E-catalog        

Библиогр.: с. 36-39

This is a synthesis of recent geochemical evidence from Cambrian granitic, gabbro-monzonitic, and few small gabbro-foidolitic intrusions in the Early Paleozoic Kuznetsk Alatau orogen (western Central Asian Orogenic Belt, Siberia). Their origin is attributed to late- and post-orogenic regional magmatism which produced different rock types sharing basic similarity in isotope systematics and trace-element compositions. The εNd(t) values of ~2 to 8.7 in main igneous lithologies record the extent of interaction between depleted and enriched mantle. Concurrent increase of initial 87Sr/86Sr (0.7039–0.7058) ratios and δ18О values (6.5–13 ‰) in rocks and minerals, as well as 207Pb enrichment (207Pb/204Pb(t) = 15.5–15.7), indicate crustal contamination of mantle melts. Trace-element patterns in the rocks correspond to a mixed IAB + OIB source. The alkaline and subalkaline rocks of the Kuznetsk Alatau area share trace element and isotopic similarity and apparently emplaced almost synchronously late during a regional-scale tectonic event. The synthesized data show that Cambrian magmatism in the area involved mixed mantle and continental crust melt components and acted in a complex tectonic setting of the former active margin of the Paleo-Asian Ocean impacted by a mantle plume.