Petrogenesis and tectonic implication for Jiaerluafu granitic porphyry pluton in western Junggar, Xinjiang:Constraints from the element and zircon Hf isotope geochemistry
Jin Song1,2, Zhang Zhaoyi2, Rong Guilin2, Zeng Wen1,3, Lin Qian2, Wu Li'ang2,4
1. Faculty of Earth Science, State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074;
2. Hebei Institute of Geological Survey, Shijiazhuang 050081;
3. Three Gorges Research Center for Geo-hazard, Ministry of Education, China University of Geosciences, Wuhan 430074;
4. School of Continuing Education, China University of Geosciences, Beijing 100083
The Jiaerluafu granite-porphyry pluton intruding the Haerjiawu Formation outcrops in the northern of western Junggar, Sara area, and consists mainly of monzonitic granite mineralogically containing plagioclase, quartz, potassium feldspar and biotie. SiO2 values between 69.54% and 71.25%, Al2O3 values between 13.92% and 14.93%, K2O/Na2O values between 1.04 and 1.07, and FeOt/MgO values between 12.31 and 22.60. Primitive mantle normalized trace elements patterns reveal that large ion lithophile elements(LILE)Rb, Ba, Th are enriched, and strength element(HFSE)Nb, Ta, Sr, P, Ti are depleted. Total REE content are high with ΣREE=122.75×10-6~172.39×10-6. Chondrite-normalized REE distribution pattern show strong enrichment in LREE and relative depletion in HREE, with obviously Eu negative anomaly(LREE/HREE=6.56~9.28,(La/Yb)N=4.58~10.58, δEu=0.29~0.47). The zircon Lu-Hf isotope analysis indicates that most εHf(t)values of the granites are big positive. εHf(t)values between 12.21 and 14.90. TDM1 values between 462~345 Ma. TDM2 values between 638~393 Ma. LA-ICP-MS isotopic dating show a zircon U-Pb isotopic age of 305±2 Ma for the pluton, indicating it belongs to Late Carboniferous. Previous studies and this study reveal that the Jiaerluafu granitic pluton formed in a post-collision tectonic environment. The pluton is partial melting product of new crustal material source area in Late Carboniferous. To join the new components of continental crust may mainly come from depleted mantle basaltic magma.
. Petrogenesis and tectonic implication for Jiaerluafu granitic porphyry pluton in western Junggar, Xinjiang:Constraints from the element and zircon Hf isotope geochemistry[J]. Chinese Journal of Geology, 2016, 51(1): 262-280.