Geology at Beruang Kanan, Central Kalimantan, Indonesia

The samples are collected during our field investigations both from out crops and from core drillings. They will be selected from rock units within the Beruang area, particularly from the pre_and all syn mineralization rocks. The Beruang area is situated within a mid-tertiary age magmatic arc that host a number of epithermal gold deposits (e.g., Kelian, Indon, Muro) and significant prospects such as Muyup, Masupa ria, Gunung Mas dan Mirah. Mineralization in the Beruang is associated with a number of intrusions that have been emplaced at shallow crustal levels at the junction between Mesozoic metamorphic rocks to the south and accreted Lower Tertiary sediments to the north. These intrusions are interpreted to be part of the Oligocene central Kalimantan Arc. The Cretaceous rock that found in Beruang Kanan is older intrusions wich associated with volcanic and volcanic clastic rocks. The Beruang Kanan mineralization is hosted in a sequence of dacite tuff of probable Oligocene age that overly lower Tertiary volcanicclastic siltstone and sandstones in the eastern prospect area. Premiered andesite, dacite to basalt-gabbro dykes are intruded into the tuffs and sediments zinc-arsenic- antimony in soils is hosted in intensely chlorite-pyrite altered tuff. In the West Zone were scattered the zones of phyllic alteration. Subsequent shearing of quatz veins was accompanied by wall rock alteration and vein deposition of the quatz veins was accompanied by wall rock alteration and vein deposition of mineral assemblages that are zone temporally from early advanced argilic, through intermediete ohyllic to late stage argilic and sub-propylitic. The alteration asseblages and associated mineralization are also spatially zoned