Abstract

Pronounced paleotemperature variations associated with the carbon cycle perturbations of oceanic anoxic events (OAEs 1b and 1d) are known to have occurred during the early and latest Albian. However, reliable paleotemperature data spanning the 12 m.y. between these two events are sparse. Here we present δ18O, δ13C, and Mg/Ca data for the middle to early-late Albian based on analysis of unusually well preserved “glassy” foraminifers from a clay-rich sequence drilled in the boreal Lower Saxony Basin (northwestern Germany; ∼45°N paleolatitude). Our records reveal pronounced variability in planktic δ18O (∼1.5‰–2.5‰) on a 100 k.y. time scale that we interpret to indicate substantial changes in sea-surface temperature (to ∼7 °C) and δ18O/salinity (to ∼3 psu). Our findings attest to the climatic sensitivity of marginal basins in these boreal latitudes during the mid-Cretaceous and suggest that the heat and salt budgets of the Lower Saxony Basin were orbitally conditioned during the Albian, presumably through atmospheric or oceanic heat transport from lower latitudes where surface waters were warmer than today, in response to strong greenhouse gas forcing.

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