolostones.

Description: The Devonian Period was a crucial interval in the evolution of plants. During its 60 myr duration, it witnessed the successive evolution of roots, wood, trees and forests, and many of the biogeomorphic phenomena that operate in modern terrestrial environments came online for the first time. The Old Red Sandstone (ORS) of Svalbard consists of a near-continuous Silurian to Late Devonian record of land plant-colonized sedimentary environments and provides a perfect natural laboratory to aid understanding of the facies signatures and evolution of these phenomena. Here we describe and illustrate a catalogue of ORS features that provide evidence for the stepwise appearance of novel plant-sediment interactions, including: preserved plant material and rooting structures, early large woody debris accumulations, cannel coal deposits, and the oldest known vegetation-induced sedimentary structures, in addition to vegetation-influenced motifs of elevated mudrock content and complex alluvial sand bodies. These characteristics are combined to reconstruct changes to non-marine environments in this Devonian ‘landscape factory’. In addition to tectonic and climate influences, plant evolution first served as a control on the construction of the sedimentary record during this period and has persisted as a fundamental influence on Earth surface processes and landforms ever since.

Description: Gaussberg is a nunatak composed of lamproite pillow lava situated on the coast of East Antarctica. It is the most isolated Quaternary volcanic centre in Antarctica but it is important palaeoenvironmentally and petrologically out of all proportion to its small size. The edifice has a likely low, shield-like, morphology c. 1200 m high and possibly up to 10 km wide, which is unusually large for a lamproite construct. Gaussberg was erupted subglacially at 56 ± 5 ka, which places it late in the last glacial, close to the peak of marine isotope stage 3. The coeval ice sheet was c. 1300 m thick, and c. 420 m has been removed from the ice surface since Gaussberg erupted. Lamproite is a rare ultrapotassic mantle-derived magma, and Gaussberg is one of two type examples worldwide. Although traditionally considered as related in some way to the Kerguelen plume, it is more likely that the Gaussberg magma is a product of a separate magmatic event. It is ascribed to the storage and long-term (Gy) isolation of sediment emplaced by subduction in the Transition Zone of the deep mantle, followed by entrainment and subsequent melting in a plume.

Description: Calc-alkaline lamprophyres from the western Carpathians occur as dykes and sills in the crystalline complexes (predominantly granites and gneisses) of the Tatric Unit. Some of the lamprophyre dykes have been strongly overprinted by tectonism and hydrothermal fluid ingress. They have a similar mineralogical composition, and they are comprised of clinopyroxene, amphibole, biotite and plagioclase. Based on their modal composition, they can be classified as spessartites and kersantites, and based on their geochemical composition, most of them are of calc-alkali type. Lamprophyres from individual core complexes (e.g. the Malá Fatra Mountains and Nízke Tatry Mountains) exhibit variable Nb, Ta and Sr-Nd isotope signatures. These differences are probably due to compositional variations in the mantle source and/or the lower crust at the site of lamprophyre melt generation, or variable incorporation of crustal material. The age of the lamprophyres is Permian (ca. 265 Ma) based on U-Pb LA-ICP-MS dating of apatite micro-phenocrysts.

Description: Aspiculate demosponges are rarely described in geological history on account of the absence of spicules that are stable and resistant to degradation. One exception is the exquisite preservation of sponges without any mineralised skeletons discovered in Lagerstätten (e.g. the Burgess Shale). The Chengjiang Biota, an early example of a Burgess Shale-type Biota in South China (Cambrian Series 2, Stage 3), is one of the only examples of convincing aspiculate sponges until now. Here, we describe Vauxia pregracilenta sp. nov. and V. paraleioia sp. nov., as well as two poorly preserved vauxiid specimens (Vauxia sp.) in open nomenclature, from the Chengjiang Biota. V. pregracilenta has a fan-like holdfast and branches in various sizes, as well as a typical two-layered net-like skeleton, without spicules. The endosomal layer is hexagonal, while the dermal layer is sub-rectangular. V. paraleioia is characterised by a two-layered subconical skeleton, with the dermal layer ornamented with vertical surface grooves. The openings of the dermal and endosomal layers of V. paraleioia are both hexagonal but of different sizes. These newly discovered Vauxia species indicate that the aspiculate sponges were diversified in the early Cambrian period. Partial silicification of the fibres of aspiculate Vauxia are confirmed from the Chengjiang Biota.Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/cc/advances-cambrian-explosion

Description: The Jurassic and Cretaceous sedimentary infill of the Irish and Celtic Sea basins is intimately associated with the breakup of the supercontinent Pangea, and the opening of the Atlantic margin. Previous basin studies have constrained tectonism, basin uplift and sediment composition, but sediment provenance and routing have not received detailed consideration. Current hypotheses for basin infill suggest localised sediment sourcing throughout the Jurassic and Cretaceous, despite a dynamic tectonic and paleoenvironmental history spanning more than 100 million years. We present detrital zircon, white mica and apatite geochronology alongside heavy mineral data from five basins. Findings reveal that basin infill derived predominantly from distal sources with lesser periods of local sourcing. We deduce that tectonically induced marine transgression and regression events had a first-order control on distal versus proximal sedimentary sourcing. Additionally, tectonism which uplifted the Fastnet Basin region during the Middle–Late Jurassic recycled basin sediments into the connected Celtic and Irish Sea Basins. Detrital geochronology and heavy mineral evidence support three distinct provenance switches throughout the Jurassic and Cretaceous in these basins. Overall an integrated multi-proxy provenance approach provides novel insights to tectonic and environmental controls on basin infill as demonstrated in the Irish and Celtic Sea Basins.

Description: This contribution is an overview of the Early Jurassic dinoflagellate cysts of the Lusitanian Basin in Portugal, with particular emphasis on the effects of the Jenkyns Event (Toarcian Oceanic Anoxic Event - T-OAE) on the evolution of this planktonic group. We review and discuss data from 214 samples from six Lower Jurassic successions (upper Sinemurian-upper Toarcian) in the Lusitanian Basin. The late Pliensbachian radiation of dinoflagellate cysts was well recognised in this basin. The pre-Jenkyns Event interval is highly productive, with maximum abundance and species richness values. However, this palaeoenvironmental perturbation severely affected the evolution of this group for the remainder of the Early Jurassic. The prolonged recovery of the dinoflagellates in the Toarcian following the Jenkyns Event is not typical of the northern regions (Arctic and Boreal realms), where new species began to evolve earlier compared with southern European basins.

Description: Late Permian to Early Jurassic strata in northern Peru allows us to carry out a seismo-stratigraphic, litho-tectonic and chemostratigraphic analysis connecting the Andean-Amazonian foreland basins of Huallaga, Ucayali, southern Marañón, and the Eastern Cordillera. This analysis and data integration from Ecuador to western Brazil and southern Peru and Bolivia, allow us to redefine the timing of the major documented tectonic phases and corresponding palaeogeographies of western Gondwana from the late Permian to Triassic. Three litho-tectonic sequences and four associated deformation stages are recognized: 1) A sequence, tectonic relaxation, during late Permian; 2) A-B intra-sequence, folding-and-thrusting attributed to a continuation in time of the Gondwanide Orogeny, during the Early to Middle Triassic; 3) B sequence, rifting, attributed to Gondwana breakup during the Middle and Late Triassic; and 4) C Sequence, thermal sag, during the Late Triassic. Evaporites and carbonates (A sequence) dominated a low subsidence basin with southern restricted marine inflow at the Permian-Triassic boundary. A novel palaeogeographic model for these evaporites suggests that this saline basin extended up to 50,000 km2 in a restricted environment area with a potential bullseye pattern. The last pulse of the Gondwanide Orogeny and associated fold and thrust belt (A-B intra-sequence) exhumed previous the sequence generating emerged areas with little to no sedimentation. Red beds (B sequence) characterize the rifting stage, representing the syn-depositional infill of continental grabens, likely extending to the Acre Basin in Brazil. Finally, during the thermal sag, a marine inflow likely from the northwestern part of Peru generated sedimentation of carbonates and evaporites (C Sequence) to the west and east of the Peruvian margin. This sediment differentiation was, in part, controlled by the existence of pre-existing grabens associated to the previous rifting stage. This interpretation, together with other evaporitic occurrences attributed here to a Late Triassic epoch in south and north Peru and west Brazil, suggest the existence of an evaporitic basin filling an undeformed area of probably ca. 170,000 km2. It is therefore suggestive of the existence of a Late Triassic (Norian to Rhaetian; 217 to 204 Ma) salt giant controlled by thermal sag in western Gondwana. Our results are of great relevance for any future interpretation related to mass extinctions, paleoclimatic analysis and ocean dynamics during the Permian and Triassic as well as natural resources distribution between Ecuador and Bolivia.

Description: In December 1903, Williams Speirs Bruce, leader of the Scottish National Antarctic Expedition, arrived in Buenos Aires and contacted Francisco Moreno, director of the Museo de La Plata to request his assistance. Bruce asked Moreno to be an intermediary with the Argentine government and to facilitate Bruce's wish for Argentina to take over the meteorological station that the Scottish expedition had established on Laurie Island (South Orkney Islands). Moreno was please to provide the necessary assistance and was instrumental in Bruce achieving his ambition. As a gesture of appreciation, before leaving Buenos Aires Bruce presented a small collection of Laurie Island rock specimens to Moreno as a donation to the Museo de La Plata. This donation initiated the museum's Antarctic collection.

Description: The Tromsø - Bjørnøya composite tectono-sedimentary element in the southwestern Barents Sea comprises strata of Late Paleozoic - Paleocene age. Since the Paleozoic Caledonian orogeny, the structural evolution of the CTSE is mainly related to extension, culminating in Late Jurassic - Early Cretaceous hyperextension. Some compressive deformation observed during Late Cretaceous - Paleogene times may relate to activity in the North Atlantic prior to the Early Eocene onset of sea floor spreading between Norway and Greenland.The sedimentary succession may be up to 14 km thick. It comprises Late Paleozoic continental facies, followed by carbonates, evaporites and eventually cherts and marine clastic material. The overlying Triassic - Paleocene succession is entirely siliciclastic, reflecting Triassic - Middle Jurassic deltaic and shallow marine conditions followed by deeper marine conditions during Late Jurassic - Paleocene times.Primary reservoirs are encountered in the latest Triassic - Middle Jurassic succession, with secondary reservoirs found in Late Jurassic - Early Cretaceous syn-rift succession, and in Paleocene strata. The primary source rock for petroleum is of Late Jurassic - Early Cretaceous age. Other source rocks include strata of Triassic and Barremian age, and a recently observed unit of Cenomanian - Early Turonian age.

Description: There is increasing acceptance of the presence of variable magmatic contributions to the mineralizing fluids in the formation of volcanogenic massive sulfide (VMS) deposits. The world-class Windy Craggy Cu-Co-Au deposit (〉300 MT @ 2.12 wt.% Cu) in northwestern British Columbia is of interest because, unlike most VMS deposits, quarts fluid inclusions from within the deposit range from relatively low to intermediate salinity (most 6-16 wt.% equivalent). In this study we used an excimer (193 nm) laser ablation system interfaced to a quadrupole inductively coupled plasma mass spectrometer to quantify key metals and metalloids that are considered by many to be indicative of magmatic contributions to hydrothermal ore deposits. Although LA-ICP-MS signals from these low-salinity inclusions are highly transient, we were able to quantify Na, Mg, K, Ca, Mn, Fe, Co, Cu, Zn, Sr, Sn, Ba, Ce, Pb and Bi consistently – of the 34 elements that were monitored. Furthermore, Cl, Sb, Cd, Mo, Rb, Br, and As were also measured in a significant number of inclusions. Comparison of the fluid inclusion chemistry with unaltered and altered mafic volcanic and sedimentary rocks and mineralized samples from the deposit indicate that enrichment in the main ore metals (Cu, Zn, Fe, Pb) in the inclusions reflects that of the altered rocks and sulfides. Metals and metalloids that may indicate a magmatic contribution typically show much greater enrichments in the fluid inclusions much greater over the host rocks at the same Cu concentration; in particular Bi, Sn and Sb are significantly elevated when compared to the host rock samples. These data are consistent with the ore-forming fluids at Windy Craggy having a strong magmatic contribution.

