Figure F66. Core images with Cretaceous/Paleogene boundary (K/Pg) at J-Anomaly Ridge Site U1403. The K/Pg boundary is set at the base of an ~1 cm thick graded spherule layer in Holes U1403A and U1403B. The spherule layer is underlain by diverse late Cretaceous nannoplankton assemblages (Zone UC20D) and overlain by abundant calcispheres with early Danian nannoplankton (Zone NP1). The close-up image of the K-Pg boundary in Hole U1403B shows the detailed stratigraphy of the boundary, including an apparently unbioturbated fine, white-gray layer <0.5 cm thick underlying the ~0.5 cm thick bed of normally graded green sand- to silt-sized impact spherules. A light greenish gray chalk (~0.5 cm thick) with abundant calcispheres and early Paleocene biomarkers sits immediately above the graded spherule bed.
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