闽北麻源群变质岩的流体包裹体研究：岩石抬升过程的p－T－t

A STUDY OF FLUID INCLUSIONS ON METAMORPHIC ROCKS OF MAYUAN GROUP, NORTHERN FUJIAN PROVINCE:UPLIFT P-T-t PATHS

根据闽北麻源群变质岩流体包裹体的世代关系和显微测温研究，获得了麻源群变质峰期之后抬升过程ｐ－Ｔ－ｔ轨迹，推测岩石遭受剪切变形事件的温压条件为ｐ＝８５～１００ＭＰａ，Ｔ＝２６５～２８５℃。本区流体演化早期以ＣＯ２为主，晚期以水溶液为主。

Fluid inclusions are studied in quartz veins and migmatitic veins in Mayuan Group, Northern Fujian province. Three types of fluid inclusions, CO2 , CO2-H2O and aqueous inclusion are identified. Petrographic studies of fluid inclusions show that they are of different generations. Based on the isochores of fluid inclusion according to the microthermometries and their time sequence of entrapment, the uplift pT-t paths of Manshan Formation after peak metamorphism and Dajinshan Formation after migmatization have been inferred. They display a clockwise direction and convex toward the temperature axis. The P-T condition at which the shear deformation of quartz veins occurred is P=85─100MPa, T=265─285℃. The fluid composition evolved from CO2-rich fluid in the early period to aqueous fluid later. CO2 is derived from host rocks.