Description: The Geological Society of London was founded in 1807. At the time, membership was restricted to men, many of whom became well-known names in the history of the geological sciences. On the 21 May 1919, the first female Fellows were elected to the Society, 112 years after its formation.This Special Publication celebrates the centenary of that important event. In doing so it presents the often untold stories of pioneering women geoscientists from across the world who navigated male-dominated academia and learned societies, experienced the harsh realities of Siberian field-exploration, or responded to the strategic necessity of the ‘petroleum girls’ in early American oil exploration and production.It uncovers important female role models in the history of science, and investigates why not all of these women received due recognition from their contemporaries and peers. The work has identified a number of common issues that sometimes led to original work and personal achievements being lost or unacknowledged, and as a consequence, to histories being unwritten.

Description: In order to reduce uncertainties around CO2 containment for the South West Hub CCS site (Western Australia), conceptual fault hydrodynamic models are defined, and numerical simulations are carried out. These simulations model worst-case scenarios with a plume reaching a main compartment bounding fault near the proposed injection depth and at the faulted interface between the primary and secondary containment interval.The conceptual models incorporate host rock and fault properties accounting for fault zone lithology, cementation, and cataclastic processes but with no account for geomechanical processes as the risk of reactivation is perceived as low. Flow simulations are performed to assess cross- and up-fault migration in case of plume-faults interaction.Results near the injection depth suggest that the main faults are likely to experience significant reduction in transmissivity and impede CO2 flow. This could promote migration of CO2 vertically or along the stratigraphic dip.Results near the interface between the primary and secondary containment intervals show that none of the main faults would critically control CO2 flow nor would they act as primary leakage pathways. CO2 flow is predicted to be primarily controlled by the sedimentological morphology. The presence of baffles in the secondary containment interval is expected to be associated with local CO2 accumulations; additional permeability impacts introduced by faults is minor.Thematic collection: This article is part of the Geoscience for CO2 storage collection available at: https://www.lyellcollection.org/cc/geoscience-for-co2-storage

Description: Eagle Foreland Basin Tectono-Sedimentary Element (TSE) comprises two separate parts: a larger rectilinear sub-basin of Cretaceous age (Eagle Plain) and a smaller fault-bounded mid-Cretaceous to Paleogene sub-basin (Bonnet Plume) in the southeast, separated from Eagle Plain by an inlier of Ogilvie Platform TSE. Faulted remnants of NW Canada Riftogenic TSE are locally preserved beneath northern parts of Eagle Plain sub-basin. Eagle Foreland Basin initiated as a Cordilleran foredeep and was incorporated into the orogen during Late Cretaceous to Paleogene deformation. It preserves dominantly marine clastic strata 〉2500 m thick, with thickest preservation in the northwest. Thermal maturity data suggest that 2000 to 3000 m of deposits were removed by Paleogene erosion. Petroleum potential exists, with principal active sources lying within subjacent successions. Eagle Plain sub-basin is an early-mature to mature basin, oil and gas prone in the deeper basin and gas prone in younger units. Bonnet Plume sub-basin, known for its coal-bearing strata, is largely unexplored. It contains non-marine to marginal marine clastic strata and is considered to be a marginally mature to mature gas-prone basin. The total mean in-place potential is 19 million m3 of oil and 22.5 billion m3 of gas in Eagle Plain sub-basin and 2.3 billion m3 of gas is expected in conceptual plays in Bonnet Plume sub-basin.

Description: The south-central Barents Sea today comprises a shallow continental shelf with water depths mainly in the 200-400m range, straddling the Norway-Russia marine boundary. Geologically it consists of a stable platform (the Bjarmeland Platform), dissected by rifts of probable Late Carboniferous age, with a significant and geologically persistent basement high (the Fedynsky High) in its south-eastern part. The rifts are the ENE-WSW trending Nordkapp Basin, the similarly-trending but less clearly demarcated Ottar Basin, and the NW-SE Tiddlybanken Basin. The varying rift trends appear to reflect the orogenic grain patchwork of the basement (Caledonide and Timanide), and these basins were infilled with a variable facies assemblage including substantial Carboniferous-Permian halites.Massive sedimentary influx of fluvio-deltaic to shallow marine sediments took place in the Triassic, from the E and SE (Urals, Novaya Zemlya and western Siberia) and south (Baltic Shield), resulting in doming and diapirism in the areas of thickest salt, particularly in the rifts. The succeeding Jurassic, Cretaceous and Cenozoic successions are generally thin, locally thickening in rim synclines and in the NE of the area towards the deep basins flanking Novaya Zemlya. Reactivation of the halokinetic structures took place in the early Cenozoic, probably associated with the development of the NE Atlantic-Arctic Ocean linkage.Marine source rocks of Triassic and Late Jurassic age are present in the area, along with Carboniferous and Permian source rocks of uncertain effectiveness. Petroleum has been found in Jurassic and Triassic clastic reservoirs, including recent shallow Jurassic oil and gas discoveries. Although none are currently in production, near-future oil development is likely in Wisting discovery, on the western margin of the area. New exploration, including drilling, is currently taking place in the east of the area as a result of recent Norwegian and Russian licensing.

Description: Special Publication 503 celebrates the career of R. Damian Nance. It features 27 articles, with more than 110 authors based in 18 different countries. These articles include contributions on the processes responsible for the formation and breakup of supercontinents, the controversies concerning the status of Pannotia as a supercontinent, the generation and destruction of Paleozoic oceans, and the development of the Appalachian-Ouachitan- Caledonide-Variscan orogens. In addition to field work, the approaches to gain that understanding include examining the relationships between stratigraphy and structural geology, precise geochronology, geochemical and isotopic fingerprinting, geodynamic modelling, regional syntheses, palaeogeographic modelling, and good old-fashioned arm-waving!The wide range of topics mirrors the breadth and depth of Damian's contributions, interests and expertise. Like Damian's papers, the contributions range from the predominantly conceptual to detailed field work, but all are targeted at understanding important tectonic processes. Their scope not only varies in scale from global to regional to local, but also in the range of approaches required to gain that understanding.

Description: A combination of aerogeophysics, seismic observations and direct observation from ice cores, and subglacial sampling, has revealed at least 21 sites under the West Antarctic Ice Sheet consistent with active volcanism (where active is defined as volcanism that has interacted with the current manifestation of the West Antarctic Ice Sheet). Coverage of these datasets is heterogeneous, potentially biasing the apparent distribution of these features. Also, the products of volcanic activity under thinner ice characterized by relatively fast flow are more prone to erosion and removal by the ice sheet, and therefore potentially under-represented. Unsurprisingly, the sites of active subglacial volcanism that we have identified often overlap with areas of relatively thick ice and slow ice surface flow, both of which are critical conditions for the preservation of volcanic records. Overall, we find the majority of active subglacial volcanic sites in West Antarctica concentrate strongly along the crustal-thickness gradients bounding the central West Antarctic Rift System, complemented by intra-rift sites associated with the Amundsen Sea–Siple Coast lithospheric transition.

Description: The Balder Field reservoir sandstone has been interpreted as remobilized from a Mesozoic parent bed. This paper seeks to address the questions raised about this unusual origin. Research and broadly analogous processes are reviewed leading to the proposal that the parent beds may have been fluidized by bedding-parallel retrogressive entrainment of Statfjord Formation sands by a connected larger source of overpressured fluids. These fluids are identified as most likely derived by lateral migration from the Viking Graben, initiated in response to early Eocene basin inversion related to North Atlantic rifting. The event probably involved breaching of the topseal in multiple places over a large section of the Utsira High. The geometry of large sills formed from small breach points and internal differentiation seen may show that the sills inflated by lateral accretion from a medial active flowing zone of turbulent, transitional or laminar flowing suspension. It is suggested that sequence-stratigraphic and structural context should be considered as additional criteria to discriminate between depositional and intruded sands.

Description: Many studies have constrained that late-Variscan buckling produced the arcuate geometry of the Ibero-Armorican belt. Nonetheless, debate remains on the associated geodynamic framework. Poorly studied Late Carboniferous intramontane basins offer an excellent framework to decipher the timing and kinematics of the late- to post-Variscan tectonics. Understanding the latter also helps constrain the structural emplacement mode of contemporaneous W-Sn-Nb-Ta-Li mineralisation. In Iberia, the Porto-Sátão syncline is exemplary of such a Late Carboniferous intramontane basin. We present a structural analysis of the syncline, its basement and the associated W-Sn deposits. The regional structure is dictated by the Alcudian angular unconformity, caused by Cadomian tectonics (575-555Ma) and separating tilted Ediacaran and subhorizontal Lower Palaeozoic formations. Superposed Variscan deformation led to F1-F3 folds with steep and gentle plunges, respectively. The late-orogenic D3 fabric is locally affected by post-orogenic F4 kink folds and a S4 crenulation cleavage. W-Sn bearing vein systems occur along granite-hosted cone sheets, or exploit cross-fold joints associated with the F3 and F4 fold generations, revealing a close kinematic relationship between granite-related mineralisation and the late- to post-Variscan deformation style. This structural history is interpreted as a plate-scale geodynamic change from Late Carboniferous N-S (D3) to Early Permian WNW-ESE (D4) convergence.

Description: A volcanogenic clay bed (tonstein) has been identified in the Balcomie Beds of the Inverclyde Group near Crail, east Fife. Its chemical composition suggests an undersaturated alkaline magma source. This horizon may be contemporaneous with the early Carboniferous Garleton Hills trachytic lavas of East Lothian (346Ma). This would make it the earliest expression of Carboniferous volcanism preserved in Fife, and also the earliest occurrence of a tonstein in Fife.

Description: Abundant mantle-derived ultramafic xenoliths occur in Cenozoic (7.7-1.5 Ma) mafic alkaline volcanic rocks along the former active margin of West Antarctica, that extends from the northern Antarctic Peninsula to Jones Mountains. The xenoliths are restricted to post-subduction volcanic rocks that were emplaced in fore-arc or back-arc positions relative to the Mesozoic-Cenozoic Antarctic Peninsula volcanic arc. The xenoliths are spinel-bearing, include harzburgites, lherzolites, wehrlites and pyroxenites, and provide the only direct evidence of the composition of the lithospheric mantle underlying most of the margin. The harzburgites may be residues of melt extraction from the upper mantle (in a mid-ocean ridge type setting), that accreted to form oceanic lithosphere, which was then subsequently tectonically emplaced along the active Gondwana margin. An exposed highly-depleted dunite-serpentinite upper mantle complex on Gibbs Island, South Shetland Islands, supports this interpretation. In contrast, pyroxenites, wehrlites and lherzolites reflect percolation of mafic alkaline melts through the lithospheric mantle. Volatile and incompatible trace element compositions imply that these interacting melts were related to the post-subduction magmatism which hosts the xenoliths. The scattered distribution of such magmatism and the history of accretion suggest that the dominant composition of sub-Antarctic Peninsula lithospheric mantle is likely to be harzburgitic.

