西藏南部聂拉木地区侏罗纪—白垩纪盆—山转换过程中的沉积学响应

Jurassic and Cretaceous Sedimentary Record during the Basin-orogeny Transition in the Nyalam area, Southern Tibet, China

西藏南部聂拉木—定日地区沉积地层记录着侏罗纪被动大陆边缘到白垩纪前陆盆地的盆—山转换演化历史。侏罗纪发育巨大的海侵—海退沉积序列,晚侏罗世喜马拉雅特提斯海底扩张速度明显加快,从0.32cm/a上升为1.24cm/a。前陆盆地演化分为早期深水复理石和晚期海相磨拉石两个阶段。前陆早期发育向上急剧加深的深水砂泥质复理石建造、黑色页岩建造和岛弧型火山岩建造沉积;前陆晚期海相磨拉石沉积总体表现为向上变粗、变浅的沉积序列。

The evolutionary history from the Jurassic passive continental margin to the Cretaceous foreland basin of the northern Indian plate where are located in the northern Himalayas of the southern Tibet. The huge transgress-regressive cycle has been developed during the Jurassic. The Himalayan Tethysan ocean-floor spreading velocity is obviously sped up at late Jurassic, from about 0.32 cm/a of the early and middle Jurassic up to 1.24 cm/a of the late Jurassic. The Cretaceous Himalayan foreland basin evolution is divided into the two stages that included the early deepwater flysch basin and the late marine molasse basin in the southern Tibet. The upward rapid deepening sand-muddy flysch formation and black shale formation and island-arc volcanic rocks are developed in the early foreland （early Cretaceous）, the upward shallowing and coarsening marine molasse formation in the late foreland （late Cretaceous-Eocene）. The Himalayan Tethysan in the southern Tibet was finally closed at about 40-38Ma of the mid-late Eocene.