Tectonics and Metallogeny of North East Russia

Australian Institute of Geoscientists > Events > AIG, GSA, MEGWA, Russia > Tectonics and Metallogeny of North East Russia

Tectonics and Metallogeny of North East Russia


1 CPD HourThis is a special joint AIG/GSA WA talk presented by Nikolai Goryachev.

About the talk

Northeast Asia consists of four major tectonic blocks, according to analysis of different modern tectonic models of the Northeast Asia and the author’s personal investigations in different parts of this huge territory. The tectonic blocks are: deformed passive margin of the Northeast Asia craton with Omolon and Okhotsk microcontinents which have been separated from the craton in Neoproterozoic times; deformed margin of the Arctic continental block; collage of island arc terranes of the Kolyma Loop – Indigirka-Kolyma accretion belt; and a collage of terranes of the Anadyr-Koryak and Okhotsk Sea tectonic blocks. These tectonic blocks form the basement for the Late Jurassic – Early Cretaceous Yana-Kolyma and Okhotsk-Koryak orogenic belts, Early Cretaceous Arctic orogenic belt and Cenozoic Koryak-Kamchatka orogenic belt.

The Late Mesozoic orogenic fold belt of different geodynamic settings have been formed as a result of the Late Jurassic – Early Cretaceous (160-135 Ma) and Cretaceous (130-100 Ma) orogenic events. These belts are the collisional Yana-Kolyma belt with S-type granite plutons; accretion-collision Arctic belt; and accretion – “uncompleted” orogenic Indigirka-Kolyma belt. We believe that Kolyma Loop structures may compare with the modern Philippine and Indonesia archipelago. Both these structures consist of collages of island arcs, back arcs, oceanic basins, and other structures. Such structures (collages) lie between continental blocks and represent of special accretion structures as a product of continental collision and interaction. Areas of interaction between different orogenic belts of the same age have specific tectonic interference structures. Different deformation structures and magmatic assemblages with complicated metallogeny occur in such interference areas.

Ore deposits in East Russia formed throughout geological history from the Precambrian to the Cenozoic. Except for the Omolon AR-PR microcontinent, the gold metallogeny of this vast region from the Precambrian to the Paleozoic was of little economic significance. By contrast, the development of gold metallogeny in the Late Mesozoic and the Cenozoic reached a maximum, with several world-class deposits being formed. This is largely because of the intense and widespread tectono-thermal activity in East Russia in the Late Mesozoic – Cenozoic. Gold deposits of orogenic and intrusion-related types are widespread in all orogenic belts. About 6,000 t Au were recovered from these deposits and many placers, which determined the overall shape of these metallogenic areas. Gold ore deposits are associated with different types of Sn, W, Sb and base metal deposits in the Yana-Kolyma orogenic belt, and W, Cu, Mo, epithermal Au and Sb-Hg deposits in the Arctic, and Okhotsk-Koryak orogenic belts.

The Yana-Kolyma orogenic belt formed in two stages: (1) the Late Jurassic – Early Cretaceous (U-Pb, Ar-Ar 154-134 Ma and (2) Early Cretaceous (Ar-Ar 125-115 Ma). Orogenic (Ar-Ar 140-135 Ma) and granitoid-related (K-Ar, Ar-Ar 149-141 Ma) Au deposits are characteristic of the early stages. They are associated with Sn-W skarn deposits (Ar-Ar 146 Ma) and greisen – quartz vein types, and small deposits of Pb-Zn and Mo. Late stage orogenic Au deposits (K-Ar, Ar-Ar 126-124 Ma) are closely associated with world class Au-Sb deposits (K-Ar 124-115 Ma). Pre-orogenic deposits are represented by small island-arc related Kuroko type deposits, Hg and Au-Ag epithermal, and Carlin-like type deposits of the Uyandina-Yasachny volcanogenic belt.

The Okhotsk-Koryak orogenic belt is characterized by an eastward change in the age of orogenic events from 140-135 to 115-103 Ma. Orogenic (Ar-Ar 120-119 Ma) and granitoid related (Ar-Ar 124 Ma) Au deposits are associated with Cu-Mo, Sn-Nb-Li and Co-As (K-Ar 134-103 Ma). Pre-orogenic epithermal Au-Ag (Ar-Ar 136 Ma) and manto-like base metal ores are associated with the formation of Uda-Murgal continental-margin magmatic belt.

Arctic (or Oloy-Chukotka) orogenic belt has sublatitudinal orientation different from the other Mesozoic belts and located along the Arctic Ocean coast from the lower reaches of the Yana River in the west to Alaska in the east. Orogenic granitoids within this belt dated at 125-103 Ma (Ar-Ar, U-Pb). Orogenic and granitoid-related Au deposits are dated by Ar-Ar (125 Ma) and K-Ar (121-115 Ma) and are associated with small deposits of Mo and Sn. Pre-accretionary Cu-porphyry deposit (U-Pb 141 Ma) and epithermal Au-Ag mineralization was formed in island arc settings within Oloy and South Anyui tectonic zones.

The Koryak orogenic belt is characterized by the association of minor orogenic Au deposits with pre-accretionary chromite-PGE deposits in ultramafic rocks and volcanogenic sulfide ores into Talovsky and Maynitsky terranes, as well as small pre-accretionary Mn ore deposits in chert beds of the Yanranay terrane.

Metallogeny of the Okhotsk-Chukotka volcanogenic belt is characterized mainly by the association of epithermal Au-Ag mineralization with Mo-Cu- porphyry, Ag – base metal, W and Sn-Ag ore deposits. Chromite-PGE ore deposits are known in the southern flank of Okhotsk-Chukotka volcanogenic belt, but their geodynamic setting is unclear.

For this region, the combination of two trends of tectonic structures and metallogenic belts was typical: (1) the Arctic, and (2) Pacific. The first were dominant in Jurassic – Early Cretaceous times. The Pacific trend dominated in Late Cretaceous times. Different combinations of ore deposits are characteristic of Mesozoic metallogeny of the northern part of Russian Far East. In some cases, they mainly reflect the crustal character of the metallogeny (Yana-Kolyma and Okhotsk-Koryak orogenic belts), in other cases (Koryak orogenic belt) the mantle. The mineral compositions, and isotopic characteristics of the ore deposits (S, Pb) and vein (O, C, Sr), suggests that mineralization in orogenic structures was formed with a noticeable influence of mantle-crust interaction.

About the speaker

Nikolay Goryachev completed a PhD in Mineralogy (Moscow State University) and Doctor of Science in Geology of ore deposits (Far East Geological Institute, Vladivostok). He is Corresponding member of Russian Academy of Sciences, and Professor of Geology in North-East State University in Magadan. His principal experience is in geology and metallogeny of lode gold deposits. Field experience is related to research in Russia, USA (Alaska), Canada (Yukon), Finland, Mongolia. He is SEG Fellow and member of Russian Geological and Mineralogical Societies, Geological Society of Australia, Society of Applied Geology and Mineralogy. He was SEG Regional Vice President Lecturer 2007, and SEG Regional Vice President on Northern Eurasia 2009-2012.