The East Groningen Massif - detection of an intrusive body by means of coalification

Abstract

Coalification data measured in Late Carboniferous strata are available from wells in the Ems estuary and in the southern part of the German North Sea. The grade of maturity was calculated for the surveyed horizons using Lopatin's method, from the burial history, present temperature gradient and surface temperature, and these calculated data were compared with the measured ones. Positive differences (measured value higher than calculated) indicate the presence of a heat anomaly probably caused by a buried intrusive body. The 'East Groningen Massif'. The shape of this anomaly coincides with the present and past regional structural trend in this area. The same applies for a positive aeromagnetic anomaly in this area. It can be assumed that the age of the East Groningen Massif is around the Jurassic-Cretaceous boundary. i.e. Late Kimmerian.