Geology,U-Pb geochronology,and stable isotope geochemistry of the Tunca semi-massive sulfide mineralization,Black Sea region,NE Turkey: Implications for ore genesis |
| |
| Institution: | 1. Department of Mineral Research and Exploration, General Directorate of Mineral Research and Exploration (MTA), 06800 Ankara, Turkey;2. Dowa Geotechnos Co. Ltd., Geoscience Division, Shimbashi, Minato-Ku, Tokyo 105-0004, Japan;3. Department of Geological Engineering, Hacettepe University, Beytepe, 06800 Ankara, Turkey;4. Department of Geological Engineering, ?stanbul University, Avc?lar, 34850 Istanbul, Turkey;5. General Directorate of Mineral Research and Exploration (MTA), Trabzon Branch, Turkey;6. Geological Institute, Bulgarian Academy of Sciences, Sofia, Bulgaria;1. MLR Laboratory of Metallogeny and Mineral Resource Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;2. Centre for Exploration Targeting, ARC Centre of Excellence for Core to Crust Fluid Systems, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia;3. Mineral Branch of Hunan Institute of Geological Survey, Changsha, China;1. Earth Science Institute, St. Petersburg University, Universitetskaya Embankment 9, 199034 St. Petersburg, Russia;2. All-Russian Geological Research Institute (VSEGEI), 199106 Sredny pr. 74, St. Petersburg, Russia;1. CAS Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;1. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;2. Centre for Exploration Targeting, University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia;1. Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China;2. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China |
| |
| Abstract: | Upper Cretaceous volcano-sedimentary sequences of the Eastern Pontide orogenic belt, NE Turkey, are host to significant VMS mineralization, including near Tunca. The initial stages of felsic volcanism within the mineralized area are marked by the eruption of dacitic lavas and breccias of the K?z?lkaya Formation. This was accompanied by the emplacement of domelike hematitic dacites. Autobrecciated and volcaniclastic rocks, both in situ and resedimented, were likely generated from extrusive portions of these dacite bodies. Basaltic volcanism is marked by the eruption of the lava flows and pillow lavas of the Ça?layan Formation. Hiatuses in basaltic activity are marked by thin horizons of volcaniclastics and mudstones. The uppermost felsic volcanic units were accompanied by resedimentation of autoclastic facies from previous volcanism and represent the latest phase of Upper Cretaceous volcanism in the area. The semi-massive sulfide mineralization is associated with a late stage of the initial felsic volcanism. U-Pb LA-ICP-MS zircon dating of a dacitic tuff breccia yielded an age of 88.1 ± 1.2 Ma (Coniacian-Upper Cretaceous), which is interpreted to be the age of the sulfide occurrences.A concentric zoned alteration pattern is observed in the footwall rocks. The alteration pattern is considered to have formed by lateral migration of hydrothermal fluids which had ascended along the discharge conduit. Fluid inclusion data indicate precipitation or mobilization processes within a relatively narrow temperature range of 152–255 °C (avg. 200 °C). The low-salinity fluids in the fluid inclusions, less than 5.9 wt% NaCl equivalent, are consistent with typical modified seawater-dominant hydrothermal vent fluids. Sulfur isotope analysis of the Tunca sulfides yields a narrow range of 1.5–4.1 per mil. These δ34S values are also typical of many VMS deposits. Most of the recorded δ18O values (+7.1 to +14.0 per mil) are greater than 9 per mil. The most intensely hydrothermally altered rocks tend to have lower δ18O values relative to the less altered rocks. Collectively, the geologic relationships, mineralization style, and the lack of seafloor ore facies suggest that mineralization is principally of sub-seafloor origin. The most geologically reasonable interpretation of the genesis of the Tunca mineralization is the continuous interaction between the host rocks and seawater-derived fluids, without significant involvement of a magmatic fluid. |
| |
| Keywords: | Eastern Pontides Tunca mineralization VMS U-Pb zircon dating Isotope geochemistry |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
