In the "Central Uplift" of Qiangtang,Northern Tibet,a large scale of mafic dyke swarms extended in E-W direction.Zircon SHRIMP U-Pb dating on two representative samples of diabase dyke yield weighted mean ag...In the "Central Uplift" of Qiangtang,Northern Tibet,a large scale of mafic dyke swarms extended in E-W direction.Zircon SHRIMP U-Pb dating on two representative samples of diabase dyke yield weighted mean ages of 284 ± 3 Ma and 302 ± 4 Ma,respectively,suggesting they emplaced in the Late Carboniferous to Early Permian.Zircon 176Hf/177Hf ratios range from 0.282852 to 0.283041,with εHf(t) values of +12.1 to +12.2 and Hf modal(TDM) ages of ～440―460 Ma.These data indicate that these mafic dykes were mainly derived from the depleted mantle.In addition,geochemical data suggest that these mafic dyke swarms are ofintra-plate origin.Therefore,the mafic dyke swarms represent products during the extensional process associated with the opening of the Paleo-Tethys Ocean in the area.展开更多
基金Supported by the National Natural Science Foundation of China (Grants Nos.40872146 and 40672147)China Geological Survey(Grant No.1212010561605)
文摘In the "Central Uplift" of Qiangtang,Northern Tibet,a large scale of mafic dyke swarms extended in E-W direction.Zircon SHRIMP U-Pb dating on two representative samples of diabase dyke yield weighted mean ages of 284 ± 3 Ma and 302 ± 4 Ma,respectively,suggesting they emplaced in the Late Carboniferous to Early Permian.Zircon 176Hf/177Hf ratios range from 0.282852 to 0.283041,with εHf(t) values of +12.1 to +12.2 and Hf modal(TDM) ages of ～440―460 Ma.These data indicate that these mafic dykes were mainly derived from the depleted mantle.In addition,geochemical data suggest that these mafic dyke swarms are ofintra-plate origin.Therefore,the mafic dyke swarms represent products during the extensional process associated with the opening of the Paleo-Tethys Ocean in the area.
