Abstract Polar and subpolar coasts are distinctive owing to the presence of ice on land as permafrost, ground ice and glacier ice, and in the sea as tidewater glaciers, icebergs, ice shelves and sea ice. Most of these coasts remain glaciated or are recently deglaciated so their geomorphology carries a strong glacial signature. The morphogenetic environment of polar and subpolar coasts is dominated by extreme seasonality with winter development of sea ice and a shore-fast ice foot that excludes wave activity and is primarily protective. However, sea ice may also be erosional at any time of year but is most effective as an erosional agent on polar coasts between freeze-up and break-up, when wave activity forces sea ice to repeatedly impact the shore. Depending on latitude, the short summers are characterized by wave and sea ice erosion at high latitudes and by wave activity at lower latitudes. The contribution of frost weathering to cliff and shore platform development in polar and subpolar rock coasts is unclear, but is likely to be an important influence. Rock coasts are widespread in the Arctic and sub-Arctic, including Iceland, and in the Antarctic and sub-Antarctic the limited ice-free coast is almost entirely rock-dominated.

In the subpolar Atlantic Ocean during the Quaternary Period, water-mass environments have migrated across more than 20° of latitude, which is equivalent to temperature oscillations of the ocean surface of at least 12°C. The migrations have occurred along a northwest-trending axis at mean rates of approximately 100 m/yr sustained over intervals of several centuries. During peak glaciations, polar water moved south to lat 42°N, where an abrupt frontal system separated the cyclonic subpolar gyre from the anticyclonic subtropical gyre. Seven complete climatic cycles have occurred in the past 600,000 yr, within which at least 11 separate major southward advances of polar water have occurred. Both in number and shape, these cycles are correlative to oxygen isotopic cycles in the western equatorial Pacific Ocean and to palynologic cycles determined from a core from Macedonia. The northeast Atlantic cycle geometries are not so uniformly saw-toothed in form as isotopic curves from the equatorial Atlantic Ocean and Caribbean Sea because of interruptions by short but severe cold climatic pulses lasting for intervals as short as a few thousand years. One such pulse, which lasted only 7,000 yr, retained at least 90% of its original peak intensity despite vertical mixing. Quantitative determination of the absolute input rates of the major sediment fractions over the glacial and interglacial portions of the last major climatic cycle shows that coccoliths and foraminifera were deposited two to three times more rapidly during interglaciations than glaciations; in converse proportions, coarse and fine terrigenous detritus was preferentially rafted into the northeast Atlantic Ocean during glaciations. The absence of coccoliths in polar water accounts for the existence of glacial coccolith-barren zones. At the scale of local sediment redistribution (related to siting factors), fine coccolith carbonate is most easily redistributed. The absolute abundance of all coarse and fine components increases at higher net sedimentation rates, but fine carbonate increases most rapidly.

Abstract: Modern cool-water, temperate, platform carbonates accumulate in seawater that is generally colder than 20°C. They are part of the Heterozoan Association (new term) of particle types produced by coralline algae and benlhic invertebrates that feed through a variety of heterotrophic means. Such sediments occur worldwide in all platform environments. In warm-water, euphotic, oligotrophic settings, they are swamped by particles from rapidly growing green calcareous algae, invertebrates with photosymbionts (corals) and active abiotic precipitation (mud, ooids, cements), here called the Photozoan Association (new term). The Heterozoan Association, however, prevails, together with photoautotrophs such as green algae, in warm-water environments where high nutrient levels enhance primary productivity and suppress growth of invertebrates with photosymbionts. Heterozoan carbonates form unrimmed ramps and open-shelves with their style being determined by local terrigenous clastic sediment input, oceanography, nutrient supply and sea-level history. Cool-water, temperate platform carbonates are typically grainy with discrete bydrodynamically- controlled facies. Kelp forests are common inboard, while subaqueous dunes are typical outboard. Slope or outer ramp environments are muddy with abundant sponge spicules and local sponge/bryozoan/coral buildups. Contemporaneous sub-tropical platform carbonates are Heterozoan in composition but contain minor Photozoan elements. They are typically rich in coralline algae and have extensive inboard grass banks. Polar and subpolar shelf carbonates are Heterozoan, are prolific at ice-fronts and are associated with biogenic siliceous and glacigene sediments. Physical sedimentary processes on cool-water carbonate shelves and banks are dominated by traction currents, storm-, swell- and tide-induced suspension of fines, active shallow-water particle abrasion and patchy development of subtidal hardgrounds. The degree of mineral-specific carbonate dissolution and/or precipitation is as yet unclear. Biotic sedimentary processes are dominated by post-mortem skeletal disarticulation, bioerosion and maceration. Criteria for the definitive identification of ancient cool-water carbonates are, at present, equivocal. Nevertheless, many Ordovician, Permo- Carboniferous, ?Upper Jurassic-Lower Cretaceous and Cenozoic limestones are strikingly similar in biotic makeup (Heterozoan), original mineralogy (calcite-dominated), sedimentary packaging (meter- and decameter-scale cyclicity) and carbonate platform geometries to modern cool-water deposits. Thus, modern cool-water carbonates may provide excellent analogues for the interpretation of many ancient ramp and shelf successions.

