Chicxulub impact structure, IODP-ICDP Expedition 364 drill core: Geochemistry of the granite basement

Autor(en)

Jean-Guillaume Feignon, S.J. de Graaff, Ludovic Ferrière, P. Kaskes, T. Déhais, Steven Goderis, Philippe Claeys, Christian Koeberl

Abstrakt

The IODP-ICDP Expedition 364 drilling recovered a 829 m core from Hole M0077A, sampling ~600 meters of near continuous crystalline basement within the peak ring of the Chicxulub impact structure. The bulk of the basement consists of pervasively deformed, fractured, and shocked granite. Detailed geochemical investigations of forty-one granitoid samples, i.e., major and trace element contents, and Sr-Nd isotopic ratios, are presented here, providing a broad overview of the composition of the granitic crystalline basement. Mainly in situ granite, but also granite clasts (in impact melt rock), granite breccias, and aplite were analyzed, yielding relatively homogeneous compositions between all samples. The granite is part of the high-K, calc-alkaline metaluminous series. Additionally, they are characterized by high Sr/Y and (La/Yb)N ratios, and low Y and Yb contents, which are typical for adakites. However, other criteria (such as Al2O3 and MgO contents, Mg#, K2O/Na2O ratio, Ni concentrations, etc.) do not match the adakite definition. In addition, present day 87Sr/86Sr is indicative of an hydrothermal overprint, affecting mainly samples located in near contact with impact melt rock dikes or cataclasite areas, where the fluid circulation was enhanced, and would have preferentially affected fluid-mobile element concentrations. The epsilon Nd (t=326 Ma) values range from -1.7 to 3.2 for the samples which were less affected by the hydrothermal overprint and indicate a moderately enriched crustal material in the source region involved in the granite genesis. Our results are consistent with previous studies, further supporting that the cored granite unit intruded the Maya block during the Carboniferous, in an arc setting with crustal melting related with the closure of the Rheic ocean associated with the assembly of Pangea. Importantly, the granites sampled in Hole M0077A are dissimilar in composition when compared to granite or gneiss clasts from other drill cores recovered from the Chicxulub impact structure. Marking them as valuable lithologies that provide new insight into the Yucatán basement.

Organisation(en)

Department für Lithosphärenforschung

Externe Organisation(en)

Naturhistorisches Museum Wien (NHM), Vrije Universiteit Brussel

Journal

Meteoritics and Planetary Science

Band

56

Seiten

1243-1273

Anzahl der Seiten

31

ISSN

1086-9379

DOI

https://doi.org/10.1111/maps.13705

Publikationsdatum

11-2020

Peer-reviewed

Ja

ÖFOS 2012

105105 Geochemie, 105120 Petrologie

Schlagwörter

ASJC Scopus Sachgebiete

Geophysics, Space and Planetary Science

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/fc1b817c-7c9d-4d10-aca9-0ae92bd6a8ae