Jurnal Riset Geologi dan Pertambangan, Vol 16, No 2 (2006)

KARAKTERISTIK DISTRIBUSI MINERAL UBAHAN: JEJAK EPISODE KEGIATAN HIDROTERMAL DI DAERAH CUPUNAGARA, SUBANG, JAWA BARAT

Toto A. F. Sumantri, Sudarsono Sudarsono

Abstract


Cupunagara Area, lies in the North-Northeastern of the Sunda Volcanic Complex, occupied by rough mountainous area consisting of two calderas and surrounded by several volcanic cones. The lithology of the studied area consists of intrusive rocks unit, andesitic – basaltic lava and pyroclastic, mostly had been altered into prophylitic and argillic zones. The prophylitic zone is distributed widely in the central part of the calderas, whilst the argillic zone is distributed confined to the Northwest-Southeast trending fault zones overprints the prophylitic zone and contains the remnants of quartz veins.

Structural geology pattern of the studied area is affected by its position as the meeting area of the Cimandiri and the Baribis Fault Systems. Two main strike slip faults are recognized consist of the Northeast-Southwest trending sinistral fault and the Northwest-Southeast trending dextral fault.

Two episodes of hydrothermal activities occurred in the studied area, in the first episode the hydrothermal fluid was relatively hot (temperature between >100 to 250oC) and neutral (pH 5-6), whilst in the second its temperature was