Abstract: Approximately 22 Gt of siliciclastic sediment are delivered to the coastal ocean each year across the Earth’s latitude-controlled climate zones. Latitude effects are seen as controls on physical and biogeochemical weathering and thus sediment production; latitude effects also influence precipitation and wind patterns and impact sediment transport through, for example, river-water density and thus through the particle settling velocities of the suspended load. Glacial transport of sediment, including subglacial processes, meltwater, and iceberg rafting, dominates polar regions (10% of land surfaces). Subpolar regions (21% of the global land surface) include many nonglacial environments receiving low intensity rainfall and with low levels of sediment production (physical weathering) and fluvial transport. Their coastal regions are dominated by storm waves modulated by seasonal sea ice. Temperate regions (14%) are zones of moderate sediment production and fluvial transport, regional pockets of eolian transport, and coastal zones highly influenced by storm waves under the westerlies. The subtropical regions (18%) experience high rates of sediment production, moderate rates of precipitation, high rates of eolian transport via the trade winds (North Africa accounts for the majority of the global dust flux), and coastal zones heavily influenced by both swells and storm waves. The tropical region comprises the largest land mass (37%), with very high rates of precipitation (via the InterTropical Convergence Zone [ITCZ]) and sediment production (from biogeochemical weathering), high rates of fluvial clay and silt and sand transport, moderate levels of eolian transport, and swell-dominated coasts. Preservation of woody debris in the tropics is much smaller than in other climatic zones. Tropical river basins can produce and transport 2.5 times more sediment than a similar scale basin located in a temperate region and 12 times more sediment than a similar scale Arctic basin. Both eolian and glacial transport rates were an order of magnitude larger under ice age conditions, and such conditions repeatedly occurred during the past several million years.

Abstract: This study investigates the Neogene strata of the AND-2A core recovered by the ANDRILL–Southern McMurdo Sound Project in the Victoria Land Basin, Antarctica, as an analog for assessing controls on reservoir quality in glacimarine deposits. The succession comprises a series of depositional sequences formed in marine environments within a failed rift under the influence of repeated advances and retreats of glacial ice, with attendant changes in sea level and sediment supply. Stratal cycles (sequences) typically follow a vertical succession from a basal diamictite deposited in ice-proximal settings fining upward into shoreface sandstone, muddy sandstone, and mudrock. The fining-upward sequence then coarsens upward into coastal and nearshore muddy sandstones and sandstones. Changes in paleoclimate mode through the Neogene caused variations in sequence development, including changes in sequence thickness, variety and range of facies, changes in the completeness of sequences, and changes in the proportion and character of diamictites. Results show that reservoir quality in glacimarine sandstone is dramatically affected by the presence of diagenetic carbonate precipitated during burial from connate cryogenic brine. Strong correlations exist between carbonate cement abundance, paleoclimate, and sequence stratigraphic systems tract. Sandstones that formed during the coldest (polar and subpolar) climate regimes have relatively low porosities (<15%) due to occlusion of pore space by carbonate cement. Decreased production and deposition of mud-sized material during the coldest climate conditions produced sequences characterized by higher overall permeability that were prone to infiltration by brine upon burial, leading to cementation. By contrast, the sandstones formed during relatively temperate climate regimes preserve higher porosities (25–45%) and lack significant cementation. Sequence stratigraphic relationships indicate that these porous sandstones are best developed in highstand delta systems that formed during ice minima. Individual sandstone bodies, which extend laterally over several kilometers, are enclosed by muddy lithologies. Porosity in these sandstones was retained as a result of discharge of dilute meltwater during deposition and subsequent isolation of sands between impermeable barriers. Trends identified in this study may prove useful in predicting and locating target reservoirs in other glaciogenic and glacimarine settings worldwide.

Abstract The term meiobenthos refers to a group of invertebrate organisms that are intermediate in size between macro- and microfauna, and inhabit all sediment types in all marine environments and in all climatic zones. They may occur at enormously high densities of millions of individuals per square metre; this means that 10 cm 3 of sediment in any given habitat may contain thousands of these organisms. Although meiobenthos in some extreme arctic habitats is uncommonly poor, the abundance and composition of the polar or subpolar meiobenthic assemblages are not essentially different from those found in boreal–tropical locations at corresponding sediments and depths.

