MASS WASTING DURING THE CRETACEOUS-TERTIARY TRANSITION IN THE NORTH ATLANTIC: RELATIONSHIP TO THE CHICXULUB IMPACT?
At Sites 386 and 398, previous studies interpreted discrete intervals of disturbed sediments associated with a thin impact spherule layer as due to impact-generated earthquakes destabilizing continental margins prior to settling of impact spherules. Our improved age control indicates deposition in the early Danian zone P1a(2) (upper Parvularugoglobigerina eugubina zone) more than 100 ky after the KTB. At Site 386, reworked Cretaceous species (35%) are common and sediments contain high calcite, mica and kaolinite, in contrast with the in situ red-brown clay devoid of carbonate, suggesting reworked shallow water sediments. Mass wasting is indicated by normal size grading through the disturbed interval with horizontal lamination at the base followed by mottled, mixed sediments. At Site 398, reworked Cretaceous species are less common (<10%) but high abundance of shallow benthic species and higher mica, in detriment of smectite, also indicate mass wasting with reworking of shallower sediments. We propose that mass wasting deposits are the result of earthquakes associated with increased tectonic activity in the Caribbean during the early Danian well after the Chicxulub impact.