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Geological Society, London, Special Publications; https://doi.org/10.1144/sp513-2021-159

Abstract:
Proterozoic to Cenozoic lamprophyres, lamproites and related rock types hold a unique potential for the investigation of processes affecting mantle reservoirs. They originated from primary mantle-derived melts that intruded both cratons and off-craton regions, that were parts of former supercontinents - Columbia, Rodinia and Gondwana-Pangea. Well-known for hosting economic minerals and elements such as diamonds, base metals, platinum-group elements and Au, they are also significant for our understanding of deep-mantle processes, such as mantle metasomatism and mantle plume-lithosphere interactions, as well as large-scale geodynamic processes, including subduction-related tectonics, supercontinent amalgamation and break-up, respectively. This Special Publication presents an overview of the state-of-the-art and recent advances as achieved by individual research groups from different parts of the world, and outlines future research directions. Mineralogical, geochemical, geochronological and isotope analyses are used to decipher the complex petrogenetic and metallogenetic evolution of these extraordinary rocks, and unravel a complete history of tectonic events related to individual supercontinent cycles. The Special Publication including this introductory chapter also deals with some issues related to the classification of these rocks.
, D. Ktenas, J. K. Nielsen
Geological Society, London, Memoirs; https://doi.org/10.1144/m57-2020-20

Abstract:
The Finnmark Platform Composite Tectono-Sedimentary Element (CTSE), located in the southern Barents Sea, is a northward-dipping monoclinal structural unit. It covers most of the southern Norwegian Barents Sea where it borders the Norwegian Mainland. Except for the different age of basement, the CTSE extends eastwards into the Kola Monocline on the Russian part of the Barents Sea. The general water depth varies between 200-350 m, and the sea bottom is influenced by Plio-Pleistocene glaciations. A high frequency of scour marks and deposition of moraine materials exists on the platform areas. Successively older strata sub-crop below the Upper Regional Unconformity (URU, which was) formed by several glacial periods. Basement rocks of Neoproterozoic age are heavily affected by the Caledonian Orogeny, and previously by the Timanide tectonic compression in the easternmost part of the Finnmark Platform CTSE. Depth to crystalline basement varies considerably and is estimated to be from 4-5 to 10 km. Following the Caledonian orogenesis, the Finnmark Platform was affected by Lower to Middle Carboniferous rifting, sediment input from the Uralian Orogen in the east, the Upper Jurassic / Lower Cretaceous rift phase and the Late Plio-Pleistocene isostatic uplift. A total of 8 exploration wells drilled different targets on the platform. Two minor discoveries have been made proving presence of both oil and gas and potential sandstone reservoirs of good quality identified in the Visean, Induan, Anisian and Carnian intervals. In addition, thick sequences of Perm-Carboniferous carbonates and spiculitic chert are proven in the eastern Platform area. The deep reservoirs are believed to be charged from Paleozoic sources. A western extension of the Domanik source rocks well documented in the Timan-Pechora Basin may exist towards the eastern part of the Finnmark Platform. In the westernmost part, charge from juxtaposed down-faulted basins may be possible.
Yuri Oki, Hiroshi Kitazato, Toyonobu Fujii, Soichiro Yasukawa
Geological Society, London, Special Publications; https://doi.org/10.1144/sp505-2021-26

Abstract:
Coastal ecosystems consist of diverse habitats, such as reed beds, salt marshes, mangrove swamps, tidal flats, river deltas, seagrass fields, coral reefs, sandy/rocky-shore beaches and other habitats that harbour biodiversity. The Great East Japan Earthquake of March 2011 caused severe damage to one-third of the fishing communities along the Pacific Ocean of northeastern Japan. Coastal species, such as seagrasses, function as nursery areas for commercially important species. Coastal ecosystems provide natural infrastructure for the prevention and reduction of hazardous events, a process known as ecosystem-based disaster risk reduction (Eco-DRR). The preparation of topographic and thematic maps of coastal marine environments is essential to establish and visualise the concept of Eco-DRR. Experience gained following the Japanese earthquake, as well as examples from Indonesia and Thailand in the wake of 2004 Indian Ocean tsunami showed that Eco-DRR is an affordable and sustainable approach. Dissemination of habitat maps should be further promoted as a means to ‘Build Back Better’. To scale up and promote Eco-DRR, scientists must work in a transdisciplinary manner and engage with society through understanding the roles of ecosystems by monitoring and analysing, providing solutions and raising the awareness of community and policy makers, enabling them to better implement Eco-DRR.
Brook Runyon, Joel E. Saylor, , James H. Reynolds, Brian Hampton
Journal of the Geological Society; https://doi.org/10.1144/jgs2021-003

Abstract:
This contribution assesses models for basin formation in the Altiplano. New magnetostratigraphy, palynology, and 40Ar/39Ar and U-Pb geochronology from the central Corque Syncline demonstrate that the 7.4 km-thick section was deposited between 36.7 and 18.7 Ma. The base of the section post-dates exhumation in both the Western and Eastern cordilleras, precluding deposition in a classic retroarc foreland basin setting. Rotated paleomagnetic vectors indicate counterclockwise rotation of 0.8°/Myr since the early Oligocene. Detrital zircon provenance data confirm previous interpretations of Eocene–early Oligocene derivation from the Western Cordillera and a subsequent switch to an Eastern Cordilleran source. Flexural modeling indicates that loads consistent with paleoelevation estimates cannot account for all subsidence. Rather, the timing and magnitude of subsidence is consistent with Eocene emplacement and Oligocene–early Miocene resteepening of a flat slab. Integration of the magmatic, basin, and deformation history provides a coherent model of the effects of flat subduction on the overriding plate. In this model flat subduction controlled basin formation in the upper plate, with subsidence enhanced in front of the zone of flat subduction but reduced over the crest of the flat slab. We conclude that the Altiplano was conditioned for plateau formation by Eocene–Oligocene flat subduction. Thematic collection: This article is part of the Fold-and-thrust belts collection available at: https://www.lyellcollection.org/cc/fold-and-thrust-belts Supplementary material: https://doi.org/10.6084/m9.figshare.c.5664345
Journal of the Geological Society; https://doi.org/10.1144/jgs2021-077

Abstract:
Abiotic synthesis was hypothesized for the occurrences of hydrocarbon gases with atypical molecular and isotopic compositions. This work provides biotic interpretations on these atypical compositions: 1) microbial CH4 oxidation and CO2-sourced methanogenesis may enrich 13C in hydrothermal CH4; 2) microbial hydrocarbon generation using serpentinization-derived H2 may deplete deuterium in hydrocarbons; 3) three processes may cause isotopic reversal with the carbon number in biotic hydrocarbons: i. the decrease of kinetic isotope effect (KIE) with the increase of carbon number during alkane biodegradation, ii. inverse KIE during the thermal decomposition of higher alkanes, and iii. isotopic fractionation during gas diffusion in rock samples; 4) random scission of long alkyl chains may form the exponential distribution of alkane abundance with respect to carbon number (“Schulz-Flory distribution”); 5) isotopic compositions are often not equilibrated; even if they are, the equilibrium temperatures are not necessarily the same as the temperature of hydrocarbon generation. Case studies demonstrate that previously proposed abiotic hydrocarbon gases in continental serpentinite-hosted seepages, continental or oceanic hydrothermal vents, volcanic emissions, gas fields in volcanic reservoirs, and fluid inclusions in alkaline or granitic rocks were formed with various biotic processes. The occurrence of abiotic hydrocarbon gas with decisive evidence is limited to fluid inclusions in some mantle minerals. Supplementary material: Appendices 1 and 2 and tables S1 and S2 are available at https://doi.org/10.6084/m9.figshare.c.5660278.
Journal of the Geological Society; https://doi.org/10.1144/jgs2021-078

Abstract:
Onshore and offshore sedimentological, geochemical, geomorphological, paleontological and geochronological studies of loess deposits located under and around the English Channel revealed that they were transported by katabatic winds generated by the British-Irish Ice Sheet. Katabatic winds, which are low-altitude wind flows, were able to jump over the low southern British hills but were stopped by the higher Brittany and Normandy hills. This regional topography is interrupted by a north-south corridor linking the northern and southern shores of Brittany where loess propagated down to the mouth of Loire River. This long transit shows that the total distance travelled by the katabatic wind was around 750 kilometres, which represents an unusual distance for the propagation of this wind under continental conditions. Strong similarities with Antarctica and Greenland, where well documented cases of katabatic winds are known, show that the transit of the trans-Channel katabatic winds were strongly enhanced by the seasonal drift of storms propagating in an eastward direction along the axis of the English Channel. This increasing strength of the North-South katabatic flux was probably at the origin of the transport of loess particles down to the mouth of Loire River.
Clara Abu, , Malcolm Francis
Journal of the Geological Society; https://doi.org/10.1144/jgs2021-032

