【摘要】 采用磷灰石裂变径迹年龄方法,对米拉山断裂两侧的岩体隆升和剥露情况进行了研究.通过对比两侧FT年龄反映的岩体剥露与隆升速率,发现始新世末至渐新世早期,米拉山断裂北侧隆升速率比南侧快.这种差异隆升是米拉山断裂在始新世末至渐新世早期的由北向南逆冲推覆活动造成的.之后,断裂两侧的剥露速率逐渐接近,反映了米拉山逆冲推覆断裂活动在逐渐减弱.中新世中期之后,米拉山断裂两侧岩体隆升明显加快,并呈现南快北慢特征,这种差异隆升反映米拉山断裂发生正断层活动.更多还原

【Abstract】 Apatite fission track geochronology is employed in revealing exhumation of the Mila-Mountain fault walls.It is indicated that significant differential exhumation occurred between the northern and southern wall since late Eocene to early Oligocene.The northern wall exhumed faster,with apparent exhumation.This differential exhumation indicates an up-to-the-south thrusting of the Mila-Mountain fault during Late Eocene to early Oligocene.And subsequently,the differential exhumation between fault walls vanished gradually,which implies a weakening or ceasing of the fault thrusting motion.Postdate middle Miocene,exhumation accelerates significantly in both fault walls.The faster southern-wall exhumation suggests that the MilaMountain Fault occurred as a normal fault.更多还原