Pseudosection Modelling of Garnet Blueschist from Rongma Area, Central Qiangtang, North Tibet: Implications to the Tectonic Evolution of Central Qiangtang
摘要
Within Qiangtang Basin, northern Tibet, a metamorphic belt divides the Qiangtang Basin into the northern and southern blocks and was designated as the central Qiangtang metamorphic belt. In this paper, the authors investigate the garnet-bearing blueschists from Rongma area of central Qiangtang in northern Tibet, where is critical to understanding the tectonic evolution of the central Qiangtang metamorphic belt. The mineral assemblage in these rocks is characterized by porphyroblastic garnet set within a matrix of fine-grained amphibole, white mica, epidote, chlorite, albite and quartz with accessory rutile, titanite and apatite. The Mn content of the garnet porphyroblasts decreases from core to rim, whereas the Fe and Mg contents show an increasing trend, respectively.