Abstract:
Submarine landslides (slides) are some of the most voluminous sediment gravity-flows on Earth and they dominate the stratigraphic record of many sedimentary basins. Their general kinematics and internal structure are relatively well-understood. However, how slides increase in volume and internally deform as they evolve, and how these processes relate, in time and space, to the growth of their basal (shear) zone, are poorly understood. We here use three high-resolution 3D seismic surveys from the Angoche Basin, offshore Mozambique to map strain within a shallowly buried, large, and thus seismically well-imaged slide (c. 530 km3). We document several key kinematic indicators, including broadly NW-trending lateral margins and longitudinal shears bounding and within the slide body, respectively, and broadly NE-trending symmetric pop-up blocks in the slide toe. Approximately 7 km downdip of the slide toe wall, thrusts and related folds also occur within otherwise undeformed slope material, with thrusts detaching downwards onto the downslope continuation of the basal shear zone underlying the slide body. Based on the style, trend, and distribution of these features, and their cross-cutting relationships, we propose an emplacement model involving two distinct phases of deformation: (i) bulk shortening, parallel to the overall SE-directed emplacement direction, with contractional shear strains reaching c. 8%; and (ii) the development of broadly emplacement direction-parallel shear zones that offset the earlier-formed shortening structures. We infer that the contractional strains basinward of the slide body formed due to cryptic basinward propagation of the basal shear zone ahead of and to accommodate updip sliding and shortening associated with, the entire slide mass. Our study demonstrates the value of using 3D seismic reflection data to reveal slide emplacement kinematics, especially the multiphase, non-coaxial nature of deformation, and the dynamics of basal shear zone growth.
Journal of the Geological Society; https://doi.org/10.1144/jgs2020-263

Abstract:
Unconformities in foreland basins may be generated by tectonic processes that operate in the basin, adjacent fold-thrust belt, and broader convergent margin. Foreland basin unconformities represent shifts from high accommodation to nondepositional or erosional conditions in which the interruption of subsidence precludes net sediment accumulation. This study explores the genesis of long duration (>1–20 Myr) unconformities and condensed stratigraphic sections by considering modern and ancient examples from the Andes. These cases highlight potential geodynamic mechanisms of accommodation reduction and hiatus development in Andean-type retroarc foreland settings, including: (a) shortening-induced uplift in the frontal thrust belt and proximal foreland; (b) growth and advance of a broad, low-relief flexural forebulge; (c) uplift of intraforeland basement blocks; (d) tectonic quiescence with regional isostatic rebound; (e) cessation of thrust loading and flexural subsidence during oblique convergence; (f) diminished accommodation or sediment supply due to changes in sea level, climate, erosion, or transport; (g) basinwide uplift during flat-slab subduction; and (h) dynamic uplift associated with slab window formation, slab breakoff, elevated intraplate (in-plane) stress, or related mantle process. These contrasting mechanisms can be distinguished on the basis of the spatial distribution, structural context, stratigraphic position, paleoenvironmental conditions, and duration of unconformities and condensed sections. Thematic collection: This article is part of the Fold-and-thrust belts collection available at: https://www.lyellcollection.org/cc/fold-and-thrust-belts
, , Martin Evans
Geological Society, London, Memoirs; https://doi.org/10.1144/m58-2021-4

Abstract:
Significant developments in soil erosion research for the period 1950-2000 are reviewed. The main emphasis is on work in Western Europe and North America. We highlight work on process studies in splash, rill and gully erosion. Important developments also occurred in monitoring, measuring, and modelling erosion as well as recording and understanding rates of erosion. We concentrate on cultivated and bare soils and have included badlands and peatland erosion in our review.
, Jon R. Ineson
Geological Society, London, Memoirs; https://doi.org/10.1144/m57-2020-6

Abstract:
The Franklinian margin composite tectono-sedimentary element (CTSE) in North Greenland is dominated by Neoproterozoic - lowermost Devonian sedimentary strata that include early syn-rift through passive margin TSEs of mixed carbonate and siliciclastic facies. The sedimentary successions are well exposed in much of northern Greenland, but locally were strongly affected by the Ellesmerian Orogeny, resulting in a fold and thrust belt that deformed the northernmost exposures. An exposed palaeo-oilfield attests to the petroleum potential of the basin. Several formations have good source potential and several others have good reservoir properties. Palaeo-heat flow indicators show that temperatures increase to the north, where much of the basin is over-mature. Because of the remoteness of the area and the restricted locations where petroleum potential is likely to remain, the basin is not currently a target for exploration.
R. W. Fitzpatrick, L. J. Donnelly
Geological Society, London, Special Publications, Volume 492; https://doi.org/10.1144/sp492

Abstract:
Forensic soil science and geology provides information and operational support to assist the police and law enforcement with criminal and environmental investigations. These include: crime scene examination and the collection of soil and other materials; analysis and interpretation of this geological trace evidence; and searches associated with homicide graves, counter-terrorism and serious and organized crime. This volume provides new and sophisticated field and laboratory methods and operational casework.
Geological Society, London, Memoirs; https://doi.org/10.1144/m56-2021-26

Abstract:
This chapter reviews the geochemistry and petrology of mantle peridotite xenoliths from across Antarctica, including parameters that are of most relevance to geophysical studies. This Memoir is the first time such a complete overview of the chemistry of Antarctic mantle xenoliths has been available and Antarctica should no longer be the ignored continent in studies of mantle xenoliths in volcanic rocks. Xenoliths indicate that the chemistry, heat flow and water content of the Antarctic lithospheric mantle varies regionally at scales of one to thousands of kilometres. The prevalence of variability in xenoliths suggests that the Antarctic mantle is ubiquitously heterogeneous. This has important, yet unquantified, implications for interpreting geophysical data and for reference Earth models used in Antarctic geophysical studies. Information about and interpretations of Antarctic mantle xenoliths can be linked to studies from once adjacent continental blocks in Africa, India, Australia, New Zealand and South America. Together, this can improve understanding of the mantle contribution to glacial isostatic adjustment and geodynamic models to show how the Antarctic mantle fits with adjacent continents in the puzzle of lithospheric blocks. Numerous, fundamental and important research questions remain unanswered making further study of the Antarctic mantle an exciting prospect for future research.
Giampaolo Proietti, Marko Cvetković, Bruno Saftić, , Valentina Romano, Sabina Bigi
Abstract:
One of the most innovative and effective technologies developed in recent decades for reducing carbon dioxide emissions to the atmosphere is CCS (Carbon Capture & Storage). It consists of capture, transport and injection of CO2 produced by energy production plants or other industries. The injection takes place in deep geological formations with the suitable geometrical and petrophysical characteristics to permanently trap CO2 in the subsurface, which is called geological storage. In the development process of a potential geological storage site, correct capacity estimation of the injectable volumes of CO2 is one of the most important aspects. There are various approaches to estimate CO2 storage capacities for potential traps, including geometrical equations, dynamic modelling, numerical modelling, and 3D modelling. In this work, generation of three-dimensional petrophysical models and equations for calculation of the storage volumesare used to estimate the effective storage capacity of four potential saline aquifers in the Adriatic Sea offshore. The results show how different saline aquifers, with different lithologies at favourable depths, can host a fair amount of CO2, that will imply a further and more detailed feasibility studies for each of these structures. A detailed analysis is carried out for each saline aquifer identified, varying the parameters of each structure identified, and adapting them for a realistic estimate of potential geological storage capacity. Thematic collection: This article is part of the Geoscience for CO2 storage collection available at: https://www.lyellcollection.org/cc/geoscience-for-co2-storage
A. Tamas, R.E. Holdsworth, J.R. Underhill, , , K. Hardman, , , K.J.W. McCaffrey, D. Selby
Journal of the Geological Society; https://doi.org/10.1144/jgs2021-066

