Metallogenic zones in the central segment of the Amur gold-bearing province

Abstract

1058 The Amur province represents a large goldbearing structure approximately 250 km 2 in size, which extends in the sublatitudinal direction along the Tuku� ringra and Dzhagdy ranges on the left side of the mid� dle reaches of the Amur River. The province is con� fined to the zone of Mesozoic collision of the rigid plates of the Aldan-Stanovoi geoblock and the Amur composite massif with the Mongol-Okhotsk fold sys� tem located between them (2). It comprises nine met� allogenic zones with three of them located in the cen� tral part of the province being most promising: Yan� kan, Dzheltulak, and Dzhagdy-Selemdzha (Fig. 1). The zones extend in the northwestern, sublatitudinal direction for over hundreds of kilometers being tens of kilometers wide. The Yankan metallogenic zone extends along the largeamplitude closely spaced Northern Tukuringra and Southern Tukuringra faults, which border the Aldan-Stanovoi, MongolOkhotsk, and Amur geoblocks. The Dezheltulak fault zone hosts the synonymous metallogenic zone. The Dzhagdy-Selemdzha zone contacts the Southern Tukuringra fault in the north. The conjunction between the Dzheltulak and Southern Tukuringra faults is marked by the Zeya-Gilyui structure of the central type initiated in the lower crust (3). All the abovementioned faults represent the main orecon� trolling structures. Potential of ore-placer districts. Gold ore and placer deposits within metallogenic zones are distrib� uted irregularly to form ore-placer districts. They are characterized by highly productive gold placer and ore deposits, which yielded approximately 900 t of this metal: 350 t in the Dzhagdy-Selemdzha zone, 278 t in the Dzheltulak zone, and 272 t in the Yankan zone. The gold production of ore deposits is an order of magnitude lower as compared with that of the placer type: 83 t versus 817 t. The high productivity of the metallogenic zones in question is explained by their structural confinement of large tectonic fractures, which determine the structural ensemble of the central part of the province. In total, 25 ore-placer districts with various gold yields are defined in the zones under consideration: 3, 9, and 13 districts in the Yankan, Dzheltulak, and Dzhagdy-Selemdzha zones, respectively. The most productive among them is the Solov'evskii district of the Yankan zone, which yielded 209 t of gold, the Mogotskii district of the Dzheltulak zone (131 t), and the Tokurskii and Kharginskii districts of the Dzhagdy-Selemdzha zone (98 and 94 t of gold,