首页|Paleo-Mesoarchean sedimentary record in the Dharwar Craton,India:Implications for Archean ocean oxygenation

Paleo-Mesoarchean sedimentary record in the Dharwar Craton,India:Implications for Archean ocean oxygenation

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The early Archean oceans were marked by significant redox changes which have subsequently shaped the Earth's biosphere.Archean chemical sediments of banded Iron and Manganese formations provide impor-tant geochemical proxies for these historical shifts in the redox conditions and to trace the ancient sed-imentation patterns and protoliths.In this study,we investigate the proto-ore of the Archean Mn-formations of the Sandur,Chitradurga and Shimoga greenstone belts of Dharwar Craton of southern Peninsular India,which is geochemically characterised as quartz arenites,Mn-arenites,Fe-arenites,Mn-argillites and Fe-argillites.The geochemical systematics suggest their deposition in shallow to deeper shelf in the Archean proto-ocean.The detrital zircon U-Pb systematics of Mn arenites and argillites indi-cate their maximum depositional age of 3230±52 Ma representing the oldest onset of sedimentation during the Paleo-Mesoarchean timeframe in the Chitradurga Group of Dharwar Supergroup.The detrital influx proxies suggest variations in sedimentation rates associated with the Archean transgressive-regres sive cycles and fluctuating hydrodynamic conditions,together reflecting an increasing trend in the con-tributions of recycled sediment from Sandur to Chitradurga and Shimoga greenstone belts.The available detrital zircon ages of the Mn arenites and argillites from these greenstone belts indicate a～600 Ma pro-longed period of Mn deposition for which high-T hydrothermal fluids from Archean mid-oceanic ridges supplied the manganese.The trace element compositions of the concordant detrital zircons suggest 3.3-3.1 Ga Dharwar basement TTG/granitoid source which is corroborated by the zircon crystallization tem-peratures of 690-820 ℃.The source-normalised ot-dose rates of the detrital zircons signify greater degrees of sediment transport and multi-cycle nature which correspond to the earliest episode of crustal growth in the Indian sub-continent associated with the Mesoarchean Ur supercontinent.The clastic-chemogenic sedimentation attained through concomitant detrital sediment-seawater-metalliferous hydrothermal fluid mixing at an epicontinental passive margin resulted in the deposition of Mn-arenites and argillites closer to the higher Eh shore,while the Fe-rich sediments formed at a relatively deeper shelf characterised by comparatively lower Eh and more alkaline conditions.The comprehensive geochemical and geochronological data of the Archean Mn arenite-argillite sequences reveal the signifi-cance of regional episodes of ocean oxygenation at the shallow shelves of Archean oceans prior to great oxygenation event(GOE)that was mediated by the prolific growth of ancient microbiota which trans-formed the Earth to a more habitable planet.

Mn-arenites-argillitesDharwar CratonZircon U-Pb geochronologyPassive margin sedimentsOcean oxygenation

G.Harshitha、C.Manikyamba、M.Santosh、Cheng-Xue Yang、A.Keshav Krishna、V.V.Sesha Sai、I.Panduranga Reddy

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CSIR-National Geophysical Research Institute(NGRI),Uppal Road,Hyderabad 500007,India

Department of Geology,Osmania University,Hyderabad 500007,India

School of Earth Science and Resources,China University of Geosciences,Beijing 100083,China

Department of Earth Science,University of Adelaide,Adelaide SA5005,Australia

Yonsei Frontier Lab,Yonsei University,Seoul 03722,Republic of Korea

Geological Survey of India,State Unit,Nagpur,India

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Emeritus Project funds of CSIRDepartment of Science and Technology(DST)for Inspire Fellowshiptalent award to Prof.M.Santosh under the 1000 plan from the Chinese Government

IF200586

2024

10.1016/j.gsf.2023.101701

地学前缘(英文版)
中国地质大学（北京） 北京大学

地学前缘(英文版)

CSTPCD
影响因子：0.576
ISSN：1674-9871
年,卷(期)：2024.15(1)
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