Abstract:
The Inner Moray Firth Basin (IMFB) forms the western arm of the North Sea trilete rift system that initiated mainly during the Late Jurassic-Early Cretaceous with the widespread development of major NE-SW-trending dip-slip growth faults. The IMFB is superimposed over the southern part of the older Devonian Orcadian Basin. The potential influence of older rift-related faults on the kinematics of later Mesozoic basin opening has received little attention, partly due to the poor resolution of offshore seismic reflection data at depth. New field observations augmented by drone photography and photogrammetry, coupled with U-Pb geochronology have been used to explore the kinematic history of faulting in onshore exposures along the southern IMFB margin. Dip-slip N-S to NNE-SSW-striking Devonian growth faults are recognised that have undergone later dextral reactivation during NNW-SSE extension. The U-Pb calcite dating of a sample from the syn-kinematic calcite veins associated with this later episode shows that the age of fault reactivation is 131.73 ± 3.07 Ma (Hauterivian). The recognition of dextral-oblique Early Cretaceous reactivation of faults related to the underlying and older Orcadian Basin highlights the importance of structural inheritance in controlling basin- to sub-basin-scale architectures and how this influences the kinematics of IMFB rifting. Supplementary material: https://doi.org/10.6084/m9.figshare.c.5635432
Geological Society, London, Memoirs; https://doi.org/10.1144/m58-2021-5

Abstract:
This chapter reviews research on solutes by fluvial geomorphologists in the period 1965 to 2000; growing links with biogeochemical research are emphasised later in the chapter. Brief reference is necessarily made to some research from before and after the study period. In relation to solutes, early research sought to relate short-term process observations to long-term landform evolution. However, very quickly, research moved into much more applied fields, less concerned with landforms and more with biogeochemical processes. The drainage basin became the focus of research with a wide range of interest including nutrient loss from agricultural and forested landscapes to dissolved organic carbon export from peatlands. In particular, the terrestrial-aquatic ecotone became a focus for research, emphasising the distinctive processes operating in the riparian zone and their contribution to river water protection from land-derived pollutants. By the end of the period, the scale and range of fluvial geomorphology had been greatly transformed from what it had been in 1965, providing a distinctive contribution to the broader field of biogeochemistry as well as an ongoing contribution to the study of Earth surface processes and landforms.
Derek Knaack, Gillian Ivey, Caitlyn MacPhee, Jordan Peterzon, Liam Price, Matthew Williams,
Geochemistry: Exploration, Environment, Analysis; https://doi.org/10.1144/geochem2021-057

Abstract:
In hydrogeochemical studies, samples are commonly filtered to limit the fraction of analyte that is adsorbed or structurally bound to suspended particles, ensuring that only the dissolved fraction is analyzed, and thereby reducing analytical bias during measurement. The standard filter size that has been adopted is 0.45 μm, however, ultrafiltration can be used to remove colloidal particles two orders of magnitude smaller. In the following, we investigate the effect that standard (0.45 μm) and ultrafiltration (0.004 μm) have on the hydrogeochemistry of groundwaters from a volcanogenic massive sulfide (VMS) deposit at the Bathurst Mining Camp, New Brunswick, Canada. Groundwater samples were collected from six monitoring wells at the Nigadoo Mine tailings facility, and major and trace geochemistry were determined using a combination of inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and ion chromatography. Waters at the Nigadoo deposit are generally enriched in Ca and SO4, relative to other major cations and anions. Some element contents - including those associated with VMS deposits - differ depending on the filtration technique used (e.g., As, Fe, Pb, rare earth elements and yttrium [REY]), some are equally affected by both techniques (e.g., Cu, Ni, Zn), and some are unaffected by filtration (e.g., Ba, Ca, Mn, Cl-). Shale-normalized REY anomalies (CeSN/CeSN*, EuSN/EuSN*, and YSN/HoSN) and overall patterns can differ greatly (e.g., changing the sign of the anomaly) depending on the filtration technique used. We observe previously undocumented, and, at this time, unexplainable fractionation of Ho and Yb (non-redox sensitive REYs, unaffected by the tetrad effect) in unfiltered waters from the Nigadoo deposit. Differences in groundwater geochemistry induced by filtration technique can result in false positive and negative anomalies during environmental and exploration projects and must therefore be carefully considered. At the Nigadoo site, oxidation of sulfide minerals can occur, resulting in the formation of relatively unstable oxide minerals. Away from the tailings, where carbonate minerals are scarce and can no longer act as a pH buffer, the unstable oxide minerals break down and release metals and metalloids into the surrounding environment. The filtration methods used in this study can provide insight into where the specific metals and metalloids are hosted and how they are likely to behave under different redox conditions. Because VMS deposit pathfinder elements are enriched in unfiltered water, and differ by degree of filtration, geochemical analysis of the filtride material may also make an effective exploration tool. Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues
, M. F. Doolittle, K. A. Eastman, S. R. Poulson
Geochemistry: Exploration, Environment, Analysis; https://doi.org/10.1144/geochem2021-068

Abstract:
This paper investigates natural acid rock drainage in two streams draining either side of Mount Evans, Montana. Bedrock consists of pyrrhotite-bearing schist intruded by granitic dikes and plutons of late Cretaceous to Tertiary age. The headwaters of both streams are moderately acidic (pH < 5.0) and carry elevated loads of dissolved sulfate, aluminum, and other trace metals (Cd, Co, Cu, Mn, Zn) as well as rare earth elements (REE). Copious aluminum precipitates inferred to be hydrobasaluminite coat boulders of both streams as pH rises > 5, with adsorption of copper and REE. Concentrations and loads of dissolved sulfate and trace elements are anomalously high in a small tributary that is sourced by meltwater from a rock glacier. The S-isotope composition of dissolved sulfate in both watersheds is similar to that of pyrrhotite in the meta-sediments, but not molybdenite in late porphyry dikes. Calculations of sulfate flux (i.e., sulfate load divided by surface area) indicate a relatively fast rate of sulfide oxidation in the study area, possibly due to exposure of fresh bedrock in the steep and recently glaciated field area. Overall, the geochemistry of the site suggests the possible presence of a metamorphosed sedimentary-exhalative (SEDEX) deposit, a possibility that is unlikely to be tested by drilling given the proximity of the site to a federal wilderness area. Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues Supplementary material: https://doi.org/10.6084/m9.figshare.c.5649850
J. Xu, C. Oppenheimer, J. Hammond, H. Wei
Geological Society, London, Special Publications, Volume 510; https://doi.org/10.1144/sp510

Abstract:
China is home to more than a dozen volcanoes that have erupted during the Holocene. Recent activity, such as the eruption of Ashikule in 1951 and unrest of Changbaishan during 2002–05, highlights the potential for future volcanic unrest and eruptions in the country. In 1999, a National Volcano Monitoring Network was established, inaugurating a programme of research and surveillance to understand the history and activity of China's volcanoes. Much progress has been made since, advancing understanding in the areas of geology, geochemistry and geophysics, and supporting hazard mitigation planning. This Special Publication reports the wide-ranging outcomes of this work for the first time to the international community.
Geological Society, London, Memoirs; https://doi.org/10.1144/m58-2021-1

Abstract:
Rock properties are a crucial control of landform development. The purpose of this chapter is to examine the progress that was made in studying rock properties in general and then to discuss developments in the study of landforms in three main rock types: granite, limestone and sandstone. From the mid-1960s onwards, geomorphology witnessed an increasing concern with the quantification of rock properties and their relationship to landforms and landscape evolution. Japanese geomorphologists led in this endeavour. Studies crossed a range of scales from those of a large size, that were susceptible to field measurements, and those of small size that involved laboratory studies. Among the basic characteristics of rocks that have been studied are fracturing and jointing, rock mass strength, hardness as determined by the Schmidt Hammer, resistance as determined by laboratory simulations, slaking susceptibility, porosity, water absorption capacity, water content and permeability, and petrological thin section analyses. The investigation of forms and processes in granite, limestone and sandstone areas has shown the value of combined geological and geographical approaches, and the increasing internationalization of studies.
Nicol Morton
Scottish Journal of Geology; https://doi.org/10.1144/sjg2021-013

Abstract:
I congratulate David Smith and his colleagues (2021) on an excellent presentation of their work on the evolution of the morphology and events involved in the evolution of the Beinn na Leac area in south-east Raasay. The summit area is a difficult and even dangerous area to work in, as I know from personal experience – learning to only follow sheep tracks to avoid the many deep fissures with openings often hidden by vegetation.
John Cosgrove, ,
Quarterly Journal of Engineering Geology and Hydrogeology; https://doi.org/10.1144/qjegh2020-144

