Sedimentary markers of ocean plateau volcanism during the Cenomanian–Turonian Oceanic Anoxic Event

The Cenomanian–Turonian transition (94 Ma) marked a major environmental and biotic crisis of the Cretaceous Period, featuring abrupt climate warming (with superimposed cooling pulses) and widespread marine
anoxia/euxinia, from which it has been classed as an oceanic anoxic event (dubbed Cretaceous OAE 2). The
cause of this event is widely believed to be linked to major volcanic activity during the emplacement of one or
more oceanic plateaus (e.g., Caribbean Plateau, High Arctic Igneous Province). Because there are few radioisotopic dates for rocks on these ocean plateaus, demonstrating a precise coincidence between this volcanic activity
and OAE 2 largely depends on utilisation of sedimentary proxies of volcanism in the stratigraphic records of the
event. A globally recorded shift to unradiogenic osmium-isotope (specifically 187Os/188Os ratios) compositions
is clearly indicative of enhanced ocean plateau volcanism at the onset of and during OAE 2, but other proxies have
shown less clear trends. In this study, we present new geochemical data for a number of proxies for volcanism
from sedimentary rocks of a near-shore shallow marine record of OAE 2 at Bass River (ODP Leg 174 AX, New
Jersey, USA). This record represents a relatively rare example of a lithologically consistent (silty claystones) OAE
2 stratigraphic succession, allowing easier interpretation of geochemical trends. We find considerable variation in
the studied proxies, and in some cases no indication of volcanism. These findings highlight the importance of eruption style and/or local marine conditions and sedimentological processes on many proxies of volcanism in records
of OAE 2.