High-resolution geochemical record of Cretaceous-Tertiary boundary sections in Mexico: New constraints on the K/T and Chicxulub events

TitleHigh-resolution geochemical record of Cretaceous-Tertiary boundary sections in Mexico: New constraints on the K/T and Chicxulub events
Publication TypeJournal Article
Year of Publication2005
AuthorsStüben, D, Kramar, U, Harting, M, Stinnesbeck, W, Keller, G
JournalGeochimica et Cosmochimica Acta
Volume69
Issue10
Pagination2559 - 2579
Date PublishedJan-05-2005
ISSN00167037
Abstract

The investigation of eight Cretaceous–Tertiary (K/T) sections in Mexico, based on major and trace element, platinum group element (PGE), stable isotope, and multivariate statistical analysis, reveals a complex depositional history across the Chicxulub and K/T boundary events. At the biostratigraphically determined K/T boundary, a minor but significant Ir-dominated PGE anomaly (0.2– 0.8 ng/g) is present in most sections. This Ir anomaly originated from an impact event and is always stratigraphically and geochemically decoupled from the underlying spherule-rich ejecta deposit related to the Chicxulub event. In all sections examined, one to three glass spherule ejecta layers and one or two chondrite-dominated PGE anomalies are separated by a bioturbated siliciclastic deposit and/or hemipelagic marl, which indicates the occurrence of at least two impact events separated by a considerable amount of time. In addition, bentonite layers and Pt and Pd-dominated PGE anomalies below and above the K/T boundary indicate volcanic activity. Above the K/T boundary, reduced bioproductivity is documented by a decrease in the biogenically bound fraction of nutrients and fluctuating ratios of immobile elements (e.g., Ti/Zr). Variations in detrital elements reflect changes in the depositional environment. Carbon and oxygen isotope and trace element distribution patterns indicate a gradually changing climate during the latest Maastrichtian, an abrupt change at the K/T boundary, and a slight recovery during the lowermost Paleocene.  PDF

URLhttp://linkinghub.elsevier.com/retrieve/pii/S0016703704008622
DOI10.1016/j.gca.2004.11.003
Short TitleGeochimica et Cosmochimica Acta