Abstract:
Structures in the basement beneath the London Basin affect the geology of relevance to geotechnical engineering within London. Unfortunately, the basement beneath London is covered by Cretaceous and Tertiary sediments. It is cut by major faults linked to the compressive phases of the Hercynian and Alpine Orogenies and to the regional extension that occurred during the Mesozoic between these compressive events. Evidence is presented that movement on basement fractures beneath London played a major role in the distribution and deformation of sediments within the Basin, causing local folding and faulting significant to engineering works. Basement rocks are exposed in SW England where the type and orientation of these fractures (faults and joints) can be examined in outcrop. This study, complemented by seismic sections in the southern UK, enable the architecture of this fault network within the basement to be determined. Understanding the fracture system in the basement provides a basis for (i), interpreting the lateral facies variations of sediments in the Basin and hence provides a means for predicting from a ground investigation the likely presence, activity or influence on site of such structures at depth and (ii), understanding the extent of local, steeply inclined and sub-horizontal planar zones of shearing when encountered on site. Thematic collection: This article is part of the Geology of London and its implications for ground engineering collection available at: https://www.lyellcollection.org/cc/london-basin
Arnab Dey,
Geological Society, London, Special Publications; https://doi.org/10.1144/sp518-2021-46

Abstract:
Dolerite dyke swarms are widespread within the Singhbhum Craton (eastern India) that emplaced from the Neoarchean to Paleoproterozoic era just after the stabilization of crust before c. 3 Ga. These dyke swarms are oriented in NE - SW to NNE - SSW, NW - SE to WNW - ESE, E - W, and N - S directions. The WNW - ESE trending c. 1.77 Ga Pipilia dyke swarm is sampled from the Satkosia area of the Orissa state. The dyke shows a noticeable disparity in terms of the modal proportion and grain size of pyroxenes, plagioclase, Fe-Ti-oxide minerals and texture across the trend. At places the primary silicates are altered to secondary hydrated mineral assemblages of amphibole, chlorite and sericite. Primary silicates are clinopyroxene (augite: Mg# = 65.7 - 82.6; En37-48Fs11-17Wo36-41), orthopyroxene (clinoenstatite: Mg# = 68.5 − 78; En63-70Fs20-29Wo4-5), plagioclase (An11-39Ab44-82Or1-7) and Fe-Ti oxides are titanomagnetite (FeO = 34.38 − 39.50 wt%, Fe2O3 = 48.26 − 56.21 wt%, TiO2 = 5.05 − 9.60 wt%) and ilmenite (FeO = 40.75 − 43.79 wt%, Fe2O3 = 3.54 − 10.03 wt%, TiO2 = 47.82 − 50.87 wt%). Application of two-pyroxene thermometry yields an equilibration temperature range of 1065oC to 978oC, and coexisting titanomagnetite-ilmenite pairs reveal 731.39oC to 573.37oC at the oxygen fugacity (fO2) condition NNO+0.3 to FMQ-1.03. The dyke contains disseminated sulfides at the interstices of Fe-Ti-oxides, and silicates. Major sulfide minerals are pyrite, chalcopyrite, and vaesite; Pyrite-vaesite assemblages occur in association with secondary silicate minerals. Pyrite grains contain variable concentration of Co = 0.01 − 5.70 wt% and Ni = 0.02 − 1.95 wt%. Coexisting vaesite contains Co = 2.42 − 10.44 wt%, Ni = 26.40 − 47.88 wt%, and Fe = 7.32 − 26.55 wt%. Texture, sulfide-silicate assemblage, and presence of low metal/S sulfides such as the pyrite-vaesite assemblage indicate primary Fe-Ni- sulfides (pyrrhotite-pentlandite) that segregated from immiscible sulfide liquid at high temperature is modified by late magmatic/hydrothermal fluid activities. Numerous sulfide-bearing deposits hosted in ultramafic-mafic intrusions of Paleoproterozoic age have been recorded globally and the occurrence of Fe-Ni-sulfides in the c. 1.77 Ga Pipilia dyke swarm in the Singhbhum Craton enhances the exploration potential of this craton in eastern India. Supplementary material at https://doi.org/10.6084/m9.figshare.c.5643989
Xiang-Dong Wang, Sun-Rong Yang, , Tetsuo Sugiyama,
Geological Society, London, Special Publications; https://doi.org/10.1144/sp512-2021-79

Abstract:
Rugose corals are one of the major fossil groups in shallow-water environments. They played an important role in dividing and correlating Carboniferous strata during the last century, when regional biostratigraphic schemes were established and may be useful for long-distance correlation. Carboniferous rugose corals document two evolutionary events. One is the Tournaisian recovery event, with abundant occurrences of typical Carboniferous rugose corals such as columellate taxa and a significant diversification of large, dissepimented corals. The other is the changeover of rugose coral composition at the mid-Carboniferous boundary, which is represented by the disappearance of many large dissepimented taxa with complex axial structures and the appearance of typical Pennsylvanian taxa characterized by compound rugose taxa. The biostratigraphic scales for rugose corals show a finer temporal resolution in the Mississippian than in the Pennsylvanian, which was probably caused by the Late Paleozoic Ice Age that resulted in glacial-eustatic changes and a lack of continuous Pennsylvanian carbonate strata. The Pennsylvanian rugose corals are totally missing in the Cimmerian Continent. High-resolution biostratigraphy of rugose corals has so far only achieved in few regions for the Mississippian time scale. In most regions, more detailed taxonomic works and precise correlations between different fossil groups are needed.
, Derek E.G. Briggs,
Journal of the Geological Society; https://doi.org/10.1144/jgs2021-105

Abstract:
Discoveries from the Late Devonian Gogo Formation, in the Canning Basin, Western Australia have provided insights into the origin and evolution of many unique gnathostome features such as the origins of teeth, internal fertilisation, air-breathing, transitional tissues between bone and cartilage, and insights into the fin to limb transition. Although vertebrate studies have dominated evolutionary work, invertebrate studies have added important insights into the palaeoecology of the site and demonstrated close faunal affinities along the margins of northern Gondwana and China. Geochemical analyses have broadened the understanding of the pathways involved in the exceptional preservation of this Devonian Konservat-Lagerstätte. Fossils from the Gogo Formation show extensive soft tissue preservation through phosphatization recording anatomical details not normally obtained from fossil sites.
Mariano Tenuta, , Rocco Dominici, Rosanna De Rosa
Geological Society, London, Special Publications; https://doi.org/10.1144/sp520-2021-89

Abstract:
The Ofanto river drains volcanic rocks from the Monte Vulture, lacustrine-fluviolacustrine deposits associated with the same volcano and sedimentary deposits of the Southern Apennines and the Bradanic foredeep sequences. Comparing the modal composition of river sands and the outcrop area of different lithologies in the different sub-basins, an over-concentration of the volcaniclastic fraction, mainly represented by loose crystals of clinopyroxene, garnet and amphibole, is shown. This has been related to the preferential erosion of pyroclastic deposits, characterized by high production of sand-sized loose minerals, together with the carbonate lability and the low sand-sized detritus production from claystones and marls. The occurrence of volcaniclastic components upstream of Monte Vulture can be explained with a contribution from the lacustrine-fluviolacustrine deposits outcropping in the upstream sector or from pyroclastic fall deposits of Monte Vulture and/or Campanian volcanoes. This research shows that the volcanic record in the fluvial sands of the Ofanto river comes from weathering and sorting processes of volcaniclastic deposits rather than of the lavas building the main edifice. Therefore, caution must be taken during paleoenvironmental and paleoclimatic reconstructions when relating the type and abundance of the volcanic component in sediments to the weathering stage and evolutionary history of the volcano. Supplementary material at https://doi.org/10.6084/m9.figshare.c.5643959
, David Banks, , Francis Bowers
Geological Society, London, Special Publications; https://doi.org/10.1144/sp516-2021-38

Abstract:
The Nalunaq deposit, Greenland, is a hypozonal, shear zone-hosted, Au deposit. The shear zone has previously been interpreted to have undergone 4 stages of deformation, accompanied by fluid flow,and vein formation. Coupled with previous trapping T estimates, fluid inclusion data are consistent with trapping of fluids with salinities between 28-45 wt. % NaCl eq., from 300-475°C during D2 and D3, with pressure varying between ∼800 and 100Mpa. The range reflects pressure cycling during seismic slip related depressurisation events. D4 fluids were lower salinity and trapped from 200-300°C, at ∼50-200Mpa during late stage normal faulting. The variation in major element chemistry is consistent with ingress of hypersaline, granitoid equilibrated fluids into the shear zone system and mixing with fluids that had reacted with the host metamorphic rocks. D4 stage fluids represent ingress of meteoric fluids into the system. Gold contents in inclusion fluids range from ∼300-10mg/kg. These data are consistent with the high P-T solubility of Au as AuHS(H2S)3 0 complexes, and Au deposition by decompression and cooling. The high salinities also suggest Au transport as chloride complexes may have been possible. Gold distribution was modified by the release of chemically bound or nanoscale Au during sulphide oxidation at the D4 stage. Supplementary material at https://doi.org/10.6084/m9.figshare.c.5635812
Yihao Liu, , Chunji Xue, Liang Yu, Haixia Chu, Xiaobo Zhao
Geological Society, London, Special Publications; https://doi.org/10.1144/sp516-2020-248

