Paleozoic Granitoids of the Southern Part of the Voznesenka Terrane (Southern Primorye): Age, Composition, Melt Sources, and Tectonic Settings

摘要

This paper presents data on the geological position, geochemistry, age, and isotopic characteristics of the granitoids of the southern part of the Voznesenka terrane, Southern Primorye (Muraviev-Amursky Peninsula and its vicinities). All of the studied granitoids were formed in three stages: the Ordovician, Silurian, and Permian. The Silurian and Permian ages of the granitoid intrusions have been previously determined (Ostrovorussky Massif, 432-422 Ma, and 250 +/- 4 Ma, early and late associations, respectively; Sedanka massif, 261 +/- 3 Ma). The granites of the Artem and Nadezhdinsky massifs define an U-Pb zircon age of 481 +/- 6 and 452 +/- 4 Ma, respectively. The geochemical and isotope data show mainly the crustal nature of the granitoids. Their formation was related to melting of relatively immature rocks of the continental crust (mafic-intermediate volcanic rocks). The Nd isotope composition of the granitods (TNd(DM-2) = 1.3 Ga) indicates the absence of the mature ancient crust at the basement of the southern Voznesenka terrane. The maximum contribution of mantle sources to the granite formation is recorded in the Permian associations. A comparison of the peaks of intrusive magmatism in the southern part of the Voznesenka terrane and adjacent territories suggests that the formation of the granitoids of the Muraviev-Amursky Peninsula and its vicinities was caused by the interaction of continental blocks with two oceanic basins: the Paleoasian (and its fragments) and Paleopacific ones.