163 Impact Cratering Processes Across the Solar System: In Memory of Dr. Bevan M. French

Session focuses on the nature of impact craters and their influence on planetary geologic evolution. We solicit contributions on aspects of impact crater formation, ejecta, shock processes, geochemical and mineralogical signatures, modeling, and geologic implications; comparison among planetary bodies.

Tuesday, 21 October 2025
8:00 AM - 12:00 PM
HBGCC, 214C

Opportunities for Planetary Analog Studies in Rochechouart Impactites

Paper number: 163-12
Program: Technical Sessions
Time: 11:00 AM – 11:15 AM

Authors

Abstract

Impact cratering is a pervasive planetary process. Terrestrial analogs in the form of impact structures and craters are extremely important for offering ground truth to remote sensing data gathered on impact-induced hydrothermal alteration and materials on other planetary surfaces. A diverse array of impactites with varying hydrothermal mineral assemblages are found at the 23 km diameter Rochechouart Impact Structure (France). The crystalline target lithology is comprised of granitoids and gneisses with felsic and more mafic compositions. This heterogeneous target likely led to the large variety of melt-rocks and breccias observed in 540 m of cores drilled by Center for International Research and Restitution on Impacts and on Rochechouart (CIRIR). While most previous work in Rochechouart was done via surface sampling, these cores present an opportunity for many studies such as: 1. Testing remote sensing techniques on impact materials and hydrothermally altered materials, 2. Examining the subsurface structure of a complex crater with a collapsed central uplift, 3. Understanding the effects of target heterogeneity on impactite generation and depositional processes, 4. Educating scientists and astronauts on outlier and typical impactites in complex impact structures. In our investigations, we use Visible-Near Infrared (VNIR) Spectroscopy, a remote sensing method sensitive to hydrothermal alteration products (e.g. clays and oxides), to explore the variations in hydrothermal alteration based on target heterogeneity and impactite type throughout the basin. The fieldwork and sample collection were conducted using CIRIR facilities in June 2025. In addition to collecting hyperspectral data on 7 cores, we prepared half sections for detailed analyses of specific impactites that will use X-ray diffraction (XRD) and micro-Fourier transform infrared spectroscopy (Micro-FTIR), to increase sensitivity to alteration minerals that are not salient in VNIR, such as zeolites, sulfides, and opal. We also examined outcrops and collected surface samples for these analyses. This work also advanced local knowledge of the impact site, through participating in outreach events such as Asteroid Day. While our team is specifically interested in questions of hydrothermal alteration and implications for possible microbial metabolisms in these impactites, we encourage the impact community to consider the wide range of questions that can be investigated at the core repository and facilities of CIRIR.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412703

© Copyright 2025 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.