Petrographic and mineral chemistry investigation of the high-grade chrysotile asbestos-bearing Zvishavane Ultramafic Complex,south central Zimbabwe |
| |
| Institution: | 1. Department of Geology and Geography, University of North Carolina at Pembroke, 1317 Oxendine Science Building, 1 University Dr., Pembroke, NC 28372, USA;2. Department of Geosciences, Midlands State University, Private Bag, 9055, Gweru, Zimbabwe;1. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;2. School of Geosciences, China University of Petroleum, Qingdao 266000, China;3. Hekou Oil Production Plant, SINOPEC Shengli Oilfield Company, Dongying 257000, China;1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;2. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China;3. Guangdong Provincial Key Laboratory of Geodynamics and Geohazards, School of Earth Sciences and Engineering, Sun Yat-Sen University, Guangzhou 510275, China;4. Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China;5. Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China;1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, School of Geosciences and Info-Physics, Central South University, Changsha 410083, China;2. Hunan Vocational College of Engineering, Changsha 410151, China;3. School of Earth Science and Resource, China University of Geosciences, Beijing 100083, China;4. Department of Earth Sciences, University of Adelaide, Adelaide, SA 5005, Australia;1. Fachbereich Erdsystemwissenschaften, Universität Hamburg, Grindelallee 48, D-20146 Hamburg, Germany;2. Dipartimento di Scienze, Università di Roma Tre, Largo S. Leonardo Murialdo 1, 00146 Rome, Italy;3. INFN-LNF, Via E. Fermi 40, Frascati, 00044 Rome, Italy.;4. INGV, Via di Vigna Murata 605, 00143 Rome, Italy;5. Mineralogisches Museum, Leibniz-Institut zur Analyse des Biodiversitätswandels, Grindelallee 48, D-20146 Hamburg, Germany;1. CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China;2. CAS Center for Excellence in Comparative Planetology, University of Science and Technology of China, Hefei 230026, China;3. School of Geosciences, East China University of Technology, Nanchang 330013, China |
| |
| Abstract: | The Zvishavane Ultramafic Complex (ZUC) in the south central part of the Zimbabwe craton is comprised of coarse-grained serpentinites, metadunites and metagabbros and hosts Africa's largest reserves, and largest mine, of high-grade chrysotile asbestos. Magnesiohornblende, actinolite, plagioclase (An0.6–41.9), augite, diopside and clinozoisite constitute the mineralogy of the ZUC. Forsteritic olivine (>Fo90) was altered to form chrysotile and antigorite minerals, although some primary olivines are preserved. Contents of Al2O3 range from <1 to >2.5 wt% at TiO2 values of <0.7 wt% consistent with an island arc setting for the ZUC that originated from tholeiitic magmas. The Zvishavane Ultramafic Complex was metamorphosed at relatively high temperatures (542-779 °C) and low pressures (1.2-2kbars), consistent with contact metamorphism. Intrusion of several granitic batholiths relatively close to the ZUC likely triggered hydrothermal fluid migration which metamorphosed the ZUC. The associated asbestos deposits likely formed during hydrothermal circulation events. Zoned amphiboles, the occurrence of magnesiohornblende and actinolite, as well as cross-cutting serpentine veins are consistent with at least two stages of alteration and/or metamorphism of the ZUC. The lack of a thrust contact between the ZUC and its country rocks is consistent with the ZUC having intruded into the host Zvishavane Gneiss Complex and possibly acted as a feeder to the nearby Mberengwa greenstone belt (MGB). However, the occurrence of near end-member forsteritic olivine, the presence of zoned amphiboles, and faulting within the ZUC are all suggestive of an ophiolitic origin although forsteritic olivines also occur in intrusive layered complexes. Metamorphism of the ZUC, ascribed to intrusion of multiple batholiths and possibly the MGB, likely led to the formation of ZUC chrysotile asbestos deposits. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
