Sutarto, Sutarto and Idrus, Arifudin and Meyer, Franz Michael and Harijoko, Agung and Setijadji, Lucas and Putranto, Sapto (2016) Mineralization Style And Fluids Evolution Of The Randu Kuning Porphyry Cu-Au And Epithermal Au-Base Metals Deposits At Selogiri, Central Java, Indonesia. In: GEOSEA XIV AND 45TH IAGI ANNUAL CONVEENTION 2016, 10-15October 2016, BANDUNG.
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2016_Sutarto et al._Mineralization styleand Hydrothermal Fluid Evolution of the Randu Kuning Porphyry Cu-Au, Selogiri, Central Java.pdf Download (2MB) | Preview |
Abstract
Based on the characteristics of many parameters such as pattern and type of hydrothermal alteration, veins type, gangue and ore minerals assemblages, fluid inclusions data, the mineralization type of the Randu Kuning prospect is a co-existing of porphyry Cu-Au to intermediate sulphidation epithermal Au-base metals. Not all porphyry vein types contribute in copper and gold mineralization. The early quartz-magnetite veins (particularly A and M veins) generally not contain Cu-Au or barren, while the later sulphide bearing veins such as AB, C and D types mostly are rich of copper and gold. Mineralization is also commonly occured as disseminated chalcopyrite within magmatic hydrothermal breccia associated with magnetite and actinolite. In epithermal environment, vein associated with golg and base metals mineralization particularly is pyrite+sphalerite+chalcopyrite+quartz±carbonate vein. Many sulphides within open space hydrothermal breccia also have important role in gold-silver-zinc-lead mineralization. The hydrothermal fluid evolution from the deep porphyry to the shallow epithermal enviroment, can be devided into at least three stages. The early porphyry stage started at temperatures more than 600°C, when the singgle phase fluid separated into two phases that are a hypersaline fluid and a low-density vapor. The hypersaline fluid is representated by the present of type III inclusion (polyphase), while the second one is represented by the present of type II (two phase), characterized by vapor more dominant than liquid. In this stage, reaction betweem the fluid and wall rocks were pointed by the development of magnetite and quartz veins such as A, B and M type within mineral assemblages of potassic alteration. The veins mostly barren or very low grade of copper and gold. The next stage or intermediate porphyry stage is represented by the present of single phase aqueous fluid with low-medium salinity at the temperature about 300°- 350°C. During generating to the surface, this fluid react with the existing magnetite-quartz vein/veinlet stockworks and potassic alteration minerals, form sulphides bearing quartz veins (AB type and C type) and an alteration mineral assemblages particularly phyllic and chloritemagnetite- sericite zone. AB and C veins are commonly associated with the porphyry Cu-Au mineralization. Late porphyry to epithermal stage is the stage when the single phase aqueous fluid continue move the surface and laterally to the peripheral, react with meteoric and connate water more intense, the salinity became lower and the temperature also decrease (200°-350°C). This fluid react with the existing veins and altered rocks will form pyritechalcopyrite bearing carbonate-quartz veins (D type) and carbonate-pyrite-sphalerite-chalcopyrite and other epithermal style veins as well as the development of outer prophyllitic, intermediet argillic and lack of anvanced argillic. D vein also gave contribution in Au deposit, while some epithermal veins contribute in Au-base metals mineralization. Key words: Porphyry; Epithermal; Mineralization style; Fluid evolution
| Item Type: | Conference or Workshop Item (Paper) |
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| Subjects: | Q Science > QE Geology |
| Divisions: | Faculty of Engineering, Science and Mathematics > School of Engineering Sciences |
| Depositing User: | Dr.Ir SUTARTO - |
| Date Deposited: | 22 Jan 2019 07:34 |
| Last Modified: | 22 Jan 2019 07:34 |
| URI: | http://eprints.upnyk.ac.id/id/eprint/18095 |
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