Geochemistry, mineralogy and plate tectonic setting of a Late Cretaceous Sn-W Granite from Sumatra, Indonesia

Abstract

The Hatapang granite was discovered during geological mapping and mineral exploration in northern Sumatra by the British Geological Survey in conjunction with the Indonesian Directorate of Mineral Resources. The pluton comprises a two-mica granite which shows significant greisenization and veining around its margins associated with Sn and W mineralization. An Rb-Sr isochron derived for the pluton indicates an age of 80 Ma and an initial S7Sr/S6Sr ratio of 0.7151. This together with major and trace element data show the Hatapang to be of clear S-type affinity.The greisens are quartz mica topaz rocks and are almost totally deficient in Na. Trioctahedral mica compositions progress from biotite through siderophyllite to zinnwaldite during final differentiation and greisenization of the granite. Accompanying dioctahedral micas are phengitic. Associated with late-stage differentiation of the granite is the precipitation of tourmaline and various Nb-Ta oxides. Sn and W mineralization is manifested as cassiterite in the greisens, while wolframite tends to be related to quartz veining. A later and lower temperature sulphide event produced a suite of base metal sulphides and Ag-Bi-Pb sulphosalts. The identification of a Sn-W granite of Cretaceous age in northern Sumatra provides a link with occurrences of economically important Late Cretaceous Sn-W granites in Thailand and Burma and increases the potential of an area which until recently was thought to lie outside the SE Asian tin belt.

Petrochemistry of Granitoids in Sibolga and its Surrounding Areas, North Sumatra, Indonesia

“…On the island of Sumatra, tin mineralization associated with the main range granites occurs in the plutons at Sungai Isahan and the adjacent areas in the Tiga Puluh region of South Sumatra, and in the batholith at Sijunjung on the eastern flank of Bukit Barisan to the northeast of Padang (Cobbing, ). The Hatapang granite which is located at the south of Lake Toba and to the east of Sibolga associated with a tin prospect, belongs to the S‐type western belt granites (Cobbing, ; Clarke & Beddoe‐Stephens, ). Uranium prospects that are hosted in Cenozoic sediments are located in Sibolga.…”

Penambangan timah di Indonesia: Sejarah, masa kini, dan prospeksi

“…Timah Tbk saat ini menjadi perusahaan terbesar yang melakukan eksplorasi, eksploitasi, dan pengolahan di Kepulauan Timah Indonesia. Deposit timah juga dilaporkan terdapat di Pulau Sumatra, yaitu di Hatapang, Pegunungan Tigapuluh, dan Bakinang (Clarke dan Beddoe-Stephens, 1987;Johari dan Umi, 1991). Indonesia memiliki sejarah penambangan timah yang panjang dan saat ini merupakan penghasil timah terbesar kedua dunia setelah Cina.…”

Primary Sn-rich titianite in the Qitianling granite, Hunan Province, southern China: An important type of tin-bearing mineral and its implications for tin exploration

“…In highly peraluminous granites, cassiterite is the most common accessory mineral of magmatic origin [1,3,26] . Additionally, mica is commonly treated as a kind of Sn-bearing mineral in the granites [5,27,28] . In contrast, titanite is a type of accessory mineral commonly present in granites, especially in calc-alkaline granites.…”