四川龙门山地区中泥盆统金宝石组混合沉积特征

四川龙门山地区是中国泥盆系出露较好、研究程度较高的地区。中泥盆统金宝石组发育由碎屑岩、碳酸盐岩、混积岩组成的混积沉积。本研究以平武县平驿铺剖面和北川县甘溪剖面为切入点，基于实测资料和薄片观察对金宝石组沉积相开展详细研究，认为龙门山地区中泥盆统金宝石组发育河流、碎屑滨岸、陆棚和碳酸盐岩缓坡4种沉积相，沉积演化经历了2个沉积旋回。金宝石组以相混合和原地混合2种方式形成混合沉积。相对海平面的变化、陆源碎屑的供应、碳酸盐生产速率和古气候是引起相混合的主要控制因素，波浪和风暴浪则是引起陆源碎屑和碳酸盐组分混合沉积的主要作用方式。对金宝石组沉积序列、沉积特征及沉积演化过程的研究，有利于增进对龙门山地区泥盆系沉积古环境的认识。

Mixed sedimentation of the Middle Devonian Jinbaoshi Formation in Longmen Mountain area,Sichuan Province

The Devonian of Longmen Mountain area is an important and highly studied area. The Middle Devonian Jinbaoshi Formation is composed of clastic rocks,carbonate rocks and mixed rocks. In this paper,the sedimentary facies of the Jinbaoshi Formation were studied in detail based on thin section observation and the measured data of the Pingyipu section in Pingwu County and Ganxi section in Beichuan County. The results show that the Middle Devonian Jinbaoshi Formation in Longmen Mountain area has four sedimentary facies,namely fluvial,clastic shore,shelf and carbonate ramp. The sedimentary evolution experienced two cycles. The mixed sedimentation of Jinbaoshi Formation was produced by facies mixing and in situ mixing. The change of relative sea level,terrigenous clastic supply,carbonate production rate and paleoclimate are the main controlling factors for the mixed deposition of facies mixing,while wave and storm waves are the main mechanisms for the mixed deposition of terrigenous clastic and carbonate components. The study on the sedimentary sequence,sedimentary characteristics and sedimentary evolution of the Jinbaoshi Formation is helpful to improve the understanding of the sedimentary paleoenvironment of the Devonian in Longmen Mountain area,Sichuan Basin.