Petrogenesis and Geological Significance of the North Liuhuangkuang Granodiorite in the West Sement of the Qilian Terrane:Evidences from Geochronology,Geochemistry,and Hf Isotopes
Tao Gang
Zhu Lidong
Li Zhiwu
Ouyang Huizi
Xie Long
Yang Wenguang
Yang Zhen
Abstract：More geological researchers are focusing on the Neoproterozoic magmatic activities of Qilian Terrane and little chron-ological and geochemical materials are about the North Liuhuangkuang Granodiorites (NLG)in the western segment of Qilian Terrane.The zircons of rock samples which havedistinct rhythmic growth zoning are long cylindrical and euhedral well,impl-ying the features of magmatic origin.The resultsof dating indicate that the rocks were formed in the Early Neoproterozoic (926±4 Ma).11 samples'new whole-rock geochemical analysis results have SiO 2 content of 59.47%~62.96%,P2 O 5 content of 0.12%~0.14% with A/CNK values of 1.01~1.15,which showed that the NLG were high-K calc-alkaline with characteristics of I-type.The ∑REE content was between 118.80 × 10 -6 and 253.07 × 10 -6 ,with (La/Yb)N ratio of 7.87 ~ 16.17 andδEu (0.89~1.03).The REE diagram showed rightward incline and mid-negative weekly negative Eu abnormity.The NLG were en-riched in large-ion lithophile elements:Rb,Th,U,LREE and depleted in high field strength elements:Nb,Ta,Ti,P.The ratios of Nb/Ta,La/Nb,Nb/U and Sm/Nd show crustal characteristics.The Hf isotopes showed that theεHf (t )of NLG mainly ranged from 0 to 7 and its crustal model ages were between 1247 Ma and 1801 Ma.With the regional magmatic activi-ties,the NLG probably were formed in a subduction tectonic environment of continental margin arc and it suggested that the primary magma was derived from the remelting of juvenile crustal materials in Mesoproterozic,experiencinga certain extent of fractional crystallization.Otherwise,the melting of the ancient crust also probably participated the formation of the NLG.The NLG magma activities may the response of the converge of the Rodinia Supercontinental,during the Neoproterozoic,which provided the attribute of the Qilian Terrane with credible research materials.
Keywords：Qilian TerraneGranodioritezircon U-Pb datingLu-Hf isotopejuvenile crustThe Rodinia Supercontinentalgeochemistry
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：18( 2258-2275 )