Correlation of Precambrian basic magmatism in lithospheric blocks of Western and Northern Prebaikalia (according to geochemical data)

A comparison is made between the geochemical compositions of metabasic rock s from Western and Northern Prebaikalia. In geochemistry metagabbros from t he Kocheriki block are most similar to metabasic rocks of the Nyurundukan s eries, various parts (plates) of which are considered to have formed in the settings of a back-are basin and a primitive island are. In addition, the Kocheriki gabbros are similar to metatholeiites of the Ol'khon series, whic h also formed in the setting of a marginal sea but, unlike the gabbros, are associated with abundant metasediments and the Anga volcanosedimentary ser ies - the product of a mature island are. The Kocheriki block passed throug h two stages of metamorphism. It formed in space and time separately from t he Sarma black and merged with the latter by the second stage of metamorphi sm, 445 Ma ago, as a result of tectonic processes. Metabasic rocks of the S arma block are compositionally close to gabbros of the Kocheriki block, and dikes of basic composition in granites of the Primorsky complex are somewh at closer to metabasic rocks of the Boguchany block in Northern Prebaikalia , which seem to be of within-plate origin. "Diorite-like" dikes are most li kely the products of metasomatic reworking of basic dikes and granites duri ng cataclasis. Dikes in granites might have formed synchronously with the c onformable horizons of basic rocks of the Sarma series.