Geochronology,Geochemistry and Zircon Hf Isotopes of the Tanjianshan Granite Porphyry Intrusion in Dachaidan Area of the North Margin of Qaidam Basin,NW China
Zhang Yanjun
Sun Fengyue
Xu Chenghan
Yu Lu
Abstract：In order to research the Variscan tectonic evolution features of Dachaidan region in North Qaidam,this paper presents LA-ICP-MS zircon U-Pb dating,geochemical and Hf isotopic data of the granite porphyry from Tanjianshan intrusion in Dachaidan region,with the aim of constraining its formation time,petrogenesis and the regional tectonic setting.The LA-ICP-MS U-Pb dating results of zircons from the granite porphyry indicate that the intrusion formed in the Late Devonian Epoch (356.0±2.8 Ma,MSWD=0.53).Geochemically,these rocks fall into the calc-alkaline to middle-K calc-alkaline series,with an A/CNK ratio of 0.97-1.10,which are weakly peraluminous granites,being of the characteristics of Ⅰ type granitoids,enriched in LILE(such as K,Ba,Rb),LREE,Th and U,relatively depleted in HFSE (such as Ta,Nb,Ti,P).TheεHf(t)values of the granite porphyry vary from ±5.43 to ±8.38,and two-stage model ages (TDM2 )range from 1017 to 1284 Ma.These char-acteristics suggest that the primary magma was derived from the remelting of juvenile crustal materials in Mesoproterozoic.In context of its regional geological background,we conclude the granite porphyry from Tanjianshan intrusion were formed exten-sional tectonic setting after the collision between Qaidam block and Qilian block.
Keywords：zircon U-Pb chronologyZircon Hf isotopesTanjianshangeochemistrygeochronology.
Publication Date：2016-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：15( 1830-1844 )