Lake‐Level Control on Ice‐Margin Subaqueous Fans, Glacial Lake Rinteln, Northwest Germany

Abstract

During the maximum advance of the Early Saalian Scandinavian Ice Sheet ice-dammed lakes developed within valleys of the Northwest German Mountain ranges. The blocking of the River Weser valley led to the formation of glacial Lake Rinteln where most of the sediment was deposited by meltwater. Two subaqueous fan complexes have been identified, which formed lakeward of retreating ice-lobes during an overall lake-level rise. The sediment transport on the fans has been dominated by sustained gravity-flows, mainly cohesionless debris flows or high-and low-density turbidity currents, reflecting discharge of semi-continuous meltwater flows. Intercalations of surge-type high-and lowdensity turbidites increase towards the mid-and lower-fan slopes, indicating more ice-distal and periodic deposition. Individual fan bodies commonly have a coarse-grained proximal core of steeply dipping gravel, overlain by gently to steeply dipping mid-to outer fan deposits. During glacier retreat commonly fine-grained sediments, rich in ice-rafted debris, were deposited on the ice-distal and ice-proximal slopes of the abandoned fans. Climbing-ripple cross-laminated sand may onlap coarse-grained upper fan gravel and in some cases overtop the older fan deposits. Phases of glacier still-stands are characterised by fan systems that display an upward flattening of fan clinoforms and minor vertical facies changes. The position of ice marginal fans was controlled by the combination of bedrock topography and water depth. At the eastern lake margin topographic highs served as pinning points for the retreating glacier and facilitated ice margin stabilisation. A strong lake-level fall probably triggered a major drainage event that tapped previously unconnected reservoirs of englacial and subglacial meltwater.

The Middle Pleistocene glaciolacustrine environment of an ice‐dammed mountain valley, Sudeten Mountains, Poland

“…Kame delta architecture (Winsemann et al . , b; Gruszka & Terpiłowski ; Wachecka‐Kotkowska ) may be similar to one created in strictly glacial environments or even in ice‐contact situations (Feenstra & Frazer ), and interbedded diamictons of glacial origin (tills) would be expected.…”

“…; Clemmensen & Houmark‐Neilsen ; Postma & Roep ; Shaw ; Krzyszkowski , ; Brodzikowski ; Gruszka ; Winsemann et al . , b, ; Pisarska‐Jamroży et al . ; Wachecka‐Kotkowska et al .…”

Sedimentary imprints of former ice-sheet margins: Insights from an end-Ordovician archive (SW Libya)

“…This grading-upwards trend from glaciomarine to proglacial deltaic and then fluvioglacial deposits suggests an initial, short-lived, ice-contact underwater glaciomarine outwash. Then, the ice-front established as a terrestrial system in order to feed a fluvioglacial deltaic system including an intervening subaerial braidplain (Girard et al, 2012a; see also Lønne, 1995;Powell and Cooper, 2002;Winsemann et al, 2007). As no relative sea-level fall is inferred from the overall architecture of the glaciomarine to fluvioglacial outwash, the aggradation intrinsically tied to the progradation of the ice-marginal depositional wedge most probably drove this subaqueous to continental transition (e.g., Lønne et al, 2001).…”

“…This is a severe limitation in our capacity to untangle former ice-sheet extents in deep time and in our capacity to propose sequence stratigraphic scenarios for related recessional ice-front development, whose associated deposits are nevertheless amongst the most abundant in the Earth glacial sedimentary record (Moncrieff and Hambrey, 1990;dos Santos et al, 1996;Von Brunn, 1996;Le Heron et al, 2006;Ghienne et al, 2007b). Ice-marginal depositional systems are of considerable economic importance as related deposits are genetically linked with groundwater reservoirs in Europe (e.g., Burval working group, 2009) or with gravel and sand quarries in Europe and America (e.g., Cutler et al, 2002;Winsemann et al, 2007) and are part of glaciogenic Palaeozoic or older petroleum systems in the Middle East and North Africa (Davidson et al, 2000;Bechstädt et al, 2009;Le Heron et al, 2009;Lottaroli et al, 2009;Roussé et al, 2009;Craig et al, 2013).…”

Depositional architecture and sequence stratigraphic correlation of Upper Ordovician glaciogenic deposits, Illizi Basin, Algeria

“…The deposits of the glacial retreat systems tract comprise a retrogradational succession of ice-proximal to ice-distal deposits. Glacial depositional sequences are commonly dominated by deposits of the glacial retreat, which have higher preservation potential than deposits of the glacial maximum or advance (Visser 1997;Lønne, 2001;Winsemann et al 2007aWinsemann et al , 2009Le Heron et al 2010). Deposits of the glacial retreat form the bulk of the glaciomarine succession in the study area.…”