Abstract The potential of using dinoflagellate cysts as proxies for palaeoceanographic conditions and as monitors of the dynamic marine environment of climatically sensitive Arctic fjords was investigated with sediment traps. Dinoflagellate cysts were analysed from three separate deployments in two high Arctic fjords in the Svalbard archipelago. Two deployments in Kongsfjorden on the west coast of Svalbard occurred during 2002 and 2006–2007 and a deployment in Rijpfjorden on the NE coast occurred during 2006–2007. The cyst production displayed peaks of abundance in the spring and late summer with distinct differences in cyst occurrence in different fjords and in different years. The recorded and identified cyst species were consistent both with the hydrography of the fjords and with changes in cyst composition that are comparable to the seasonal shifts in water mass characteristics. The presence of the heterotrophic species Protoperidinium conicum in Kongsfjorden during 2002 is of note and may reflect the availability of a particular food source possibly associated with the strong influx of Atlantic Water. Cysts recovered from Kongsfjorden during 2006–2007 were dominated by Islandinium minutum , an indicator of cold, polar to subpolar conditions. The temperature and salinity characteristics of the ambient hydrography in this period indicated less influence by Atlantic Water than in 2002, and the cyst production was consistent with regional cyst distribution patterns. In Rijpfjorden, cyst assemblages were dominated by Pentapharsodinium dalei , consistent with the fjord being dominated by full Arctic conditions during the mooring deployment and the possible occurrence of stratified water with high productivity during the spring phytoplankton bloom.

Abstract Glacimarine dynamics and associated sedimentary processes are closely tied to glacial regime and reflect dominant climatic conditions. Quantitative measurements for subpolar glaciers, such as sediment yield, are limited especially near glacial termini where most sediment accumulates. Here we characterize the modern glacimarine environment, quantify sediment flux and yield, document landform genesis and hypothesize potential future behaviour of Kronebreen and Kongsvegen glaciers in inner Kongsfjorden, Svalbard. A minimum of 6.74×10 3 g m −2 d −1 (at least 300 mm a −1 ) of glacimarine sediment is building a grounding-line fan via submarine stream discharge from Kronebreen. Average daily sediment flux to the ice-contact basin is recorded to be 2.6×10 3 g m −2 d −1 or an average annual flux of 1.56×10 5 g m −2 a −1 . We measure an average annual ice-contact sediment yield of 1.20×10 4 tonnes km −2 a −1 associated with the rapid genesis of grounding-line landforms. With forecasted warming we expect meltwater volumes and sediment flux to increase. Grounding-line deposits may aggrade above water, tending to stabilize the terminus at least initially if the sediment is sufficient to counteract total terminus ablation. This would hold until either the glaciers next surge or climatic warming ablates the glaciers through surface melting.

Two thick sequences of ancient glacial and glacial marine rocks, the late Proterozoic Mineral Fork Formation of Utah and the Late Paleozoic Whiteout Conglomerate of West Antarctica, reflect similarities and differences in temperature regimes of the glacial delivery systems, climatic settings in the zones of ablation, and nature of the glacier interfaces with the depositional environments. Both units attain thicknesses of about 1,000 m and both are segments of widely distributed glacigenic deposits covering thousands of km 2 . They appear to represent significant erosion of platformal areas beneath basal ice at or near its melting point. In the Mineral Fork Formation, facies patterns indicate supraglacial melt-out, sediment gravity flow, and deposition from meltwater streams, all characteristic of glacier ice where the climate is subpolar or temperate in the zone of ablation. The vertical sequence, which includes subglacial tills, supraglacial melt-out facies, and a complex glacial marine facies, indicates multiple advances of a grounded ice sheet along the margin of a craton, and final retreat accompanied by a marine transgression. In contrast, the Whiteout Conglomerate lacks facies indicative of supraglacial melting; the absence of meltwater-generated fluvial and plume deposits is especially striking. Rather, subglacial melt-out from grounded ice and basal melting of ice shelves and perhaps icebergs, all accompanied by vertical settling, are indicated. Lateral changes represent a regional transition from grounded marine-based glaciers at the pressure melting point in the basal zone to a shelf of polar ice warmed sufficiently at the base to release sediment there by melting as well as by iceberg calving. The study of thick ancient glacigenic sequences accumulated on subsiding continental margins provides information not yet obtainable from sedimentary piles of Quaternary age.