Recognition of chron C25n in the upper paleocene upnor formation of the London Basin, UK

Abstract

Lithostratigraphic studies of four borehole cores drilled through the late Paleocene Lambeth Group (Upnor, Woolwith and Reading Formations) and basal London Clay Formation of central London have been supplemented with palaeomagnetic, calcareous nannoplankton and palynological data. The Woolwich and Rending Formations and the lower London Clay Formation are reversely magnetized and were deposited during the early part of Chron C24r. The first record of both NP9 and Chron C25n, hitherto missing from the Paleogene record in southern England, has been identified in the Upnor Formation (formerly the Woolwich Bottom Bed). It provides a key reference marker for linking events associated with the Paleocene-Eocene boundary (positioned within Chron C24r) to the type area of the internationally recognized Thanetian and Ypresian Stages.