The Middle Pleistocene glacial evolution of northern East Anglia, UK: a dynamic tectonostratigraphic–parasequence approach

Abstract

ABSTRACTThe Middle Pleistocene glacial history of northern East Anglia is a controversial topic with differing opinions surrounding chronology, provenance and the relative stratigraphic framework. Reconciling the stratigraphic framework of the region is an essential first step to developing onshore–offshore geological models and a robust event‐driven chronological framework. Within this study a dynamic tectonostratigraphic–parasequence methodology is applied to deposits traditionally attributed to the Anglian Glaciation (Marine Isotope Stage 12). This approach offers an insight into ice‐bed coupling during glaciation and how evolving boundary conditions influenced glacier dynamics. Six major tectonostratigraphic–parasequence assemblages (A1–A6) are recognized in northern East Anglia and correlate with successive advances into the region of North Sea or Pennine lobes of the British Ice Sheet. Individual tectonostratigraphic–parasequence assemblages are bound at their base by a sedimentary contact or, more commonly, a glacitectonic zone. The geometry and structural characteristics of these glacitectonic zones reflect temporal and spatial variations in ice‐bed coupling (traction), a function of substrate rheology and, in turn, variations in lithology, porewater availability and thermo‐mechanical properties. The role of permafrost may also be significant, promoting proglacial/ice‐marginal thrust stacking in front of advancing ice and enhanced ice‐bed decoupling during subsequent overriding and subglacial till accretion. © 2016 British Geological Survey, NERC Journal of Quaternary Science © 2016 John Wiley & Sons Ltd