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The present study brings out the reappraisal of mode of depositional conditions of the Talchir sediments from Savarla village of Bandar Basin, Chandrapur district of Maharashtra. These sediments correspond to four lithofacies namely, (i) basal massive diamictite (bmd), (ii) stratified diamictite and sandstones (sds), (iii) medium- to fine-grained sandstones (mfs) and (iv) siltstones-shale. The bmd facies characterizing laterally discontinuous, unstratified and matrix- to clast-supported sediments represent the continental tills. The sds facies corresponding to melting of glaciers at outwash plains reveal the decrease in the boulder and cobble clasts and increase in pebble clasts. The mfs facies associated with the very thin, fine-grained sand and varves represent glacio-lacustrine depositional conditions with suitably developed still water bodies and even ice-dammed lakes. The petrographic characteristics of these sediments, which bring out textural immaturity and depiction of QFR triangular diagram, divulge interior type of continental block provenance with cold-arid palaeoclimate. The microtextures like high relief, conchoidal breakage pattern, arc shaped steps, semi parallel steps, globular protuberances as well as striations along with ‘v’ shaped indentations noted from SEM photomicrograph clearly point out towards the glaciogenetic influence.

The article contains detailed petrographic studies, which covered a coarse and medium-grain gravel fraction of two layers of glacial till (units ŁS II and ŁS IV) and two layers of sand-gravelly outwash deposits (units ŁS I and ŁS III) related to the Odranian Glaciation (MIS6, Saalian) in Łubienica-Superunki, North Mazovian Lowland, central Poland. Additionally, the indicator erratics were identified to indicate their Scandinavian source areas and the directions of the ice sheet transgressions. This case study is discussed against the background of similar sediments and forms from the same age but from other places in the Polish Lowlands. Regardless of the facies types and fractions, crystalline rocks dominated over all other petrographic groups in all samples. The most common were the indicator erratics derived from the Åland Islands, followed by those from the south-eastern area of Sweden (Småland) and from Dalarna in central Sweden. Amongst the erratics of limited indicative significance, the most common were Lower Palaeozoic limestones and the Jotnian red sandstones. The complex petrographic analyses point to the dipartite nature of the studied profile. This separateness was confirmed by the TBC: 59.1–59.2° N and 18.0–18.2° E for the lower units and 58.8–59.4° N and 17.3–17.9° E for the upper ones.

Carboniferous glaciogenic strata (Itarare Gp.) in the southernmost Parana Basin, Brazil exhibit soft-sediment deformation features previously interpreted as glaciotectonism. These sediments were studied in detail to confirm that they were deformed by ice and to assess the nature of the glaciation, depositional environments, and paleoclimate in this region during the Carboniferous. Five outcrops were described along a railroad transect that contains a conglomerate and diamictite facies with striated and faceted clasts, a medium sandstone facies, a fine grained silt/clay rhythmite and mudstone facies with dropstones and diamictite pellets, a sandy clinoform facies, and a folded sandstone with interbedded mudstone facies. The depositional environment for these sediments is interpreted as an outwash fan and fan delta from an ice-proximal, transitional terrestrial-to-estuarine setting. Rb/K values from the rhythmites reflect a transition from a freshwater to brackish environment and the Chemical Index of Alteration (CIA) of the rhythmites ranges from 65 to 73, reflecting a relative increase in the degree of chemical weathering through time. Deformation features include widespread folding, thrust faults, hydrofractures, decollement surfaces, and piggyback fold-thrust complexes. The deformation is interpreted as evidence of a push-moraine complex formed by at least two complete ice advance/retreat cycles. The occurrence of decollement surfaces, plastically deformed proglacial sediments, and hydrofractures indicate a dynamic, warm-based or polythermal glacier. Abundant outwash sediments, rhythmites with dropstones, and the shift to average CIA values all support a temperate paleoclimate. Deformation structures indicate a NW direction of ice shove that is in agreement with the regional-scale hypothesis that a NNW flowing lobe extended out of Uruguay during the Carboniferous and terminated in the southernmost Parana Basin. This study demonstrates that late Paleozoic glaciation in this region was more dynamic than previously understood, with high frequency fluctuations in ice marginal positions.

Thick Quaternary sediments of the Breiðavik Group are intercalated between lava flows and tuffs on Tjornes, North Iceland. The present chapter is a compilation of lithostratigraphic and fossil data, combined with an interpretation of the sedimentary and volcanic facies. The vertical column of strata displays a rhythmic character, and a model for sedimentation during glacial-interglacial cycles in a volcanic environment is presented. The Quaternary part of the Tjornes sequence contains evidence of 14 separate glaciations with tillite horizons. The tillites are typically associated with kame and outwash conglomerates, followed at first by glacio-lacustrine and glaciomarine mudrocks and diamictites, and then by deltaic and/or bar-lagoon assemblages, fluvial sediments, and subaerial lava flows. Depositional environments are reconstructed for several steps in the geological history of the Breiðavik Group. The oldest tillite has been dated to c. 2.6 Ma. Several of the tillite beds are succeeded by marine sediments with fossils, especially in the lower part of the sequence. During the first million years of the accumulation, the deposition took place in a transitional environment while the area was subsiding, but the latter part of the geological record reflects terrestrial deposition and increased volcanism in the region.

Glaciofluvial and glaciolacustrine sediments were discovered in a small sandpit situated 800 m SE from Vindava (the Polský kopec Site). Sediments fill two channels located in superposition. Three facies associations (FA) were distinguished in this sedimentary section. The base of the lower channel is formed by gravel lag overlain by gravel-sandy sediments of 3-D dunes and a side bar (FA1). The upper channel infill begins also by basal lag and grades to a fining-upwards sequence from sand to silt (FA2). The sequence is formed from the base up by sediments of small 3-D dunes, A-type ripples, B-type ripples, C-type ripples, and horizontally laminated sediments. The sequence reveals a vertical transition from glaciofluvial (sand) to glaciolacustrine (silt) sedimentation. The sedimentary section is terminated by flat glaciofluvial bedforms (FA3) deposited under upper plane bed conditions. These bedforms arose after the restoration of glaciofluvial conditions. The base of the glaciolacustrine sequence is located at an altitude of ~ 275 m as well as the Old Kaolin Mine Site (850 m SW from the Polský kopec Site) where very similar sediments have been already described. The sediments of both localities represent a proglacial outwash plain in front of the retreating ice sheet (FA1 consists of ~ 23% of erratic rocks), where a relatively large lake, or a system of smaller lakes evolved at the same time.

The favorable overall conditions for the utilization of groundwater in fluvioglacial aquifers are impacted by significant heterogeneity in the hydraulic conductivity, which is related to small-scale facies changes. Knowledge of the spatial distribution of hydraulically relevant hydrofacies types (HF-types), derived by sedimentological analysis, helps to determine the hydraulic conductivity distribution and thus contribute to understanding the hydraulic dynamics in fluvioglacial aquifers. In particular, the HF-type “open framework gravel (OW)”, which occurs with the HF-type “bimodal gravel (BM)” in BM/OW couplings, has an intrinsically high hydraulic conductivity and significantly impacts hydrogeological challenges such as planning excavation-pit drainage or the prognosis of plumes. The present study investigates the properties and spatial occurrence of HF-types in fluvioglacial deposits at regional scale to derive spatial distribution trends of HF-types, by analyzing 12 gravel pits in the Munich gravel plain (southern Germany) as analogues for outwash plains. The results are compared to the reevaluation of 542 pumping tests. Analysis of the HF-types and the pumping test data shows similar small-scale heterogeneities of the hydraulic conductivity, superimposing large-scale trends. High-permeability BM/OW couples and their dependence on recognizable discharge types in the sedimentary deposits explain sharp-bounded small-scale heterogeneities in the hydraulic conductivity distribution from 9.1 × 10−3 to 2.2 × 10−4 m/s. It is also shown that high values of hydraulic conductivity can be interpolated on shorter distance compared to lower values. While the results of the HF-analysis can be transferred to other fluvioglacial settings (e.g. braided rivers), regional trends must be examined with respect to the surrounding topography., Bayerisches Staatsministerium für Umwelt und Verbraucherschutz http://dx.doi.org/10.13039/501100010219

