摘要
川西类前陆盆地与龙门山造山带为一个典型的盆—山系统。从川西地区的层序充填特征出发,分析了龙门山造山带晚三叠世隆升作用与川西类前陆盆地充填过程的耦合关系。认为盆内充填的由砂砾岩组成的类磨拉石建造和三个结构明显的构造层序,反映了龙门山晚三叠世隆升强度的幕次变化;同时盆地北部、中部和南部地区层序结构的差异性揭示了龙门山造山带隆升分段性:受印支运动的影响,北段于小塘子期(TS1BW)开始隆升,向盆地供源,形成以中细粒沉积物为特征的三角洲沉积,区别于盆地中部和南部地区来自东部川中古隆起的碎屑沉积物;须三期(TS2BW),南部地区以发育来自西部造山带的低成熟度砂岩为特征,标志着龙门山南段亦开始隆升;由于须三(TS2BW)与须四(TS3BE)间的安县运动,中段的海湾消失,龙门山全面隆升,前陆盆地最终成型,形成山前带状展布的河流—三角洲体系。
In order to knowing the relationship between the uplifting of Longmenshan Orogen and the filling characteristic of western Sichuan foreland-like basin during late Triassic,this article guided by sequence stratigraphy and sedimentology,integrated researched the outcrops,cores,then detailed studied the tectonic sequence filling characteristic in western Sichuan foreland-like Basin,founding when the setting of western Sichuan foreland-like Basin changed form marine to continental,and how was the stage.The main achievements as follow were obtained：①From late Triassic to Jurassic,the environment of western Sichuan foreland-like basin was difference,at the beginning,the setting was marine,then changed to transition,finally changed to continental environment,and the key stage was Anxian tectonic movement. ②The tectonic movement of Longmenshan orogenisc belt was eposide,the movement of each part of Longmenshan orogenisc belt was different form late Triassic to Jurassic,and the adjacent area＇s setting was different too.So the sedimentary models built up in different place or at the different time was difference. ③During the Ma＇antang Stage（TS1BE）,tectonic movement of Longmenshan orogenisc belt was weak and entire underwater,mixed shelf is the mainly setting of the western Sichuan foreland baisn and sponge reefs found in the Anxian district.During the Xiaotangzi Stage（TS1BW）,the north part of Longmenshan orogenisc belt uplifted firstly and marine delta found in the corresponding place of western Sichuan foreland basin. During the stage of TS2BE,tectonic movement of the north part of Longmenshan orogenisc belt rivived,which led sedimentary structures with rapid filling characters forming in the north-west part of western Sichuan foreland-like basin,and tectonic movement of the middle part and the south part of Longmenshan orogenisc belt remainly quiet.In this situation,form west to east,marine delta to coastal-shallow sea setting formed in the north-west Sichuan foreland-like baisn,and coastal-shallow sea to marine delta setting formed in the other place.During the stage of TS2BW,the south part of Longmenshan orogenisc belt uplifted,too.The fragmentary material stripped form the south part and the north part of Longmenshan orogenisc belt were transported into the western Sichuan foreland-like basin.During this time,tectonic movement of the middle part of Longmenshan orogenisc belt was not obvious,the environment of western Sichuan foreland-like basin remain transition. When the time come to the end of TS2BW and the begin of TS3BE,the middle part of Longmenshan orogenisc belt uplifted,and the sea water dismiss form the western Sichuan foreland-like basin.After that,fluvial delta and lake were the mainly setting of western Sichuan foreland-like basin.
出处
《沉积学报》
CAS
CSCD
北大核心
2011年第4期622-630,共9页
Acta Sedimentologica Sinica
基金
国家自然科学基金重点项目(批准号:40739901)资助