Abstract:
The temporal-spatial relationships of porphyry and orogenic gold mineralization in the Eastern Tianshan Orogenic Belt are ambiguous. The newly-discovered Changshagou deposit in this belt contains both porphyry and orogenic gold mineralization, which are characterized by polymetallic-sulfide veinlets and quartz-pyrite veins, respectively. Fluid inclusions in the porphyry mineralization episode were trapped at 290–340 °C with salinities of 3.0–8.0 wt.% NaClequiv. The homogenization temperatures and salinities in the orogenic mineralization episode range from 240 to 300 °C and 1.0–5.0 wt.% NaClequiv. Coexisting V-type and L-type fluid inclusions with similar homogenization temperatures are indicative of fluid immiscibility. The δ18Ow and δDw values range from 7.6 to 9.1 ‰ and −70.9 to −84.0 ‰ in the porphyry mineralization episode, and from 6.4 to 7.1 ‰ and −65.7 to −72.1 ‰ in the orogenic mineralization episode, overlapping magmatic and metamorphic ranges, respectively. The pyrite δ34S values range from 3.5 to 4.9 ‰, falls into the magmatic range. Pyrite in porphyry and orogenic mineralization episodes yield Re-Os isotopes ages of 269.1±2.9 Ma and 257.4±2.4 Ma. The porphyry and orogenic gold mineralizations are genetically associated with the quartz syenite porphyry and Kanggur strike-slip shear activity, respectively. Supplementary material at https://doi.org/10.6084/m9.figshare.c.5635584
Julien Perret, , Aurélien Eglinger, Julien Feneyrol, Alexandre Voinot, Christophe Morlot, , Yoram Teitler, Diego Seira, Rémi Bosc
Geological Society, London, Special Publications; https://doi.org/10.1144/sp516-2021-37

Abstract:
Integrating structural control on mineralisation and geochemical ore-forming processes is crucial when studying deformed ore deposits. Yet, structural and geochemical data are rarely acquired at the same scale: structural control on mineralisation is typically investigated from the district to the deposit and macroscopic scales whereas geochemical ore processes are described at the microscopic scale. The deciphering of a deformation-mineralisation history valid at every scale thus remains challenging. This study proposes a multi-scale approach that enables the reconciliation of structural and geochemical information collected at every scale, applied to the example of the Galat Sufar South gold deposit, Nubian shield, northeastern Sudan. It gathers field and laboratory information by coupling a classical petrological-structural study with high-resolution X-ray computed tomography, electron back-scattered diffraction and laser ablation inductively-coupled plasma mass spectrometry on mineralised sulphide mineral assemblages. This approach demonstrates that there is a linear control on mineralisation expressed from the district to microscopic scales at the Galat Sufar South gold deposit. We highlight the relationships between Atmur-Delgo suturing tectonics, micro-deformation of sulphide minerals, syn-pyrite recrystallisation metal remobilisation, gold liberation and ore upgrading. Our contribution therefore represents another step forward a holistic field-to-laboratory approach for the study of any other sulphide-bearing, structurally-controlled ore deposit type. Supplementary material at https://doi.org/10.6084/m9.figshare.c.5635726
, A. Tenny
Proceedings of the Yorkshire Geological Society; https://doi.org/10.1144/pygs2021-006

Abstract:
Only the second bored cup of the disparid crinoid Synbathocrinus conicus Phillips is described, infested by a pit of Oichnus paraboloides Bromley. Both bored specimens are from the Mississippian of Salthill Quarry, Clitheroe, Lancashire, UK, although the search for others has extended from northern Europe to North America. The first, described 30 years ago, infested a plate triple-junction of the cup on the presumed up-current side of the crinoid; the new specimen, in contrast, is in the centre of a radial plate, which is inflated as a growth response to infestation. We informally name the producing organism the ‘Salthill bug’. Although unknown, this was a small, unmineralized invertebrate that commonly attached to elevated positions on living crinoids and was likely a filter feeder. It constructed a domicile by boring into the crinoid endoskeleton, and could invade both living and dead crinoid skeletons. On crinoid stems it was commonly gregarious, a habit perhaps favoured by secretions by the first ‘Salthill bug’ to settle, attracting conspecific larvae and similar to the settling patterns of some modern sessile invertebrates. Comparison with Oichnus from Trearne Quarry, Ayrshire, UK, reveals several differences between the pits in infested crinoids at the two sites.
John K. Wright
Proceedings of the Yorkshire Geological Society; https://doi.org/10.1144/pygs2021-008

Abstract:
The sequence of Jurassic and Cretaceous strata laid down in north Lincolnshire is traced northwards onto the Market Weighton High, and compared with the equivalent Cleveland Basin sequence as it is traced south onto the High. Understanding of the manner of operation of the High has long been hindered by the amount of erosion of strata over the High, particularly in the Early Cretaceous. Facies analysis of the remaining strata present on either side of the High is used to estimate the thickness and the facies of strata originally deposited over the High. Although there were periodic uplifts of the High, leading to increasing omissions of strata approaching the High, there is little evidence that during the Jurassic the High was emergent for significant periods. Most strata were either originally present at Market Weighton in marginal marine facies, or continued across the High without interruption. The operation of the High in the light of modern understanding of crustal stresses during the Mesozoic is reviewed.
Morteza Mozafari, Ezzat Raeisi
Quarterly Journal of Engineering Geology and Hydrogeology; https://doi.org/10.1144/qjegh2021-102

Abstract:
Water leakage has been reported from several dams constructed on karst terrains in Iran. In this study the main reasons for dam leakage were identified by studying ten examples, the Lar, Kowsar, Seymareh, Tangab, and Shah-Ghasem dams with considerable leakage, and the Karun I, Karun III, Karun IV, Salman-Farsi, and Marun dams with negligible leakage. The “Potential Leakage Passage (PLP)” is defined as those parts of a karst aquifer which transfer reservoir water to downstream. The most important control on leakage is in the narrowest part of the PLP, the “bottleneck” that depends mainly on the geological settings. At the dams with negligible leakage, sealing of the PLPs was found to be technologically and economically feasible by connecting all the edges of grout curtain to the natural impermeable barriers. In the cases of dams with considerable leakage, wider PLPs were not completely sealed and the installed grout curtain did not fully connect to the impermeable rock. To reduce the risk of leakage and inform effective design of grout curtains, the characteristics of the PLP should be determined during the initial stage of dam studies, and incorporate geological and hydrogeological information in the ground model. This study highlights the significant risk of engineering project failures that can occur if hydrogeological conditions are not properly assessed, understood and managed early in development of dam location, design and construction.
Alexander Hall, Martin Gillespie, Paul Everett, Vyron Christodoulou, Jo Walsh
Quarterly Journal of Engineering Geology and Hydrogeology; https://doi.org/10.1144/qjegh2020-183

Abstract:
The ability to identify similar sandstones to a given sample is important where the provenance of the sample is unknown or the quarry of origin is no longer in operation. In the case of building stones from heritage buildings in protected areas, it may be mandatory. Here, a proof of concept for an automated similarity measure is presented by means of a convolutional autoencoder that is able to extract features from a sample thin section and use these features to identify the most similar sample in an existing image library. The approach considers only the shape of the pore space between grains, as, if the pore space alone contains enough information to distinguish between samples, the required image pre-processing and training of a model is greatly simplified. The trained model is able to predict correctly the progenitor quarry of a thin section, from an eight-class dataset of Scottish sandstones, with an accuracy of 47.9%. This prototype, although insufficient for commercial purposes, forms a benchmark for future models against which improvements can be assessed and some of which are suggested. 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
Sonja Breuer,
Geological Society, London, Special Publications; https://doi.org/10.1144/sp505-2021-24

Abstract:
Our publication presents the first draft of a geomorphological map of the German North Sea and Baltic Sea. The inspiration for this map comes from the international collaboration of marine researchers within the European EMODnet Geology Project (https://www.emodnet-geology.eu/). The current climate change intensifies the natural processes of change in nature. Within the framework of various nature conservation projects, the importance of marine sediment structures on marine fauna and their reproductive cycles, sedimentation conditions, currents, etc. has been investigated. In order to be able to make statements for the German seas and document changes, the current state must first be recorded.
Geological Society, London, Special Publications; https://doi.org/10.1144/sp512-2021-124