The Fiskarheden quarry, situated in NW Dalarna, central Sweden, reveals thick coarse-grained sediments of Scott type facies association representing a sandur deposited in an ice-proximal proglacial environment. Optically Stimulated Luminescence (OSL) dating of the sandur sediments suggests a pre-Last Glacial Maximum (LGM) age. Most acquired ages are pre-Saalian (>200 ka) and we regard each of these ages to represent non/poorly bleached sediment except for one small-aliquot OSL age of 98±6 ka. This age comes from the top surface of an arguably well-bleached sand bed deposited on the lee-side of a braid-bar, putting the sandur build-up into the Early Weichselian. Large-scale glaciotectonic structures show an imbricate thrust fan involving both ductile and brittle deformation. The deformation was from the WNW, which largely coincides with the formative trend of the predominating streamlined terrain and Rogen moraine tracts surrounding Fiskarheden. It is suggested that the deformation of the sandur sediments took place when the advancing glacier approached and pushed its own proglacial outwash sediment, during an ice-marginal oscillation either at the inception of one of the Early Weichselian glaciations in the area, or during a general ice retreat amid a deglacial phase. The Fiskarheden sandur deposits are covered by a subglacial traction till deposited from the NE/NNE. This direction corresponds with younger streamlined terrain flowsets cross-cutting the older NNW–SSE system and probably represents deglaciation in the area following the LGM. This study will add to the understanding of the formation and deformation of Pleistocene sandur successions and their relationship to past ice-sheet behaviour. (Less)

Buried channel systems are important sedimentary repositories for documenting environmental changes in response to eustatic events. Here we investigate the morphology, infilling structure, and evolutionary history of buried channel systems offshore of Long Beach Island, New York, through dense, ultra-high resolution seismic profiles. On the basis of stratigraphic superposition, characteristic of bounding seismic surfaces, seismic geometries as well as previous studies, we identify four seismic units interpreted, top-to-bottom, as: Holocene marine sand sheet (SU1); Pleistocene-Holocene channel system (SU2); younger Pleistocene outwash lobe (SU3); and older Pleistocene outwash sediments (SU4). Two sets of channel systems are observed, one shallower (SU2) and the other deeper (inside SU4). The shallower channel system, consists of both fluvial/glaciofluvial incised valley and tidal channels/inlets, incised during or near Last Glacial Maximum and was filled during the ensuing Pleistocene-Holocene transgression, associated closely with estuarine process. The channel fill sediments, the only preserved stratigraphic record of the last sea-level cycle around this area, comprises six seismic facies, which are interpreted as: fluvial/glaciofluvial lag deposits (SF1); relict estuarine complex (SF2); retrogradational barrier system (SF3); later-formed bayhead delta (SF4); an undetermined facies which has the potential to be either barrier, central basin, bayhead delta deposits, or their complex inside the incised valley (SF5); and tidal channel/inlet/flat complex outside the valley (SF6). These facies are bounded by either ravinements (bay flooding, tidal, shoreface) or sedimentary surfaces. This interpretation and seismic geometry reveal evolution of the shallower channel system experienced (1) fluvial/glaciofluvial incision and lag preservation, (2) back-filling of estuarine complex (bayhead delta and central basin sediments), (3) landward rollover of barrier system (river mouth complex), (4) progradation of a new bayhead delta that onlaps the barrier sediments, and (5) reworking and partial erosion resulting in the transgressive ravinement (T surface). This suggests that the estuarine process was the primary factor that resulted in the infilling structure. Our results indicate the deeper channel system comprises two discontinuous channel segments. Although several seismic horizons and facies are identifiable in association with this channel system, we are unable with these data to determine if these segments are connected, nor can we confidently determine the origin and filling structure of the deeper channel system.

The glaciogenic Sarah Formation (Hirnantian) is a potential tight gas sandstone reservoir in the Rub’ al Khali Basin and other basins in Saudi Arabia. This study investigated the facies heterogeneity and paleoenvironments of the Sarah Formation using cores, petrographic thin sections, and spectral gamma-ray (SGR) analyses. The study revealed four facies associations (FAs), including massive to ripple-laminated sandstone (FA1), gray massive sandstone (FA2), diamictites (FA3), and partially deformed, massive-graded sandstone (FA4), interpreted to have been deposited in fluvial, glaciofluvial, glaciolacustrine delta, and subglacial outwash environments, respectively. The sandstone varies from fine-, to medium-, and coarse-grained and is a moderately to poorly sorted quartz arenite, subarkose, and to sublithic arenite. The integration of facies analysis with SGR analysis allowed us to classify the facies further into low matrix and argillaceous sandstones in the fluvial and glaciofluvial facies, mixed sandstones in the glaciolacustrine delta facies, and clast-supported and matrix-supported diamictites with shales in the subglacial facies. The results of this study might provide guidelines for facies identification and the prediction of reservoir-quality targets in the tight sandstone in the subsurface. This classification could facilitate the identification of and distinction between the glaciogenic lithofacies of tight gas reservoirs in the subsurface and provides a tool for correlating the lithofacies. This work might also provide guidelines for the exploration and development of Paleozoic tight gas sandstone reservoirs in the subsurface that are deeply buried and show a wide range of facies, paleoenvironments, and paleogeographic settings.

In the Rub' al-Khali Basin, the Late Ordovician glacial sediments were deposited in a vast water body where laterally shifting depositional environments resulted in lateral facies changes, from well-sorted glacio-fluvial reservoir sandstone to diamictite deposits. The predominantly fluvial channel deposits, consisting of medium to very fine grained sheet sands and interfluve muddy siltstones, were widely distributed, the thicknesses of which ranged from tens to several hundreds of feet. In core, glacial outwash channels, braided plain sands, and lacustrine shale layers with drop-stones from melting ice were observed. The net sand-to-gross ratio is generally high due to the sedimentation dynamics, whereby moving icepressured meltwater jets became sorting agents in the process of glacial sedimentation. In the central Rub' al-Khali, core studies from drilled wells and associated log responses show variable reservoir quality. The overall reservoir quality is controlled by a number of primary and secondary factors. Primary controls are related to sedimentation and the depositional environment, which are manifested in these type of facies, grain size and sorting. Well-sorted, coarse sandstone is associated with high energy currents, and is mainly present in the fluvial system. Non-reservoir facies such as lacustrine shale and diamictite deposits are associated with low energy lacustrine or deep water deposits. The characteristic high net-to-gross ratio observed in the Rub' al-Khali Basin is primarily due to grain sorting. Thin sections from core indicate that mechanical compaction and silica cementation had, in areas, effected reservoir quality. Post-deposition diagenesis, particularly clay coatings, preserved intergranular porosity by preventing continued silica growth on sand grains. Mineral dissolution is not prevalent, and likely did not have significant effect on porosity. Evidence of pressure solution, such as micro-stylolites and sutured contacts between grains are present, indicating sandstone grains were subjected to significant mechanical compaction. Compaction is related to the depth of burial, and its impact on reservoir quality varies throughout the Rub' al-Khali Basin. Silica cementation appears to be sourced from stress inducing stylolites, where the silica cement is formed around the grains.

The Kingston Peak Formation is an archetypal Cryogenian succession that crops out across the Death Valley region of eastern California. Above pre-glacial strata (KP1), two distinct glacial phases have been recognized and are interpreted to be allied to the panglacial Sturtian (KP2 and KP3) and Marinoan (KP4) icehouse events. The thickest and most extensive unit, KP3, forms the entire exposed section at Sperry Wash. At this locality, ice-distal turbidites are succeeded in turn by ice-medial and ice-proximal facies, comprising a spectrum of ice-rafted debris-bearing turbidites, debrites and shales. These are overlain by ice-marginal grounding-line fan deposits interbedded with glacitectonically deformed heterolithics, supporting local advance to an ice-contact position. The succession records accumulation within a glacier-fed subaqueous shelf, wherein the clear progradational signature is driven by ice advance towards the south-east. Evolution of the subaqueous complex is five-fold, comprising: (i) ice-distal outwash; (ii) build-out of ice-medial depositional lobes; (iii) ice-proximal deposition and increased calving; (iv) resumed ice-margin advance; and (v) growth of ice-contact grounding-line fan. This sequence is unique in the Death Valley region for recording the first evidence of advance to ice-marginal and ice-contact settings, thereby enabling the location of the glacier terminus to be documented for the first time.

The Unayzah Formation exposed on the southwestern margin of the Arabian Plate presents an example of the glacial and post-glacial facies deposited on the passive continental margin above the Hercynian unconformity. The glacial facies (lower lithologic unit) includes one depositional sequence that occurs in narrow incised valleys within the subjacent Hercynian unconformity. It consists of stratified diamictite (glacial outwash deposits), mottled mudstone–diamictite (glaciofluvial) and rooted sandstones (orthoquartzite) (subaerial weathering). These deposits show an unconformbale relation with the overjacent post-glacial facies. The contact between them coincides with the end of glaciation at the end of Carboniferous and the subsequent initial sea level rise at the Early Permian. The upper lithologic unit represents the post-glacial facies. It constitutes the main thickness of the Unayzah Formation and comprises two depositional sequences separated by an erosional surface. The main facies in the upper unit are laminated claystone–marl, burrowed dolomicrite, pebbly sandstone (orthoquartzite), sandstone–marl, heterolithic facies and evaporite. These sediments contain numerous escaped trace fossils and were deposited during the processes of meltwater release during glacial recession.

