Gold Related Sulfide Mineralization and Ore Genesis of the Penjom Gold Deposit, Pahang, Malaysia
The Penjom gold deposit lies on the eastern side of the Raub Bentong Suture line within the Central Belt of Permo Triassic rocks, near Kuala Lipis, Pahang, Malaysia. The geology of the deposit is dominated by a sequence of fine to coarse grained rhyolitic to rhyodacitic tuff, tuff breccia and a minor rhyolitic rhyodacitic volcanic series, associated with argillaceous marine sedimentary rocks consisting of shale with subordinate shalely limestone of Padang Tungku Formation and Pahang Volcanic Series. Fine to coarse grained tonalite and quartz porphyry intruded this unit. The main structural features of the area are north south trending left lateral strike slip faults and their subsidiaries, which generally strike north south and dip moderately to the east (350deg 360deg/40deg 60deg) Mineralization at the Penjom gold deposit is structurally controlled and also erratic laterally and vertically. The gold mineralization can be categorized as (i) gold associated with carbonate rich zones hosted within dilated quartz veins carrying significant amount of sulfides; (ii) gold disseminated within stockwork of quartz carbonate veins affiliated with tonalite; and (iii) gold often associated with arsenopyrite and pyrite in quartz carbonate veins and stringers hosted within shear zones of brittle ductile nature in all rock types and in brittle fractured rhyodacitic volcanic rocks. Sphalerite, chalcopyrite, tetrahedrite and pyrrhotite are the minerals accompanying the early stage of gold mineralization. These minerals also suffered from local brittle deformation. However, most of the gold mineralization took place after the deposition of these sulfides. Galena appears somewhat towards the end of gold mineralization, whereas tellurium and bismuth accompanied gold contemporaneously. The gold mineralization occurred most probably due to the metamorphogenic deformational origin concentrated mostly in the shear zone. The mineralization is strongly controlled by the wall rock (e.g. graphitic shale) the sulfide minerals and fluid rock interaction.