Geochemical evidence for the ophiolitic nature of the gabbros,gabbroanorthosites, and ultramafic rocks of the Gerbikan fragment of the Baladek Massif of the southeastern framing of the North Asian craton

The Baladek Massif represents a tectonic block located at the boundary between the SE framing of the North Asian craton and the fold structures of the Galam terrane of the Mongol-Okhotsk fold belt. According to the existing concepts, the rocks of this massif are regarded as Precambrian complexes of the aforementioned craton. This paper reports the results of studying the fragment of the Baladek Massif in the Gerbikan River basin. New geochemical data obtained on the gabbros, gabbroanorthosites, and ultramafic rocks testify to their similarity with typical ophiolite complexes. An underlying complex of metamorphic ultrabasic rocks, a layered complex of pyroxenites and “cumulate” gabbros, gabbroanorthosites, and a complex of isotropic gabbros were distinguished within this fragment. It is highly possible that the basic volcanic rocks and jaspers of the Silurian-Lower Devonian sequences of the Galam segment of the Mongol-Okhotsk fold belt also belong to the inferred ophiolite complex.     

Results of the Study of Zircon (SIMS) from Granitoids of the Konstantinovskii Stock (Area of the Sukhoi Log Gold Deposit): Age,Sources, and Geological Consequences

Doklady Earth Sciences - The results of U–Pb geochronological (SIMS) study of zircons from granitoids of the Konstantinovskii Stock located 6 km from the Sukhoi Log gold deposit are reported....     

The Early Cambrian Age and Crustal Sources of Granitoids of the Goryachinskiy Pluton (Northern Baikal): Geodynamic Implications

Doklady Earth Sciences - New results of U–Pb zircon and Nd–isotope analyses of the Goryachinskiy Pluton adakite granites have been obtained. The pluton is exposed along the Baikal coast...     

The Vendian age of granodiorites and plagiogranites of the Tallainskii complex (Baikal–Muya Belt): U–Pb isotope data

This work presents the results of U–Pb isotope dating of zircons from granodiorites and plagiogranites of the Tallainskii gabbro–granodiorite–plagiogranite complex of the Karalon–Mamakan zone of the Baikal–Muya belt, ascribed to the Tallainskii pluton. The age datings obtained for granodiorite of the Eleninskii massif (605 ± 6 Ma) and plagiogranite of the Ust-Berezovo massif (609 ± 6 Ma) are in close agreement within the limits of error. Taking into account previously published data, the emplacement of the Tallainskii complex occurred within the age interval of 615–603 Ma in connection with postcollision extension. The “island arc” geochemical characteristics of granodiorites and plagiogranites can be explained by magmatic differentiation and (or) participation in the formation of a melt source enriched in the suprasubduction component involved in petrogenesis during the preceding Neoproterozoic period.