Deglacial sequences typically include backstepping grounding zone wedges and prevailing glaciomarine depositional facies. However, in coastal domains, deglacial sequences are dominated by depositional systems ranging from turbiditic to fluvial facies. Such deglacial sequences are strongly impacted by glacio-isostatic rebound, the rate and amplitude of which commonly outpaces those of post-glacial eustatic sea-level rise. This results in a sustained relative sea-level fall covering the entire depositional time interval. This paper examines a Late Quaternary, forced regressive, deglacial sequence located on the North Shore of the St. Lawrence Estuary (Portneuf Peninsula, Québec, Canada) and aims to decipher the main controls that governed its stratigraphic architecture. The forced regressive deglacial sequence forms a thick (>100 m) and extensive (>100 km2) multiphased deltaic complex emplaced after the retreat of the Laurentide Ice Sheet margin from the study area ca 12 500 years ago. The sedimentary succession is composed of ice-contact, glaciomarine, turbiditic, deltaic, fluvial and coastal depositional units. A four-stage development is recognized: (i) an early ice-contact stage (esker, glaciomarine mud and outwash fan); (ii) an in-valley progradational stage (fjord head or moraine-dammed lacustrine deltas) fed by glacigenics; (iii) an open-coast deltaic progradation, when proglacial depositional systems expanded beyond the valley outlets and merged together; and (iv) a final stage of river entrenchment and shallow marine reworking that affected the previously emplaced deltaic complex. Most of the sedimentary volume (10 to 15 km3) was emplaced during the three-first stages over a ca 2 kyr interval. In spite of sustained high rates of relative sea-level fall (50 to 30 mm·year-1), delta plain accretion occurred up to the end of the proglacial open-coast progradational stage. River entrenchment only occurred later, after a significant decrease in the relative sea-level fall rates (-1), and was concurrent with the formation and preservation of extensive coastal deposits (raised beaches, spit platform and barrier sands). The turnaround from delta plain accretion to river entrenchment and coastal erosion is interpreted to be a consequence of the retreat of the ice margin from the river drainage basins that led to the drastic drop of sediment supply and the abrupt decrease in progradation rates. The main internal stratigraphic discontinuity within the forced regressive deglacial sequence does not reflect changes in relative sea-level variations.

A thick succession of Al Khlata glacio-lacustrine deposits, including diamictites, crops out in the Wadi Daiqa inlier and there are other possible Al Khlata outcrops in Wadi Amdeh and Wadi al Arabiyin. These outcrops in the Oman Mountains are 100 km north of where the Al Khlata had been thought to pinch out by non-deposition or erosion. Fossil spores and pollen from Wadi Daiqa are highly carbonized having been subject to greenschist facies metamorphism, but are still clearly identifiable as taxa from the Late Carboniferous 2159A zone of the oil-producing areas of interiorOman. This northernmost Al Khlata is sand rich and interpretedto be glacio-lacus- trine. Previously the sand-dominated Al Khlata successions north of the Central Oman High have been consideredto be glacio-fluvial outwash largely based on their context. The Al Khlata deposits in Wadi Daiqa and the underlying several-kilometre-thick Amdeh succession are preserved in Saih Hatat, probably in a continuation of the Ghaba Salt Basin that itself overlies an accreted terrane from the Pan African orogeny. Gold Open Access: This article is published under the terms of the CC-BY 3.0 license. Al Khlata glacial deposits occur widely in the sub- surface of interior Oman. They are absent along the easternmost coastal area and were believed absent from northern Oman and the Oman Moun- tains due to non-deposition. Here we describe a c. 300 m succession of Al Khlata P9 deposits from Wadi Daiqa, and other possible outcrops of Al Khlata lithologies in the Saih Hatat area. The Wadi Daiqa sections are important in being outcrop analogues of sand-prone oil-producing intervals in the subsurface of southern Oman. Unfortunately, the most easily accessible section was flooded with the filling of the Wadi Daiqa water reservoir in 2009. The better-known outcrops at Al Khlata, in the Huqf area, are of younger P5 and P1 age and are predominantly of non-reservoir facies.

Soft-sediment glacially striated surfaces are common structures in ancient glacial successions, such as the Gondwanic Paleozoic record, and document ice erosion on non lithified beds. In most cases, they have been interpreted as the product of subglacial erosion beneath advancing marine or terrestrial glaciers, although direct evidence for glacial sedimentation in associated strata is infrequent. In this paper we document soft-sediment striated surfaces of Carboniferous age occurring in cross-laminated sandstones of the lower Itarare Group, southern Parana Basin, Brazil, and interpret them as scour marks generated by keels of floating ice. Striated surfaces occur in closely spaced, multiple stratigraphic horizons in the lower half of a deglacial sequence, whose facies characteristics indicate sedimentation in subaqueous outwash and deltaic settings. Surfaces are laterally discontinuous, commonly bordered by marginal berms, and in some cases capped by mudstones with dropstones; they have orientations that deviate from the regional paleo-ice flow indicated by glacial grooves carved on the pre-glacial basement. The characteristics observed are consistent with modern and Pleistocene ice-keel scour marks. In addition, soft-sediment striated surfaces from other Gondwanic localities have similar attributes, suggesting that ice-keel scour marks may be more common in the geological record than previously considered and that vertically repeated striated surfaces do not necessarily indicate multiple ice-sheet advances. Therefore, paleo-ice flow reconstructions based on soft-sediment striated surfaces need to be revaluated considering that the movement of free-floating ice masses is controlled by phenomena other than glacier advance.

The Spiti River drains the rain shadow zone of western Himalaya. In the present study, the fluvial sedimentary record of Spiti valley was studied to understand its responses to tectonics and climate. Geomorphic changes along the river enable to divide the river into two segments: (i) upper valley with a broad, braided channel where relict sedimentary sequences rise 15–50 m high from the riverbed and (ii) lower valley with a narrow, meandering channel that incises into bedrock, and here, the fluvio-lacustrine sediments reside on a bedrock bench located above the riverbed. The transition between these geomorphic segments lies along the river between Seko-Nasung and Lingti villages (within Tethyan Himalaya). Lithofacies analyses of the sedimentary sequences show six different lithofacies. These can be grouped into three facies associations, viz. (A) a glacial outwash; (B) sedimentation in a channel and in an accreting bar under braided conditions; and (C) formation of lake due to channel blockage by landslide activities. Seventeen optically stimulated luminescence ages derived from ten sections bracketed the phases of river valley aggradation between 14–8 and 50–30 ka. These aggradation phases witnessed mass wasting, channel damming and lake formation events. Our record, when compared with SW monsoon archives, suggests that the aggradation occurred during intensified monsoon phase of MIS 3/4 and that proceeded the Last Glacial Maxima. Thus, the study reports monsoon modulated valley aggradation in the NW arid Himalaya.

This paper presents the sedimentary analysis of an exceptional Ordovician glacial tunnel valley in the eastern part of the Anti-Atlas. The valley infill comprises two major glacial erosion surfaces (striated pavements) each overlain by a fining-upward glacial unit. These units are composed of five distinct facies associations, recording the evolution from subglacial to proglacial environments, and an additional sixth facies association, overtopping the tunnel valley infill, and associated with post-glacial environments. The tunnel valley infill also records a transitional environment between the subglacial and proglacial settings, which is compared with the Antarctic ice-sheet margin. These three environments are defined by the position of the grounding line and the coupling line. The new proposed depositional model also differs from usual Ordovician depositional models in which the main tunnel valley infill is interpreted as essentially proglacial outwash deposits, in a range of glaciomarine to glaciofluvial environments. Overall, a substantial part of the valley infill (~ 50% of volume) was deposited in a subglacial setting. The sedimentary bodies could form potentially thick and laterally extended, although these were limited by the shape and extent of the subglacial accommodation space. Finally, the sedimentary record, when compared with regional analogues, also provides information for the palaeogeographic reconstruction of the Ordovician ice-sheet in this region.

