Significance of Secondary Fe-Oxide and Fe-Sulfide Minerals in Upper Peak Ring Suevite from the Chicxulub Impact Structure

Christina M. Verhagen, Ji In Jung, Sonia M. Tikoo, Axel Wittmann, David A. Kring, Stefanie Brachfeld, Laying Wu, Dale H. Burns, Sean P.S. Gulick

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1 Scopus citations

Abstract

The suevite (polymict melt rock-bearing breccia) composing the upper peak ring of the Chicxulub impact crater is extremely heterogeneous, containing a combination of relict clasts and secondary minerals. Using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS) and electron probe microanalysis (EPMA), we investigated the nature and occurrence of primary and secondary Fe-oxide and Fe-sulfide minerals to better understand hydrothermal trends such as mineral precipitation and dissolution, and to document the remobilization of Fe and associated siderophile elements within suevites. Large primary Fe-oxides (~20–100 µm) reveal decomposition and dissolution patterns, forming sub-micrometer to micrometer Fe-oxide phases. Secondary sub-micrometer Fe-oxide crystals are also visibly concentrated within clay. The occurrence of Fe-oxide crystals within clay suggests that these likely formed at temperatures ≤100 °C, near the formation temperature of smectite. The formation of Fe-oxide minerals on clay surfaces is of interest as it may form a micro-setting, where free electrons (from the oxidation of Fe2+) and the adsorption of simple organic molecules on the surface of clay could generate reactive conditions favorable to microbial communities. Primary and secondary Fe-sulfide minerals exhibiting a variety of morphologies are present within samples, representing different formation mechanisms. Secondary Fe-sulfide minerals occur within rims of clasts and vesicles and in fractures and voids. Some secondary Fe-sulfide grains are associated with Ni- and Co-rich phases, potentially reflecting the post-impact migration of siderophile elements within the suevite of the Chicxulub crater.

Original languageEnglish
Article number353
JournalMinerals
Volume13
Issue number3
DOIs
StatePublished - Mar 2023

Keywords

  • Fe-oxide minerals
  • Fe-sulfide minerals
  • hydrothermalism
  • impact cratering
  • suevite

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