Sutarto, Sutarto and Idrus, Arifudin and Harijoko, Agung and Lucas Donny, Lucas Donny and Meyer, Franz M. (2015) VEINS AND HYDROTHERMAL BRECCIAS OF THE RANDU KUNING PORPHYRY Cu-Au AND EPITHERMAL Au DEPOSITS AT SELOGIRI AREA, CENTRAL JAVA INDONESIA. J. SE Asian Appl. Geology.
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Veins and Hydrothermal breccia of Randu Kuning, Central Java.pdf - Published Version Restricted to Repository staff only until 24 January 2023. Download (20MB) |
Abstract
The Randu Kuning prospect is situated at Selogiri
area, Wonogiri, Central Java, Indonesia. This location is about 40 km to the south-east from Solo
city or approximately 70 km east of Yogyakarta
city. Many Tertiary dioritic rocks related alterationmineralisation were found at the Randu Kuning area
and its vicinity, including hornblende microdiorite, hornblende-pyroxene diorite and quartz diorite.
Mineralisation type of the Randu Kuning prospect
was interpreted as porphyry Cu-Au and a number
epithermal Au-base metals deposits in its surrounding. The closed existing of porphyry Cu-Au and epithermal Au-base metals type deposits at the Randu
Kuning area produced a very complex of veins and
hydrothermal breccias crosscutting relationship. A
lot of porphyry veins types were found and observed
at the Randu Kuning area, and classified into at
least seven types. Most of the porphyry veins were
cross cut by epithermal type veins. Many epithermal veins also are found and crosscut into deeply
porphyry vein types. There are genetically at least
two type of hydrothermal breccias have recognized
in the research area, i.e. magmatic-hydrothermal
breccia and phreatomagmatic breccia. Magmatic hydrothermal breccias are mostly occured in contact be-
*Corresponding author: SUTARTO, Department of
Geological Engineering, Gadjah Mada University. Jl.
Grafika 2 Yogyakarta, Indonesia. E-mail: sutarto -
geo@upnyk.ac.id
tween hornblende microdiorite or quartz diorite and
hornblende-pyroxene diorite, characterized by angular fragments/clasts supported or infilled by silicas,
carbonates and sulphides matrix derived from hydrothermal fluids precipitation. Phreatomagmatic
breccias are characterized by abundant of the juvenil clasts, indicated contact between hot magma
with fluid or water as well as many wall rock
fragments such as altered diorites and volcaniclastic rock clasts set in clastical matrix. The juvenil
clasts usually compossed by volcanic glasses and
aphanitic rocks in rounded-irregular shape. Both
veining and brecciation processes have an important role in gold and copper mineralisation of the
Randu Kuning Porphyry Cu-Au and epithermal
Au-base metals deposits, mostly related to the presence of quartz veins/veinlets containing significant
sulphides, i.e., quartz with thin centre line sulphides (Abtype) veins, pyrite±chalcopyrite (C type)
veinlets, pyrite+quartz± chalcopyrire±carbonate (D
type) veins of porphyry types as well as epithermal
environment quarts+ sulphides+carbonate veins.
Keywords: Veins, Hydrothermal breccia, Porphyry, Epithermal
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | Veins, Hydrothermal breccia, Porphyry, Epithermal |
| Subjects: | Q Science > QE Geology |
| Depositing User: | Ir., MT SITI UMIYATUN CHOIRIAH |
| Date Deposited: | 24 Jan 2022 09:14 |
| Last Modified: | 28 May 2024 04:16 |
| URI: | http://eprints.upnyk.ac.id/id/eprint/27908 |
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