Abstract:
Icehouses are the less common climate state on Earth, and thus it is notable that the longest lived (∼370 to 260 Ma) and possibly most extensive and intense of icehouse periods spanned the Carboniferous Period. Mid- to high-latitude glaciogenic deposits reveal a dynamic glaciation-deglaciation history with ice waxing and waning from multiple ice centers and possible transcontinental ice sheets during the apex of glaciation. New high-precision U-Pb ages confirm a hypothesized west-to-east progression of glaciation through the icehouse, but reveal that its demise occurred as a series of synchronous and widespread deglaciations. The dynamic glaciation history, along with repeated perturbations to Earth System components, are archived in the low-latitude stratigraphic record revealing similarities to the Cenozoic icehouse. Further assessing the phasing between climate, oceanographic, and biotic changes during the icehouse requires additional chronostratigraphic constraints. Astrochronology permits the deciphering of time, at high resolution, in the late Paleozoic record as has been demonstrated in deep- and quit-water deposits. Rigorous testing for astronomical forcing in low-latitude cyclothemic successions, which have a direct link to higher latitude glaciogenic records through inferred glacioeustasy, however, will require a comprehensive approach that integrates new techniques with further optimization and additional independent age constraints given challenges associated with shallow-marine to terrestrial records.
Wanchese M. Saktura, , Allen P. Nutman, Renjie Zhou
Journal of the Geological Society; https://doi.org/10.1144/jgs2021-035

Abstract:
The Jurassic–Cretaceous Tsoltak Formation from the eastern borderlands of Ladakh Himalaya consists of conglomerates, sandstones and shales, and is intruded by norite sills. It is the oldest sequence of continent-derived sedimentary rocks within the Shyok Suture. It also represents a rare outcrop of the basement rocks to the voluminous Late Cretaceous–Eocene Ladakh Batholith. The Shyok Formation is a younger sequence of volcaniclastic rocks that overlie the Tsoltak Formation and record the Late Cretaceous closure of the Mesotethys Ocean. The petrogenesis of these formations, ophiolite-related harzburgites and norite sill is investigated through petrography, whole-rock geochemistry and U–Pb zircon geochronology. The youngest detrital zircon grains from the Tsoltak Formation indicate Early Cretaceous maximum depositional age and distinctly Gondwanan, Lhasa microcontinent-related provenance with no Eurasian input. The Shyok Formation has Late Cretaceous maximum depositional age and displays a distinct change in provenance to igneous detritus characteristic of the Jurassic–Cretaceous magmatic arc along the southern margin of Eurasia. This is interpreted as a sign of collision of the Lhasa microcontinent and the Shyok ophiolite with Eurasia along the once continuous Shyok–Bangong Suture. The accreted terranes became the new southernmost margin of Eurasia and the basement to the Trans-Himalayan Batholith associated with the India-Eurasia convergence. Supplementary material: https://doi.org/10.6084/m9.figshare.c.5633162
, Shen Ma, Xianghong Lu, Sainan Wu, Mongkol Udchachon, Yuzhi Zhang, Yuejun Wang
Journal of the Geological Society; https://doi.org/10.1144/jgs2021-079

Abstract:
Volcanic rocks in the Chanthaburi zone are rarely reported and important for investigating the tectonic evolution of Paleotethyan Ocean in SE Thailand. Four rhyolitic samples from the Ko Chang Island yield zircon ages of 254–258 Ma, confirming the presence of Late Permian volcanic rocks in SE Thailand. These rocks consist of Group 1 rhyolites and Group 2 rhyolitic ignimbrites and have high K2O contents of 4.92–7.10 wt.% and A/CNK values of 1.10–1.69. They are enriched in LREEs, Rb, Th, U, Zr and Y, and show negative anomalies of Ba, Sr, Nb, Ta and Ti with obvious Eu anomalies. Their whole-rock εNd (t) values range from −1.7 to −3.1. Zircon in-situ εHf (t) and δ18O values range from 0.0 to +5.6 and 8.2‰ to 9.6‰, respectively. They belong to peraluminous, ultrapotassic A-type rhyolites, and were derived from partial melting of a mixed source of Mesoproterozoic metasedimentary rocks with a component of juvenile mafic crust. These ultrapotassic rhyolites formed in a continental rift setting in response to the rollback of subducted Paleotethyan oceanic slab beneath the Indochina Block. Combining previous geological observations, we propose that there are some sporadically distributed continental rift basins along the Eastern Paleotethyan domain during the Permian. Supplementary material: https://doi.org/10.6084/m9.figshare.c.5635390
Geological Society, London, Memoirs; https://doi.org/10.1144/m56-2021-22

Abstract:
Geodynamic processes in Antarctica such as glacial isostatic adjustment (GIA) and post-seismic deformation are measured by geodetic observations such as GNSS and satellite gravimetry. GNSS measurements have been comprising continuous measurements as well as episodic measurements since the mid-1990s. The estimated velocities typically reach an accuracy of 1 mm/a for horizontal and 2 mm/a for vertical velocities. However, the elastic deformation due to present-day ice-load change needs to be considered accordingly. Space gravimetry derives mass changes from small variations in the inter-satellite distance of a pair of satellites, starting with the GRACE satellite mission in 2002 and continuing with the GRACE-FO mission launched in 2018. The spatial resolution of the measurements is low (about 300 km) but the measurement error is homogeneous across Antarctica. The estimated trends contain signals from ice mass change, local and global GIA signal. To combine the strengths of the individual data sets statistical combinations of GNSS, GRACE and satellite altimetry data have been developed. These combinations rely on realistic error estimates and assumptions of snow density. Nevertheless, they capture signal that is missing from geodynamic forward models such as the large uplift in the Amundsen Sea sector due to low-viscous response to century-scale ice-mass changes.
Geological Society, London, Special Publications; https://doi.org/10.1144/sp512-2021-107

Abstract:
This paper proposes a synthesis of the taxonomy, phylogeny, palaeogeographic distribution, regional biostratigraphy, and palaeobiogeographic faunal development of Carboniferous fusuline foraminifers. They appeared in the latest Tournaisian and comprised a small-sized, morphologically conservative taxonomic group during the Mississippian. Fusulines became larger and prevailed in Pennsylvanian foraminiferal assemblages. Carboniferous fusulines consist of Ozawainellidae, Staffellidae, Schubertellidae, Fusulinidae, and Schwagerinidae, in which 95 genera are considered as valid taxonomically. Upsizing their shells throughout the Pennsylvanian is likely related to symbiosis with photosynthetic microorganisms, which was accelerated by the acquisition of a keriothecal wall in Late Pennsylvanian schwagerinids. Regional fusuline succession data from 40 provinces provide a refined biostratigraphy, enabling zonation and correlation with substage- or higher-resolution precision in the Pennsylvanian. Their spatio-temporal faunal characteristics show that fusulines had a cosmopolitan palaeobiogeographic signature in Mississippian time, suggesting unrestricted faunal exchange through the palaeoequatorial Rheic Ocean. After the formation of Pangea, Pennsylvanian fusulines started to show provincialism, and their distributions defined the Ural-Arctic Region in the Boreal Realm, Palaeotethys, Panthalassa, and North American Craton regions in the Palaeoequatorial Realm, and Western Gondwana and Eastern Peri-Gondwana regions in the Gondwana Realm. The Western Palaeotethys and East European Platform Subregions maintained higher generic diversity throughout the Pennsylvanian.
, , D. A. Wiens, A. J. Lloyd,
Geological Society, London, Memoirs; https://doi.org/10.1144/m56-2020-19

Abstract:
The Antarctic mantle and lithosphere are known to have large lateral contrasts in seismic velocity and tectonic history. These contrasts suggest differences in the response time scale of mantle flow across the continent, similar to those documented between the northeastern and southwestern upper mantle of North America. Glacial isostatic adjustment and geodynamical modeling rely on independent estimates of lateral variability in effective viscosity. Recent improvements in imaging techniques and the distribution of seismic stations now allow resolution of both lateral and vertical variability of seismic velocity, making detailed inferences about lateral viscosity variations possible. Geodetic and paleo sea-level investigations of Antarctica provide quantitative ways of independently assessing the three-dimensional mantle viscosity structure. While observational and causal connections between inferred lateral viscosity variability and seismic velocity changes are qualitatively reconciled, significant improvements in the quantitative relations between effective viscosity anomalies and those imaged by P- and S-wave tomography have remained elusive. Here we describe several methods for estimating effective viscosity from S-wave velocity. We then present and compare maps of the viscosity variability beneath Antarctica based on the recent S-wave velocity model ANT-20 using three different approaches.
Geological Society, London, Memoirs; https://doi.org/10.1144/m58-2021-14

