Possibilities of large gold deposit origin during the Mesozoic stage of ore formation (East Siberian Platform)
Abstract
Identification of gold deposits in the East Siberian platform is problematic, because the studied area is overlain by thick cover of Mz-Kz deposits, where traditional exploration methods are ineffective. Thereby, it became necessary to study typomorphic properties of placer gold, as long as this research complex contains important information about endogenic ore formation. Study of placer gold typomorphism is a challenge for the development of mineralogic criteria of identification of types of ore sources and justification of large gold deposit prediction in the studied area. Result summary of the study of placer gold typomorphic features and analysis of the gold distribution allowed identifying two types of gold for the first time (I-type gold and II-type gold) with specific indicator signs, corresponding to two types of ore formation – Precambrian and Mesozoic. Analysis of geology evolution and result summary of the study of II-type gold typomorphic features suggest formation of large Mesozoic gold deposits, spatially confined to deep faults, or to occurred volcanic activity of andesite-dacite composition in the zones of intracontinental paleorifts. Comparison of mineralogic-geochemical features of placer gold and regularities of its distribution with gold of the North-American platform, and features of geology evolution of these regions allowed predicting formation of large Mz-Kz deposits of gold-sulfide-quartz association (Karlin type) – in the Molodo-Popigay fault system (Udzhinsky paleorift), Kuranakh type – in conjuction zone of the Urinsky anticlinorium with the north-eastern part of the Baikal-Patom thrust belt and gold-silver association (Cripple-Creek type) within the Kempenday dislocation zone (Viluy paleorift).