Foraminiferal biostratigraphy of the Woo Dale Borehole, Derbyshire and the age of the Dinantian-Basement unconformity

A R E Strank

doi:10.1144/jm.5.1.1

Abstract

Abstract. Detailed micropalaeontological analysis of the Woo Dale Borehole shows that Dinantian strata of Holkerian and Arundian age lie unconformably on top of the pre-Carboniferous basement beds. The Chadian and Tournaisian are missing. The chronostratigraphy here recognised is compared with that proposed by Cope (1973) and the differences in the two interpretations explained in the light of recent palaeontological and Midlands regional research.

Highlights

Two deep boreholes, namely Eyam and WooDale, have penetrated the complete Dinantian :succession on the Derbyshire Dome
T h e brecciated limestones, lava a n d pyroclastics in the basal Dinantian sequence indicate deposition of Arundian limestones onto a basement high land area, of pre-Carboniferous age
During the early Arundian, a shallow, warm water shelf environment was established in which 137.66m of richly bioclastic limestones were deposited. This shelf environment persisted throughout the overlying Holkerian when over 115.97 m of limestones accumulated

Summary

INTRODUCTION

Dale, have penetrated the complete Dinantian :succession on the Derbyshire Dome. During the Dinantian, North Derbyshire was a shallow shelf province depositing thick richly bioclastic limestone sequences off the northern shores of St:. A possible deepening of basement from Woo Dale (273.60m) to Eyam (1803.25m) corresponds to a descent in the gravity anomaly over the area (Cope, 1973) Cope interprets this as a condensed sequence, a view he supports by the presence of clay band breaks in the succession, the intense dolomitisation and the fabric of the non dolomitised limestones (Cope, 1973). He concludes that differential subsidence of the North Derbyshire basement during the Dinantian is the mechanism responsible for the thickness change.

E G - EDALE GULF

Stratigraphy

CONCLUSIONS