ANATOMY OF AN EPITHERMAL MINERALIZATION: MUMCU (BALIKESİR-SINDIRGI), INNER-WESTERN ANATOLIA, TURKEY

An epithermal mineralization at Mumcu has been developed on the "simple transfer faults" vertically cross-cutting the main breakaway of the Simav Graben, and between the metamorphics of Paleozoic (?) and Miocene andesitic volcanic. An argillic alteration composed of kaolinite, montmorillonite, and cristobalite takes place around the mineralization, within both two types of the rocks. Silicification, brecciation, and opalisation are also observed along the fault which constitutes the boundary between the metamorphics and volcanics. Breccias partly have a matrix composed of black silica or limonite. Pervasive and intensive jasperoids occur in the west of the studied area. Epithermal mineralization which is situated in the opalite zone within the metamorphics is represented with cinnabar associated with arsenopyrite, electrum (?) and rare gold particles. The gold values determined both in the Hg-bearing opalite and pyrites are 500 and 340 ppb. respectively. Given these data, it is likely suggested that the Hg-bearing opalite represents the top of an epithermal gold mineralization which has not eroded yet. According to the genetic model designed for Mumcu epithermal mineralization, one could except a bonanza zone dominated by gold towards the deeper parts

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