Description: The provenance of Devonian Old Red Sandstone (ORS) continental successions in the northern Scottish Caledonides is poorly known: were they derived locally or from more distal sources? The integration of U-Pb and Hf isotope analyses in detrital zircon crystals reduces potential ambiguities arising from non-unique age populations and yields information on the crustal evolution of source terranes. Samples of basal ORS successions yield zircon U-Pb age groupings of c. 1800–1500 and c. 1200–900 Ma, with minor Neoarchaean, Tonian, Ediacaran and Ordovician contributions. SW Baltica provides the best match for detrital zircon ages and Hf isotopic signatures, and much of the 〉900 Ma zircon population was probably recycled from Neoproterozoic successions. εHf(t) values in c. 1800–1000 Ma grains reflect the assembly of Nuna, development of a long-lived retreating subduction system along its margin, and Grenville collisional orogenesis. These basal ORS successions were likely deposited within the same regional fluvial system as coeval sedimentary rocks in the Midland Valley, draining an area of positive relief in SW Baltica where continental convergence continued through the Early Devonian.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5301780

Description: The Antarctic Peninsula contains a record of continental-margin volcanism extending from Jurassic to Recent times. Subduction of the Pacific oceanic lithosphere beneath the continental margin developed after Late Jurassic volcanism in Alexander Island that was related to extension of the continental margin. Mesozoic ocean-floor basalts emplaced within the Alexander Island accretionary complex have compositions derived from Pacific mantle. The Antarctic Peninsula volcanic arc was active from about Early Cretaceous times until the Early Miocene. It was affected by hydrothermal alteration, and by regional and contact metamorphism generally of zeolite to prehnite–pumpellyite facies. Distinct geochemical groups recognized within the volcanic rocks suggest varied magma generation processes related to changes in subduction dynamics. The four groups are: calc-alkaline, high-Mg andesitic, adakitic and high-Zr, the last two being described in this arc for the first time. The dominant calc-alkaline group ranges from primitive mafic magmas to rhyolite, and from low- to high-K in composition, and was generated from a mantle wedge with variable depletion. The high-Mg and adakitic rocks indicate periods of melting of the subducting slab and variable equilibration of the melts with mantle. The high-Zr group is interpreted as peralkaline and may have been related to extension of the arc.

Description: The voluminous continental margin volcanic arc of the Antarctic Peninsula is one of the major tectonic features of West Antarctica. It extends from the Trinity Peninsula and the South Shetland Islands in the north to Alexander Island and Palmer Land in the south, a distance of c. 1300 km, and was related to east-directed subduction beneath the continental margin. Thicknesses of exposed volcanic rocks are up to c. 1.5 km, and the terrain is highly dissected by erosion and heavily glacierized. The arc was active from Late Jurassic or Early Cretaceous times until the Early Miocene, a period of climate cooling from subtropical to glacial. The migration of the volcanic axis was towards the trench over time along most of the length of the arc. Early volcanism was commonly submarine but most of the volcanism was subaerial. Basaltic–andesitic stratocones and large silicic composite volcanoes with calderas can be identified. Other rock associations include volcaniclastic fans, distal tuff accumulations, coastal wetlands and glacio-marine eruptions.Other groups of volcanic rocks of Jurassic age in Alexander Island comprise accreted oceanic basalts within an accretionary complex and volcanic rocks erupted within a rift basin along the continental margin that apparently predate subduction.

Description: Young volcanic centres of the Bransfield Strait and James Ross Island occur along back-arc extensional structures parallel to the South Shetland island arc. Back-arc extension was caused by slab rollback at the South Shetland Trench during the past 4 myr. The variability of lava compositions along the Bransfield Strait results from varying degrees of mantle depletion and input of a slab component. The mantle underneath the Bransfield Strait is heterogeneous on a scale of approximately tens of kilometres with portions in the mantle wedge not affected by slab fluids. Lavas from James Ross Island east of the Antarctic Peninsula differ in composition from those of the Bransfield Strait in that they are alkaline without evidence for a component from a subducted slab. Alkaline lavas from the volcanic centres east of the Antarctic Peninsula imply variably low degrees of partial melting in the presence of residual garnet, suggesting variable thinning of the lithosphere by extension. Magmas in the Bransfield Strait form by relatively high degrees of melting in the shallow mantle, whereas the magmas some 150 km further east form by low degrees of melting deeper in the mantle, reflecting the diversity of mantle geodynamic processes related to subduction along the South Shetland Trench.

Description: The South Chukchi-Hope Tectono-Sedimentary Element rests on the Neocomian folded basement formed as a result of the South Anyui palaeo-ocean closure. The interpretation of 2D seismic data as well as results of onshore structural field studies and dating of post-kinematic granite plutons suggest post-collisional extensional/transtensional regimes, potentially driving development of the South Chukchi-Hope Basin. The orogenic collapse occurred during the Aptian-Albian and followed by continued poly-phase extensional/transtensional regime during the Late Cretaceous and Cenozoic. Depositional environments in the basin were most likely non-marine in the Cretaceous and Early Tertiary and marine from the Late Oligocene (?) - Miocene onwards. Three onshore wells in the adjacent depocentres penetrated Tertiary sediments and have had gas shows from two sites. Geochemical surveys registered anomalies of thermogenic and biogenic methane and in some instances higher molecular ethane to penthane gases in sea-bottom sediments above gas chimneys observed on seismic lines. The tectono-sedimentary element is characterized by a very high present-day thermal gradient of up to 48 deg. C/km recorded in the Alaskan wells and was previously considered to be gas-prone.

Description: Nineteen large (2348–4285 m above sea level) central polygenetic alkaline shield-like composite volcanoes and numerous smaller volcanoes in Marie Byrd Land (MBL) and western Ellsworth Land rise above the West Antarctic Ice Sheet (WAIS) and comprise the MBL Volcanic Group (MBLVG). Earliest MBLVG volcanism dates to the latest Eocene (36.6 Ma). Polygenetic volcanism began by the middle Miocene (13.4 Ma) and has continued into the Holocene without major interruptions, producing the central volcanoes with 24 large (2–10 km-diameter) summit calderas and abundant evidence for explosive eruptions in caldera-rim deposits. Rock lithofacies are dominated by basanite and trachyte/phonolite lava and breccia, deposited in both subaerial and ice-contact environments. The chronology of MBLVG volcanism is well constrained by 330 age analyses, including 52 new 40Ar/39Ar ages. A volcanic lithofacies record of glaciation provides evidence of local ice-cap glaciation at 29–27 Ma and of widespread WAIS glaciation by 9 Ma. Late Quaternary glaciovolcanic records document WAIS expansions that correlate to eustatic sea-level lowstands (MIS 16, 4 and 2): the WAIS was +500 m at 609 ka at coastal Mount Murphy, and +400 m at 64.7 ka, +400 m at 21.2 ka and +575 m at 17.5 ka at inland Mount Takahe.

Description: Korotaikha Composite Tectono-Sedimentary Element constitutes the northeastern part of the Timan-Pechora petroleum province. It is evolved through rifting, continental margin development, and two-stage collisional phase related to the Uralian Orogeny in the Late Artinskian-Late Permian and the Pay-Khoy Orogeny in the Late Triassic. In course of the later one, the sedimentary cover was delaminated along the Upper Ordovician evaporites which produced general uplift. The complex tectonostratigraphic history resulted in accumulation of up to 15 km-thick sedimentary section which has all essential ingredients of prolific petroleum systems, including the word-class Domanik source rock, and a large variety of structural and stratigraphic traps. Nevertheless, up to now, no commercial discoveries have been made yet. A review of geological setting and petroleum habitat suggests that the petroleum systems development was more complex than it was assumed previously. The amount of uplift and erosion related to the updip displacement on the salt detachment was underestimated. Reinterpretation of the available data shows the presence of large untested exploration opportunities including duplex thrust sheets and subsalt structures related to squeezed diapirs.

Description: Geological carbon sequestration (GCS) is necessary to help meet emissions reduction goals, but groundwater contamination may occur if CO2 and/or brine were to leak out of deep storage formations into the shallow subsurface. For this study, a natural analogue was investigated: in the Virgin River Basin of southwest Utah, water with moderate salinity and high CO2 concentrations is leaking upward into shallow aquifers that contain heavy metal-bearing concretions. The aquifer system is comprised of the Navajo and Kayenta formations, which are pervasive across southern Utah and have been considered as a potential GCS injection unit where they are sufficiently deep. Numerical models of the site were constructed based on measured water chemistry and head distributions from previous studies. Simulations were used to improve understanding of the rate and distribution of the upwelling flow into the aquifers, and to assess the reactive transport processes that may occur if the upwelling fluids were to interact with a zone of iron oxide and other heavy metals, representing the concretions that are common in the area. Various mineralogies were tested, including one in which Pb+2 was adsorbed onto ferrihydrite, and another in which it was bound within a solid mixture of litharge (PbO) and hematite (Fe2O3). Results indicate that metal mobilization depends strongly on the source zone composition and that Pb+2 transport can be naturally attenuated by gas phase formation and carbonate mineral precipitation. These findings could be used to improve risk assessment and mitigation strategies at geological carbon sequestration sites.Thematic collection: This article is part of the Geoscience for CO2 storage collection available at: https://www.lyellcollection.org/cc/geoscience-for-co2-storage

Description: This study examined the potential of some shales obtained from different formations in Yazd province to produce Lightweight aggregates (LWAs) as natural materials and without the application of additives. Before heating the samples, the materials' usefulness for producing lightweight aggregates was examined by detecting the elemental and mineralogical composition of the shale samples. The presence of aluminosilicates and flux content confirmed and met the required conditions discussed by Riley's theory for the bloating process. Among the studied shale samples, Kharanagh shale samples of Kh1 and Kh2 were found as the most suitable materials to produce highly porous, light and mechanically durable aggregates after heating at the optimum temperature of 1200°C for a heating duration of 10min. The produced LWAs showed low density (for sample Kh1 equal to 0.7gr/cm3 which is close to the commercial LECA), low water absorption (quick water absorption indices of 5.35% and 5.48% for samples Kh1 and Kh2, respectively, which are less than one-third of LECA water absorption), porous microstructure (porous like LECA but with smaller pore size), and good mechanical properties (with aggregate impact and aggregate crushing values less than that of LECA and in the range of values suggested for construction aims). Finally, it was revealed that the produced LWAs have suitable microstructure, physical and mechanical properties, comparable with the commercial ones, which approve their potential for use as construction materials in lightweight concrete and road surface constructions.

Description: Timan-Pechora Composite Tectono-Sedimentary Element represents a significant part of the Timan-Pechora petroleum province, which is the second largest in the Circum-Arctic. It contains as much as up to 10 km of Paleozoic and Mesozoic strata hosting world-class hydrocarbon source rock, the Domanik Formation, and a variety of hydrocarbon plays prolific for both, oil and natural gas. Complex tectonic structure of the composite tectono-sedimentary element formed as result of several tectonic phases: two extensional events, post-rift thermal sag in a passive margin setting, and a series of late Paleozoic and early Mesozoic compressional events. The latter modified the extensional fabric and led to the formation of a number of inverted swells and smaller anticlinal structures providing the major trapping capacities. The deposition of source and reservoir facies occurred during the extensional tectonic phases, while the main reservoir-prone sedimentary units were deposited during late Paleozoic and early Mesozoic orogenic phases.

Description: In Marie Byrd Land and Ellsworth Land 19 large polygenetic volcanoes and numerous smaller centres are exposed above the West Antarctic Ice Sheet along the northern flank of the West Antarctic Rift System. The Cenozoic (36.7 Ma to active) volcanism of the Marie Byrd Land Volcanic Group (MBLVG) encompasses the full spectrum of alkaline series compositions ranging from basalt to intermediate (e.g. mugearite, benmoreite) to phonolite, peralkaline trachyte, rhyolite and rare pantellerite. Differentiation from basalt is described by progressive fractional crystallization; however, to produce silica-oversaturated compositions two mechanisms are proposed: (1) polybaric fractionation with early-stage removal of amphibole at high pressures; and (2) assimilation–fractional crystallization to explain elevated 87Sr/86Sri ratios. Most basalts are silica-undersaturated and enriched in incompatible trace elements (e.g. La/YbN 〉10), indicating small degrees of partial melting of a garnet-bearing mantle. Mildly silica-undersaturated and rare silica-saturated basalts, including tholeiites, are less enriched (La/YbN 20) materials. Geophysical studies indicate a deep thermal anomaly beneath central Marie Byrd Land, suggesting a plume influence on volcanism and tectonism.

Description: Mount Melbourne and Mount Rittmann are quiescent, although potentially explosive, alkaline volcanoes located 100 km apart in Northern Victoria Land quite close to three stations (Mario Zucchelli Station, Gondwana and Jang Bogo). The earliest investigations on Mount Melbourne started at the end of the 1960s; Mount Rittmann was discovered during the 1988–89 Italian campaign and knowledge of it is more limited due to the extensive ice cover. The first geophysical observations at Mount Melbourne were set up in 1988 by the Italian National Antarctic Research Programme (PNRA), which has recently funded new volcanological, geochemical and geophysical investigations on both volcanoes. Mount Melbourne and Mount Rittmann are active, and are characterized by fumaroles that are fed by volcanic fluid; their seismicity shows typical volcano signals, such as long-period events and tremor. Slow deformative phases have been recognized in the Mount Melbourne summit area. Future implementation of monitoring systems would help to improve our knowledge and enable near-real-time data to be acquired in order to track the evolution of these volcanoes. This would prove extremely useful in volcanic risk mitigation, considering that both Mount Melbourne and Mount Rittmann are potentially capable of producing major explosive activity with a possible risk to large and distant communities.

