Late Cretaceous fish debris from Demerara Rise exhibits a dramatic positive excursion of 8 ϵNd units during ocean anoxic event 2 (OAE2) that is superimposed on extremely low ϵNd(t) values (−14 to −16.5) observed throughout the rest of the studied interval. The OAE2 ϵNd excursion is the largest yet documented in marine sediments, and the majority of the shift is estimated to have occurred over <20 k.y. Low background ϵNd values on Demerara Rise are explained as the Nd isotopic signature of the South American craton, whereas eruptions of the Caribbean large igneous province or enhanced mixing of intermediate waters in the North Atlantic could have caused the excursion.

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