Abstract:
The advances in understanding of Quaternary geomorphology in the latter half of the 20th Century were closely linked with the improved knowledge of Quaternary climatic fluctuation, principally derived from isotopic evidence from ocean and ice cores. An important goal was finding terrestrial sedimentary records that can be correlated with the globally applicable isotopic sequence. From a geomorphological viewpoint, river terraces are paramount, particularly since they can provide semi-continuous sequences that record palaeoclimate and landscape evolution throughout the Quaternary, as well as the interaction of rivers with glaciation, sea-level change and notable geomorphological events. In coastal areas, shoreline terraces and raised beaches can provide similar sequences. The chapter discusses the progress made in understanding these archives and, in particular, the various mechanisms for dating and correlation, as well as touching upon contributions from other environments, namely slopes and karstic systems, as well as the role of soils in deciphering geomorphological evidence.
Haiyan Liu, Weimin Zhang, Jingyi Mo, Zhen Wang, Jiahong Chen, Junhua Chen, Zhen Zhuo
Geochemistry: Exploration, Environment, Analysis; https://doi.org/10.1144/geochem2021-052

Abstract:
Uranium (U) ion contamination in aquatic systems has received considerable attention worldwide. In this paper, an adsorption material was synthesized with Fe/Ca-based phosphate (CFB-PM) by a sol-gel method. The effect of pH, reaction time and initial concentration of U ions on its capacity of removing U ions from aqueous solution was investigated by static batch experiments. Comparative studies of U ion removal by CFB-PM with four sorbents, namely: nano zero-valent iron (nZVI), hydroxyapatite (HAP), hydroxyapatite-loaded nano zero-valent iron ([email protected]) and high basicity steel slag loaded hydroxyapatite ([email protected]), were performed. Results showed that U ion adsorption capacity of CFB-PM was better than that of nZVI, HAP, [email protected] and [email protected] The adsorption capacity showed a decreasing order as: CFB-PM (643.34 mg/g) > HAP (549.86 mg/g) > [email protected] (321.82 mg/g) > [email protected] (153.62 mg/g) > nZVI (102.65 mg/g). SEM-EDS examination suggested that the adsorbed U ions were mainly in the form of spheres, sheets or petals on the surfaces of CFB-PM. XRD detection revealed several U-bearing mineral phases (i.e. Ca(UO2)2(PO4)2·3H2O, HPUO6·4H2O and (UO2)3PO4·4H2O). The U ion adsorption behaviors were further explored by FTIR spectroscopy. The uranium ion adsorption process of CFB-PM could be well described by quasi-second-order adsorption kinetics model and the Langmuir adsorption isotherm model. The separation coefficient (R L) was close to zero, indicating that U ion adsorption was dominated by single-layer chemisorption. The findings reported in this study have implications for applying the synthesized material for remediation of U ion-contaminated groundwater.
David W. Houseknecht
Geological Society, London, Memoirs; https://doi.org/10.1144/m57-2018-26

Abstract:
The Arctic Alaska region includes three composite tectono-sedimentary elements (CTSEs): the (1) Arctic Alaska Basin (AAB), (2) Hanna Trough (HT), and (3) Beaufortian Rifted Margin (BRM) CTSEs. These CTSEs comprise Mississippian to Lower Cretaceous (Neocomian) strata beneath much of the Alaska North Slope, the Chukchi Sea and westernmost North Slope, and Beaufort Sea, respectively. These sedimentary successions rest on Devonian and older sedimentary and metasedimentary rocks, considered economic basement, and are overlain by Cretaceous to Cenozoic syn- and post-tectonic strata deposited in the foreland of the Chukotka and Brooks Range orogens and in the Amerasia Basin. (1) The Mississippian-Neocomian AAB CTSE includes two TSEs: (a) The Ellesmerian Platform TSE comprises mainly shelf strata of Mississippian to Middle Jurassic age and includes a relatively undeformed domain in the north and a fold-and-thrust domain in the south. (b) The Beaufortian Rift Shoulder TSE includes Middle Jurassic to Neocomian deposits related to rift-shoulder uplift. (2) The HT CTSE includes four TSEs: (a) The Ellesmerian Syn-Rift TSE comprises Late Devonian(?) to Middle Mississippian growth strata deposited in grabens and half grabens during intracontinental rifting. (b) The Ellesmerian-Beaufortian Sag-Basin TSE comprises Middle Mississippian to Upper Triassic strata deposited in a sag basin following cessation of rifting. (c) The Beaufortian Syn-Rift TSE comprises Jurassic to Neocomian graben-fill deposits related to rifting in the Amerasia and North Chukchi Basins. (d) The Beaufortian Rift-Shoulder TSE comprises Jurassic to Neocomian strata related to rifting and deposited outside rift basins. (3) The BRM CTSE includes two TSEs: (a) The Beaufortian Syn-Rift TSE comprises Middle Jurassic to Neocomian syn-rift strata deposited on attenuated continental crust associated with opening of the Amerasia Basin. (b) The Ellesmerian Platform TSE comprises mainly shelf strata of Mississippian to Middle Jurassic age that lie beneath Beaufortian syn-rift strata. The AAB, HT, and BRM CTSEs contain oil-prone source rocks in Triassic, Jurassic, and Cretaceous strata and proven reservoir rocks spanning Mississippian to Lower Cretaceous strata. A structurally high-standing area in the northern AAB CTSE, northern HT CTSE, and southernmost BRM CTSE lies in the oil window whereas all other areas lie in the gas window. Known hydrocarbon accumulations in the three CTSEs total more than 30 billion barrels of oil equivalent and yet-to-find estimates suggest a similar volume remains to be discovered.
Ekta Singh, Raman Patel, Rakesh Chandra Bhatt
Geological Society, London, Special Publications; https://doi.org/10.1144/sp515-2020-108

Abstract:
Spiti valley is located in the Trans-Himalayan terrain of India, from where non-geometric microliths have been discovered. While the Siwalik Hills have been subjected to extensive prehistoric surveys, this is the first evidence of lithic tools discovered in the Trans-Himalayan region of Himachal Pradesh, India. Due to its topographic and intense climatic features, the Trans- Himalayan region has generally been regarded as a barrier since prehistoric times. However, Dzamathang cannot be considered as an isolated site in the Trans- Himalayas. In fact, in the adjoining areas of Ladakh, Tibet and Nepal, similar lithics have been reported from several sites and assigned to the Middle and Upper Palaeolithic. The discovery of this site suggests that the Trans Himalayan zone may have acted as a possible route instead of a barrier during human migration. Large numbers of lithics have been recovered in the Dzamathang area of Spiti Valley. Based on the collection of the artefacts from the surface, this article tries to understand the geological and geographical setting of the area, particularly concerning prehistoric settlements in the Trans-Himalayas. This assemblage consists of assorted artefacts which includes a unifacial chopper, microlithic cores, flakes, blades, bladelets, burin, and a large amount of debitage fragments. The majority of artefacts are on quartzite or quartzarenite. Future surveys will be targeted at recovering primary context sites for excavations and absolute dating.
, , Britt Bluemel, Richard D. Walshaw
Geological Society, London, Special Publications; https://doi.org/10.1144/sp516-2021-47

Abstract:
Detrital gold fulfils the criteria of chemical inertia and physical durability required by indicator minerals but it has not found wide application in this role because it may be formed in different deposit types. This problem is soluble, because the generic compositional features of hydrothermal gold differ according to mineralization environment. The wide distribution of gold as a minor component of mineralization where other commodities are the principle exploration target extends the potential of an indicator methodology based on detrital gold to beyond the search for gold itself. Here we highlight how distinctive gold compositional signatures derived from alloy composition and deposit- specific suites of mineral inclusions could contribute to exploration for Cu-Au porphyries, redox- controlled uranium mineralization and ultramafic-hosted PGE mineralization. Future refinement this approach will focus on establishing the spatial distribution of elements at trace levels within gold particle sections using ToF-LA-ICP-MS and application of Exploratory Data Analysis to the resulting data sets. This approach is in its infancy, but aims to develop a classification algorithm useful to researchers irrespective of their previous experience. A pilot study has that random forests provide the best approach to establishing gold particle origins. Supplementary material at https://doi.org/10.6084/m9.figshare.c.5625450
Weitao Yang, Jin Xu
Quarterly Journal of Engineering Geology and Hydrogeology; https://doi.org/10.1144/qjegh2021-073

