Mongush A.A.,Russian Academy of Sciences |
Lebedev V.I.,Russian Academy of Sciences |
Kovach V.P.,Institute of the Precambrian Geology and Geochronology |
Sal'nikova E.B.,Institute of the Precambrian Geology and Geochronology |
And 6 more authors.
Russian Geology and Geophysics | Year: 2011
In the Tannu-Ola zone, there are island-arc (Late Vendian) and subduction-accretionary (first half of the Early Cambrian) complexes whose mantle sources were generated from melts produced in suprasubduction conditions as a result of the melting of mantle wedge peridotites. The island arc, whose fragment is present in the Tannu-Ola zone, formed tentatively at 570 Ma and ceased as an individual structure at the Vendian-Cambrian boundary, though the subduction continued till the middle Early Cambrian. From the Vendian-Cambrian boundary to middle Early Cambrian, the accretion of island-arc, back-arc, oceanic, and metamorphic structure-lithologic complexes took place at this segment of the Central Asian Fold Belt. From middle to late Early Cambrian, the Tannu-Ola zone was an active continental margin, where basalts with island-arc characteristics, quartz microdiorites of adakite composition, basalts, dolerites, and quartz microdiorites of intraplate type, and diorite-tonalite-plagiogranite association of island-arc type formed. To explain the spatial and temporal conjugation of different magmatism manifestations on the active margin, we applied the slab-window model. © 2011.