Description: Magnetic stripes have long been assumed to be indicative of oceanic crust. However, continental crust heavily intruded by magma can also record magnetic stripes. We re-evaluate the nature of the Cuvier Abyssal Plain (CAP), offshore NW Australia, which hosts magnetic stripes and has previously been defined as oceanic crust. We show chemical data from a basalt within the CAP, previously described as an enriched MORB, could equally be interpreted to contain evidence of contamination by continental material. We also recognise seaward-dipping reflector (SDR) sequences in seismic reflection data across the CAP. Borehole data from overlying sedimentary rocks suggests these SDRs were emplaced in a shallow-water (500 km further offshore NW Australia than currently thought; this would impact plate tectonic reconstructions, as well as heat flow and basin modelling studies. Our work also supports the growing consensus that magnetic stripes cannot, by themselves, be used to determine crustal affinity.Supplementary material: Enlarged and uninterpreted versions of the magnetic data and seismic reflection lines are available at https://doi.org/10.6084/m9.figshare.c.5332172.

Description: The Foxe Platform and Basin Tectono-Sedimentary Element is an ovoid-shaped, predominantly marine basin located in the Canadian Arctic. The Paleozoic sedimentary succession (Cambrian to Silurian) unconformably overlies the Precambrian basement and reaches a maximum measured thickness of slightly over 500 metres in the only exploration well drilled in this basin. The Lower Paleozoic Foxe Platform and Basin Tectono-Sedimentary Element is surrounded by Precambrian basement and by the Paleozoic Arctic Platform to the north and by the Paleozoic-Mesozoic (?) Hudson Bay Strait Platform and Basin to the south. The Paleozoic succession consists of a Cambrian clastic-dominated interval overlain by Ordovician to lower Silurian predominantly shallow marine carbonate. Other than a single well drilled in the northern part of the basin, no subsurface information is available. Thermally immature Upper Ordovician organic matter rich calcareous black shales have been mapped on the onshore extension of the basin to the southeast. Potential hydrocarbon reservoirs consist of Cambrian porous coarse-grained clastics as well as Upper Ordovician dolostones and reefs.

Description: High-resolution LiDAR-derived datasets from a 1.5-m digital elevation model and a detailed landslide inventory (N ≥ 1,000) for Magoffin County, Kentucky, USA, were used to develop a combined machine-learning and statistical approach to improve geomorphic-based landslide-susceptibility mapping.An initial dataset of 36 variables was compiled to investigate the connection between slope morphology and landslide occurrence. Bagged trees, a machine-learning random-forest classifier, was used to evaluate the geomorphic variables, and 12 were identified as important: standard deviation of plan curvature, standard deviation of elevation, sum of plan curvature, minimum slope, mean plan curvature, range of elevation, sum of roughness, mean curvature, sum of curvature, mean roughness, minimum curvature, and standard deviation of curvature. These variables were further evaluated using logistic regression to determine the probability of landslide occurrence and then used to create a landslide-susceptibility map.The performance of the logistic-regression model was evaluated by the receiver operating characteristic curve, area under the curve, which was 0.83. Standard deviations from the probability mean were used to set landslide-susceptibility classifications: low (0–0.10), low–moderate (0.11–0.27), moderate (0.28–0.44), moderate–high (0.45–0.7), and high (0.7–1.0). Logistic-regression results were validated by using a separate landslide inventory for the neighboring Prestonsburg 7.5-minute quadrangle, and running the same regression function. Results indicate that 74.9 percent of the landslide deposits were identified as having moderate, moderate–high, or high landslide susceptibility. Combining inventory mapping with statistical modelling identified important geomorphic variables and produced a useful approach to landslide-susceptibility mapping.Thematic collection: This article is part of the Digitization and Digitalization in engineering geology and hydrogeology collection available at: https://www.lyellcollection.org/cc/digitization-and-digitalization-in-engineering-geology-and-hydrogeology

Description: Detecting zones of considerable early-orogenic displacement in rather monotonous rock sequences which have undergone a late and pervasive tectonometamorphic overprint is challenging. It has been proposed that the alleged Zas shear zone in the passive-margin sequence of the Cycladic Blueschist Unit (CBU) on Naxos Island, Greece, separates amphibolite-facies, non-high-P rocks (Koronos Unit) below from Eocene high-P rocks (Zas Unit) above the shear zone. We review existing pressure-temperature (P-T) data from the Koronos Unit and present new kinematic data from the anticipated Zas shear zone to evaluate the tectonic significance of this recently proposed structure. This has implications for unravelling the subduction history of rock units from tectonometamorphic data sets. Common to all P-T data from the Koronos Unit is a well-defined amphibolite-facies equilibration stage at 8-11 kbar and 600-700°C, followed by initial near-isothermal to slightly prograde decompression and subsequent pronounced cooling. This segment of the high-T P-T loop was associated with top-to-the-NNE extensional deformation in the footwall of the Miocene Naxos-Paros detachment. Little is known about metamorphism preceding the amphibolite-facies overprint in the Koronos Unit. Our review shows that it is likely that the rocks experienced a prior high-P metamorphic overprint that is typical for rocks of the CBU. Our kinematic data show that the Zas shear zone contains variably deformed rocks with dominantly top-to-the-NNE shear-sense indicators that developed under greenschist-facies metamorphism in the footwall of the Naxos-Paros detachment. No significant offset can be detected across the Zas shear zone and the geology on either side of it does not support large-scale movement across the shear zone. We discuss a model in which the Zas shear zone is considered a minor zone of deformed schist near the biotite-in isograd of Miocene high-T metamorphism. We conclude that there is no need to tectonically subdivide the CBU passive-margin sequence on Naxos.

Description: The Boneh Shurow metamorphic core complex (BSMCC) in the Central East Iranian Microcontinent (CEIM) provides a good example of the Mesozoic succession of nonsynchronous compressional and extensional deformation events attributed to the transitional Cimmerian events. The D1 compression developed subvertical dextral ductile shear zones and corresponds to continental accretion and crustal thickening producing kyanite- and sillimanite-grade rocks and migmatites in the Early Cimmerian orogeny in the CEIM. The D2 deformation event is marked by extension during the mid-Cimmerian orogeny. It is characterized by top-to-the-NE normal sense of shear along a low angle detachment surface. Field evidence for cross cutting relationships of D1- by D2-related structures reveal that the occurrence of Barrovian facies metamorphism and associated partial melting in the core of BSMCC formed during compressional tectonic events. These structures formed before the initiation of extension and the formation of the low-angle detachment shear zone. Finally, during the Late Cimmerian D3 event, the east and west Boneh Shurow reverse faults ruptured on both sides of the MCC. Recognition of the complicated origin and exhumation mechanisms of the BSMCC provide crucial constraints on the prolonged evolution of Paleo- and Neo-Tethys ocean basins and collisional and post-collisional events in this region.

Description: Despite surviving longer than any other blastozoans, blastoids were exceptionally conservative in their morphology and usually symmetrically pentaradiate. Astrocrinus is a rare exception that lacked a stem and some thecal plates, although differing interpretations of its morphology and taxonomy have been published. Astrocrinus had a flattened, tetralobate theca covered in minute spines, and with a plane of symmetry through the AB interray and the D ray. Four ambulacra are long, thin, and curved down deep sinuses between the thecal lobes to reach the basal surface. The D ambulacrum is short, broad and horizontal. Astrocrinus tetragonus was first described from the Carboniferous Limestone of Settle, Yorkshire. Here it is recorded for the first time from the Brigantian, near Grassington. The new specimens confirm that A. tetragonus had a single basal plate which is kite- shaped, entirely surrounded by four radials and separated from the D ray radial. Astrocrinus benniei was described from the Scottish Brigantian and its basal plate is elongate pentagonal with a short common suture with the D ray radial. Astrocrinus occurs in the Irish Asbian and Brigantian. To date, only A. tetragonus can be confirmed from Ireland.

Description: Cenozoic magmatic rocks related to the West Antarctic Rift System crop out right across Antarctica, in Victoria Land, Marie Byrd Land and into Ellsworth Land. Northern Victoria Land, located at the northwestern tip of the western rift shoulder, is unique in hosting the longest record of the rift-related igneous activity: plutonic rocks and cogenetic dyke swarms cover the time span from c. 50 to 20 Ma, and volcanic rocks are recorded from 15 Ma to the present. The origin of the entire igneous suite is debated; nevertheless, the combination of geochemical and isotopic data with the regional tectonic history supports a model with no role for a mantle plume. Amagmatic extension during the Cretaceous generated an autometasomatized mantle source that, during Eocene–present activity, produced magma by small degrees of melting induced by the transtensional activity of translithospheric fault systems. The emplacement of Eocene–Oligocene plutons and dyke swarms was focused along these fault systems. Conversely, the location of the mid-Miocene–present volcanoes is governed by lithospheric necking along the Ross Sea coast for the largest volcanic edifices; while inland, smaller central volcanoes and scoria cones are related to the establishment of magma chambers in thicker crust.

Description: Yukon Flats is a vast and remote lowland that straddles the Arctic Circle and is located along the Yukon River in east-central Alaska. Seismic reflection and gravity indicate that low-density sedimentary strata beneath Yukon Flats are as thick as 8 km and are underlain by Jurassic to Devonian oceanic rocks of the Angayucham-Tozitna terrane. On the basis of shallow core hole penetrations and by analogy with nearby outcrops, the low-density strata are thought to consist of fluvial and lacustrine deposits of Neogene, Paleogene, and possibly Late Cretaceous age. No deep petroleum exploration wells have been drilled in Yukon Flats, but a coalbed methane test reached a total depth of nearly 700 m and found small amounts of microbial methane. Geochemical data from outcrops and shallow core holes suggest that potential source rocks include nonmarine coal, mudstone, and shale, whereas potential reservoirs include nonmarine sandstone and conglomerate. Numerous potential structural and stratigraphic traps are evident on seismic profiles. The United States Geological Survey estimates that undiscovered, technically recoverable oil resources in the Yukon Flats Basin tectono-sedimentary element range from zero to almost 600 million barrels (MMBO) and that undiscovered, technically recoverable gas resources range from zero to almost 15 trillion cubic feet (TCF).

Description: Considerable progress has been made by international teams in refining the traditional ammonoid zonation that remains the backbone of Carboniferous stratigraphy. The Carboniferous ammonoid genozones, with a few gaps, are now recognized throughout the entire system in most successions worldwide. Refined collecting and documentation of occurrences in Western Europe, North Africa, the Urals, China, and North America, aimed to establish the first evolutionary occurrences, and facilitated correlation with foraminiferal and conodont scales for most of the Carboniferous. From ten to eleven ammonoid genozones are now recognized in the Mississippian, and eight to nine genozones in the Pennsylvanian. Of these, the established lower boundaries of the subsystems are reasonably well correlated with the ammonoid zonation, whereas correlations with the ratified foraminiferal-based lower boundary of the Viséan and other stage boundaries, currently under discussion, need further research. Future success in the ammonoid geochronology will also depend on accurate identification and re-illustration of the type material, including material described by pioneers of ammonoid biostratigraphy.

