New data on the stratigraphy and geophysics in the area around Hollowell, Northamptonshire, provided by a coal exploration borehole

Abstract

The Hollowell Borehole, drilled by British Coal, commenced in the Middle Jurassic Northampton Sand then proved Lower Jurassic and Triassic sediments resting unconformably on Charnian tuffs and agglomerates. The biostratigraphy of the Lias is described based on macrofauna collected from cored sections and geophysical logs. A marginal facies of the Triassic Mercia Mudstone Group was proved. The Charnian volcaniclastic rocks are assigned to the Maplewell Group. The proven absence of a thick sedimentary basin coupled with a major negative gravity anomaly around the borehole have led to a proposed granite model to fit the geophysical data.