A brief warming event in the late Albian: Evidence from calcareous nannofossils, macrofossils, and isotope geochemistry of the Gault Clay Formation, Folkestone, southeastern England

Abstract

This paper documents a warming event across the middle-upper Albian interval in a â 1/4â €22â €m long section from the Gault Clay Formation of Copt Point, Folkestone (UK). Evidence for the event comes from three independent datasets: calcareous nannofossils, ammonites, and the bulk sediment carbon and oxygen stable isotope record, which collectively indicate a brief period (â 1/4 500â €kyr) of significant surface water warming (in excess of 6â €°C) at around 107.5â €Ma (the base of the Dipoloceras cristatum Ammonite Zone). A surface water productivity increase based on high percentages of the eutrophic nannofossil Zeugrhabdotus noeliae is found to be concomitant with this warming event, suggesting that surface waters were nutrient-rich and the warming was associated with increased precipitation and run-off, delivering more nutrients into the basin.