Abstract:
Most analytical and semi-analytical models for pumping-induced land subsidence invoke the simplifying assumptions regarding characteristics of geomaterials, as well as the pattern of drawdown response to pumping. This paper presents an analytical solution for one-dimensional consolidation of the multilayered soil due to groundwater drawdown, in which viscoelastic property and time-dependent drawdown are taken into account. The presented solution is developed by using the boundary transformation techniques. The validity of the proposed solution is verified by comparing with a degenerated case for a single layer, as well as with the numerical solutions and experimental results for a two-layer system. The difference between the average consolidation degree Up, defined by hydraulic head, and Us, defined by total settlement, is discussed. Detailed parametric studies are conducted to reveal the effects of viscoelastic properties and drawdown patterns on the consolidation process. It is revealed that while the effect of different drawdown response patterns is significant during the early–intermediate stages of consolidation, the viscoelastic properties may have a more dominant influence on long-term consolidation behaviour, depending on the values of the material parameters, which are reflected in both the deformation process of soil layers and the dissipation of excess pore-water pressure.
Isabel C. Zutterkirch, , ,
Journal of the Geological Society; https://doi.org/10.1144/jgs2021-070

Abstract:
Detrital zircon U-Pb geochronology has enabled advances in the understanding of sediment provenance, transportation pathways, and the depositional age of sedimentary packages. However, sample selection and processing can result in biasing of detrital zircon age spectra. This paper presents a novel approach using in-situ detrital zircon U-Pb measurements on thin-sections to provide greater confidence in maximum depositional ages and provenance interpretations. New U-Pb age data of 310 detrital zircon grains from 16 thin-sections of the Triassic Mungaroo Formation from two wells in the Northern Carnarvon Basin, Australia, are presented. Whilst detrital zircon age modes are consistent with previous work, there are some differences in the relative proportions of age modes, which is partly attributed to a lack of small grains in hand-picked grain mounts. The relative sample bias is quantified via grain size comparison of dated zircon (in thin-sections or hand-picked mounts) relative to all zircons identified in bulk-mounts and thin-sections. The youngest age mode (∼320 – 195 Ma) is consistent with an active margin to the north, likely South West Borneo and/or Lhasa terrane. The dated zircons reveal a maximum depositional age of 197 Ma for the upper part of Mungaroo Formation, suggesting deposition continued into the Early Jurassic. Supplementary material: https://doi.org/10.6084/m9.figshare.c.5628911
Journal of the Geological Society; https://doi.org/10.1144/jgs2021-044

Abstract:
Thermally metamorphosed rocks on the Moon are an important, yet under-studied suite of lithologies that have been identified within the Apollo and lunar meteorite collections. These rocks, with granoblastic and poikilitic textures, are generally referred to as granulites. However, unlike their terrestrial counterparts which are the metamorphic products of both high temperatures and pressures, lunar granulites are thought to be the products of only high-temperature (> 1000 oC) thermal metamorphism that completely recrystallised their protoliths. We summarise the range of textures and chemical systematics reported from lunar granulites. These data enable constraints to be placed on the thermal conditions in the lunar crust required for high-temperature metamorphism to have taken place. Most studies indicate that impact melt sheets have the relevant thermal properties to sustain high temperatures over the time scales required to fully recrystallise surrounding crustal lithologies. However, the roles of alternative heat sources, such as magmatic intrusions into the crust, have not been extensively investigated and, as such, cannot be ruled out. Additionally, chemical data yields important insights into the protoliths of the granulite suite. By identifying protoliths, we greatly enhance our understanding of the range of lithologies that make up the primary lunar crust. In turn, this enables crustal formation models to be better constrained. Supplementary material: https://doi.org/10.6084/m9.figshare.c.5623326
F. Marret, J. O'Keefe, P. Osterloff, M. Pound, L. Shumilovskikh
Geological Society, London, Special Publications, Volume 511; https://doi.org/10.1144/sp511

Abstract:
This long-awaited book about non-pollen palynomorphs (NPPs) aims to cover gaps in our knowledge of these abundant but understudied palynological remains. NPPs, such as fungal spores, testate amoebae, dinoflagellate cysts, acritarchs and animal remains, are routinely recovered from palynological preparations of marine or terrestrial material, from Proterozoic to recent geological times. This book gives the reader a comprehensive overview of the different types of NPPs, with examples from diverse time periods and environments. It provides guidance on sample preparation to maximize the recovery of these NPPs, detailed information on their diversity and ecological affinity, clarification on the nomenclature and demonstrates their value as environmental indicators. This volume will become the reference guide for any student, academic or practitioner interested in everything else in their palynological preparations.
Sadegh Saberi Mehr,
Quarterly Journal of Engineering Geology and Hydrogeology; https://doi.org/10.1144/qjegh2021-053

Abstract:
An investigation of seepage was conducted at the Golfaraj Reservoir Dam with a particular emphasis on determining the seepage areas based on regional and site-specific hydrogeological studies. The primary goal of the investigation was to develop strategies intended to minimize dam and reservoir seepage. Leakage from the reservoir is a serious problem and of considerable concern to the local populace. Substantial reduction of seepage from the Golfaraj Reservoir Dam is the ultimate goal of the investigations conducted. The Golfaraj Reservoir Dam, located in the East Azerbaijan province, NW Iran, was built to provide water for agricultural and industrial needs in the Golfaraj plain and neighbouring lands. The Golfaraj Reservoir was constructed through the Miocene Upper Red Formation, which consists of sequences of sandstone, mudstone, conglomerate and gypsiferous marl. Following reservoir filling, seepage of water into adjacent formations was found to occur at an estimated rate of 70 l s−1. After reservoir impoundment, groundwater levels in Shahmar village, 2 km downstream and just north of the dam axis, rose and land surfaces became abnormally wet. Lugeon values in some boreholes drilled around the Golfaraj Dam before and after dam construction were high enough to indicate that the dam base had sufficient permeability to allow water to escape by underflow. Twenty-four Casagrande piezometers installed around the dam axis at four sectors provided additional information on seepage pathways through the dam body and underneath or through the cutoff wall. Water-level variations in the Casagrande piezometers confirmed the seepage routes. Study results showed that reservoir water is likely to seep through the reservoir bottom, and beneath and through the cutoff wall. The west side of the dam and near the reservoir reflected water-level rises in accordance with the rise in reservoir-water level. Seepage in this area is probably due to its proximity to the Golfaraj Reservoir. Hydrogeochemical analyses further suggest that the water source at the Shahmar Drain, c. 1800 m north of the Golfaraj Dam, cannot be from the east or west embankments of the dam because the electrical conductivity in the Shahmar Drain water approximates to the electrical conductivity of the Golfaraj Reservoir water and is lower than the electrical conductivity of groundwater in some of boreholes. Potential future seepage mitigation measures will focus on methods to seal the reservoir floor and cutoff wall sections I2–I2 and I3–I3, although some efforts may be directed at the west side of the dam. Such measures could take the form of the installation of a geomembrane barrier over the west side of the dam, concrete cutoff walls downstream of the dam and pumping wells to intercept seepage. Thematic collection: This article is part of the Sustainability in engineering geology and hydrogeology collection available at: https://www.lyellcollection.org/cc/sustainability-in-engineering-geology-and-hydrogeology
, , , R. D. Walshaw, J. A. Sheridan
Geological Society, London, Special Publications; https://doi.org/10.1144/sp516-2021-59

Abstract:
Compositional studies of natural gold usually have a geological focus, but are also important in archaeological provenancing. Both methodologies rely on compositional comparison of two sets of samples, one of which is geographically constrained. Here we describe how experiences in gold characterization resulting from geological studies are relevant to archaeology. Microchemical characterization of polished sections of natural gold identifies alloy compositions, alloy heterogeneity and mineral inclusions. Gold from all deposit types shows Cu and Sn values much lower than those recorded during numerous studies of artefacts. Inclusions in artefact gold include various Cu- and Sn-bearing compounds which indicate specific high temperature reactions that could ultimately illuminate the conditions of (s)melting. The use of LA-ICP-MS to generate a wide range of elemental discriminants for provenance studies may be compromised by alloy adulteration and/or unrepresentative analysis of natural/artefact alloys, which are commonly highly heterogeneous at the micron scale. Geological studies normally characterize only the earliest-formed (hypogene) alloy, whereas archaeology-focussed studies should entail analyses of bulk alloy compositions and impurities that may be incorporated during (s)melting. Isotopic-based provenancing alleviates many of these problems but, to date, generates regional rather than locality specific targets. A dual isotopic-compositional approach is recommended.
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