T241 The Cretaceous–Paleogene Boundary: From Impact Cratering Processes to Mass Extinction Mechanisms

Wednesday, 13 October 2021
1:30 PM - 5:30 PM
D139/D140

DEEP-MARINE RECORDS OF DECCAN TRAP VOLCANISM BEFORE, DURING, AND AFTER THE CRETACEOUS–PALEOGENE (K-PG) MASS EXTINCTION

Paper number: T241-13
Program: Technical Sessions
Time: 4:30 PM – 4:45 PM

Authors

Abstract

The Cretaceous–Paleogene (K-Pg) transition was marked by one of the ‘Big Five’ mass extinctions of the Phanerozoic Eon. The Late Maastrichtian Warming Event characterizes the ~400 kyr prior to the K-Pg event as a period of climate warming. Whilst the extinction itself is widely linked to the Chicxulub meteorite impact, the Deccan Traps Large Igneous Province (LIP) is the likely cause of the Late Maastrichtian Warming Event. In recent years, the timing of Deccan eruptions has been directly assessed through both U-Pb and Ar/Ar radio-isotopic dating of the volcanic products themselves, as well as the stratigraphic records of sedimentary proxies for volcanism, such as mercury (Hg) concentrations and osmium- (Os-) isotope compositions. Volcanism is a major natural source of mercury to the Earth’s surface, whilst primitive basalts feature a ‘mantle’ osmium-isotope composition which is much less radiogenic than the average continental crust. Thus, sedimentary rocks deposited during a time of LIP emplacement could record Hg enrichments and unradiogenic shifts in the Os-isotope ratio.

In this study, we present Hg concentration and Os-isotope data from three stratigraphically well-constrained deep-marine records of the K-Pg transition (Bottaccione Gorge and Morello, Umbria-Marche Basin, Italy, and IODP Site 1262, Walvis Ridge, Atlantic Ocean). All three sites feature precise cyclostratigraphic and magnetostratigraphic age models that enable direct temporal correlation with the Deccan Trap basalts, as well as oxygen-isotope records of climate changes in the latest Cretaceous and earliest Paleogene. The robust common timeline allows for a consistency assessment of the geochemical trends across this dynamic stratigraphic interval. Comparison with other, shallow-marine, records grants key insights into the recording and influence of Deccan volcanism on the global environment and cycling of mercury and osmium prior to and during the K-Pg mass extinction.

Geological Society of America Abstracts with Programs. Vol. 53, No. 6

doi: 10.1130/abs/2021AM-368317

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