The early Cretaceous(ca.118-100 Ma)alkaline/ultraalkaline silicate and carbonatite magmatism,exclusively recorded in the Chhotanagpur Gneissic Complex and the Shillong Plateau-Mikir Hills in the eastern/northeastern r...The early Cretaceous(ca.118-100 Ma)alkaline/ultraalkaline silicate and carbonatite magmatism,exclusively recorded in the Chhotanagpur Gneissic Complex and the Shillong Plateau-Mikir Hills in the eastern/northeastern regions of the Indian Shield,have been reviewed to understand their genetic aspects.These are thought to be associated to the Kerguelen hot spot,active in this region during ca.118-100 Ma.The existing geochemical,geochronological and isotopic data do not support any definite emplacement order for these diverse groups of magmatic suites.It is likely that they were derived from distinct magma batches with direct or indirect involvement of the Kerguelen plume.The available data suggest their possible derivation from the depleted asthenosphere/lithosphere with negligible contribution from the Kerguelen mantle plume.It is likely that mantle plume provided additional heat necessary to melt the asthenosphere/lithosphere.These data also suggest effects of low-pressure crustal contamination,crystal accumulation and fractional crystallization,rather than mantle-derived heterogeneity.These identified magmatic events together with other known magmatic events such as southeastern Xizang,Abor volcanics,SW Australia and eastern Antarctica during ca.140-100 Ma could be related to the Kerguelen plume and integral part of the Greater Kerguelen Large Igneous Province,and have possible impact on the breakup of East Gondwanaland.展开更多
基金the Science and Engineering Research Board(SERB)for the financial support through a research project(No.EMR/2016/000169)DST-PURSE grant(Scheme 5050)and UGC-CAS-Ⅱ grant(Scheme 5055)during this work.
文摘The early Cretaceous(ca.118-100 Ma)alkaline/ultraalkaline silicate and carbonatite magmatism,exclusively recorded in the Chhotanagpur Gneissic Complex and the Shillong Plateau-Mikir Hills in the eastern/northeastern regions of the Indian Shield,have been reviewed to understand their genetic aspects.These are thought to be associated to the Kerguelen hot spot,active in this region during ca.118-100 Ma.The existing geochemical,geochronological and isotopic data do not support any definite emplacement order for these diverse groups of magmatic suites.It is likely that they were derived from distinct magma batches with direct or indirect involvement of the Kerguelen plume.The available data suggest their possible derivation from the depleted asthenosphere/lithosphere with negligible contribution from the Kerguelen mantle plume.It is likely that mantle plume provided additional heat necessary to melt the asthenosphere/lithosphere.These data also suggest effects of low-pressure crustal contamination,crystal accumulation and fractional crystallization,rather than mantle-derived heterogeneity.These identified magmatic events together with other known magmatic events such as southeastern Xizang,Abor volcanics,SW Australia and eastern Antarctica during ca.140-100 Ma could be related to the Kerguelen plume and integral part of the Greater Kerguelen Large Igneous Province,and have possible impact on the breakup of East Gondwanaland.
