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Communication Dans Un Congrès Année : 2020

UNRAVELING THE MAGNETIC HISTORY OF PEAK RING GRANITOID ROCKS FROM THE CHICXULUB IMPACT STRUCTURE

Résumé

The pristine drillcore, M0077A, includes uplifted target rock capped with impact melt rock, suevite and post-impact Paleogene carbonate rocks. Target rock, recovered from 747.02-1334.15 meters below sea floor, (mbsf) is composed of syenogranites that are crosscut by preimpact felsic and mafic dikes as well as impact-related material [2,3]. The target granitoids, originally part of the Maya Block, crystallized 326 ± 5 million years ago (Ma) during the convergence of Gondwana and Laurentia in the formation of supercontinent Pangea [3]. Preimpact dikes likely formed concomitant to granitoid emplacement or shortly after. During the 66 Ma Chicxulub impact event, the granitoid rocks were pervasively affected by the passage of the initial impact shock wave up to ~20 GPa [4]. They were subsequently uplifted from ~10 km and emplaced during the dynamic collapse of the central uplift, forming the peak ring [5]. The initial shock alteration of the granitoids increased porosity, facilitating the circulation of post impact hydrothermal fluids driven by long-lived heat sources such as the impact melt sheet and central uplift [4, 6]. As a result, the entire sequence in M0077A shows evidence of pervasive post-impact hydrothermal activity including hydrothermal minerals such as dachiardite-Na, zeolites and hydrothermal garnet [7,8]. We use paleomagnetism to explore the magnetic history recorded within the target granitoid sequence. We employ rock magnetism and petrographic microscopy to identify the occurrence of magnetic minerals. Our efforts seek to elucidate syn-and postimpact cratering processes including shock, heating, and hydrothermal alteration and aim to identify relationships between primary and secondary magnetic components within all lithologies of the lower peak ring.
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Dates et versions

hal-03532937 , version 1 (18-01-2022)

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  • HAL Id : hal-03532937 , version 1

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C M Verhagen, S M Tikoo, J. Gattacceca, M Schmieder, P. Rochette, et al.. UNRAVELING THE MAGNETIC HISTORY OF PEAK RING GRANITOID ROCKS FROM THE CHICXULUB IMPACT STRUCTURE. Lunar and Planetary Science Conference, 2020, Houston, United States. ⟨hal-03532937⟩
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