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

Abstract. This paper documents a warming event across the middle–upper Albian interval in a ∼  22 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 ( ∼  500 kyr) of significant surface water warming (in excess of 6  ∘ C) at around 107.5 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.