The metamorphic evolution and tectonic significance of the Sumdo HP–UHP metamorphic terrane, central-south Lhasa Block, Tibet

• DOI: 10.1144/sp474.4
• Publication Date: 2018-03-22T12:10:39Z
• Authors: Cong Zhang; Thomas Bader; Herman van Roermund; Jingsui Yang; Tingting Shen; Tian Qiu; Peng Li
• Keywords: Metamorphic core complex

Abstract The Lhasa terrane, forming one of the main tectonic components Himalayan–Tibetan orogen, has received a lot attention as it records multiple episodes plate spreading, subduction and collision within realm Paleo-Tethys Ocean. A review mineralogical, petrological, geochemical geochronological data eclogites, associated blueschists garnet-bearing mica schists from Sumdo high- ultrahigh-pressure metamorphic (HP/UHP) complex in central/southern part is present here so that origin tectono-metamorphic evolution this important suture can be deduced. By re-evaluating original published P – T conditions for rocks Complex, we consider Complex experienced low temperature HP/UHP conditions, characteristic fast (and exhumation) typical oceanic zone setting. wide spread maximal peak could reduced size due to thus far unknown inconsistencies usage applied geothermobarometric techniques. remaining ( c. 200°C/10 kbar) regions explained by mechanism individual slices were subducted different depths followed juxtaposition on their way back surface. re-consideration isotopic ages eclogites demonstrates opening Ocean, located between two major was initiated prior 280 Ma eclogite facies metamorphism likely late Permian 260 Ma) early Triassic age (245–225 Ma), recording crust. closure Ocean resulted, no earlier than 210 Ma, final northern southern blocks. This event may have been triggered initial Bangong–Nujiang Tethys north.