MAJOR COPPER DEPOSIT TYPES IN TRANSBAIKALIA AND CONTIGUOUS AREAS: RUSSIA, CHINA AND MONGOLIA

The area under consideration includes eastern and western Transbaikalia, southern Yakutiya, Mongolia and northern China. The major geological provinces are the southern part of Siberian platform (Aldan shield) and the northern edge of the Northern China platform. Between these platforms are mobile folded belts which formed during Proterozoic-Paleozoic and Mesozoic-Cenozoic tectonic-magmatic cycles.

A number of copper deposits and ore prospects of different ages and formation types are found in this region.

In the southern part of Siberian platform are Cu-Ni prospects in Upper Archean greenstone belts associated with komatiite complexes, sandstone-and shale-hosted stratabound copper deposits in the Lower Proterozoic Udokan sedimentary complex, and copper-bearing differentiates in layered gabbroic intrusions (Chineisky massif, Late Proterozoic).

Significant exploration has occurred in this region, but there is further potential for undiscovered deposits beyond the locations of known resources. We estimate additional undiscovered copper resources in the Transbaikalia area of about 30 million tons in sandstone-hosted copper deposits and about 10 million tons in layered gabbroic intrusions.

In the Mongolian-Transbaikalian mobile folded zone, the copper deposits (often with Mo, Au, Ag) are mainly porphyry-type associated with Late Paleozoic-Mesozoic granodiorite-granosyenite intrusions. Three copper belts are known in Mongolia and nearby areas: (1) a northern belt (including the Erdenetuin-Obo deposit) extending to west (Aksug deposit); (2) a central belt with continuation to the east (Gazimurskaya group of the deposits, East Transbaikalian area) and (3) a southern belt (Oyu-Tologoy deposit) extending to west (Zaysan-Balkhash group of deposits).

The following types of the copper deposits occur near the northern border of the Northern China platform: (1) Cu-Ni and Fe-V-Cu deposits in basite intrusions, (2) porphyry-copper deposits and skarns, (3) sandstone-hosted copper deposits, (4) copper-pyrite deposits in an ophiolite complex.

The metallogenic potential of copper in Transbaikalia and contiguous territories is very significant. The copper resources (industrial, explored, assessed) in this area are estimated at 80M tons, and this potential is not exhausted.