Geochemical evidence of an extraterrestrial component in impact melt breccia from the Paleoproterozoic Dhala impact structure, India

Autor(en)
Jayanta Kumar Pati, Wen Jun Qu, Christian Koeberl, Wolf Uwe Reimold, Munmun Chakarvorty, Ralf Thomas Schmitt
Abstrakt

The Paleoproterozoic Dhala structure with an estimated diameter of ~11 km is a confirmed complex impact structure located in the central Indian state of Madhya Pradesh in predominantly granitic basement (2.65 Ga), in the northwestern part of the Archean Bundelkhand craton. The target lithology is granitic in composition but includes a variety of meta-supracrustal rock types. The impactites and target rocks are overlain by ~1.7 Ga sediments of the Dhala Group and the Vindhyan Supergroup. The area was cored in more than 70 locations and the subsurface lithology shows pseudotachylitic breccia, impact melt breccia, suevite, lithic breccias, and postimpact sediments. Despite extensive erosion, the Dhala structure is well preserved and displays nearly all the diagnostic microscopic shock metamorphic features. This study is aimed at identifying the presence of an impactor component in impact melt rock by analyzing the siderophile element concentrations and rhenium-osmium isotopic compositions of four samples of impactites (three melt breccias and one lithic breccia) and two samples of target rock (a biotite granite and a mafic intrusive rock). The impact melt breccias are of granitic composition. In some samples, the siderophile elements and HREE enrichment observed are comparable to the target rock abundances. The Cr versus Ir concentrations indicate the probable admixture of approximately 0.3 wt.% of an extraterrestrial component to the impact melt breccia. The Re and Os abundances and the

187Os/

188Os ratio of 0.133 of one melt breccia specimen confirm the presence of an extraterrestrial component, although the impactor type characterization still remains inconclusive.

Organisation(en)
Department für Lithosphärenforschung
Externe Organisation(en)
University of Allahabad, Chinese Academy of Geological Sciences, Naturhistorisches Museum Wien (NHM), Museum für Naturkunde Berlin - Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Humboldt-Universität zu Berlin, Universidade de Brasília
Journal
Meteoritics and Planetary Science
Band
52
Seiten
722-736
Anzahl der Seiten
15
ISSN
1086-9379
DOI
https://doi.org/10.1111/maps.12826
Publikationsdatum
04-2017
Peer-reviewed
Ja
ÖFOS 2012
105105 Geochemie, 105120 Petrologie
Schlagwörter
ASJC Scopus Sachgebiete
Geophysics, Space and Planetary Science
Link zum Portal
https://ucris.univie.ac.at/portal/de/publications/geochemical-evidence-of-an-extraterrestrial-component-in-impact-melt-breccia-from-the-paleoproterozoic-dhala-impact-structure-india(78612d25-9860-468a-90f4-039b3b368962).html