A large integrated data set of cores, outcrop data, and seismic transects from the mud-buried Vars-Winchester esker in the Champlain Sea basin, Canada, was studied to gain insight into how muddy glaciated basins fill with sediment, and how esker sedimentary systems contribute to this process. Three stratigraphic units—a till sheet over carbonate bedrock, the Vars-Winchester esker , and overlying Champlain Sea mud—are identified in the data set. The till is massive, mud rich, carbonate rich, and drumlinized. The esker is also carbonate rich, and rests erosively on till or bedrock. It consists of two elements, a narrow gravelly central ridge and a broad sandy carapace. Three units comprise the overlying mud package: gray carbonate-rich rhythmites, massive bioturbated mud, and carbonate-poor, red-and-gray rhythmites. A sequence stratigraphic model is proposed to explain these observations. Emphasis is placed on gradual ice-front translation superimposed by rapid meltwater events. The esker is interpreted to have been derived from the underlying till by water that flowed through a subglacial conduit (R-channel), within which the narrow gravelly central ridge was deposited. Most mud and finer sand bypassed the conduit and was deposited proglacially on the floor of the Champlain Sea, first as sandy outwash and, farther basinward, as muddy carbonate-rich rhythmites. Gradual ice-front retreat superposed distal facies over proximal facies, generating the upward-fining succession that starts with the esker gravel and ends with muddy rhythmites. Most esker sediment appears to have been deposited during rapid, jokulhlaup-like floods that punctuated gradual retreat. Discharges are estimated to have been high, possibly on the order of several hundred to, perhaps more commonly, several thousand cubic meters per second. The chaotic and random-looking appearance of the resultant sedimentological signatures in the esker sensu stricto is sharply contrasted with the regularity of the muddy rhythmites. If the rhythmites are indeed correlative to the esker, which seems reasonable given their geochemistry and the fact that their volume scales to the volume of mud in the till, the flood events that deposited the esker must have been seasonally mediated, and the basin water must have attenuated the flood signal, resulting in a rhythmic “on-off” signature in more distal portions of the system. The regularity of the rhythmites does not betray the chaotic nature of the esker sensu stricto, and vice versa. Studying either one in isolation would lead to a very different “end-member” impression of how eskers form and how esker sedimentary systems operate during the infilling of glaciated basins.

This study aims to characterize the morphology and contemporary floodplain deposit dynamics within a braided sandur system in upper Erdalen, a steep U-shaped valley in western Norway. The braided sandur system is fed by two tributary valleys connected to the Jostedalsbreen Ice Field. Based on field observations, two different sub-systems can be identified within the braided sandur system: fine-grained to sandy flood sediments down-valley, and coarser, gravelly deposits in the upper part. A combination of different methods is applied for studying sediment dynamic processes within the braided sandur system (sedimentological and stratigraphic analyses, 14C dating, dendrochronology and lichenometry). The coarser deposits are interpreted as originating from the Little Ice Age advance in Erdalen. Preliminary results indicate that the floodplain sediments were deposited after the Little Ice Age advance. Different sedimentary facies types are present and different phases of flooding can be identified. Within the entire braided sandur system, multiple sub-systems characterized by different levels of process intensities exist.

Unusual development of sandur sedimentary succession, an example from the Pleistocene of S PolandAn atypical lithological development of outwash deposits in the Carpathians Foreland (S Poland) shows lower and middle parts of the sedimentary succession that are characterized by sinuous palaeochannels. This channel facies consists of laterally accreted sands derived from side bars. The sedimentary environment was a proglacial system of anabranching channels, presumably of anastomosed type. The outwash channel pattern was most probably controlled by the raising base level of the fluvial system. Both proglacial and extraglacial waters were dammed by a sandur within a small upland valley. Aggradation and progradation of the glaciofluvial deposits resulted in progressive rising of the dammed lake level. The low hydraulic gradient of the outwash streams resulted in a sinuous planform as well as a low-energy style of deposition. Afterwards, the rising lake water was drained off through a low watershed and the entire valley became filled with outwash sediments. The bedrock morphology thus became buried and a typical unconfined sandur with a braided channel network developed during the last phase of the glaciomarginal sedimentation (upper part of the sedimentary succession under study).

Late Devonian strata in the eastern United States are generally considered as having been deposited under warm tropical conditions. However, a stratigraphically restricted Late Devonian succession of diamictite-mudstone-sandstone within the Spechty Kopf and Rockwell Formations that extends for more than 400 km along depositional strike within the central Appalachian Basin may indicate otherwise. This lithologic association unconformably overlies the Catskill Formation, where a 3- to 5-m-thick interval of deformed strata occurs immediately below the diamictite strata. The diamictite facies consists of several subfacies that are interpreted to be subglacial, englacial, supraglacial meltout, and resedimented deposits. The mudstone facies that overlies the diamictite consists of subfacies of chaotically bedded, clast-poor mudstone, and laminated mudstone subfacies that represent subaqueous proximal debris flows and distal glaciolacustrine rhythmites or varvites, respectively. The pebbly sandstone facies is interpreted as proglacial braided outwash deposits that both preceded glacial advance and followed glacial retreat. Both the tectonic and depositional frameworks suggest that the facies were deposited in a terrestrial setting within the Appalachian foreland basin during a single glacial advance and retreat. Regionally, areas that were not covered by ice were subject to increased rainfall as indicated by wet-climate paleosols. River systems eroded deeper channels in response to sea-level drop during glacial advance. Marine facies to the west contain iceborne dropstone boulders preserved within contemporaneous units of the Cleveland Shale Member of the Ohio Shale. The stratigraphic interval correlative with sea-level drop, climate change, and glacigenic succession represents one of the Appalachian Basin's most prolific oil- and gas-producing intervals and is contemporaneous with a global episode of sea-level drop responsible for the deposition of the Hangenberg Shale/Sandstone of Europe. This interval records the Hangenberg biotic crisis near the Devonian-Carboniferous boundary.

This paper documents the glaciovolcanic landsystem of the Brekknafjoll–Jarlhettur ridge in Central Iceland. Glaciolacustrine diamict is found beneath, and in association with, a complex assemblage of pillow lava, lava breccias and hyaloclastites. Three depositional environments are identified: glaciolacustrine fan, pillow lava dome, and hyaloclastite fan. These subaqueous environments occurred both simultaneously and at different times along the volcanic fissures which underlie the ridge and have given rise to a complex facies architecture. This facies architecture provides evidence that the ridge evolved in a time transgressive fashion during several episodes of volcanism, some of which may have been punctuated by periods of ice erosion. Associated with the ridge are large-diapiric folds in diamict and gravel which form by the loading and lateral displacement of saturated diamict beneath the developing volcanic pile. A depositional model is presented which emphasises the glaciolacustrine component and the time transgressive nature of the glaciovolcanic landsystem. Much of the eruption occurred in subglacial to englacial lakes or vaults, which were probably linked by water and sediment exchange. The initial subglacial vaults appear to have extended beyond the fissure limits and were infilled by glaciolacustrine diamicts, subaqueous outwash and the eruption of pillow lava. This was followed by the eruption of hyaloclastite sand and breccia forming an elongated fan.

The Talchir Formation of Permian age is the lowermost lithostratigraphic unit of the Indian Gondwana successions preserving a record of the Late Paleozoic glaciation that affected the whole Gondwanaland. The formation unconformably overlies the Precambrian basement in all the Gondwana basins of India, and marks initiation of sedimentation after a long hiatus since the Proterozoic. The Talchir Formation of the Satpura Gondwana basin of central India shows features diagnostic of deposition under glacial regime such as the presence of diamictites, boulder pavements, bedding plane striation, faceted/striated gravels, bullet-shaped clasts, dropstone, cryoturbation, etc. The Talchir strata of the Satpura basin, in addition to tidal signatures, contain marine bivalve and trace fossils. A proglacial marine environment is thus inferred for their deposition. The dominant lithologies are conglomerate, pebbly sandstone, sandstone and shale with little limestone, which can be classified into the following major facies: • matrix-supported conglomerate, • clast-supported conglomerate, • cross-stratified, channel form pebbly sandstone, • hummocky, swaley or low-angle cross-stratified pebbly and non-pebbly sandstone, • turbidite/tempestite sheet sandstone, • massive to fissile, green to black claystone with carbonate layers and nodules. The conglomerates are interpreted as deposits of a spectrum of sub-aqueous sediment gravity flows including debris flow, hyperconcentrated/concentrated density flow and grain flow. The crossstratified pebbly sandstone bodies, on the other hand, represent braidplain delta deposits of glacial outwash origin. Hummocky, swaley, low-angle cross-stratified sediment bodies were deposited by storm-generated combined flows in a shoreface setting. In contrast, the sheet sandstone bodies are products of turbidity currents and storm-induced density currents in an inner shelf setting below fair weather wave base. The claystone facies is interpreted as a product of suspension fallout from hypopycnal sediment plumes in the outer shelf domain below storm wave base. All the lithofacies described above occur repetitively in the succession. Three facies-associations have been recognized in the Talchir Formation, representing ice-contact fandelta, outwash braidplain delta and a virtually ice-free, non-deltaic open marine realm. The different marine facies of the Talchir Formation define a number of shallowing-upward packages, which are arranged in the succession with a retrogradational trend to result in an overall fining- and deepening-upward succession. The overlying coal-bearing Barakar Formation has been interpreted to have formed in a tide-wave influenced

