| Title | Fluorite REE-Y (REY) geochemistry of the ca. 850 Ma Tumen molybdenite-fluorite deposit, eastern Qinling, China: Constraints on ore genesis |
| Authors | Deng, Xiao-Hua Chen, Yan-Jing Yao, Jun-Ming Bagas, Leon Tang, Hao-Shu |
| Affiliation | Peking Univ, Key Lab Orogen & Crustal Evolut, Beijing 100871, Peoples R China. Beijing Inst Geol Mineral Resources, Beijing 100012, Peoples R China. Chinese Acad Sci, Key Lab Mineral & Metallogeny, Guangzhou Inst Geochem, Guangzhou 510640, Guangdong, Peoples R China. Univ Western Australia, ARC Ctr Excellence Core Crust Fluid Syst, Ctr Explorat Targeting, Crawley, WA 6009, Australia. Chinese Acad Sci, State Key Lab Ore Deposit Geochem, Inst Geochem, Guiyang 550002, Peoples R China. |
| Keywords | Fluorite REY Molybdenite-fluorite deposit East Qinling Mo Belt North China Craton RARE-EARTH-ELEMENTS ULTRAHIGH-TEMPERATURE METAMORPHISM EARLY PRECAMBRIAN SEDIMENTS ZHAIWA MO-CU TRACE-ELEMENT SOUTHERN MARGIN COLUMBIA SUPERCONTINENT ISOTOPE GEOCHEMISTRY HYDROTHERMAL FLUIDS CRATON IMPLICATIONS |
| Issue Date | 2014 |
| Publisher | ore geology reviews |
| Citation | ORE GEOLOGY REVIEWS.2014,63,532-543. |
| Abstract | The Turners molybdenite-fluorite vein system is hosted by carbonate rocks of the Neoproterozoic Luanchuan Group, located on the southern margin of the North China Craton (NCC) in central China. Previous studies divided the mineralization into four stages according to the crosscutting relationships between veinlets and their mineral assemblages. In this contribution, two distinctive types of fluorite mineralization are recognized: 1) the first type (Type 1) includes colourless, white or green fluorite grains present in Stage 1 veins; and 2) the second type includes Type 2a purple fluorite present in Stage 2 veins and does not coexist with sulfides, and Type 2b purple fluorite crystals associated with sulfides in Stage 2 veins. The rare earth element (REE) content in the fluorite ranges between 13.8 and 27.9 ppm in Type 1, 16.9 and 27.2 ppm in Type 2a, and 42.5 and 75.1 ppm in Type 2b, which suggests that the fluorite was precipitated from acidic fluids (given that REEs are mobile in saline HCI-bearing fluids at high temperature (similar to 400 degrees C)). Comparing the REE chemistry of the Stage 1 against Stage 2 fluorite, the LREE/HREE ratios decrease from 9.8 to 4.0, La/Yb ratios decrease from 16.0 to 6.9 and La/Ho ratios decrease from 102 to 3.0, indicating that the hydrothermal process was at high-T and low-pH conditions. The Eu/Eu* ratios in the fluorite decrease from 1.11 +/- 0.35 for Type 1 through 0.89 +/- 0.19 for Type 2a to 0.75 +/- 0.17 for Type 2b, suggesting a gradual increase in oxygen fugacity (fO(2)) and pH of the mineralising fluid. The Tb/Ca, Tb/La and Y/Ho ratios of the fluorite types indicate that they were formed from the interaction between magmatic fluids and carbonate wallrocks. The fluorite samples show similar REE + Y (REY) patterns to those of dolostone units in the Luanchuan Group and the nearby Neoproterozoic syenite, suggesting that the REY in the fluorite was mainly sourced from the host-rocks, although the syenite could be an additional minor source. (C) 2014 Elsevier B.V. All rights reserved. |
| URI | http://hdl.handle.net/20.500.11897/207775 |
| ISSN | 0169-1368 |
| DOI | 10.1016/j.oregeorev.2014.02.009 |
| Indexed | SCI(E) EI |
| Appears in Collections: | 造山带与地壳演化教育部重点实验室 |
