Data report: revised age models for IODP Sites U1480 and U1481, Expedition 3621

Jan Backman, Wenhuang Chen, Sarah Kachovich, Freya Mitchison, Katerina Petronotis, Tao Yang, and Xixi Zhao

A revised age model for Site U1480 was generated for the 0–67 Ma time interval using biomagnetostratigraphic data from which age-depth tie points have been selected to determine sediment accumulation rates and durations of identified hiatuses. This revised age model relies on biostratigraphic data between ~2 and 67 Ma and biomagnetostratigraphic data between 0 and 1.8 Ma and differs from the shipboard age model in terms of (1) the timing and duration of the major Cenozoic hiatus, (2) the late Miocene–early Pliocene transition, (3) the 0–1.8 Ma interval, and (4) the age of the sediment/volcanic interface at 1415 meters below seafloor (mbsf), here determined to be ≤67.4 Ma. Two intervals of igneous strata totaling 60 m occur in the Paleocene sedimentary rock sequence, giving a thickness of 1355 m for sediments and sedimentary rocks. In Hole U1481A, sedimentary rocks were recovered between 1150 and 1499 mbsf. The revised age model differs from the shipboard version mainly in more clearly acknowledging the lack of biostratigraphic data between 1411 and 1495 mbsf.

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