The lowland region of north Norfolk contains some of the best preserved evidence for glacial deposition during the Middle Pleistocene in northwest Europe. Despite the importance of these deposits, there is limited chronological control and it is debated whether they belong to a single glaciation, equated to the Anglian Glaciation (Marine Isotope Stage 12), or represent deposition over a number of Middle Pleistocene cold stages. In order to develop an improved chronology for glaciation in this region, we obtained 18 samples for optical stimulated luminescence (OSL) dating from glacial outwash facies. Samples of coarse-grained quartz sand were measured using the SAR (single aliquot regenerative-dose) protocol. The low radioactive isotope concentrations in sediments of this region enable the traditionally accepted age limit of luminescence dating to be extended. The form of the dose response curves, pre-heat plateaux tests, and dose recovery experiments also indicate that laboratory doses can be reliably measured in these samples. Age overestimation due to partial bleaching is thought to be insignificant. The OSL ages suggest that the glacial sediments studied were deposited during MIS 12 rather than in different post MIS 12 stages.

Recent studies on Neoproterozoic climate change has prompted renewed interests in Neoproterozoic glacial deposits and renewed debates over the criteria used to identify the nature of glacial influence on sedimentation. Analysis of soft sediment deformation structures have provided important clues to distinguish between competing paleoenvironmental interpretations of Quaternary glacial deposits. A similar approach is presented here in the analysis of Neoproterozoic glacial deposits of the Smalfjord Formation, northern Norway. Detailed sedimentological and structural analysis at several sites in the Varangerfjorden area reveals complex soft sediment deformation at various scales in conglomerate, sandstone and diamictite. Deformation is predominantly ductile and includes anticlinal and synclinal folding, flow noses, flame structures, recumbent folding and shear structures. The deformed sediments are predominantly associated with conglomerate and sandstone, which record glaciofluvial and deltaic depositional conditions. Some deformation can be attributed to rapid deposition and slumping, whereas others appear to record shear stress associated with overriding ice. The scale,style and range of deformation together with the coarse-grained nature of the deformed sediments and facies associations suggests these were unfrozen outwash sediments that were overridden by ice and resedimented in a dynamic ice proximal setting. Whereas recent previous studies of diamictite-bearing strata of the Smalfjord Formation had revealed no clear evidence of glacial influence on deposition, deformation structures documented here suggest that glacial conditions prevailed on the basin margin during deposition of Smalfjord Formation sediments, with sedimentary facies and deformation structures typical of temperate ice proximal settings.

At Godoya near Alesund sequences of unconsolidated fine sand and silt below two till beds are interpreted as remains of a sandur. Two facies sequences dominate: One comprises erosional scours followed by horizontally and current-ripple laminated fine sand, massive silt and erosional scours. The other sequence differs by planar wedge-shaped cross-beds replacing the horizontal lamination. The planar cross-beds are assumed to represent migrating linguoid or transverse bars, with an orientation partly at a high angle to current ripples in the same beds. The frequent silt beds are interpreted as a result of rapid vertical accretion due to isostatic subsidence during deposition. A Middle Weichselian age is assumed from thermoluminescence, radiocarbon and amino acid dates.

Prior to the collection of a series of sediment cores, a high- and very-high-resolution reflection seismic survey was carried out on Lago Puyehue, Lake District, South-Central Chile. The data reveal a complex bathymetry and basin structure, with three sub-basins separated by bathymetric ridges, bedrock islands and interconnected channels. The sedimentary infill reaches a thickness of >200 m. It can be sub-divided into five seismic-stratigraphic units, which are interpreted as: moraine, ice-contact or outwash deposits (Unit I), glacio-lacustrine sediments rapidly deposited in a proglacial or subglacial lake at the onset of deglaciation (Unit II), lacustrine fan deposits fed by sediment-laden meltwater streams in a proglacial lake (Unit III), distal deposits of fluvially derived sediment in an open, post-glacial lake (Unit IV) and authigenic lacustrine sediments, predominantly of biogenic origin, that accumulated in an open, post-glacial lake (Unit V). This facies succession is very similar to that observed in other glacial lakes, and minor differences are attributed to an overall higher depositional energy and higher terrigenous input caused by the strong seismic and volcanic activity in the region combined with heavy precipitation. A long sediment core (PU-II core) penetrates part of Unit V and its base is dated as 17,915 cal. yr. BP. Extrapolation of average sedimentation rates yields an age of ca. 24,750 cal. yr. BP for the base of Unit V, and of ca. 28,000 cal. yr. BP for the base of Unit IV or for the onset of open-water conditions. This is in contrast with previous glacial-history reconstructions based on terrestrial records, which date the complete deglaciation of the basin as ca. 14,600 cal. yr. BP. This discrepancy cannot be easily explained and highlights the need for more lacustrine records from this region.

The Orrisdale Outwash Member was deposited during retreat of the Late Devensian Irish Sea ice-sheet in a series of diachronous marginal sandur formed on an unstable, ice-cored supraglacial topography. Sedimentation was controlled by dead-ice ridges running parallel to the ice-margin but as buried ice melted the topographic constraints diminished and individual sandur systems widened and coalesced. The sediments are characterized by very rapid lateral and yertical facies variation caused by channel migration, abandonment, and adjustment to a rapidly-changing ice and sediment substrate. Facies assemblages consequently show marked lateral transition from high energy, laterally impersis-tent, gravel dominated longitudinal bar sequences to extensive, low-energy overbank flood basin successions.

We investigated proglacial fluvial sedimentation processes in the SE Lithuanian Plain by means of lithofacies analysis. The main parameters on which interpretations were based, were depositional structures of sandy sediments, paleohydraulic parameters and grain-size distribution. The development of the SE Lithuanian Plain illustrates the phenomenal shift of proglacial fluvial sedimentation from outwash plain to ice-marginal river during the ice retreat of the last glaciation. Three facies assemblages of braidplain deposits and two facies assemblages of palaeovalley deposits were distinguished in the sandy plain by means of qualitative and quantitative sedimentological research. This raises the question how the commonly accepted development of a SE orientated outwash plain could turn into an almost perpendicular (SW running) ice-marginal river. The vertical and lateral transitions of outwash plain facies present a classical example of braidplain evolution on slightly inclined lowlands, with well expressed proximal, middle and distal parts. Mid- and side-channel (point-bar) deposits of the proglacial valley point, however, which is unusual for proglacial fluvial systems, to a meandering character of the ice-marginal river. River types of various scale show a change from braided into meandering in the proglacial subenvironment. Lithofacies analysis and paleohydraulic parameters show distinct differences of the hydrodynamic regime during the first stage of the sandy plain development: from sedimentation on an outwash plain in a proglacial valley to sedimentation on a braidplain in a wide ice-marginal valley. The outwash system is characterized by a distinct downstream decrease in energy, whereas the ice-marginal river maintained most of its power and velocity.

The Late Carboniferous–Early Permian Itarare Group is a thick glacial unit of the Parana Basin. Five unconformity-bounded sequences have been defined in the eastern outcrop belt and recognized in well logs along 400 km across the central portion of the basin. Deglaciation sequences are present in the whole succession and represent the bulk of the stratigraphic record. The fining-upward vertical facies succession is characteristic of a retrogradational stacking pattern and corresponds to the stratigraphic record of major ice-retreat phases. Laterally discontinuous subglacial tillites and boulder beds occur at the base of the sequences. When these subglacial facies are absent, deglaciation sequences lie directly on the basal disconformities. Commonly present in the lowermost portions of the deglaciation sequences, polymictic conglomerates and cross-bedded sandstones are generated in subaqueous proximal outwash fans in front of retreating glaciers. The overlying assemblage of diamictites, parallel-bedded and rippled sandstones, and Bouma-like facies sequences are interpreted as deposits of distal outwash fan lobes. The tops of the deglaciation sequences are positioned in clay-rich marine horizons that show little (fine-laminated facies with dropstones) or no evidence of glacial influence on the deposition and likely represent periods of maximum ice retreat.

