Early Ordovician granites from the South Qiangtang terrane, northern Tibet: Implications for the early Paleozoic tectonic evolution along the Gondwanan proto-Tethyan margin
Journal
Lithos
Journal Volume
220-223
Pages
318-338
Date Issued
2015
Author(s)
Abstract
Early Ordovician granites occur in the Gemuri and Bensong Co areas of the South Qiangtang terrane, northern Tibet, and LA-ICP-MS zircon U-Pb dating reveals that the magmatism took place between 486 and 480Ma. The Geochemical features of these Early Ordovician granites are comparable to those of high-K, calc-alkaline S-type granites. They exhibit negative values of zircon εHf(t) (-8.5 to +1.7) and whole-rock εNd(t) (-8.1 to +0.5), as well as old zircon Hf model ages (TCDM=1349-1992Ma) and whole-rock Nd model ages (TCDM=1145-1804Ma). These Early Ordovician granites can be attributed to partial melting of the Paleoproterozoic metasedimentary rocks of the South Qiangtang terrane, while minor amounts of mantle-derived components were introduced into their magma sources. Taking into account previous data, we propose that the Early Ordovician granites developed in a post-collisional tectonic setting and that they were related to the collisional accretion of Asian microcontinental fragments (such as the South China, North China, Tarim, and Qaidam-Kunlun terranes) that took place as a result of oceanic subduction along the Gondwana proto-Tethyan margin during the early Paleozoic.
SDGs
Type
journal article