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TYPOMORPHIC FEATURES OF NATIVE GOLD PLACER OF THE LEFT ULAKHAN KHAPTASYNNAKH RIVER AND ITS PROBABLE INDIGENOUS SOURCES (ANABAR SHIELD)
B. B. Gerasimov
Diamond and Precious Metal Geology Institute, SB RAS, Yakutsk, Russia
The paper deals with studied typomorphic features of placer gold of the Left Ulakhan Haptasynnakh River, drainage rocks of the central Billakhskaya tectonofluid zone of the Anabar Shield, aimed at identifying its indicator signs and probable indigenous sources. The predominance of poorly rounded, mainly angular-cloddy individuals with rough pitted-lumpy surface, often with coatings of variable aluminosilicate composition, with small accretions of quartz and potassium feldspar, as well as a fraction >0.5 mm to 40% allowed the studied gold to be attributed to the autochthonous type. The study of nearby sulphidized rocks of the Haptasynnaakh zone showed that an ore mineralization is represented by a variety of mineral forms. The main ore mineral is pyrite. A wide range of telluride minerals was identified with predominance of silver and bismuth tellurides. For the first time, medium-high-grade gold of lamellar and rod-shaped forms was distinguished from crushed samples of mineralized rocks. Comparative analysis of the mineral inclusions composition in poorly rounded placer gold with a wide variation in gold fineness of the Left Ulakhan Haptasynnaakh and mineral parageneses of ores of the Haptasynnaakh ore zone allows researchers to assert that the zone ore manifestations are indigenous sources of the studied gold. The discovery of gold with an ore appearance of fraction >0.5 mm in the placer suggests the presence of mineralization of its coarser fractions in relatively deep horizons. This fact determines positive prospects for further study of the territory.
Keywords: Anabar shield, Billyakh zone, Khaptasynnakh ore zone, typomorphic features, placer gold, gold ore mineralization.
DOI 10.20403/2078-0575-2024-3-84-92