The blueschist-bearing Qiangtang metamorphic belt (northern Tibet, China) as an in situ suture zone: Evidence from geochemical comparison with the Jinsa suture

Eclogites in the interior of the Tibetan Plateau and their geodynamic implications

“…The protolith of metasediments from central Qiangtang generally is a mature continental sandstone-mudstone assemblage with a high content of quartz, which is consistent with geochemical [42] and Nd isotopic [43] analyses. Preliminary SHRIMP U-Pb zircon dating of blueschists and eclogites shows that there are plenty of Paleozoic and Precambrian zircons in these rocks (ref.…”

“…The relatively low Mg contents of garnet (X Mg < 0.09) and clinopyroxene (X Mg ~0.53-0.68) compared to mantle eclogites imply that the central Qiangtang eclogites are very unlikely of mantle origin [10] . Geochemical analyses of the blueschists and eclogites show that they are characterized by high TiO 2 content (> 2%) and extreme enrichment of light-rare-earth-elements, as well as no depletion of Nb and Ta, suggesting that their protoliths must be the continental basalts similar to the Emeishan basalts [42] . Clearly, the central Qiangtang metamorphic belt represents a deep-seated passive continental margin [10,42,43] , composed dominantly of the Precambrian and Paleozoic shelf facies sediments interbedded with minor basalts.…”

Tectonic evolution and high-pressure rock exhumation in the Qiangtang terrane, central Tibet

“…Maximum temperature and pressure ranges are 410-460 • C and 2.0-2.5 GPa. All authors agree that the exhumation was related to subduction, although the mechanism and plate tectonic setting remains under debate ( Kapp et al, 2003b;Zhang et al, 2006b;Li et al, 2009;Pullen and Kapp, 2014).…”

“…They proposed that the Qiangtang terrane was separated into a northern and a southern terrane by the Paleo-Tethys Ocean. As a result of northward subduction of this PaleoTethys underneath the north Qiangtang terrane (NQT), highpressure rocks and subduction mélange were thrusted southward onto the south Qiangtang terrane (SQT) (Zhang et al, 2006b;Zhai et al, 2011b;Zhao et al, 2014). The inferred suture between the two terranes is called the Longmu CoShuang Hu suture (short "Shuanghu" suture).…”

Paleo-Tethyan evolution of Tibet as recorded in the East Cimmerides and West Cathaysides

“…3; Lepvrier et al, 2008). Considering the distinct Permian sedimentary sequences and faunal successions of the Cimmerides and Cathaysides, (Metcalfe, 2002;, we interpret the Longmu Tso ShuanghuChangning Menglian suture zone as the main Paleo-Tethyan suture zone (Li, 1987;Li et al, 1995;Metcalfe, 2006;Zhang et al, 2006a, b;Zhai et al, 2011a, b).…”