Geochemistry, geochronology and Hf isotope of granitoids in the Chinese Altai: Implications for Paleozoic tectonic evolution of the Central Asian Orogenic Belt

查看全文 作　　者：Dengfeng [1]He;Yunpeng [1,2]Dong;Xueyi [3]Xu;Junlu [3]Chen;Xiaoming [1]Liu;Wei [1]Li;Xiangmin [3]Li

机构地区：[1]State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University;[2]Department of Earth Science, Western University;[3]MLR Key Laboratory of Genesis and Exploration of Magmatic Ore Deposits, Orogen Research Centre of China Geological Survey

出　　处：《Geoscience Frontiers》索引2018年第9卷第5期,共17页

基　　金：Financial support for this study was jointly provided by the National Natural Science Foundation of China (Grant Nos. 41421002, 41225008, 41702231);Program for Changjiang Scholars and Innovative Research Team in University (Grant No. IRT1281);MOST Special Fund from the State Key Laboratory of Continental Dynamics, Northwest University, China 摘　　要：The Chinese Altai in northwestern Xinjiang has numerous outcrops of granitoids which provide critical information on accretionary orogenic processes and crustal growth of the Central Asian Orogenic Belt.Zircon U-Pb ages, Hf-isotopic compositions and whole-rock geochemistry of monzogranite and granodiorites in the Qinghe County are employed to elucidate Paleozoic tectonics of the Chinese Altai. Granodiorites have crystallization ages of 424.6 ± 3.1 Ma(MSWD = 0.23) and 404.0 ± 3.4 Ma(MSWD = 0.18);monzogranite was emplaced in the early Permian with a crystallization age of 293.7 ± 4.6 Ma(MSWD = 1.06). Both granodiorites and monzogranite are I-type granites with A/CNK ratios of 0.92 -0.97 and 1.03 -1.06, respectively. They also show similar geochemical features of high HREE and Y contents, low Sr contents and Sr/Y ratios, as well as enrichment of Cs, Rb, Th and U, and depletion of Nb, Ta, P and Ti.These geochemical features indicate that the monzogranite and granodiorites were formed in an arc setting related to subduction. The gneissic monzogranites display high SiO_2 and K_2 O contents, and belong to the high-K calc-alkaline series. In the chondrite normalized REE distribution pattern, the monzogranite samples exhibit enrichment of LREE with strong negative Eu anomalies(σE u =0.44 -0.53), zircon εHf(t) values from +7.24 to +12.63 and two-stage Hf model ages of 463 -740 Ma. This suggests that the monzogranite was generated from the mixing of pelitic and mantle material. The granodiorite samples are calc-alkaline granites with lower contents of Si O_2 and Na_2 O + K_2 O, higher contents of TiO_2, Fe_2O_3~t, MgO and CaO compared to the monzogranite samples. They also show enrichment of LREE and moderate negative Eu anomalies(σE u= 0.54 =0.81), as well as slightly higher differentiation of LREE than that of HREE. The425 Ma granodiorite has zircon εHf(t) values from -0.51 to +1.98 and two-stage Hf model ages of 1133 -1240 Ma, whereas the 404 Ma granodiorite displays those of +2.52 to +7.50 and 816 -1071 Ma.Geochemistry and zircon Hf isotopic compositions indicate that granodiorites were formed by partial melting of juvenile lower crust. Together with regional geology and previous data, the geochemical and geochronological data of the monzogranite and granodiorites from this study suggest long-lived subduction and accretion along the Altai Orogen during ca. 425 -294 Ma. 关键词：GEOCHEMISTRY U-Pb GEOCHRONOLOGY Hf isotopic composition GRANITOIDS CHINESE ALTAI Central Asian OROGENIC Belt

相关文献

参考文献（79）
引证文献（3）
耦合文献（1069）

参考文献(79)

引证文献(3)

耦合文献(1069)

互联网出版许可证新出网证(渝)字10号全国400电话 - 免长途话费

Geochemistry, geochronology and Hf isotope of granitoids in the Chinese Altai: Implications for Paleozoic tectonic evolution of the Central Asian Orogenic Belt

参考文献(79)

引证文献(3)

耦合文献(1069)

用户提示