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

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

机构地区：[1]CSIR-National Geophysical Research Institute(NGRI),Uppal Road,Hyderabad 500007,India [2]Department of Geology,Osmania University,Hyderabad 500007,India [3]School of Earth Science and Resources,China University of Geosciences,Beijing 100083,China [4]Department of Earth Science,University of Adelaide,Adelaide SA5005,Australia [5]Yonsei Frontier Lab,Yonsei University,Seoul 03722,Republic of Korea [6]Geological Survey of India,State Unit,Nagpur,India

出　　处：《Geoscience Frontiers》2024年第1期126-154,共29页地学前缘（英文版）

摘　　要：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 important geochemical proxies for these historical shifts in the redox conditions and to trace the ancient sedimentation 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 indicate 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-regressive cycles and fluctuating hydrodynamic conditions,together reflecting an increasing trend in the contributions 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 prolonged 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 temperatures of 690-820℃.The source-normalisedα-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 attain

关 键 词：Mn-arenites-argillites Dharwar Craton Zircon U-Pb geochronology Passive margin sediments Ocean oxygenation 

分 类 号：P534[天文地球—古生物学与地层学] P581[天文地球—地质学] P597.3