Description: Neogene volcanism is widespread in northern Victoria Land, and is part of the McMurdo Volcanic Group. It is characterized by multiple coalesced shield volcanoes but includes a few relatively small stratovolcanoes. Two volcanic provinces are defined (Hallett and Melbourne), with nine constituent volcanic fields. Multitudes of tiny monogenetic volcanic centres (mainly scoria cones) are also scattered across the region and are called the Northern Local Suite. The volcanism extends in age between middle Miocene (c. 15 Ma) and present but most is

Description: Abrasion and plucking are important subglacial erosional processes which create different landforms. This study shows that properties of bedrock control subglacial erosion and bedrock morphology. Softer and less jointed bedrock favours abrasion, while denser jointed bedrock and harder bedrock do not. Field work for this study was done near Drumnadrochit in NE Scotland, where the lithology, geology and morphology of rôches moutonnées and crag-and-tails were examined. In this area, the rôches moutonnées, which have an abraded stoss side, are only shaped out of a relatively soft, biotite rich gneiss, with not much jointing. The crag-and-tails have more densely jointed stoss sides and are shaped out of serpentinite or a harder, more felsic gneiss. Foliation appears not to influence subglacial erosion, since the foliation in rôches moutonnées and crag-and-tails in the study area is similar.Thematic collection: This article is part of the Early Career Research collection available at: https://www.lyellcollection.org/cc/SJG-early-career-research

Description: Only three localities of mantle xenoliths are known from all of East Antarctica, occurring at the Jetty Peninsula (Lambert-Amery Rift), Vestfold Hills and Gaussberg volcano. The latter two are spinel-facies peridotites, whereas the Jetty Peninsula rocks also include garnet-spinel lherzolites; all come from Indo-Antarctica. The mantle xenoliths of Jetty Peninsula and Vestfold Hills contain abundant geochemical and mineralogical evidence for multiple enrichment events that are attributed to infiltration of melts and their fluid products. Many of these episodes are spatially related to precursory activity along major trans-lithospheric structures that eventually led to the separation of India from Antarctica. Mantle rocks also occur at Schirmacher Oasis (Dronning Maud Land) and Haskard Highlands (Shackleton Ranges) as blocks tectonically emplaced in high-grade crustal rocks. These show varying degrees of alteration due to reaction with silicic crustal rocks or hydrous fluids: none correspond to unchanged mantle compositions. Geophysical surveys are our only information on the mantle lithosphere beneath the inland ice, and these can be used to infer the locations of thicker lithosphere probably related to cratons by southward extrapolation of coastal geological correlations. Intense local modification of the mantle lithosphere by melt infiltration and fluid movements may influence the large-scale images derived from geophysical data, and may be incorrectly interpreted as homogeneous compositions.

Description: We report Mesoproterozoic 40Ar-39Ar (whole-rock) ages of lamproites from (i) the Ramadugu field (R4 dyke : 1434 ± 19 Ma and R5 dyke: 1334 ± 12 Ma) and the Krishna field (Pochampalle dyke: 1439 ± 3 Ma and Tirumalgiri dyke: 1256 ± 12 Ma) from the Eastern Dharwar Craton (EDC) and (ii) the Garledinne (1433 ± 8 Ma) and the Chelima (1373 ± 6 Ma) dykes from within the Paleo-Mesoproterozoic Cuddapah Basin, southern India. The ages reported for the Ramadugu and Tirumalgiri lamproites constitute their first radiometric dates. Ages of the Pochampalle and the Chelima lamproites from this study are broadly comparable to their previously reported 40Ar-39Ar (phlogopite) ages of c. 1500 Ma and 1418 ± 8 Ma, respectively. The ages of all these lamproites are much older than those of the (i) c. 1.1 Ga kimberlites from the Wajrakarur and Narayanpet fields of the EDC and (ii) c. 1.09 Ga lamproitic dykes at Zangamarajupalle which intrude the Cumbum Formation of the Cuddapah Basin. However, the age of the Tirumalgiri lamproite (c. 1256 Ma) is similar to that of the Ramannapeta lamproite (c. 1224 Ma) within the Krishna field. Our study provides evidence for protracted ultrapotassic (lamproitic) magmatism from c. 1.43 to 1.1 Ga over a widespread area (c. 2500 km2) in and around the Cuddapah Basin and the EDC. Implications of the obtained new ages for the diamond provenance of the Banganapalle Conglomerates, the age of the Kurnool Group and for the timing of break-up of the Paleo-Mesoproterozoic supercontinent of Columbia/Nuna are explored.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5289354

Description: Igneous rocks of the Erebus Volcanic Province have been investigated for more than a century but many aspects of petrogenesis remain problematic. Current interpretations are assessed and summarized using a comprehensive dataset of previously published and new geochemical and geochronological data. Igneous rocks, ranging in age from 25 Ma to the present day, are mainly nepheline normative. Compositional variation is largely controlled by fractionation of olivine + clinopyroxene + magnetite/ilmenite + titanite ± kaersutite ± feldspar, with relatively undifferentiated melts being generated by

Description: This volume brings together 17 comprehensive, data-rich analyses to provide an updated perspective on the Mexican sector of the Gulf of Mexico, Florida and the northern Caribbean. The papers span a broad range of scales and disciplines from plate tectonic evolution to sub-basin-scale analysis. Papers are broadly categorized into three themes: (1) geological evolution of the basins of the southern Gulf of Mexico in Mexico, Bahamas and Florida and their hydrocarbon potential; (2) evolution of the region's Late Cretaceous to Neogene orogens and subsequent denudation history; and (3) geological evolution of the basins and crustal elements of the northern Caribbean. This book and its extensive datasets are essential for all academic and exploration geoscientists working in this area. The volume also includes two large maps detailing the Mexican Gulf of Mexico and the Northern Caribbean areas.

Description: We welcome the constructive comments of Manning et al. (2021) that our paper on the Palaeogeographical Evolution of the Rattray Volcanic Province (RVP) provides a very valuable synthesis of this suite of rocks. Our paper presented a new evaluation of the stratigraphy and palaeogeographical setting of the RVP before, during and after the eruptions. The discussion underlines the fundamental science that can be undertaken and value attached to using subsurface data and cores obtained in the North Sea in general and the RVP in particular.

Description: The accurate characterization of mafic and ultramafic rocks is a challenging but necessary task given the spatial and genetic relationship of mineralization with specific lithologies (e.g. komatiite hosted nickel-sulfides preferentially associated with cumulate-rich ultramafic rocks). Rock classification is further complicated as most mafic and ultramafic rocks have undergone varying degrees of alteration. The accuracy and reproducibility of characterization can be significantly improved by using portable energy dispersive X-ray Fluorescence (pXRF) chemical data with portable Visible and Near-Infrared (pVis-NIR) mineralogical data.A new workflow using pXRF and pVis-NIR is presented and used to reliably characterize mafic and ultramafic rocks from the Yilgarn Craton, Western Australia. The workflow involves 6 steps: Mitigate and identify compound processing and closure issues. For example, we used a pXRF with helium flush to reliably and rapidly measure light elements and mitigate closure, i.e. problems related to data failing to sum to 100%.Identify and exclude geochemically heterogeneous samples. Heterogeneity may be unrelated to alteration and caused by veining or small-scale structure interleaving of different rock types. Geochemical heterogeneity was evaluated using skewness and kurtosis of SiO2 data.Relate rocks from similar magmatic, weathering and alteration events. This was achieved by interpreting data grouping of Vis-NIR ferric and ferrous iron data via a 852 nm/982 nm reflectance v. 651 nm/982 nm reflectance plot and the Ferrous Abundance Index. Unrepresentative data were omitted.Correct XRF iron data, and characterize lithology and alteration. Values ascribed to regions in the TAS (Total Alkali Silica) diagram were used to approximate FeO and Fe2O3. Subsequently, geochemical indices (e.g. Mg#) were used to characterize the alteration box plot.Characterize fractionation in detail. Fractionation variation diagrams were used to interpret fractionation, e.g. MgO v. Al2O3, Ca/Al v. Al2O3, Ni/Cr v. Ni/Ti, and MgO v. Cr.Identify and quantify talc alteration and serpentinization. This included the use of a new alteration plot (Mg# v. 1410 nmRAD/Albedo) to estimate serpentinization and identify relationships between serpentine, carbonate, chlorite and talc abundances. The results and observations contained in this contribution have important implications for progressive technologies such as core logging platforms that are equipped with pXRF and pVis-NIR instruments.

Description: The Rock Canyon Creek carbonate-hosted REE-F-Ba deposit has tectonic, stratigraphic, and structural similarities with Mississippi Valley-type and sparry magnesite deposits in the southeast Rocky Mountains. The main REE-fluorite zone is a steeply dipping body, extending 1100 m along strike, 50 m wide, and 100 m deep. It spatially coincides with pre-existing crackle breccias in carbonate rocks, and consists of dolomite, fluorite, barite, pyrite, quartz, K-feldspar, calcite, porous apatite, REE-fluorocarbonates, and REE-phosphates. The main fluorocarbonates are bastnaesite, parisite, and synchysite. Monazite, crandallite group minerals, and apatite are the main phosphates. Fluorite content varies from less than 1 to 13.5% (by weight) and ∑REE+Y concentrations vary from trace to 1.95% (by weight). The mineralized zone is heterogeneous on the deposit scale, as indicated by three-dimensional geochemical modeling combined with a geochemical assessment based on 89 mineralized samples and detailed downhole mineral and geochemical profiles of a key borehole. Chemical heterogeneity and key elemental co-variations are explained by strong mineralogical control and have implications for the design of exploration and development programs for this type of deposit. The chondrite-normalized REE pattern of samples from the mineralized zone shows enrichment in LREE, similar to typical carbonatite-related mineralization; however, no carbonatite is exposed nearby.

Description: The geochemistry of rare earth elements (REEs) was studied in rock samples from host formations, ore samples from two mineral deposits (the Hetaoping Cu-Pb-Zn mine: HTP and the Heiyanao Fe-Cu-Pb-Zn mine: HYA) and the overlying or nearby soils to better understand REE concentrations, distributions and behaviour during weathering from different parent materials at the regional scale, Baoshan area, Yunnan Province, Southwest China. The mudstone and sandstone formations have highest total REE (ΣREE) contents. Chondrite-normalized diagrams for rocks and ores show significant light REEs (LREEs) enrichments and Eu depletion (except for ores in HYA). Cerium displays an obvious negative anomaly in carbonate rocks (Є-3-R, C-R, D-R, T-1-R, and T-2-R). Soils overlying carbonate rock formations (T-1-S, C-S, and Є-3-S) have the highest ΣREE contents, while soils overlying basalts have the lowest ΣREE contents. Soils show enrichments in LREEs with negative Eu anomalies and slight Ce anomalies in the studied soils. Soils with high ∑LREE/∑heavy REE (HREE) values may result from the preferential absorption of LREEs by organic matter. Negative Eu anomalies in soils occur for parent materials in the study area lacking feldspar, especially soils developed from carbonates. Compared to the parent materials, most soils show REE enrichment because alkali metals are removed and REEs are concentrated by low mobility in surficial processes and positive Ce anomalies because of weathering dissolution of other trivalent REEs with ionic radii similar to that of Ca2+.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5303140

Description: A review of northern Victoria Land ultramafic xenoliths, collected and studied over more than thirty years, was carried out. More than 200 samples were gathered and characterised in a coherent and comparative manner, both for mantle-derived and cumulate xenoliths. Almost 2,000 analyses of major elements and more than 300 analyses of trace elements of in situ and separated olivine, pyroxenes, amphibole, spinel and glass were taken into consideration. Particular attention was devoted to mantle lithologies in order to emphasize the composition and the evolution of this portion of the sub-continental lithosphere. The three main localities in northern Victoria Land where mantle xenoliths were found, i.e. Mount Melbourne (Baker Rocks), Greene Point and Handler Ridge, over a 〉200 km distance, were described and compared with the ultramafic xenoliths in three other localities, Harrow Peaks, Browning Pass and Mount Overlord, which are mainly cumulate in nature. Altogether, these data enabled us to reconstruct a long evolutionary history from old depletion, to most recent refertilisation and metasomatic events for this large sector of the northern Victoria Land sub-continental lithospheric mantle.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5303103

Description: The Zagros Fold and Thrust Belt (ZFTB) in southern Iran is a seismically active tectonic zone, where SW-vergent thrust faults and NW-SE- and NE-SW-oriented strike-slip fault systems accommodate for crustal shortening, resulting from the active Arabia-Eurasia collision. The majority of earthquakes in Iran occur within the ZFTB, posing a major hazard for the society. The April 9th, 2013, Kaki Earthquake (Mw = 6.3) in the southern part of the ZFTB took place along a fault that was previously unknown, regarding its surface expression, geometry and kinematics. We have used surface-subsurface distributions and focal mechanism solutions of the Kaki Earthquake aftershocks to characterize the fault system responsible for the quake. Our results indicate that it was a NE-vergent thrust fault with a minor dextral component that slipped ∼7 to 17 km at depth, causing the Kaki Earthquake. There were no surface ruptures, although some surface fissures developed in fluvial terraces during the main shock. We interpret this fault as a blind backthrust, which likely represents a reactivated Mesozoic basement fault, emanating from the Zagros detachment surface. An upper shallow décollement zone within the Miocene Gachsaran Salt facilitated its upward propagation on the back-limb of an overturned syncline.

