Magnetic Susceptibility and Geochemistry Records in the Yax-1 Borehole in the Chicxulub Impact Crater: A paleoclimatic approach in the K/Pg and P/E Boundaries.

Abstract:

Chicxulub impact crater is located in the northwestern sector of Yucatan Peninsula, Mexico. It is the best-preserved multi-ring impact crater on Earth. Several studies have been focused in this crater structure due its association with the Cretaceous/Paleogenous boundary events. The aim of this study is document the abrupt climate changes during the K/Pg and P/E boundaries based on the stratigraphy, magnetic properties (magnetic susceptibility) and geochemical (major elements) records in the Yaxcopoil-1 (Yax-1) borehole in the Chicxulub impact crater.

The Yax 1 was drilled at 20° 44' 38.45'' N, 89° 43' 6.70'' W. Two intervals from 830 to 750 and between 750 and 700 m depth were selected for this study. Magnetic susceptibility logs and X-Ray Fluorescence (XRF) measures were taken every 10 cm using a Bartington magnetic susceptibility meter and a Thermo Scientific Niton XL3tGOLDD XRF analyzer.

Results show variations in magnetic susceptibility logs and major elements (Ca, Si, Fe, Ti and Si) content in the K/Pg boundary at ca. 794 m depth. Magnetic susceptibility decrease abruptly, Ca values increase, and the other elements show low values.

Geochemical results, manly the Ca-record, suggest that the P/E boundary might have happened around 745 m depth. These values are compared with ¹³C isotopes and they coincide with the Carbon Isotope Excursion (CIE), suggesting their relationship with the abrupt climate change and with the ocean acidification.