Shniukova K. Magmatism in the Junction Zone of the Western Black Sea, Mountainous Crimea and Scythian Platform

A new region of magmatism which hasn't analogues onshore has been found in the junction zone of the Scythian Platform and Western Black Sea, named Lomonosov submarine massif (LSM). An island-arc, subduction-related origin has been established for the LSM magmatism. It was considered to be a fragment of paleoisland arc. Three island-arc series have been divided among the LSM volcanic rocks, namely boninite, calc-alkaline and shoshonite. They form a clear petrochemical zonality within LSM. Three plutonic series have been divided, too. Two of them, namely plagiogranite and trondjemite, are proved to be connected with SSZ ophiolites. By comparison between LSM and magmatic site in the South-Western Crimea the lattest was divided into western part (magmatism of passive continental margin) and eastern part (fragment of ophiolites related to LSM). Other one site, also being of passive continental margin origin, has been found and studied offshore South-Western Crimea on the continental slope. For the first time the age and geochemical peculiarities of zircons from different rocks have been determined. The continental crust of the Northern Black Sea periphery was proved to be consolidated in the early Proterozoic. Few not one stages of the subduction-related magmatism were established in the region. LSM island-arc series may be formed by the participation of crust material due to the slab roll-back which is considered to form Western Black Sea.