Description: A series of offshore intra-basinal igneous centres have been documented across the North Atlantic Igneous Province including the United Kingdom, Ireland and Greenland. However, inconsistent cross-border terminology implies that similar features are not present in the Norwegian offshore which, in turns, leads to misperceptions of cross-border geological differences. This manuscript presents evidence for a series of Norwegian igneous centres and suggests a consistent non-genetic cross-border terminology. In the Møre Basin, several igneous centres sit close to the continent ocean boundary (COB) which have previously been identified as seamounts and/or ‘outer highs’. To provide cross-border consistency these features are consolidated under umbrella terms; igneous centres or volcanic fissures. Further centres are likely present within the Møre Basin (east of the COB) where 3D seismic data were not available. In the Vøring Basin two new igneous centres, one intrusive and one extrusive, are identified within the continental domain. Additionally, a possible deep magmatic upwelling associated with the regionally significant T-Reflector is identified. These igneous centre end-members represent the complexity of the magmatic plumbing across the Norwegian margin. With further data it is likely that further igneous centres will be identified offshore mid Norway.

Description: Scattered occurrences of Miocene–Recent volcanic rocks of the alkaline intraplate association represent one of the last expressions of magmatism along the Antarctic Peninsula. The volcanic rocks were erupted after the cessation of subduction which stopped following a series of northward-younging ridge crest–trench collisions. Volcanism has been linked to the development of a growing slab window beneath the extinct convergent margin. Geochemically, lavas range from olivine tholeiite through to basanite and tephrite. Previous studies have emphasized the slab-window tectonic setting as key to allowing melting of peridotite in the asthenospheric void caused by the passage of the slab beneath the locus of volcanism. This hypothesis is revisited in the light of more recent petrological research, and an origin from melting of subducted slab-hosted pyroxenite is considered here to be a more viable alternative for their petrogenesis. Because of the simple geometry of ridge subduction, and the well-established chronology of ridge crest–trench collisions, the Antarctic Peninsula remains a key region for understanding the transition from active to passive margin resulting from cessation of subduction. However, there are still some key issues relating to their tectonomagmatic association, and, principally, the poor geochronological control on the volcanic rocks requires urgent attention.

Description: This chapter describes the application and coverage of gravity and magnetic data for Antarctica with emphasis on airborne and satellite models. Low resolution satellite data help to fill gaps between high-resolution airborne data. Satellite gravity data is best used to study broad-scale lithospheric architecture while airborne data, especially magnetic data, provides finer detail. We review examples of gravity and magnetic analysis and describe the possibilities and pitfalls for estimating the properties of the lithosphere as it relates to the mantle. This is followed by a discussion on geothermal heat flow and possible ways to combine different geophysical and petrological models for a better understanding of the Antarctic mantle.

Description: The Silurian was an interval of profound change in terrestrial ecosystems as the earliest non-marine animal communities began to become established on the continents. Whilst much is known about the transition of pioneering animals from shallow marine to coastal and alluvial habitats, evidence for animal activity in contemporaneous aeolian strata is rare. Here, we present trace fossil evidence that closes this knowledge gap, indicating that Silurian desert environments, dominated by aeolian processes, were occupied by resident invertebrate communities. The evidence comes from the Mereenie Sandstone, Northern Territory, Australia, which is demonstrated to have been deposited in a wet inland aeolian system, typified by small crescentic sand dunes and extensive interdune flats. The invertebrate trace fossil associations from the Mereenie Sandstone (Arenicolites isp., “Burrow entrance with radial feeding traces”, Didymaulichnus lyelli, Diplichnites gouldi, Helminthopsis isp., Laevicyclus isp., Palaeophycus isp., Polarichnus garnierensis, Skolithos isp.) are restricted to damp interdune deposits, whereas dune strata are barren. The ichnofauna are described and compared to those from other Palaeozoic aeolian systems, in order to re-evaluate the timing of the early stages of arthropod terrestrialization.

Description: This note presents the effect of lime, cement, fly ash and ground granulated blast furnace slag (GGBS) on free swell index (FSI), liquid limit (LL), plasticity index (PI), compaction characteristics, hydraulic conductivity (k) and strength characteristics of an expansive soil. The effect of the above chemicals on California bearing ratio (CBR) was also presented. Lime content was varied as 0%, 1%, 2%, 4% and 6% and the amounts of other additives were varied as 0%, 5%, 10%, 15% and 20% by dry weight of the soil. FSI, LL and PI decreased significantly with increasing additive contents. Compaction characteristics also improved with increasing additive contents. Strength characteristics showed improvement at higher additive contents especially at higher curing periods. CBR (determined in soaked condition) also increased significantly with increasing additive contents.

Description: The development of a robust understanding of the response of the Antarctic Ice Sheet to present and projected future climatic change is a matter of key global societal importance. Numerical ice sheet models that simulate future ice sheet behaviour are typically evaluated with recourse to how well they reproduce past ice sheet behaviour, which is constrained by the geological record. However, subglacial topography, a key boundary condition in ice sheet models, has evolved significantly throughout Antarctica's glacial history. Since mantle processes play a fundamental role in the generation and modification of topography over geological timescales, an understanding of the interactions between the Antarctic mantle and palaeotopography is crucial for developing more accurate simulations of past ice sheet dynamics. This chapter provides a review of the influence of the Antarctic mantle on the long-term evolution of the subglacial landscape, through processes including structural inheritance, flexural isostatic adjustment, lithospheric cooling and thermal subsidence, volcanism and dynamic topography. The uncertainties associated with reconstructing these processes through time are discussed, as are important directions for future research and the implications of the evolving subglacial topography for the response of the Antarctic Ice Sheet to climatic and oceanographic change.

Description: The description of the Rattray Volcanic Province presented by Quirie et al. (2020) represents a very valuable synthesis of this suite of rocks particularly in terms of hydrocarbon exploration and production. Interestingly, the authors report the presence of nepheline in intrusive rocks, described as minor intrusions (up to 50m thick) that have undergone extensive alteration.

Description: The aim of this paper is to document and compare the 2D qualitative and semi-quantitative methods currently used to describe the shape of gold grains in fluvial environment to 3D quantitative methods using microtomography and SEM photogrammetry. These 3D methods are used to compute flatness, roundness, convexity, sphericity, and ellipticity shape descriptors of 13 gold grains from the Rivière du Moulin (Québec, Canada) in order to quantify the morphological change along 9 km of fluvial transport. Gold grains have moderate to high values of flatness, compactness, sphericity, and ellipticity indices that do not change significantly with distance of transport, whereas the roundness increases during transport. Gold grains are used to compare 2D and 3D methods and the results show small differences (〈 8%) when shape descriptors are computed using image analysis software, whereas the difference (up to 70%) is more important for 2D measurements performed by a human operator. For application and characterization on a large set of gold grains, the 2D methods offer the advantage of speed, whereas, for a more detailed study on a limited number of gold grains, 3D methods enable estimation of the volume and yield more detailed shape descriptors changes during fluvial transport.

Description: The Middle Devonian lacustrine sediments of Orkney, off the northeast Scottish mainland, are composed largely of the Lower and Upper Stromness Formations and overlying Rousay Formation. These three formations have been subdivided and defined by vertebrate biostratigraphic biozones with recent division of the Rousay Formation into three further units based on characteristic fish fossils. The division of the Rousay Formation has enabled a map to be constructed of the solid geology of the island of Westray, Orkney, based on fish identification, detailed logging of sedimentary cycles throughout the Rousay succession, parameters of divisional boundaries, and a survey of faults marking sinistral transtensional movement parallel to the Great Glen Fault. Post-Carboniferous shortening and basin inversion led to uplift, folding and reactivation of normal faults as reverse faults, to form a positive strike-slip flower structure in Westray. A suite of Permian igneous dykes intruded across Orkney include three minor offshoots in Westray. The resulting map is the first to make use of biostratigraphic units within the Rousay Flagstone which are now regarded as Members.

Description: The Lower Son Valley is generally overlooked despite a lengthy history of archaeological and geological studies in the adjacent Middle Son Valley. However, recent explorations in the former have yielded a large number of Palaeolithic and microlithic sites. This paper provides an initial report on Doma, a newly discovered site with the first-known stratified bifaces in this part of the valley. The site preserves multi-period technologies in different contexts including terminal Acheulean/early Middle Palaeolithic, and Upper Palaeolithic (all tentatively assigned based on respective typologies). Preliminary field observations are presented on the sedimentary sequence, archaeological surveys, topographical mapping, raw material, and the overall palaeoanthropological assessment of Doma. The raw material utilised at the site is primarily porcellanite, derived from exposures of the Semri Group of the Vindhyan Supergroup. The oldest Palaeolithic evidence at Doma broadly resembles Late Acheulean sites dated to ∼140-120 ka in the nearby Middle Son Valley. The Pleistocene sediments here also yielded mammalian fossil specimens such as long bone fragments, dental specimens and antler fragments. Along with the lithics and fossils, the site also preserves datable sedimentary sequence with calcrete, all key proxies to develop a testable model of technological transitions within a palaeoenvironmental framework, in the future.

Description: Progress over the last 20 years in establishing reliable benchmarks in the Palaeolithic of India has been uneven but major successes have been the dating of the earliest Acheulean assemblages in India; the dating of the onset of the Middle Stone Age; the dating of the earliest microlithic assemblages in India; and the dating of the antiquity of human occupation of rain forests in South India and Sri Lanka. Also important is our greater understanding of the Younger Toba Tuff and the impact of the Toba mega-eruption 74 ka-ago on hominin populations in India. Major uncertainties persist over when the genus Homo first entered South Asia; when our own species, H. sapiens first entered South Asia; the age of the earliest blade assemblages in India; and the antiquity of its rock art.

Description: Landscape adaptation in central India is quite exceptional as more than 300 Lower Palaeolithic occurrences have been reported in different contexts. The present work deals with these assemblages and associated raw material sources in central Narmada valley. The central Narmada valley is rich in various rock types which were used as raw material by various hominin populations. Narmada River divides the region into northern and southern parts. In the north, there are mainly the Vindhyan Supergroup and Deccan Trap, whereas, in the south, there are primarily the Gondwana Supergroup, Deccan Trap and the Mahakoshal Group. Along the river, there are exposures of Vindhyan Supergroup and thick deposits of Quaternary alluvium. The main raw material types in the north of Narmada are quartzite and sandstone (Vindhyan Supergroup), whereas, in the south of Narmada, the main raw materials are quartzite (Gondwana Supergroup) and chert (Deccan Trap). Acheulean sites are mostly found along the foothills of Vindhyan as well as along the banks of the Narmada River and its tributaries. In this chapter, the author has tried to link these raw material sources with the occurrences of Palaeolithic sites to have a better understanding of past hominin land use patterns and ecological adaptations.

Description: The Bigorne gold deposit, located in the Iberian Variscan belt, is a gold-bearing vein system, which crosscuts Variscan granites. The hypogene mineralization corresponds to sheet-veins parallel to the late-Variscan Penacova-Régua-Verín fault.A combined study was undertaken of gold particles from hypogene mineralization and locally derived eluvial material, as well as gold from alluvial deposits in local drainages, to assess possible source(s) of the alluvial gold.The geochemistry and mineralogy of heavy mineral concentrates revealed a similar signature as the hosted granites and hypogene mineralization, which indicates a local source for the surficial materials, with limited contribution from surrounding rocks.Hypogene and detrital gold particles at Bigorne area are entirely primary in origin and correspond essentially a Au-Ag alloy (〈 22 wt.% Ag), locally with minor amounts of Cu. The compositional range of Ag and Cu is a consequence of variation in parameters formation of the deposit, such as temperature. Our study highlights the first results on gold detrital particles chemistry for granite-hosted gold deposits in Iberian Variscan belt and has provided a platform for further work to characterize gold from this environment such that it may be used as a generic indicator mineral together with other resistant ore minerals.

