龙门山中段推覆体内流体包裹体特征

CHARACTERISTICS OF FLUID INCLUSIONS IN THE CENTRAL LONGMENSHAN NAPPE

采用流体包裹体研究和地质研究相结合的方法 ,研究了龙门山茂汶推覆体和彭灌推覆体内流体特征 ,讨论了盆山间流体的温度、盐度变化规律和流体可能的流动方向。研究表明推覆体内流体的均一温度为 1 0 1 .9～ 2 2 6℃ ,压力为 1 3 .5～ 1 8.0 MPa,密度为 0 .91～ 1 .1 4g/cm3。从茂汶推覆体至彭灌推覆体 ,流体的盐度具有增高、温度总体有降低特征 ;靠近造山带一侧的盆地内流体 ,其盐度和温度明显低于造山带内推覆体中的流体。在推覆体内部 ,从推覆体前锋到主滑面流体的均一温度逐渐降低。断层是流体运移的主要通道 ,盆山间流体有运移和热交换 ,盆地流体有可能通过滑动面被带入造山带内部。

Combining fluid inclusion studys with geological research, the authors study characteristics of the fluid in the Maowen nappe and Pengguan nappe in central Longmenshan and discuss the change of temperature and salinity, and the possible migration path of the fluid. The studies indicate that homogeneous temperature, pressure and density of the fluid in the nappes were 101.9~226℃, 13.5~ 18.0 MPa and 0.91~1.14 g/cm 3. The salinity increased while temperature decreased from the Maowen nappe to the Penguan nappe. Close to orogen, the salinity and temperature of the fluid in the western Sichuan forland basin were lower than that in the nappe located in orogen. The homogeneous temperature in the nappe decreased gradually from the nappe front to the fault surface underlying the nappe. Fault is the main channel way for fluid migration; there was exchange of heat flow and fluid migration and basin fluid may be transported into orogen.