CAO Li
1 College of Geographic Sciences, Hunan Normal University, Changsha 410081, ChinaYI Liwen
1 College of Geographic Sciences, Hunan Normal University, Changsha 410081, China 2 Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring (Central South University), Ministry of Education, Changsha 410083, ChinaDAI Wei
3 The Third of Qinghai Geological and Mineral Exploration Institute, Xining 810012, ChinaXIE Binggeng
1 College of Geographic Sciences, Hunan Normal University, Changsha 410081, ChinaLI Xiaoqing
1 College of Geographic Sciences, Hunan Normal University, Changsha 410081, ChinaLU Anhuai
4 College of Geosciences and Info–Physics, Central South University, Changsha 410083, ChinaGU Xiangping
4 College of Geosciences and Info–Physics, Central South University, Changsha 410083, ChinaThis work is granted by National Key R&D Program of China (Grant No. 2019YFC1805900), Scientific Research Project of Hunan Provincial Department of Education (Grant No. 19C1178), Open Research Fund Program of Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring (Central South University, Hunan), Ministry of Education (Grant No. 2019YSJS07). Thanks to Electronic Probe laboratory of Central South University during the project. Anonymous reviewers are thanked for constructive suggestions on improving the quality of the manuscript. Susan Turner (Brisbane) assisted with English language.
The Jingren deposit is part of the Qimantage metallogenic belt within the eastern Kunlun orogenic belt, the largest metallogenic belt in Qinghai Province, northwestern China. Exploration data show that the metal resources of the Jingren deposit are greater than 93000 t in a mining area of 76.15 km2, which indicates significant exploration potential in the near future. Three W–E-trending faults, F1-3, dominate the extension of the mineralization zone, which consists of chalcopyrite, pyrite, magnetite, galena, sphalerite, and molybdenite as well as bismuth-bearing minerals. The deposit contains a large amount of late Triassic intrusive rocks, however, previous research did not reach a consensus on the timing or the origin of the mineralization owing to a lack of geochronological data and poor exposure conditions. In the present study, Re-Os isotopic dating from six molybdenite samples collected from a borehole of the granodiorite in the Jingren deposit using negative thermal ionization mass spectrometry (NTIMS) showed 187Re and 187Os concentrations of 0.26–4.40 ppm and 1.03–16.46 ppb, respectively, with an initial 187Os/188Os value of 0.06 ± 0.19. This proves that the Jingren deposit has a metallogenic age of (225 ± 4) Ma and is the product of united mineralization of the Qimantage metallogenic belt and that the Jingren deposit might actually be an Indosinian metallogeny. In addition, the Re content of these samples, at 0.42 ppm to 7.00 ppm shows that the mineralization was derived mainly from a crustal source. Furthermore, electron probe microanalysis (EPMA) conducted on chalcopyrite obtained from 22 metallic mineral samples revealed (Fe + Cu)/S ratios of 1.801–1.947 with an average of 1.852, which is lower than the ideal value (1.875). Besides, the main ore body formed in a relatively higher temperature environment than the surrounding rocks in the Jingren deposit. These data indicate that the Jingren deposit formed in a metallogenic environment at lower temperature. Moreover, according to the TiO2-Al2O3-(MgO + MnO) and TiO2-Al2O3-MgO genetic classification diagram for magnetite, the Jingren deposit most likely belongs to the skarn family. In addition, the Co-Ni-As genetic classification diagram of the pyrite indicates sedimentary and skarn genetic characteristics.
CAO Li, YI Liwen, DAI Wei, XIE Binggeng, LI Xiaoqing, LU Anhuai, GU Xiangping.2021. Re-Os Isotopic Age of Molybdenite of the Jingren Deposit and its Mineralogical Significance of Magnetite, Pyrite and Chalcopyrite[J]. Acta Geologica Sinica(),95(4):1236-1248
Copy
