The Albian to Turonian record of IODP Site U1407 (SE Newfoundland Ridge)

At IODP Site U1407 (SE Newfoundland Ridge, IODP Expedition 342) a 270-m-thick sedimentary succession of Cretaceous and Paleogene age has been recovered. The two holes U1407A and B contain the transition from the reef basement to fine grained (hemi-)pelagic marls at ~270 mCCSF. The basal, incomplete short-cores of these two holes revealed a number of shallow-water fossils such as gastropods, corals, rudists and larger foraminifera (orbitulinids; Norris et al., 2014) from the top of the reef. In addition, a well-developed Cenomanian-Turonian Boundary (CTB) with its typical black shale expression of the Oceanic Anoxic Event 2 is represented in the cores. Here, we present a high-resolution carbon isotope record of the 40-m-thick succession from the top of the reef to the bathyal CTB black shales. Beside the typical δ¹³C anomalies associated with the CTB we identified the decline of δ¹³C values related to the top of the Albian-Cenomanian boundary interval and the Mid-Cenomanian Event. We further present new biostratigraphic results based on calcareous nannofossils as well as ⁸⁷Sr/⁸⁶Sr isotope ages for the top of the reef analyzed on Orbitulina. These new data in combination with the identified, stratigraphically well-calibrated events allow for a detailed comparison with other mid-Cretaceous records around the world and provide new insights into the subsidence history of the western Atlantic margin off Newfoundland.

Reference:
Norris, R.D., et al. 2014. Site U1407. Proceedings of the Integrated Ocean Drilling Program, Volume 342, doi:10.2204/iodp.proc.342.108.2014.