首页|Breakup of the Neoarchean supercontinent Kenorland:Evidence from zircon and baddeleyite U-Pb ages of LIP-related mafic dykes in the Coorg Block,southern India

Breakup of the Neoarchean supercontinent Kenorland:Evidence from zircon and baddeleyite U-Pb ages of LIP-related mafic dykes in the Coorg Block,southern India

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The Coorg Block in southern Peninsular India is one of the oldest crustal blocks on Earth that preserves the evidence for continental crust formation during the Paleo-Mesoarchean through subduction-related arc magmatism,followed by granulite facies metamorphism in the Mesoarchean.In this study,we report for the first time,the'bar codes'of a major Paleoproterozoic Large Igneous Province in the Coorg Block through the finding of mafic dyke swarms.The gabbroic dykes from the Coorg Block,dom-inantly composed of plagioclase-pyroxene assemblage,show a restricted range in SiO2 values of 50.04-51.27 wt.％,and exhibit a sub-alkaline tholeiitic nature.These rocks show relatively flat LREE and constant HREE patterns and lack obvious Eu anomalies.Trace element modeling suggests that the dyke swarm was fed from a melt that originated at a shallow mantle level in the spinel stability field.Zircon grains are rare in the gabbro samples and those separated from two samples yielded 207Pb/206Pb weighted mean dates of 2214±12 Ma and 2221±7 Ma.The grains show magmatic features with depleted LREE and enriched HREE and positive Ce and negative Eu anomalies.Baddeleyite grains were dated from five gabbro samples which yielded 207Pb/206Pb weighted mean ages ranging between 2217±7 Ma and 2228±10 Ma.The combined data show a clear age peak at ca.2.2 Ga.The mafic dykes in the Coorg Block show geochemical similarities with ca.2.2 Ga mafic dyke swarms in different regions of the Dharwar and other cratons in Peninsular India and elsewhere on the globe.The data also support the inference that the global mafic magmatism at ca.2.2 Ga was linked with intracontinental rifting of the Archean cratons through mantle upwelling or plume activity.We correlate the mafic dyke swarms in the Coorg Block with attempted rift-ing of the Neoarchean supercontinent Kenorland.

Mafic dyke swarmPaleoproterozoic Large Igneous ProvinceGeochronologyContinental riftingNeoarchean supercontinent

Cheng-Xue Yang、M.Santosh、Jarred Lloyd、Stijn Glorie、Y.Anilkumar、K.S.Anoop、Pin Gao、Sung-Won Kim

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School of Earth Sciences and Resources,China University of Geosciences Beijing,Beijing 100083,PR China

Institute of Earth Sciences,China University of Geosciences Beijing,Beijing 100083,PR China

Department of Earth Sciences,University of Adelaide,Adelaide SA,Australia

Department of Geology,University of Kerala,Kariavattom,Trivandrum,India

Geology Division,Korea Institute of Geoscience and Mineral Resources,Daejeon 34132,Republic of Korea

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Foreign Expert grant from China University of Geosciences Beijing,ChinaProfessorial Fellow Research Grant from University of Adelaide,AustraliaBasic Research Project of Korea Institute of Geoscience and Mineral Resources(KIGAM)Ministry of Science,ICT(Information,Communication,and Technology),Future Planning,KoreaAustralian Research Council Future Fellowship

GP2020-003FT210100906

2024

10.1016/j.gsf.2024.101804

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(4)
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