Description: Kibbanahalli is an important Lower Palaeolithic site-complex in southern Karnataka, a state in the southern region of Peninsular India. This region is crucial as it is somewhat centrally located between areas to the north, east and south, where decades of systematic Palaeolithic research has led to the establishment of firm cultural stratigraphy(s), and even, in cases, of chronology(s). However, in stark contrast to these regions, southern Karnataka is often ignored in prehistoric research. Over 90 years of (intermittent) investigations at this site-complex have laid the foundation of our understanding of the Palaeolithic occupation of this region. It is of utmost importance to continue Palaeolithic research in this area as it is one of the fastest industrialising and urbanising zones of the world, with large population centres such as Bangalore (Bengaluru), Mysore (Mysuru) and others located here. Documenting the rich Palaeolithic heritage in this region, before its eventual surrender to the forces of 'development' is thus a priority. Further, it is also necessary, if possible, to qualify and quantify the impact of these developmental processes on the visibility and preservation of the archaeological record, in general, and the Palaeolithic record, in particular, which might serve as a model for future research in similar regions. These recent investigations have led to the identification of many new Palaeolithic localities and a secure identification of the technological attribution of their lithic assemblages. The presence of a uniform stratigraphical association of the archaeological horizon and similarities in their lithic collections have led to the reclassification of the many localities at Kibbanahalli and its vicinity into a site-complex. This paper reports on a series of field observations and remotely-sensed data collected to understand the distribution pattern of the various Palaeolithic localities of this site-complex. Results of this study highlight the critical role played by modern-day land-use patterns on the observed distribution of the archaeological record, as well as its visibility. This observation challenges previous interpretations regarding the settlement patterns and strategies suggested for the Palaeolithic occupation of this region. Further, this study draws attention to the need and necessity to understand the role of various site formation processes, especially modern-day land-use activities, on the observed and observable patterns in the archaeological record as well as the visibility, or lack thereof, of the archaeological record.

Description: Whilst the Late Devensian glaciation (MIS2) of the Vale of Pickering is well-documented, earlier glaciations within it are not. A proposed limited glaciation in the Mid-Pleistocene, thought to be of Marine Isotope Stage 8 (MIS) age is not well constrained. This paper aimed to obtain preliminary ages for two of the most prominent geomorphic features in the Vale of Pickering to see if they related to pre-Devensian glaciations. New luminescence dating by infra-red stimulation of feldspars from sand accumulations near the summit of Gallows Hill, part of the Wykeham Moraine, and from a section through poorly sorted fluvial sand and gravel on the flanks of the Hutton Buscel Terrace in Yedman Dale gave ages of 176±14 ka and 156±12 ka respectively. Evidence suggests they represent a glacial incursion (MIS 6) into the Vale of Pickering blocking its eastern end and forming a pre-Devensian Glacial Lake Pickering. Whilst they could be older, this style of glaciation is very different to the limited plateau ice-field proposed for MIS 8 at the western end of the Vale of Pickering. Taken at face value, these preliminary ages suggest that the Vale of Pickering was partially glaciated in MIS 6 as part of a wider ice-sheet and contemporary with the Saalian glaciation in Europe.

Description: The Yaou deposit, located in French Guiana within the Guiana Shield, is one of the most promising gold deposits of the regional Palaeoproterozoic greenstone belt. It displays numerous quartz monzodiorite bodies aligned along a sinistral shear zone where a five-deformation phases model is established at the camp scale. The ductile D1/2YA phase is responsible for the main penetrative foliation while the D3YA phase is related to shearing. An intrusive event is identified as being pre to syn-D3YA. The following phase D4YA represents a brittle quartz-carbonate veining set hosted preferentially within intrusive bodies and along the shear zone. A local D5YA brecciation event crosscuts the D4YA veins. Among this deformation history, two auriferous events (D3YA and D4YA) control the overall grade of the Yaou gold deposit. More specifically, most of the Au grade is associated with the main economic D4YA veining event, where the gold is visible and linked to Py4 within an ankerite/hematite rich alteration halo. At the microscopic scale, results of in situ analyses using LA-ICP-MS on pyrite show that metasediment-hosted Py0 is a primary source of submicroscopic gold having a low contribution to the total endowment. Py3 shows some gold content due to possible remobilisation of AuD0YA. Gold in Py4 is found as submicroscopic gold, as micro-inclusions and as infilling fractures in association with elements such as Te, Ag and Bi. Most contribution to the Au grade is from micro-inclusions and, to a lesser extent, from free and submicroscopic gold. The ore shoot locations are lithologically controlled for AuD0YA (metasedimentary unit-hosted), structurally controlled (shear zone-hosted) for AuD3YA and rheologically controlled for the AuD4YA (intrusion-hosted). The deposit is clearly polyphase both at the macroscopic and the microscopic scales, invisible gold is associated with As whereas visible gold is observed as inclusions in pyrite with high contents of Ag, Te and Bi. We define an early low-grade enrichment of AuD0YA to AuD3YA followed by a later high-grade event, AuD4YA supporting polyphase mineralisation processes. This study confirms that orogenic gold deposits can be formed by remobilisation and/or new gold inputs during multiple deformation, veining and hydrothermal events.

Description: Triassic evaporites have a very particular location in the Pyrenees, close to detachment areas between the basement and the sedimentary cover, and constitute enormous chlorine and potentially brine reservoir. During the two successive deformation cycles related successively to the Cretaceous rifting and the convergence during early Cenozoic, brines were expulsed and implied in fault activity, breccia formation and fluid-rock interactions. Fluid inclusions from fault infillings and alpine-style fissures sampled all along the Pyrenean chain have a maximal chlorinity close to that of halite-water equilibrium at temperatures between 250 and 350°C. Mixing of brines with low chlorinity waters formed a series of fluids covering an extensive range of salinities. During syn-rift events, the hotter dilute end-member is likely derived from seawater infiltrated and heated near the exhumed mantle as no emerged areas were present at that time. During convergence and thrusting, brines again predominate and mixing occurred with a colder end-member, probably of meteoric origin, consistent with a significant period of relief formation. Brines played, therefore, an essential role in mass and heat transfer during the whole orogenic cycle in the Pyrenees.

Description: The informative paper by Carrasquero (2021) reveals the personal contribution made by Francisco Moreno to the success of the 1902-04 Scottish National Antarctic Expedition (SNAE) during the time it spent in Buenos Aires, Argentina. It was a crucial intervention, and for the hospitality and generous assistance that Moreno arranged for the expedition's leader, William Speirs Bruce (Fig. 1), the presentation of a few rock specimens might seem scant reward, although as an additional mark of respect Bruce named Point Moreno on the expedition's published map of Laurie Island (Brown et al. 1906, p. 145): the name is still valid – 60° 44’ S, 44° 41’ W. Bruce would have been deeply satisfied by the knowledge that his donation of specimens from the South Orkney Islands had initiated the development of an Antarctic collection at the Museo de La Plata. His scientific outlook was always international and collaborative.

Description: We review here data and information on Antarctic volcanism resulting from recent tephrostratigraphic investigations on marine cores. Records include deep drill cores recovered during oceanographic expeditions: DSDP, ODP and IODP drill cores recovered during ice-based and land-based international cooperative drilling programmes DVDP 15, MSSTS-1, CIROS-1 and CIROS-2, DVDP 15, CRP-1, CRP-2/2A and CRP-3, ANDRILL-MIS and ANDRILL-SMS, and shallow gravity and piston cores recovered in the Antarctic and sub-Antarctic oceans. We report on the identification of visible volcaniclastic horizons and, in particular, of primary tephra within the marine sequences. Where available, the results of analyses carried out on these products are presented. The volcanic material identified differs in its nature, composition and emplacement mechanisms. It was derived from different sources on the Antarctic continent and was emplaced over a wide time span.Marine sediments contain a more complete record of the explosive activity from Antarctic volcanoes and are complementary to those obtained by land-based studies. This record provides important information for volcanological reconstructions including approximate intensities and magnitudes of eruptions, and their duration, age and recurrence, as well as their eruptive dynamics. In addition, characterized tephra layers represent an invaluable chronological tool essential in establishing correlations between different archives and in synchronizing climate records.

Description: The Stappen High-Bjørnøya tectono-sedimentary element (TSE) is located in the western Barents Shelf and is one of the prominent tectonic elements in the area. The Stappen High comprises a shallow platform, and Bjørnøya forms its highest point with exposed outcrops. Modern seismic reflection data of improved quality in the southern part of the TSE and vintage seismic data in the northern portion are utilised. Together with updated geological information at Bjørnøya, the study provides insights into the Palaeozoic to early Cenozoic evolution of the Stappen High-Bjørnøya TSE. In this context, we discuss structural inheritance, the rift development, and we account for confirmed and potential hydrocarbon systems and plays.

Description: Large-scale electrical resistivity investigations of the Antarctic crust and upper mantle utilizing the magnetotelluric method (MT) are limited in number compared to temperate regions, but provide physical insights difficult to obtain with other techniques. Key to the method's success are instrumentation advances that allow micro-volt level measurements of the MT electric field in the face of mega-ohm contact resistances. Primarily in this chapter, we reanalyze existing data from three campaigns over the Antarctic interior using modern 3D non-linear inversion analysis and offer additional geophysical conclusions and context beyond the original studies. A profile of MT soundings over transitional Ellsworth-Whitmore block in central West Antarctica implies near-cratonic lithospheric geothermal conditions with interpreted graphite-sulphide horizons deformed along margins of high-grade silicate lithologic blocks. Reanalysis of South Pole soundings confirms large-scale low resistivity spanning Moho depths that is consistent with limited seismic tomography and elevated crustal thermal regime inferences. Upper mantle under a presumed adiabatic thermal gradient below the Ross Ice Shelf near the central Transantarctic Mountains appears to be of a moderately hydrated state but not sufficient so as to induce melting. The degree of hydration there is comparable to that below the north-central Great Basin province of the western U.S.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5332327

Description: The Hammerfest Basin is an E -W trending graben located between the Loppa High and the Finnmark Platform in the southern part of the Norwegian Barents Sea. Mainly siliciclastic strata of Carboniferous to Cenozoic age cover the Caledonian basement and have a total estimated thickness of 5-8 km. The basin evolved through several tectonic phases: the Carboniferous rifting, Late Jurassic rifting, the opening of the Atlantic Ocean, Oligocene reorganisation of plate movements and postglacial isostatic rebound. An E-W trending dome in the centre of the basin developed during the main extensional tectonic event in Late Jurassic. Horst structures represent the main hydrocarbon traps. Erosional channels on the flanks of the basin represent entry points for Lower Cretaceous sands. For the rest of the Cretaceous and Cenozoic intervals no significant reservoir sands are expected.The first exploration well in the Barents Sea in 1980 was located in the Hammerfest basin, and by 2019 a total of 45 wells had been drilled in the basin where 34 are classified as exploration wells. The result is 18 oil and gas discoveries, which gives a discovery rate of 53%. Two fields are now in production: the Snøhvit gas-condensate fields and the Goliat oil field.A total of 340 Msm3 (2140 Mbbl) recoverable oil equivalents have been discovered. For the middle Jurassic Play, the yet-to-find potential may be around 50 Msm3, distributed in several small structures in the basin. Following the oil discovery in the Middle Triassic interval in the Goliat structure, and because several of the previously drilled structures only penetrated the Jurassic and the uppermost Triassic section, considerable exploration potential may exist in the deeper Triassic interval in structures with the best reservoir facies. Stratigraphic traps of Cretaceous age may have a moderate petroleum potential, with excellent reservoirs encountered along the flank of the basin. Exploration potential may also exist in Upper Permian sandstones along the southern and eastern flanks of the basin. However, in large parts of the basin, the remaining potential is in the deep structures and hence is gas prone.