Quaternary sands and gravels form important, yet often highly heterogeneous economic deposits. Detailed 3-D analysis of the sedimentary structure and stratigraphy of these deposits allows for an accurate estimation of exploitable material. This paper presents a case study in SW Germany reconstructing the 3-D distribution of glacial sediments based on a high-resolution, process-orientated sedimentary facies classification and lithostratigraphy integrated within the geo-modelling package gOcad. Situated along the maximal ice-extent of the Rhine glacier during the last glaciation, the study area is characterised by a morphologically prominent terminal moraine and its associated sandur, which form the stratigraphically youngest sediments of a glacial basin, partially exposed in two gravel pits. These outcrops helped to reconstruct the complex sedimentary architecture of the northern part of the glacial basin. The regional analysis is based on core data, as well as geoelectric and geomagnetic surveys. All data were integrated into km-scale, high-resolution geological 3-D models, depicting the large-scale dynamics of multiple glacier advances and retreats during the Early to Late Pleistocene. These models allow quantifying the thickness and volume distribution of exploitable sandy gravel and help to evaluate the occurrence of non-exploitable interbedded diamicton horizons. The high quality and quantity of gravels particularly north of the terminal moraine classifies the investigated area as very prospective for raw materials exploitation in the future.

The study area near Chelm in Western Pomerania, NW Poland, is located between the end moraine and outwash plain of the glaciomarginal zone of the Pomeranian Phase (Weichselian glaciation) Four assemblages of deposits are exposed in the Chem pits: gravelly diamictons derived from debrisflows, sandy diamictons derived from hyperconcentrated flows, alternating sand and gravel deposited by sheetflows and sandy deposits filling shallow, braided-stream channels. The first facies association predominates in the proximal part of the transition zone and the last one in the distal part. This spectrum of facies associations, some resembling those of the end moraines and others those of the adjacent outwash plain, is considered to be unique, and is attributed to the formation of an array of coalescent ice-contact fans (‘transition’ fans). Architectural element analysis highlights the southwards change from debrisflow processes accompanied by sheetflows to hyperconcentrated flows and further to channelized streamflow. This transition zone in the present case is c. 1–km wide. It is suggested that analogous transitional zones, with similar or different widths, may have been developed in other glaciomarginal belts and remain to be recognized.

In this study, we introduce the architecture and style of sedimentation of two outwash fans in front of the Myrdalsjokull ice cap, central south Iceland, that broaden different types of ice-marginal sedimentation. At Kotlujokull, a southeastern outlet of the ice cap, fan formation was monitored from the late 1970s to 2002; thus, the style of sedimentation is well understood and the relationship to the depositional architecture easily established. In front of Slettjokull, a northern lobate extension of the ice cap, a fan from the 10th century AD is capped by neoglacial till sheets. At both sites, the fan surfaces were reconstructed in three dimensions. Ground Penetrating Radar (GPR) provided the thickness and internal structure of sediment bodies. Geological exposures and excavations were used for detailed sedimentological documentation of the outwash deposits in proximal-to-distal transects. The outwash deposits at both Kotlujokull and Slettjokull are considered to be alluvial fans of the hochsander type, i.e., supraglacially fed, as they show all the architectural characteristics of alluvial fans with a semiconical shape, a restricted radial length of ca. 0.5-1.5 km, a plano-convex cross-profile and a slope gradient ranging between 1 and 5. Fan deposits are dominated by planar or low-angle cross-bedded sand facies interbedded with thin laminae of fine gravel occasionally draped by mud. Sedimentation occurs during upper flow regime sheetflows associated with antidune migration within an aggrading, shallow braided-stream network. Hochsanders are intimately linked to advancing or stationary glaciers with steep ice-cored frontal slopes that favor supraglacial over subglacial drainage. Most important, hochsander fans lack any proximal-to-distal transition in the grain-size distribution, sediment facies or facies associations. Because much classification of glacial outwash sediments is based on proximal-to-distal distinctions, it is crucial to consider the depositional model for hochsanders. This study also indicates a strong dependence between the altitudes of the buried fan surface and the present-day terrain in the forefield of Slettjokull, illustrating that subsequent to fan formation, subglacial landforms merely mask many of the pre-existing morphological features. (Less)

High-resolution seismic data (onshore and offshore), geophysical borehole data as well as detailed lithofacies from airlift boreholes were acquired in northern Netherlands on and around the island of Ameland. Marine and land seismic data combined with information from land boreholes have been explored with the objective of providing a sedimentary model. Qualitative seismic facies analysis of the valley fill commonly shows a thin unit with high amplitude reflectors at the base. Thick units of variable seismic facies (transparent to high amplitude) occur higher up in the sequence. Onlap is common at mid-upper levels within the sandy valley fill (with clay in mm layering), and a transparent seismic facies, corresponding to firm clays, is common at the top. Almost all lithological unit boundaries recognised within core parameters correspond with seismic unconformities within error margins. Subunits contain multiple cyclical trends in gamma ray and grain size. Cyclical trends show lower order fluctuations in gamma radiation on a scale of less than 1 m. Gamma-ray pattern variability between units, e.g. in general coarsening-up or fining-up units, suggests migration of subaqueous outwash fans or ice margin fluctuations. Seismic results could support a headward excavation and backfilling process suggested by Praeg [Morphology, stratigraphy and genesis of buried Elsterian tunnel valleys in the southern North Sea basin [PhD thesis]: University of Edinburgh, 207 pp.; Journal of Applied Geophysics, (this volume)] as being responsible for the formation of buried valleys. On a lithological scale, a more complicated, detailed and cyclical pattern arises. Catastrophic processes are considered unlikely as being responsible for the infill sequence because of the observed small-scale facies variability and because of the presence of diamicton layers. Diamicton layers at the base of basal unconformities as well as higher in sequence could suggest subglacial deformation by grounded ice before and during the valley-fill process.

Recent disintegration of a number of Antarctic Peninsula ice shelves has given us a unique opportunity to investigate sub-ice-shelf sediments. We characterize three sediment facies associations of two Antarctic Peninsula ice shelves (Larsen-A and Larsen Inlet). Subglacial facies consist mainly of basal till (diamicton) with high shear strengths deposited under a grounded ice sheet. Progressive upward decrease in shear strength reflects a gradual decrease in the confining vertical effective pressure of grounded ice during till deposition. Proximal ice-shelf glacimarine facies (diamicton, gravel-rich and sand-rich facies, gravelly mud, dropstone mud and sandy muds) were deposited by sub-ice-shelf rain out, bottom current activity and sediment gravity flows following decoupling of grounded ice from the sea-floor. Distal, ice-shelf glacimarine and/or open marine facies comprise terrigenous and diatom-bearing bioturbated muds and gravelly muds that contain limited ice-rafted debris; these accumulated after recession of the grounding line to the coast, with coarse-grained surface sediments possibly documenting most recent ice-shelf break-up. Antarctic Peninsula ice-shelf sediments are more heterogeneous than ice-shelf facies deposited elsewhere in Antarctica. Cold, polar Antarctic ice shelves can be differentiated from temperate and sub-polar marine-terminated glacial sedimentary systems by the dominance of coarse-grained proximal, ice-shelf glacimarine facies and an absence of subaqueous outwash/meltwater sediment facies.

Ground penetrating radar (GPR) measurements have been carried out on an outwash plain and in the rim of an adjacent ice-push ridge in northwest Zealand, Denmark. The radar profiles are differentiated into radar facies with distinct reflection characteristics. The lithology and depositional environment of the radar facies is interpreted by correlating information from profiles in gravel pits, geological maps and bore hole data. The GPR profiles reveal sedimentary structures and glaciotectonic deformation structures. Several thrust planes and folds are interpreted from the GPR data. The deformation style of the tectonised glaciofluvial sediments is a pro-glacial thin-skinned thrust complex, with associated folding. The deformations have resulted in the present ridge morphology seen in the rim of the ice-push ridge. On top of the deformed sediments and in front of them penecontemporaneous and post tectonic sediments are deposited, smoothing the ridge relief created by the thin-skinned thrust complex.

