Abstract Is groundwater abundant in Antarctica and does it modulate ice flow? Answering this question matters because ice streams flow by gliding over a wet substrate of till. Water fed to ice-stream beds thus influences ice-sheet dynamics and, potentially, sea-level rise. It is recognized that both till and the sedimentary basins from which it originates are porous and could host a reservoir of mobile groundwater that interacts with the subglacial interfacial system. According to recent numerical modelling, up to half of all water available for basal lubrication, and time lags between hydrological forcing and ice-sheet response as long as millennia, may have been overlooked in models of ice flow. Here, we review evidence in support of Antarctic groundwater and propose how it can be measured to ascertain the extent to which it modulates ice flow. We present new seismoelectric soundings of subglacial till, and magnetotelluric and transient electromagnetic forward models of subglacial groundwater reservoirs. We demonstrate that multifaceted and integrated geophysical datasets can detect, delineate and quantify the groundwater contents of subglacial sedimentary basins and, potentially, monitor groundwater exchange rates between subglacial till layers. The paper thus describes a new area of glaciological investigation and how it should progress in future.

Abstract Load structures are a type of soft-sediment deformation structure comprising synforms (load casts and pseudonodules) and antiforms (flame structures and diapirs) at an interface. They form in response to unstable density contrasts (density loading) or lateral variations in load (uneven loading) when sediment becomes liquidized or otherwise loses strength. They are here classified into five varieties: simple and pendulous load casts, in which the upper (denser) layer is laterally continuous; and attached pseudonodules, detached pseudonodules and ball-and-pillow structure, in which discrete masses of the upper layer are separated by matrix. Conceptual models demonstrate that there are several possible modes of formation for each type of load structure. One interpretation of the variation of load structure morphology is as a deformation series representing varying degrees of deformation, controlled by the magnitude of the driving force and/or the duration of its effective action. An interpretation of the commonly observed pattern of wide load casts and narrow flame structures is presented in terms of their differential growth. Fluidization has an important influence on the development of load structures and their relationship to other products of sediment mobilization.

Abstract The southern Kirthar Fold Belt (KFB) and the contiguous Middle Indus Basin (MIB) constitute a major oil and gas province on the southern Pakistan foreland. In the Middle Indus Basin, gas is reservoired in Early Cretaceous marginal marine sandstones sealed by Paleocene shales. Reservoir quality of the Early Cretaceous sediments deteriorates towards the fold belt, but recent discoveries of gas in Upper Cretaceous sandstones sealed by Paleocene shales have highlighted its potential. To understand better the petroleum systems of this region and provide a potential correlation scheme for comparison with other areas of the country, a sequence stratigraphic interpretation was carried out on the Jurassic to Recent sediments of the KFB and MIB. On the basis of outcrop and well data, 23 depositional sequences have been identified: five in the Jurassic units, 10 in the Cretaceous units and eight in the Tertiary units. Sequence boundaries have been defined according to the Exxon method of identifying unconformities and their correlative conformities. However, equal importance has been given to identifying the potentially more chronostratigraphically significant maximum flooding surfaces between these sequence boundaries so as to define accurately the component systems tracts of each sequence. The depositional systems are described in terms of their relationship to the existing lithostratigraphic framework and interpreted in terms of sedimentary responses to external (eustatic) or local (tectonic) events. Notwithstanding the presence of a eustatic signature on some sequences, the majority appear to be tectonically driven and can be related to plate margin events affecting the NW margin of the Indo-Pakistan Plate during its rift-drift-collision history.

Abstract Coals most suited for conversion to liquids by pyrolysis and, especially, by hydrogenation have a high content of vitrinite and range in rank from soft brown coal to high volatile bituminous coal. Of the 15 major occurrences in Australia which could be considered for conversion, the following three stand out because of their properties and availability: (1) coals of the Walloon Coal Measures in the Surat basin of southern Queensland; (2) coals of the Singleton Coal Measures in the Sydney basin, New South Wales; and (3) brown coals of the Latrobe Valley in Victoria.

Abstract The Cambrian geographical and temporal distributions of many clades remain poorly understood, despite their importance for elucidating the palaeobiogeographical context of the Cambrian radiation. New species and genus level occurrence databases were developed to analyse temporal and geographical distributional patterns in taxa belonging to 14 clades from over 60 globally distributed early and Middle Cambrian Burgess Shale-type lagerstätten. Analyses demonstrate that clades with confirmed Precambrian origins were, on average, more widespread and temporally persistent than clades with first fossil occurrences in the Cambrian. Despite their dominance in diversity, arthropods were less widely distributed and temporally persistent than many other groups. Finally, a significant correlation between geographical range and temporal persistence is demonstrated, supporting the hypothesis that Cambrian taxa with wider geographical ranges were less likely to go extinct than those with narrower ranges. Supplementary material: Species and genus data tables are available at: http://www.geolsoc.org.uk/SUP18665