Structural control of orogenic gold deposits of the Verkhoyansk-Kolyma folded region, northeast Russia

Abstract

The Verkhoyansk-Kolyma folded region (VKFR) contains numerous Late Jurassic – Early Cretaceous orogenic gold deposits which are the source for large alluvial gold placers. This study is focused on determination of the relationship between ore-controlling structures, tectonic evolution of the region and analyzing different-aged deformations and structure of gold deposits in the region. Tectonic structures of mesothermal orogenic gold deposits were formed as a result of Late Jurassic-Barremian frontal accretion, generally prior to the onset of transpressional deformation. The accretionary events were different in different parts of VKFR. In the Allakh-Yun metallogenic zone this was the accretion of the Okhotsk terrane to the eastern margin of the North Asian craton, and in the Verkhoyansk and Yana-Kolyma metallogenic belts the accretion of the Kolyma-Omolon superterrane to the same craton. Regional-scale thrust faults are main tectonic structures controlling distribution of gold deposits in the area. Ore-controlling structures for the early orogenic gold-sulfide disseminated and gold-quartz lode deposits, which were formed prior to the emplacement of orogenic granitoid plutons, are shear zones. They form systems of listric-type imbricate fans closely associated with a detachment of the Verkhoyansk fold-and-thrust belt. Late orogenic gold-quartz deposits in fault zones, which were formed after the emplacement of orogenic granitoid plutons, are controlled by intersections of thrusts and lateral and oblique ramps and by the related folds. Formation of the ore-hosting structures of the late orogenic intrusion (granitoid)-related deposits is due to the dynamic effect of intruding magma on the host rocks.