The glacial landscape in south-central Michigan is a dissected surface with streamlined, residual, and upland blocks surrounded by lowland valleys dominated by outwash. The upland surface has ridges, hills, and hummocks composed of boulder gravel, which are transitional to drumlins in a down-ice direction, and is dissected by tunnel channels with eskers within them. Sedimentary descriptions from 14 gravel pits indicate a consistent stratigraphy across a width of 15 km. The upland consists of bedrock covered by a lower till with subglacial melt-out or lodgment characteristics. Above the lower till is a sand-and-gravel facies that passes upward into a boulder-gravel facies. Nestled within depressions on the boulder-gravel surface is a discontinuous facies of laminated sand and silt. Above the gravel is an upper till with supraglacial melt-out and flow till characteristics. Analyses of the till and gravel indicate an upward change in clast lithology from locally derived carbonates to clastics and finally to crystallines from the lower till through the gravel facies into the upper till. The transition mimics the bedrock lithology up-ice of the study area, and is explained by meltwater erosion of bedrock, previously deposited subglacial sediment, and overlying debris-rich basal ice. The systematic change in clast lithology and the stratigraphic position of the gravel facies between a subglacial and supraglacial till strongly suggests that the gravel facies sediment was deposited subglacially and that the entire till–gravel–till sequence resulted from the same glacial advance.

Variations in lake seepage were studied along a 130 m shoreline of Mirror Lake NH. Seepage was downward from the lake to groundwater; rates measured from 28 seepage meters varied from 0 to -282 cm/d. Causes of this variation were investigated using electrical resistivity surveys and lakebed sediment characterization. Two-dimensional (2D) resistivity surveys showed a transition in lakebed sediments from outwash to till that correlated with high- and low-seepage zones, respectively. However, the 2D survey was not able to predict smaller scale variations within these facies. In the outwash, fast seepage was associated with permeability variations in a thin (2 cm) layer of sediments at the top of the lakebed. In the till, where seepage was slower than that in the outwash, a three-dimensional resistivity survey mapped a point of high seepage associated with heterogeneity (lower resistivity and likely higher permeability). Points of focused flow across the sediment-water interface are difficult to detect and can transmit a large percentage of total exchange. Using a series of electrical resistivity geophysical methods in combination with hydrologic data to locate heterogeneities that affect seepage rates can help guide seepage meter placement. Improving our understanding of the causes and types of heterogeneity in lake seepage will provide better data for lake budgets and prediction of mass transfer of solutes or contaminants between lakes and groundwater.

Different methods have been used to determine the stratigraphic position of Pleistocene alluvial deposits, particularly fluvial interglacial deposits. Near-surface deposits of a meandering river, developed in point-bar and oxbow lake facies, in the Samica River valley (near Łukow, eastern Poland) have been investigated. The fossil valley is incised into the till plain and the outwash. The fluvial succession is locally overlain by solifluction deposits. All the deposits underwent sedimentological analysis. The petrographic composition of basal till occurring in the vicinity of a fossil valley was determined with the method of indicator erratics. Fluvial deposits were examined by pollen analysis and plant macrofossil analysis of oxbow lake facies. Absolute dating methods were applied to the deposits (thermoluminescence methods: TL and additionally IRSL). Lithological differences between fluvial and the surrounding glaciofluvial deposits were identified and their lithostratigraphic position assigned. Petrographic analysis of till and palaeobotanical analyses of oxbow lake facies gave compatible results. Fluvial deposits were formed after the Sanian 2/Elsterian Glaciation, during the Mazovian/Holsteinian Interglacial. Luminescence dating of the fluvial deposits by the TL MAX method yielded the most relevant results (412-445 ka), which indicate that these deposits were formed during the end of the MIS 12 and beginning of the MIS 11 stage.

The loess deposits of western Poland are a periglacial facies, having been deposited in the Plenivistulian. So far, western Poland is the onlypart of the countryin which Vistulian loess deposits, occurring as small patches on di !erent glacial and glacio#uvial landfoms, have been found. The diagnostic features of these sediments provide a tool for the sub-division of the main lithofacies. Loess deposits occur in two main lithofacies: massive loess (Lm) and laminated loess (Ll). There are three sub-lithofacies within the laminated loess: cryptolaminated (sl), laminated loess sensu stricto (ll) and banded loess (sm). Loess lithofacies are associated with a varied topographyand are distributed in the end moraines, till plains and outwash plains. There is a signi "cant correlation with the periglacial zone and aeolian processes active during the Vistulian in western Poland. 2001 Elsevier Science Ltd and INQUA. All rights reserved.

Outwash plains, such as Skeiaararsandur, serve as prototypes for braided river facies and analogs for the Mars Pathfinder and Viking 1 landing sites on the margins of the Chryse Basin. Glacier outburst floods (jokulhlaups) have generated some of the largest known terrestrial freshwater flows and recent studies suggest that the stratigraphy of outwash plains (sandur) is dominated by sedimentary sequences laid down during jokulhlaups, rather than by braided river facies produced by an ablation-related flow regime. The modern point-source drainage configuration on Skeiaararsandur evolved from a diffuse, multipoint distributary system during glacier retreat, when meltwater began to be routed parallel to the ice front. The contemporary pattern of water and sediment dispersal across Skeiaararsandur differs from the conditions that prevailed when the ice front was coupled to the sandur, and the November 5–6 1996 outburst flood from Skeiaararjokull had little impact on the proximal surface of Skeiaararsandur beyond the confines of the entrenched channels that traverse it. Thus, the point-source dispersal system on Skeiaararsandur may not provide an exact analogue for the pattern of meltwater dispersal responsible for the sediment assemblage laid down during past jokulhlaups, and caution may be required when comparing conditions on Skeiaararsandur to those presumed to have been experienced during massive outburst floods elsewhere.

Upper and Middle Waterton lakes fill a glacially scoured bedrock basin in a large (614 km2) watershed in the eastern Front Ranges of the Rocky Mountains of southern Alberta, Canada and northern Montana, U.S.A. The stratigraphic infill of the lake has been imaged with 123 km of single-channel FM sonar (`chirp') reflection profiles. Offshore sonar data are combined with more than 2.5 km of multi-channel, land-based seismic reflection profiles collected from a large fan-delta. Three seismic stratigraphic successions (SSS I to III) are identified in Waterton Lake resting on a prominent basal reflector (bedrock) that reaches a maximum depth of about 250 m below lake level. High-standing rock steps (reigels) divide the lake into sub-basins that can be mapped using lake floor reflection coefficients. A lowermost transparent to poorly stratified seismic succession (SSS I, up to 30 m thick) is present locally between bedrock highs and has high seismic velocities (1750–2100 m/s) typical of compact till or outwash. A second stratigraphic succession (SSS II, up to 50 m thick), occurs throughout the lake basin and is characterised by continuous, closely spaced reflectors typical of repetitively bedded and rhythmically laminated silts and clays most likely deposited by underflows from fan-deltas; paleo-depositional surfaces identify likely source areas during deglaciation. Intervals of acoustically transparent seismic facies, up to 5 m thick, are present within SSS II. At the northern end of Upper Waterton Lake, SSS II has a hummocky surface underlain by collapse structures and chaotic facies recording the melt of buried ice. Sediment collapse may have triggered downslope mass flows and may account for massive facies in SSS II. A thin Holocene succession (SSS III

This paper discusses the main causes and characteristics of jokulhlaup (‘glacier burst’) floods, and explores the extent to which they generate depositional landform and sediment assemblages that are distinct from those of ‘normal’, braided river outwash (‘Type I’ outwash). Two main jokulhlaup outwash environments are identified: Type II outwash, produced by sudden drainage of ice-dammed lakes; and Type III, associated with drainage during subglacial geothermal activity, and distinguished by deposits resulting from high sediment concentrations and hyperconcentrated flows. In fluid flows, especially ones yielding Type II outwash, the most common deposits are large-scale expansion bars (and locally, eddy and pendant bars), and ‘mega-ripples’ or dunes, both forms normally composed of large-scale gravel-cobble cross-bedding, often capped by an imbricated boulder lag (a ‘Type B2’ lithofacies sequence). The armour is absent only where runoff decreased too rapidly to allow surface winnowing. Other jokulhlaup facies include extensive boulder beds (Type C), inverse-normally graded cobble beds (Type DS), ice-proximal debris flow deposits and deformed bedding containing diamicton clasts (Types G and H), and slack-water sediments (Type A). Type III outwash is dominated by massive, homogeneous, flood surge granules, underlain by pre-surge gravels, and capped by post-surge fluid bedforms, reflecting deposition during both the rising and falling limbs of the flood hydrograph (Type E4). The paper demonstrates that jokulhlaups do generate distinctive assemblages of depositional landforms and sediments, and concludes with a model of the dominant lithofacies sequences and associated landforms in proglacial environments subject to jokulhlaup drainage.

