Time‐transgressive tunnel‐valley infill revealed by a three‐dimensional sedimentary model, Hamburg, north‐west Germany

Abstract

Deep, elongated incisions, often referred to as tunnel valleys, are among the most characteristic landforms of formerly glaciated terrains. It is commonly thought that tunnel valleys were formed by meltwater flowing underneath large ice sheets. The sedimentary infill of these features is often highly intricate and therefore difficult to predict. This study intends to improve the comprehension of the sedimentology and to establish a conceptual model of tunnel-valley infill, which can be used as a predictive tool. To this end, the densely sampled, Pleistocene tunnel valleys in Hamburg (north-west Germany) were investigated using a dataset of 1057 deep wells containing lithological and geophysical data. The stratigraphic correlations and the resulting three-dimensional lithological model were used to assess the spatial lithological distributions and sedimentary architecture. The sedimentary succession filling the Hamburg area tunnel valleys can be subdivided into three distinct units, which are distinguished by their inferred depositional proximity to the ice margin. The overall trend of the succession shows a progressive decrease in transport energy and glacial influence through time. The rate of glacial recession appears to have been an important control on the sedimentary architecture of the tunnel-valley fill. During periods of stagnation, thick ice-proximal deposits accumulated at the ice margin, while during rapid recession, only a thin veneer of such coarse-grained sediments was deposited. Ice-distal and non-glaciogenic deposits (i.e. lacustrine, marine and terrestrial) fill the remaining part of the incision. The infill architecture suggests formation and subsequent infill of the tunnel valleys at the outer margin of the Elsterian ice sheet during its punctuated northwards recession. The proposed model shows how the history of ice-sheet recession determines the position of coarse-grained depocentres, while the post-glacial history controls the deposition of fines through a progressive infill of remnant depressions.

The Middle Pleistocene tunnel valley at Schöningen as a Paleolithic archive

“…Tunnel valleys commonly represent the depocentres for glacigenic and interglacial deposition (e.g., Krohn et al, 2009;Stackebrandt, 2009;Janszen et al, 2012a;van der Vegt et al, 2012). Since the incision of tunnel valleys is one of the deepest-reaching erosional processes, they provide sites with a high preservation potential, especially in areas affected by multiple glaciations.…”

“…Synglacial tunnel valley fills include glacifluvial and glacilacustrine deposits and till, which are deposited both subglacially and proglacially during deglaciation. Interglacial infills of tunnel valleys commonly comprise lacustrine deposits or, if the setting is at the interglacial coastline, paralic or marine deposits (Kuster and Meyer, 1979;Piotrowski, 1994;Janszen et al, 2012a;Kehew et al, 2012;Lang et al, 2012;van der Vegt et al, 2012).…”

Morphological properties of tunnel valleys of the southern sector of the Laurentide Ice Sheet and implications for their formation

“…In other cases, aligned tunnel valley segments could indicate a time-transgressive origin (e.g. Mooers, 1989;Patterson, 1994;Jørgensen and Sandersen, 2006;Janszen et al, 2013). This is particularly apparent where the valley segments terminate in outwash fans, and/or where segments cross-cut each other (Fig.…”

Glaciogenic reservoirs and hydrocarbon systems: an introduction

“…Accumulations of proglacial gravel and sand-rich reservoir deposits can be found within deeply incised glacial valleys (e.g. Ehlers et al 1984;Ehlers & Linke 1989;Huuse et al 2003;Janszen et al 2012a;Kehew et al 2012). They typically accumulate at the ice margin during ice-recessional phases, associated with punctuated ice stagnation conditions.…”

“…Ghienne & Deynoux 1998;Le Heron et al 2004;Moreau et al 2005;Lang et al 2012b). Detailed study of reservoir architecture from 3D seismic data, large borehole data sets, integrated with outcrop data for shallower Pleistocene tunnel valleys in NW Europe provide a valuable subsurface analogue for tunnel valley systems in the Palaeozoic van der Vegt et al 2012) and aid the quantitative understanding of morphological parameters, the lateral variability of the nature of the sedimentary infill and its architecture (Cummings et al 2012;Janszen et al 2012a). Such studies can provide measurable parameters that can be used by operators to direct their exploration and development activities in glaciogenic reservoirs.…”