Revision and update of the Callovian-Ryazanian Stratigraphic Nomenclature in the northern Dutch offshore, i.e. Central Graben Subgroup and Scruff Group

Abstract

Exploration in a mature basin requires a detailed classification and standardisation of rock stratigraphy to adequately comprehend the depositional history and prospect architecture. The pre-Quaternary Stratigraphic Nomenclature of the Netherlands compiled by Van Adrichem Boogaert & Kouwe in 1993 provided a consistent framework for use by the Dutch geological community. Over the past twenty years, new biostratigraphic techniques and continued exploration in the Netherlands have provided additional stratigraphic information. Based on this information the Late Jurassic lithostratigraphy in particular, shows significant inaccuracies. The Callovian-Ryazanian strata from the northern offshore of the Netherlands' territorial waters, termed the Central Graben Subgroup and Scruff Group, reveal a complex sedimentary history. The combination of non-marine to shallow marine lateral facies changes, repetitive log and facies characteristics in time, sea-level and climate change, salt tectonics and structural compartmentalisation hamper straightforward seismic interpretation and log correlation. Recognition of three genetic sequences by Abbink et al. in 2006 enabled an improved reconstruction of the geological history. Further improvements in refinement and reliability of the stratigraphy together with new information on the facies and ages of the successions and about the subsequent tectonostratigraphic development of the northern Dutch offshore area form the basis of the present revision. As a result, earlier lithostratigraphic models have been changed and new lithostratigraphic relationships and names are introduced in this paper.