Objective
Modern ideas on the tectonic evolution of North-East Russia are based mainly on studies of the Mesozoic Verkhoyansk-Chukotka and the Cenozoic Koryak-Kamchatka thrust-fold belts, two areas that are different, especially in crustal thickness, structural pattern and tectonic history. The Verkhoyansk-Chukotka thrust-fold belt was formed as the result of collisional processes involving large blocks of continental crust, whereas Koryak-Kamchatka thrust-fold belt is an accretionary structure typical of the Pacific margin. The relationship between these two contrasting thrust-fold belts is the key to understand accretionary tectonics of North-East Russia and many aspects of the Pacific and North-East Asian plates interaction.
The project will focus on the late Mesozoic Western Koryak thrust-fold belt located between the Verkhoyansk-Chukotka and Koryak-Kamchatka thrust-fold belts. The Western Koryak thrust- fold belt is clearly expressed in magnetic and gravity field data and its structural trend is discordant to those of the Verkhoyansk-Chukotka and Koryak-Kamchatka thrust-fold belts. The study area consist of various tectonostratigraphic units (terranes) including high-grade metamorphic rocks, island arc complexes, ophiolite, melange, etc., that range in age from Precambrian to Mesozoic and contain evidence of interaction between Pacific and North-East Asian plates for a very long time interval (more then 450 M. yr.). Of particular interest are the early Palaeozoic ophiolites, the oldest in North-East Asia.
The project will therefore focus on the most representative example of accretionary tectonics in North-East Russia. During long-term research, participants of proposals have compiled significant information on the stratigraphy, tectonics and geochemistry leading to the suggestion that the Western Koryak thrust-fold belt was formed along a long-lived convergent margin. The main task of the proposed project is to test this hypothesis and to produce model of the Western Koryak tectonic evolution. The following points are planned to be investigated: Tectonic setting of terranes; Structural analysis of terranes with emphasis on terrane-bounded fault zones; Geochemical and isotope characteristics of the island-arc and oceanic complexes; Study of accretionary prisms and melange; Age and nature of ophiolite terranes; Composition, age and nature of metamorphic complexes. It requires extensive field and laboratory research including modern technologies (e.g. microprobe, some isotope and radiometric analysis) widespread in the INTAS countries and still not available to Russian geologists. Therefore, one of the main aims of the proposed project is to carry out joint field researches in North-East Russia involving experts from both INTAS and NIS countries. Such field expeditions will provide an opportunity to exchange ideas, data and to collect additional samples for laboratory work. Another idea of co-operation is to assist Russian scientists (especially young scientists) to be involved in the international scientific community. For this reason we propose several visits by Russian participants to Edinburgh and Brest universities.
The project will thus not only improve knowledge of accretionary tectonics and related processes, but also stimulate international co-operation and exchange of information in a practical and timely manner.
Topic(s)
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EH9 3JW Edinburgh
United Kingdom