Greater South China extended to the Khanka block: Detrital zircon geochronology of middle-upper Paleozoic sandstones in Primorye, Far East Russia

摘要

In order to examine paleogeographic link between Primorye and Japan with respect to other continental blocks in East Asia, middle-upper Paleozoic shallow marine sandstones of the Khanka block and Sergeevka belt were analyzed by LA-ICPMS U-Pb dating of detrital zircons. The age spectra of detrital zircons of the Devonian Lyutorgian Formation, Lower Carboniferous Shevelevka Formation, and Permian Lyudyanza Formation in the Vladivostok-Nakhodka area share more or less the same age range; the majority of detrital zircons are dated 500-400 Ma (Cambrian to Silurian). These ages are common in previously dated granitoids with arc signature in Primorye and also in Japan, thus suggest a probable derivation from a single subduction-related Paleozoic batholith belt along the Pacific rim. The zircon age spectra of the Devonian and Carboniferous sandstones show similarities to those of coeval sandstones in NE and SW Japan. The middle-late Paleozoic sedimentary basins in Primorye and Japan commonly had a provenance featuring early Paleozoic arc rocks. In addition, all of these Paleozoic terrigenous clastics in Primorye and Japan consistently contain Proterozoic zircons. Occurrence of Meso- to Neoproterozoic (ca. 1500 and 600 Ma) grains positively suggests a link to the South China block, as other blocks in East Asia lack crusts of this age of pan-African affinity. The common age spectra of detrital zircons of the Paleozoic sandstones in southern Primorye and NE-SW Japan support the concept of "Greater South China" that is comprised of conterminous South China to extend to Japan/Primorye, which is consistent with the mutual similarities recognized in Paleozoic marine fauna. Paleozoic South China was much larger than previously imagined, and this greater size, almost double the present conterminous South China, requires much larger area in the paleogeographical reconstruction of Rodinia.