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Distribution and thickness of depositional units

From the 3D subsurface model depth maps, thickness maps and 2D cross-sections were extracted to illustrate the large-scale depositional architecture of the studied succession.

Base of the Pleistocene (Fig. 10A)

The base of the Pleistocene succession is defined by an unconformity, separating the Pleistocene de-posits from the underlying Palaeogene dede-posits or Mesozoic basement rocks. The base of the Pleisto-cene has an elevation between 68 and 157 m a.s.l. The highest elevations are located in the north and the west of the modelled area. In the southern portion of the modelled area the base of the Pleistocene displays a trough-shaped, 3.5 km long depression. The width of the trough typically is 300-400 m, but may range between 250 and 850 m. The bottom of the trough has an elevation between 68 and 100 m a.s.l. and is thus up to 40 m deeper than the surrounding area. The deepest parts of the trough are sepa-rated by up to 15 m high sills. The trough trends NNW-SSE in the northern part, then bends towards the SSW and leaves the modelled area on the southwestern margin. At the southeastern margin of the modelled area probably parts of a second trough are cut by the model.

Elsterian meltwater deposits (Fig. 10B)

The Elsterian meltwater deposits comprise light gray or brown gravel, pebbly sand or sand, which contains abundant lignite fragments. The Elsterian meltwater deposits are restricted to the trough formed by the base of the Pleistocene, usually at an elevation below 100 m a.s.l. High thickness of Elsterian meltwater deposits correspond to the deepest parts of the trough. The maximum thickness is 24 m.

Elsterian till (Fig. 10C)

The Elsterian till comprises dark gray diamicton, commonly containing pebbles and cobbles. The El-sterian till is restricted to the trough formed by the base of the Pleistocene, usually at an elevation be-low 100-110 m a.s.l. The maximum thickness of the Elsterian till is 15 m.

Fig. 10: Depth and thickness maps derived from 3D subsurface modelling (GOCAD). A) Geometry of the base of the Pleistocene (5 m contours). B) Distribution and thickness of the Elsterian meltwater deposits (2 m con-tours). C) Distribution and thickness of the Elsterian till (2 m contours) D) Distribution and thickness of the Holsteinian deposits (1 m contours). E) Distribution and thickness of the Saalian meltwater deposits of the gla-cial advance (2 m contours). F) Distribution and thickness of Saalian till (2 m contours). G) Distribution and thickness of the Saalian meltwater deposits of the glacial retreat (2 m contours). H) Distribution and thickness of the Eemian deposits (1 m contours).

Middle Pleistocene interglacial deposits (Fig. 10D)

The interglacial deposits comprise black or brown fine-grained sand, silt and peat, commonly contain-ing plant debris and shell fragments. Middle Pleistocene interglacial deposits overlie the Elsterian deposits and infill the lowest elevations on top of the Elsterian deposits. The Middle Pleistocene inter-glacial deposits form an elongate NNW-SSE trending body, which is 2500 m long, 200-400 m wide and covers an area of ~ 1 km². The maximum thickness is 7.5 m.

Saalian meltwater deposits of the glacial advance (Fig. 10E)

The meltwater deposits comprise yellow, orange or red gravel, pebbly sand or sand. Thin beds of silt may be intercalated. The meltwater deposits cover the southern part of the modelled area. The thick-ness is relatively consistent between 2 and 5 m. Two elongate, NNW-SSE trending thickthick-ness maxima (up to 18 m) are observed in the central southern area.

Saalian till (Fig. 10F)

The Saalian till comprises yellow, orange or red, sand-rich diamicton. The Saalian till occurs in the complete modelled area. The maximum thickness of the Saalian till is 25 m in northwest-southeast trending ridges in the northern part of the modelled area. In the southern part of the modelled area the till has a patchy appearance with thicknesses typically ranging 1-3 m with local maxima of up to 8 m.

Saalian meltwater deposits of the glacial retreat (Fig. 10G)

The meltwater deposits comprise yellow or orange pebbly sand or sand. The meltwater deposits of the glacial retreat occur only in the northern part of the modelled area, where they form a ~2 km long, north-south trending, up to 35 m thick sedimentary body. This body has a very steep margin towards the north and thins rapidly towards the south.

Eemian deposits (Fig. 10H)

The Eemian deposits comprise black or brown silt or peat, commonly containing plant debris and shell fragments. Eemian deposits form an elongate, NNW-SSE trending body, which is 1000 m long, 300 m wide and covers an area of ~0.3 km². The maximum thickness is 5 m.

Extracted 2D sections

Two 2D cross-sections have been extracted from the subsurface model (Fig. 11A, B). Cross-section CS-1 runs parallel to the basin axis and section CS-2 perpendicular to the basin axis. Both cross-sections show the deep incision of the base of the Pleistocene into the underlying tilted Palaeogene strata. In cross-section CS-1 the undulating bottom profile of the Pleistocene succession becomes ob-vious (Fig. 11A). Cross-section CS-2 demonstrates the occurrence of the Pleistocene incision at the boundary between Mesozoic bedrock and unconsolidated Palaeogene deposits (Fig. 11B). Both cross-sections indicate the restriction of Elsterian and Middle Pleistocene interglacial deposits to the deep erosional trough. Due to the curved shape of the Pleistocene depocentre the Middle Pleistocene inter-glacial deposits are cut twice by line CS-1 (Fig. 11A). The upper part of the sedimentary succession consists of Saalian meltwater deposits and till. In the northern part of cross-section CS-1 the Saalian till reaches the maximum thickness and is unconformably overlain by Saalian meltwater deposits of the glacial retreat.