High‐resolution shallow sub‐bottom seismic survey data obtained for the Dudgeon windfarm site located 50 km offshore of the north Norfolk coast in the southern North Sea have revealed that the chalk bedrock in this area is overlain by sediments deposited during the Elsterian and Weichselian glacial periods. A buried N–S‐trending subglacial drainage channel (tunnel valley) filled with Swarte Bank Formation (MIS 12) sediments indicates that the maximum extent of the Elsterian ice‐sheet margin occurred further to the south. Detailed cross‐sections constructed from the seismic data reveal the presence of buried thrust‐block moraine system composed of deformed (folded and thrusted) Swarte Bank Formation sediments, lying beneath a younger sequence of sediments dominated by the glacigenic Bolders Bank Formation (MIS 2). The geometry of the folds and sense of offset on the thrusts, coupled with the morphology of the ridge‐like landforms within this buried moraine system, are consistent with deformation having occurred in response to ice‐push from the N/NE. The chalk bedrock that underlies the glaciotectonized sequence is thought to have provided an antecedent control on the location and preservation of this moraine system. A three‐phase model is proposed to explain the evolution of this thrust‐moraine complex that formed at the oscillating ice margin during the overall active retreat of the Elsterian ice sheet.

中文翻译：

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北海南部的埃尔特斯冰盖撤退：大型冰构造和冰床以下条件的前期控制

在北海南部诺福克海岸北侧50公里处的Dudgeon风电场现场获得的高分辨率浅层底部地震勘探数据表明，该地区的白垩基岩被Elsterian和Weichselian冰河时期沉积的沉积物覆盖期。一条充满N-S趋势的冰川下排水通道（隧道谷）充满了Swarte Bank形成（MIS 12）沉积物，这表明Elsterian冰盖边缘的最大范围发生在南部。根据地震数据构造的详细横截面显示，存在由变形的（折叠的和逆冲的）斯图尔特河岸组沉积物组成的埋藏逆冲块冰lying系统，该沉积物位于由成冰的波尔德斯河床组（MIS 2）主导的较年轻的沉积物序列之下。褶皱的几何形状和推力上的偏移感，再加上该埋藏冰ora系统内的山脊状地形形态，与N / NE响应于冰推而发生的变形是一致的。人们认为，在冰晶构造序列基础上的白垩岩层已经对该冰ora系统的位置和保存提供了前期控制。提出了一个三个阶段的模型来解释在Elsterian冰盖的整体主动退缩期间在振荡冰边缘形成的逆冲冰a复合体的演化。人们认为，在冰晶构造序列基础上的白垩岩层已经对该冰ora系统的位置和保存提供了前期控制。提出了一个三个阶段的模型来解释在Elsterian冰盖的整体主动退缩期间在振荡冰边缘形成的逆冲冰a复合体的演化。人们认为，在冰晶构造序列之下的白垩基岩层已经对该冰ora系统的定位和保存提供了前期控制。提出了一个三个阶段的模型来解释在Elsterian冰盖的整体主动退缩期间在振荡冰边缘形成的逆冲冰a复合体的演化。