Leonid M. Parfenov

Tectonic setting of the plutonic belts of Yakutia, northeast Russia, based on 40Ar/39Ar geochronology and trace element geochemistry

Samples from plutonic belts and individual intrusions in the Sakha Republic (Yakutia), northeastern Russia, were analyzed using 40Ar/39Ar geochronology and trace element geochemistry. Four phases of activity were identified: a subduction event along the southwest margin of the Kolyma-Omolon superterrane with apparent ages of ca. 160–140 Ma, a superposed collisional event dated at 143–138 Ma, a subduction event along the northern margin of the superterrane dated at 130–123 Ma with a slightly older to contemporaneous extensional event to the west; and intrusions associated with east-west extension between 106 and 92 Ma. These phases are interpreted to represent (1) subduction under and (2) accretion to Asia of Kolyma-Omolon followed by local extension, (3) subduction along the northern edge of this superterrane, and (4) regional extension following closure of the South Anyui suture and/or the start of subduction associated with the Okhotsk-Chukotka volcanic belt.

Cooperative program helps decipher tectonics of northeastern Russia

Recently obtained paleomagnetic, geochronologic, and seismic data are greatly improving our understanding of the tectonics of northeastern Russia, which lies in an accretionary zone between the stable platforms of the North American and Eurasian plates. In particular, the present-day plate boundaries and motions have been clarified and a model has been developed for the accretionary history of the poorly understood Mesozoic fold belts of northeastern Russia. The evolution of northeastern Russia appears to be similar to that of Alaska and the Canadian Cordillera, and many similar tectonic and stratigraphic features can be identified in all three regions.

Major products of the international collaborative project on mineral resources, metallogenesis, and tectonics of northeast Asia

A major international collaborative project on the mineral resources, metallogenesis, and tectonics of Northeast Asia is being concluded by the Russian Academy of Sciences, the Mongolian Academy of Sciences, Jilin University (China), the Korean Institute of Geoscience and Mineral Resources, the Geological Survey of Japan, and the U.S. Geological Survey. The project area includes eastern and southern Siberia, the Russian Far East, Mongolia, northern China, South Korea, and Japan. The project is a multi-national study at 5.0 m scale with over 50 international collaborators from six countries. The Northeast Asia project extends and builds on data and interpretations resulting from a similar previous project on the mineral resources, metallogenesis, and tectonics of the circum-north Pacific (Russian Far East, Alaska, and the Canadian cordillera). The Northeast Asia project is associated with a new project of the U.S. Geological Survey entitled a Global Mineral Resource Assessment.

Tectonic and metallogenic evolution of northeast Asia: Key to regional understanding

The vast, mountainous terranes of Northeast Asia hold the key to the tectonic and metallogenic evolution of a major and geologically complicated region of the world. This region stretches from the Ural Mountains and the Arctic Islands of central Russia to the Kamchatka volcanic arc in the Russian Far East. The region also includes northern Kazakhstan, China, Mongolia, the Korean Peninsula, and Japan. The tectonic development of the region is recorded in a series of cratons, craton margins, oceanic plates, active rifts, and orogenic collages of the present-day Northeast Asia continent. The collages consist of tectonostratigraphic terranes that are composed of fragments of igneous arcs, accretionary-wedge and subduction-zone complexes, passive continental margins, and cratons. The tectonostratigraphic terranes are overlapped by continental-margin-arc and sedimentary-basin assemblages. The tectonic history of cratons, craton margins, oceanic plates, terranes, and overlap assemblages is complex due to extensional dispersion and translation during strike-slip faulting that occurred subparallel to continental margins.