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.
Preview |
Text
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) |
|---|---|
| Subjek: | Q Science > QE Geology |
| Divisions: | x. 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 |
Actions (login required)
 |
View Item |