Description: Deception Island (South Shetland Islands) is one of the most active volcanoes in Antarctica, with more than 15 explosive eruptive events registered over the past two centuries. Recent eruptions (1967, 1969 and 1970) and volcanic unrest episodes in 1992, 1999 and 2014–15 demonstrate that the occurrence of future volcanic activity is a valid and pressing concern for scientists, logistic personnel and tourists that are visiting or are working on or near the island. Over the last few decades, intense research activity has been carried out on Deception Island to decipher the origin and evolution of this very complex volcano. To that end, a solid integration of related scientific disciplines, such as tectonics, petrology, geochemistry, geophysics, geomorphology, remote sensing, glaciology, is required. A proper understanding of the island's evolution in the past, and its present state, is essential for improving the efficiency in interpreting monitoring data recorded during volcanic unrest periods and, hence, for future eruption forecasting. In this chapter, we briefly present Deception Island's most relevant tectonic, geomorphological, volcanological and magmatic features, as well as the results obtained from decades of monitoring the island's seismic activity and ground deformation.

Description: The Mackenzie-Peel Platform tectono-sedimentary element, and the overlying Ellesmerian Foreland tectono-sedimentary element, consist of Cambrian to Early Carboniferous shelf and slope sedimentary deposits in Canada&s northern Interior Plains. In this chapter, these elements are combined into the Mackenzie-Ellesmerian Composite Tectono-Sedimentary Element. The history of the area includes early extensional faulting and subsidence in the Mackenzie Trough, passive margin deposition across the Mackenzie-Peel Platform, local uplift and erosion along the Keele Arch, subsidence and deposition in the Ellesmerian Foreland, possible minor folding during the Ellesmerian Orogeny, and folding and faulting in Cretaceous to Eocene time associated with the development of the Canadian Cordillera. Recorded petroleum discoveries are within Cambrian sandstone (Mount Clark Formation), Devonian carbonate strata (Ramparts and Fort Norman formations), and Devonian shale (Canol Formation). Additional oil and gas shows are documented from Cambrian to Silurian carbonate units (Franklin Mountain and Mount Kindle formations), Devonian carbonate units (Arnica, Landry, and Bear Rock formations), and Late Devonian to Early Carboniferous siliciclastic units (Imperial and Tuttle Formations). Petroleum exploration activity within the area has occurred in several phases since 1920, most of it associated with the one producing oil field at Norman Wells.

Description: Upper Jurassic to Paleocene siliciclastic strata comprise the Cordilleran Foreland tectono-sedimentary element of Canada's northern Interior Plains. These strata record 4 major packages deposited on top of Paleozoic shelf strata on the northwest margin of the Canadian craton. These packages are: a Jurassic interval interpreted to record deposition associated with extension at the Arctic Ocean margin, a Lower Cretaceous, dominantly marine interval deposited on the flexural margin of the foreland basin, and two Upper Cretaceous intervals of west-to-east progradational marine and non-marine strata deposited on the orogenic margin. The full succession has been affected by Cordilleran deformation within Mackenzie Plain, Franklin Mountains, and Colville Hills. Organic-rich shale is documented from Lower and Upper Cretaceous successions, but these strata only reach thermal maturity in deeper parts of the basin, close to the Canadian Cordillera. Potential reservoirs exist within sandstone-dominated intervals throughout the succession, though some locally lack a top seal. One natural gas discovery has been reported from Upper Cretaceous sandstone of the Little Bear Formation at the Stewart D-57 well in southeastern Mackenzie Plain. Oil sourced from Upper Cretaceous shale is reported from the Mackenzie Plain East Mackay B-45 well.

Description: Recent U-Pb igneous ages obtained in the SW Domain of the Anti-Atlas are not consistent with the model proposed in the recently published paper by Errami et al. (2020). The formations of the Taghdoute and Lkest groups in the SW Domain, also known as the “limestones and quartzites” series, were previously considered to have a Cryogenian age due to similarities with the series of limestone and quartzite of the Tachddamt Bleida Formation in the Bou-Azzer Inlier located in the NE Domain of the Anti-Atlas. However, recent U-Pb ages on zircon and baddeleyite of 1.71-1.65 Ga obtained on intrusive sills and dykes in the Taghdoute and Lkest groups, constrain this sedimentary series of the SW Domain to be approximately 1 Ga older than previously thought. Absence of Paleoproterozoic series in the NE Domain combined with the available age constraints suggests that it has a Pan-African age. However, recent 1.71-1.65 Ga ages of mafic magmatism in the SW Domain conflict with the previously inferred Tonian to Cryogenian age for the mixed carbonate-siliciclastic series of the Taghdoute and Lkest groups and raises uncertainty about the age of tectonic events previously attributed to the Pan-African Orogeny in this part of the Anti-Atlas. Furthermore, the age difference between the NE and SW domains of the Anti-Atlas suggests their independent geodynamic evolution before the Ediacaran Period.

Description: The comment of Ikenne et al. concerns recently described U-Pb baddeleyite ages, around 1.71 and 1.65 Ga, obtained on intrusive sills and dykes in the Taghdout-Lkest Group in the SW domain of the Anti-Atlas (AA). These authors suggest an independent geodynamic evolution of the eastern and western domains of the Anti-Atlas prior to the Ediacaran period. Furthermore, they state that we do not take this magmatic event into account when interpreting our data. We like to emphasize that this is beyond the scope of our paper and does not affect our interpretation of the AA evolution during the deposition of the Ediacaran sedimentary successions (Saghro, Mgouna, and Ouarzazate goups). We agree with the comment that we did not distinguish the Taghdout-Lkest from the Bleida-Tachdamt groups and now we separate them in the revised figure 2. The different geodynamic evolution of the SW and NE Anti-Atlas domains in pre-Ediacaran times sensu Ikenne et al., is not consistent with abundant inherited Paleoproterozoic zircon detritus and Nd model ages (0.80-1.82 Ga) from the northeastern Anti-Atlas and the Meseta. There is no doubt about Late Paleoproterozoic baddeleyite ages, but they do not have an analogue in the zircon age record of the West African Craton, which is expected from ultramafic rocks with few zircon grains. However, they locally allow assuming a Late Paleoproterozoic deposition of the lower Taghdout-Lkest Group. Any age constraints for the upper parts of this group are lacking, thus allowing a hypothetic deposition between ca. 1.65 Ga and 0.83 Ga (the assumed age of initial Bleida-Tachdamt Group deposition). Therefore, it is very important to close the gap in detailed stratigraphic studies that would allow differentiating between the different Late Paleoproterozoic and Early Neoproterozoic events including the stratigraphic position of the upper Taghdout-Lkest Group and Bleida-Tachdamt group.

Description: Disentangling the factors underlying the appearance of macroscopic, often skeletonized, bilaterians during the Ediacaran-Cambrian diversification of animals requires carefully parsing the contributions of ecological opportunity, environmental potential and developmental capacity. The early evolution of animals involved the introduction of genomic, developmental, morphologic and behavioral novelties, identified as the individuation of new characters, which led to the construction of new ecological networks (innovation). Here I employ a recently introduced conceptual framework for novelty and individuation that distinguishes between potentiation, novelty, innovation and adaptive adjustments to the Ediacaran-Cambrian radiation, and focus on the roles of potentiation and novelty in the expansion of developmental capacity. Comparative developmental studies combined with molecular clock estimates and data from the fossil record suggest that developmental capacity, the potential to generate a range of morphologies, may expand rapidly through developmental novelties without leading directly to morphological novelties, or to innovation. The expected patterns from this framework are markedly different from those in adaptive radiation scenarios.Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/cc/advances-cambrian-explosion

Description: Classical sections, such as the Maidiping and Daqiao Mine sections of South Sichuan (China), expose early Cambrian deposits that are crucial for understanding the biological and environmental evolution of Yangtze Craton. These sequences are rich in Terreneuvian small shelly fossils, which can be assigned to assemblages I and III from South China. The Anabarites trisulcatus– Protohertzina anabarica Assemblage Zone (Assemblage I) is recognized at the lower Maidiping Formation. The second assemblage (Paragloborilus subglobosus – Purella squamulosa Assemblage Zone) cannot be verified in South Sichuan, although previous reports claimed its existence based on the occurrence of Paragloborilus subglobosus. The third assemblage (Watsonella crosbyi Assemblage Zone) is confirmed in the upper Maidiping Formation. The abundant bioclasts in this interval indicate abrasions and bioerosions by winnowing or starved sedimentation. Carbon isotope values from the Maidiping section present no negative excursion at the presumed Ediacaran–Cambrian transition. A positive carbon isotope excursion is observed in the upper Maidiping Formation (Assemblage III) which is correlated to the ZHUCE excursion in the Dahai Member of eastern Yunnan. The shallow water deposits of South Sichuan can be correlated with the South China, western Mongolia and Siberia successions based on biozonations and carbon isotope trends.Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/cc/advances-cambrian-explosionSupplementary material:https://doi.org/10.6084/m9.figshare.c.5326834

Description: A new scheme is introduced for classifying and naming mappable rock bodies that lack primary stratification. In recognition of their distinctive geological characteristics, these ‘nonstratiform’ bodies are defined and classified according to their 3D form, spatial distribution and genetic relationships, in two hierarchical (parent-child) chains: one for intrusions and one for tectonometamorphic units. Geologically complex units, encompassing bodies of different genetic classes, are classified in a third chain reserved specifically for ‘mixed-class’ units. The new classification scheme is offered as an alternative to existing recommendations in the International Stratigraphic Guide and North American Stratigraphic Code, in which nonstratiform bodies are recognised and defined primarily by their lithological character. BRUCS (the BGS Rock Unit Classification System) combines the three new parent-child chains for nonstratiform units with the well-established chain for stratiform units (bed-member-formation-group-supergroup) to create a flexible, practical and effective solution for classifying and naming all mappable rock bodies. The taxonomic rigour of BRUCS means the considerable capabilities of modern digital systems for managing and communicating mapping data can be exploited fully.

Description: Earthquakes and tsunamis are high–impact geohazard events that could be extremely destructive when they occur at large magnitudes and intensities, respectively, although their causes and potential locations are, for the most part, predictable within the framework of plate tectonics. Amongst the main reasons for their high impact include enormous numbers of casualties, extensive property damage in vast areas, and significant social and economic disruptions in urban settings where populous residential areas, global banking centres, industrial factories, and critical facilities (nuclear power plants, dams) may be located. In order to reduce the impact of these geohazards, the nations, societies, professional organizations and governments need to collaborate to prepare more effective seismic and tsunami risk assessments, disaster management plans, educational and training programmes for increased preparedness of the public, and strategic plans and objectives for capacity building, skill and knowledge transfer, and building of societal resilience. Improved building design and construction codes, and emergency preparedness and evacuation plans should be part of disaster management plans in countries where destructive earthquakes and tsunamis occurred earlier. Fast increasing population in coastal corridors in developing and developed countries is likely to escalate the social and economic impacts of these geohazards exponentially in the future. The chapters in this book present case studies of some of the most salient earthquake and tsunami events in historical and modern times, their origins and manifestations, and efforts and most effective practices of risk assessment and disaster management implemented by various governments, international organizations and inter–governmental agencies following these events. New methods of computing probabilistic seismic hazard risks, delineating respect distance and damage zones along–across seismically active faults and recognizing tsunamigenic and submarine landslides on the seafloor are introduced. The conclusions presented in the chapters show that: (1) scientific understanding of the characteristics of seismically active faults is paramount; (2) increased local (community), national and global resilience is necessary to empower societal preparedness for earthquake and tsunami events; and, (3) all stakeholders, including policy–makers, scientists, local, state and national governments, media, and world organizations (UNESCO, IUGS, GeoHazards International–GHI, Global Geodetic Observing System–GGOS; National Earthquake Hazards Reduction Program–NEHRP) must work together to disseminate accurate and timely information on geohazards, to develop effective legislation for risk reduction, and to prepare realistic and practical hazard mitigation and management measures.