Submarine jet processes are inferred from glaciomarine facies exposed in gravel pits in southwestern coastal Maine. The geometry and distribution of fan facies depend on (1) the proximity to the grounding line and stream effluxes, (2) the angle of jet trajectory from glacier conduits, and (3) sediment remobilization processes. Syndepositional glaciotectonic deformation further augments morainal bank formation through pushing and squeezing of fan sediments at the grounding line. Complex process-sediment interactions along the temperate tidewater margin of the Laurentide ice sheet are recorded in the facies architecture of sedimentary sequences in morainal banks. Morainal bank accumulation was governed by rapid fluvial deposition, and outwash jet dynamics that controlled the spatial distribution of sedimentary facies. Near the grounding line, meltwater dynamics change rapidly where sediment-laden fresh water is discharged at or near the sea floor. Turbulent mixing with ambient sea water and discharge fluctuations cause rapid changes in flow competence, accompanied by the dumping of bed-load gravel and sand at the apices of grounding-line fans in the morainal banks. Jet trajectory relative to the morainal-bank slope determines whether a jet will make contact with the morainal bank. Gravel and sand remain in bed-load traction as long as the jet is in contact with the morainal bank. Bed-load dumping and settling of the coarse suspended load occurs where buoyant forces in the jet overcome momentum forces or where the jet is deflected by the morainal bank. Below these buoyant jets, backflow eddies can produce currents that drive ripple migration toward the grounding line. Abrupt facies changes record fluctuations in jet discharge and trajectory and sediment redistribution by sediment gravity flows initiated near the grounding line.

In the glacially-filled valleys of the western and central glaciated plains of North America, assemblages of sand-and-gravel outwash form large, productive regional aquifer systems. In these buried-valley aquifers, low-permeability facies, including till or lacustrine clay, are commonly juxtaposed with the permeable outwash. The geometry of the boundary between these facies must be defined in order to address contaminant problems. Although the exact geometry of the boundary between high- and low-permeability facies can only be determined by a prohibitive amount of subsurface information, indicator geostatistics can be used to evaluate the uncertainty at points between actual observations. As an example, the heterogeneity in the Miami Valley aquifer system, which extends 150 km through southwestern Ohio, USA, was examined. In a northern reach, a three-dimensional lithological data base with 30,094 observations was developed by coding all available logs with a binary indicator system, indicating the presence of either high-permeability facies (aquifer) or low-permeability facies (aquitard). This reach of the aquifer system has 36 percent by volume aquitard material, based upon the declustered global mean of the data. The aquitard material is stratified, and the elevation between 204–213 m has the most aquitard material. An interval 6.1 m thick within this zone was studied in more detail to determine the spatial correlation and areal distribution of the aquitard material. Within this interval, the aquitard facies occupies 45 percent of the volume. Based upon variography, the spatial correlation of the facies is greatest in the N50°E direction with a range of about 700 m. The min/max anisotropy ratio is 0.4. The probability of aquitard material existing at any given location was examined with indicator point kriging. Locations in the subsurface having a higher probability for the existence of aquitard material occur more along the valley margins, and locations with a lower probability occur more in the valley interior.

This study combines geostatistical analyses with geologic interpretations to further the quantitative understanding of physical heterogeneity within glaciofluvial aquifers. The stochastic simulation of aquifers requires quantitative measures of heterogeneity, including both cumulative distribution and spatial correlation functions. The heterogeneity in glaciofluvial aquifers is typified by low-permeability facies (e.g., till or lacustrine clay) juxtaposed with high-permeability facies (e.g., sand and gravel outwash). The Miami Valley aquifer system was examined at multiple sites for the spatial distribution and correlation of these two hydrofacies. Binary indicator geostatistics were used to quantitatively determine, at each site, the relative volume of each hydrofacies, their spatial distribution, the major principal direction of their spatial correlation, the minor principal direction, and the correlation range in these directions. The percent by volume of the system that is aquitard material decreases down the valley, from 31% to 12%. Each site has an elevation zone with more aquitard material relative to other elevations at that site. The percent aquitard material in these zones decreases down the valley from 45% to 22%. The maximum principal direction of spatial correlation in the aquitard zones generally is NE-SW, subparallel to the trend of the bedrock valley, with a range of the order of 0.75 km and minimum/maximum anisotropy ratio of 0.4. The locations exceeding 0.5 probability of aquitard occurrence generally occur on the valley margins. Thus, among the sites investigated, there is a trend down the valley in the ratio of aquitard volume to aquifer volume, and the spatial correlation and distribution of aquitard material are similar within the aquitard zones. Furthermore, these findings are consistent with aspects of the subglacial and proglacial depositional environments responsible for the facies assemblage and thus are likely to be applicable to other parts of the aquifer system and other aquifer systems where similar geologic processes are inferred to have existed.

In the buried-valley aquifers of the western and central glaciated plains of North America, assemblages of permeable outwash facies may form large and productive regional aquifer systems. In glacially derived aquifers it is common to have low-permeability facies (e.g., till or lacustrine clay) juxtaposed with high-permeability facies (e.g., sand and gravel outwash). The heterogeneity in the Miami buried-valley aquifer system in southwestern Ohio was examined as an example. Practical approaches for evaluating the lithological uncertainty were explored in the areas lacking data. The facies types were represented by an indicator random function, which exhibited an isotropic, exponential covariance structure. A comparative, quantitative analysis of the facies boundaries was accomplished using three different indicator geostatistical methodologies: (1) hydrostratigraphic analysis with indicator point kriging and probability cutoff, (2) hydrostratigraphic analysis with conditional indicator simulation, and (3) leakance zonation with indicator block kriging and grid-cell averaging. With the first method, it was shown in a theoretical analysis that the 0.5 probability level computed by indicator point kriging may or may not correspond to the boundary between high- and low-permeability facies, depending upon the level of data support. With the data support for the Miami aquifer system, the 0.65 probability contour gave an areal distribution of low-permeability facies that honored both the original data and the declustered global mean of the original indicator data. The first and third methods gave rise to a single model, in which the facies distribution was best in some local accuracy sense. The second method gave rise to many alternative models, in which the global texture of the facies distribution took precedence over local estimation of the expected value. The first two methods involved evaluating the geometry of the boundaries between the facies types in advance of creating the grid of the numerical ground-water model, so that grid cell boundaries could be made to correspond to facies boundaries. The third method was useful when updating an existing ground-water model that has grid cell boundaries not necessarily corresponding to facies boundaries.

The Icelandic sandur plains have for long acted as classic sites for models of braided river behaviour and of associated lithofacies assemblages. However, many of the Icelandic sandurs are subject to repeated catastrophic flood events, or jokulhlaups, which are likely to have played a significant role in sandur construction. Established lithofacies models based on the Icelandic sandurs have failed to take account of the varying runoff regimes which characterise the different sandur environments. In addition, sediment inputs to sandur channel systems are highly variable, fluctuating in response both to varying runoff patterns, and to advance and retreat of the source glacier, that affect sediment availability within the proglacial zone. This paper describes the main lithofacies types and vertical profiles that characterize the sandurs of south Iceland, and demonstrates that they can largely be attributed to extreme runoff events, with few deposits typical of “braided river” facies occurring within the sedimentary record. A preliminary qualitative model is developed that allows interpretation and prediction of vertical lithofacies profiles derived from glacial outwash in terms of: (i) the drainage mechanism, which in turn controls the dominant runoff population; (ii) sediment availability; and (iii) the spatial variability in flow dynamics.

In this paper we examine the viability of using sedimentological, facies-modelling techniques in the exploration for a specific aggregate mineral resource: blending sand. Blending sand is a naturally occurring, medium-grained, poorly sorted aggregate that is an integral component of asphalt mixes. In Canada and the northern United States and Europe, glacial outwash deposits are a common exploration target. A glaciogenic complex in southeastern Ontario that contains blending sand was examined in order to document the facies organization and origin of the complex as a whole, and the blending-sand deposits in particular. In this study blending sand is located only within the proximal portion of the esker fans, and can be characterised as a distinct facies that was formed by sustained, high-density underflows which deposited cross-bedded, medium sand. Periodic fluctuations in flow speed allowed interbeds of rippled fine sand to accumulate, giving the facies its overall poor sorting. A comparison with similar deposits elsewhere indicates that local facies associations have more widespread applicability. Therefore, the surface morphology and the spatial arrangement of sediment facies within esker-ridge/esker-fan complexes can be used as predictive exploration tools to locate blending sand in these types of deposits. Different facies models are needed for other deposit types and aggregate products.