2026-10-15T12:11:33Z https://oai.datacite.org/oai

doi:10.1594/pangaea.712634 2024-07-21T10:12:33Z PANGAEA PANGAEA.REPOSITORY

Iridium contents and microprobe analyses of DSDP Leg 77 samples Alvarez, Walter Smit, Jan Lowrie, William Asaro, Frank Margolis, Stanley V Claeys, Philippe Kastner, Miriam Hildebrand, Alan R PANGAEA 1992 Issued: 1992 doi:10.1130/0091-7613(1992)020<0697:pidatc>2.3.co;2 Drilling/drill rig Leg77 Glomar Challenger Deep Sea Drilling Project (DSDP) Restudy of Deep Sea Drilling Project Sites 536 and 540 in the southeast Gulf of Mexico gives evidence for a giant wave at Cretaceous-Tertiary boundary time. Five units are recognized: (1) Cenomanian limestone underlies a hiatus in which the five highest Cretaceous stages are missing, possibly because of catastrophic K-T erosion. (2) Pebbly mudstone, 45 m thick, represents a submarine landslide possibly of K-T age. (3) Current-bedded sandstone, more than 2.5 m thick, contains anomalous iridium, tektite glass, and shocked quartz; it is interpreted as ejecta from a nearby impact crater, reworked on the deep-sea floor by the resulting tsunami. (4) A 50-cm interval of calcareous mudstone containing small Cretaceous planktic foraminifera and the Ir peak is interpreted as the silt-size fraction of the Cretaceous material suspended by the impact-generated wave. (5) Calcareous mudstone with basal Tertiary forams and the uppermost tail of the Ir anomaly overlies the disturbed interval, dating the impact and wave event as K-T boundary age. Like Beloc in Haiti and Mimbral in Mexico, Sites 536 and 540 are consistent with a large K-T age impact at the nearby Chicxulub crater. Supplement to: Alvarez, Walter; Smit, Jan; Lowrie, William; Asaro, Frank; Margolis, Stanley V; Claeys, Philippe; Kastner, Miriam; Hildebrand, Alan R (1992): Proximal impact deposits at the Cretaceous-Tertiary boundary in the Gulf of Mexico: A restudy of DSDP Leg 77 Sites 536 and 540. Geology, 20(8), 697-700 en Collection Supplementary Publication Series of Datasets application/zip Creative Commons Attribution 3.0 Unported https://creativecommons.org/licenses/by/3.0/legalcode