Metamorphic P-T Paths of Blueschist and Lawsonite-Bearing Phengite Schist in Lanling Area,Central Qiangtang
Wang Shilin
Du Jinxue
Wang Genhou
Liang Xiao
Abstract：The blueschist is lenticularly wrapped in the lawsonite-bearing phengite schist in Lanling area,central Qiangtang. The lawsonite included in quartz,which,on its part,is enclosed in porphyroblastic garnet in the phengite schist,is discovered for the first time.Studying on the metamorphic P-T paths of the blueschist and lawsonite-bearing phengite schist is important for the further research of the formation and evolution of the Longmu Co-Shuanghu low-temperature and high-pressure meta-morphic belts.The detailed petrography and phase equilibria modeling reveal that the blueschist experienced a more obvious thermal relaxation process(the peak pressure conditions are 490 ℃ and 2.4 GPa,and the peak temperature conditions are 540℃, 2.1 GPa)while the lawsonite-bearing phengite schist has barely experienced a thermal relaxation process(the peak temperature and pressure conditions are 530℃ and 2.2 GPa).The similarity of the retrograde P-T paths of the blueschist and lawsonite-bearing pheng-ite schist reveals that the exhumation of the blueschist from Lanling area,central Qiangtang,may have resulted from the exhumation of the low-density lawsonite-bearing phengite schist,which carried the denser blueschist to the earth's crust levels.
Keywords：Tibetan plateaucentral QiangtangLanlingblueschistlawsonite-bearing phengite schistmetamorphic P-T pathpetrology
Publication Date：2018-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：16( 1237-1252 )