The Cenomanian-Turonian transition witnessed one of the most widely studied events of marine deoxygenation on the history of the Earth System, the Oceanic Anoxic Event – OAE 2. The low dissolved oxygen levels that characterized the OAE 2 oceans seem to have resulted from a global increase in marine primary productivity, which, in turn, favored the rapid export of large amount of organic matter into the global marine substrates. The rapid and large export of organic matter into the seafloor subsequently enhanced the marine biological pump and ultimately promoted a transient perturbation of the oceanic carbon cycle; the latter characterized by a positive C-isotope anomaly. Although the increase on primary productivity during the OAE 2 has been attributed to an enhanced input of bioessential elements (nutrients) from continents to oceans, primarily triggered by an intensified continental weathering regime resulting from volcanism, the limited geochemical records that support this hypothesis are not conclusive. In this contribution we report Hg, Sr and C isotope data from several OAE2 sedimentary records from Colombia to support the hypostasis that enhanced continental weathering regime and elevated nutrients input to the Cenomanian-Turonian oceans increased the marine primary productivity and thus favored the decrease on marine oxygen levels during the OAE2. Our data also suggest that enhanced weathering likely was likely associated to volcanism. The effectiveness of the continental weathering process led to a transient amelioration of the global climate after the onset of the OAE2.
- Juan Carlos Silva-Tamayo, Alcides N. Sial, Christopher Junium