The Lamandau IOCG deposit,southwestern Kalimantan Island,Indonesia: Evidence for its formation from geochronology,mineralogy, and petrogenesis of igneous host rocks |
| |
| Institution: | 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. College of Earth Science, Guilin University of Technology, Guilin 541004, China;3. CAS Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, The Chinese Academy of Sciences, Guangzhou 510640, China;1. Czech Geological Survey, Geologická 6, 152 00 Praha 5, Czech Republic;2. ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS),Department of Earth and Planetary Sciences, Macquarie University, Sydney, NSW 2109, Australia;3. GEMOC National Key Centre, Department of Earth and Planetary Sciences, Macquarie University, Sydney, NSW 2109, Australia;4. Andean Geothermal Center of Excellence, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago, Chile;1. AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection, Department of Economic Geology, al. A. Mickiewicza 30, 30-059 Krakow, Poland;2. Economic Geology Research Institute, School of Geosciences, University of the Witwatersrand, Private Bag 3, 2050 Wits, Johannesburg, South Africa;3. Resource Mineralogy, Department of Applied Geosciences and Geophysics, Montanuniversitaet Leoben, Peter-Tunner-Str. 5, 8700 Leoben, Austria;4. Department of Geological Sciences, Stockholm University, 10691 Stockholm, Sweden;5. Kryvorizkiy National University, Kryvyj Rig, XXII Partzyizdu Str., 11, 50027 Krivoy Rog, Ukraine;6. Burlinson Geochemical Services Pty. Ltd., Darwin, NT, Australia;1. School of Geosciences, Monash University, Melbourne, Australia;2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China |
| |
| Abstract: | The Lamandau region of Kalimantan Island, Indonesia is located in Sandaland, in the southern part of the Kuching tectonic belt. A series of Cenozoic epithermal gold deposits and Fe–Cu–Au deposits are located in the Kuching belt. The Lamandau Fe–Cu–Au deposit is hosted by diorite porphyry. In-situ zircon U–Pb dating of the diorite porphyry shows that it formed between 82.1 ± 1.7 Ma and 78.7 ± 2.3 Ma. Geochemical data indicate a depletion of high field strength elements (HFSE) in the diorite porphyry and related basalt is similar to that of arc-related igneous rocks. The diorite porphyry and basalt were probably derived from typical arc magmas related to continental margin subduction and thus are characterized by light rare earth element (REE) enrichment and HFSE depletion. The sub-chondritic Nb/Ta ratios for the basalt in the Lamandau region indicate that the subducted Pacific slab began partial melting at depths where amphibole was the major residual phase, with some residual rutile. The basalt was derived from a depleted mantle source. The composition of apatite and zircon in the diorite porphyry indicates that the dioritic magma was produced from the subcontinental mantle after it was metasomatized by slab-derived fluids. The magma had a high oxygen fugacity, thus and therefore it was particularly conducive to the precipitation of Cu, Au and other ore-forming elements. The composition of magnetite indicates that it was of volcanic origin. The magnetite has a low REE content, and a high Cu–Au content. The deposit may be classified as an IOCG mineral system. In summary, the ore-related diorite porphyry in the Lamandau region might have formed in an extensional environment during rollback of the subducting western Pacific plate. The convergent velocity between the Philippine Sea and Eurasian plates was at a minimum during the rollback, so that the margin of East Asian began to undergo rifting with associated magmatism. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
