川西前陆盆地侏罗纪构造层序地层格架内沉积充填特征

摘要

为了研究侏罗纪龙门山造山带与川西前陆盆地盆山关系,以侏罗系3个构造层序(TS1 - TS3)体系域(BE,BW)为研究的基本单元,通过对川西前陆盆地构造层序充填特征的研究发现:龙门山造山带构造运动与沉积盆地的构造层序充填特征吻合较好,并且龙门山造山带北段,中段,南段在各期次构造活动中活动情况具有差异.TS1 BE期,川西前陆盆地北部和南部地区都发育有冲积扇-扇三角洲沉积,中部地区为三角洲沉积,显示该期龙门山造山带北段和南段构造活动可能较为剧烈,中段相对较平缓.TS1BW期,川西前陆盆地北部和南部地区都以湖泊沉积为特征,仅在川西前陆盆地中部地区发育有三角洲沉积,显示本期龙门山造山带构造活动不发育,较为平稳.TS2BE期,川西前陆盆地北部和南部地区自西而东为冲积扇,三角洲一滨湖、浅湖沉积环境,中部地区为三角洲沉积,显示龙门山造山带又一次剧烈隆升,且北段和南段活动较为剧烈,中段相对较弱.TS2BW期,层序充填结构表明龙门山造山带北段和中段活动情况再次趋缓,但南段构造活动仍然较为活跃.TS3BE期,川西前陆盆地北部和南部地区发育有冲积扇沉积,中部则以三角洲-湖泊沉积为特征,显示该期龙门山造山带北段和南段都发生了较为剧烈的构造隆升运动,龙门山造山带中段,构造活动相对较为平缓.TS3BW期,龙门山造山带北段和中段构造活动减弱,南段活动持续加剧,于芦山两河口地区沉积有巨厚的冲积扇沉积物.%In order to knowing the relationship between the uplifting of Longmenshan Orogen and the filling characteristics of western Sichuan foreland basin during Jurassic, this article detailed studied the tectonic sequence filling characteristics in western Sichuan foreland basin. According to the characteristics of three tectonic sequences with obvious deposited structures and sediment, founding that Longmenshan Orogen segmental uplifted during Jurassic. During the stage of TSIBE, alluvial fan and delta developed in the north and south part of western Sichuan foreland basin, braided river delta developed in the middle part of western Sichuan foreland basin, this situation reflected the tectonic movement of Longmenshan Orogen was different, the south part and north part might be hard, the middle part might be kind. During the stage of TSI BW, delta and lake was the mainly setting of western Sichuan foreland basin, and the tectonic movement of Longmenshan Orogen might be kind, too. During the stage of TS2BE, alluvial fan developed in the north part and south part of western Sichuan foreland basin again, and delta developed in the middle part, showing the tectonic movement of Longmenshan Orogen reactive, the north and the south hard again, the middle relative quiet During the stage of TS2BW, the tectonic sequence filling characteristics of western Sichuan foreland basin reflected the tectonic movement of the north part and the south part peaceful, but the south part might be serious. Like the stage of TSI BE, TS2BE, during the stage of TS3BE, alluvial fan was the main setting of the north part and the south part of western Sichuan foreland bain, delta-lake was the main setting of the middle part, showing the tectonic movement of the north part and the south part of Longmenshan Orogen severe, the middle part was quiet. During the stage of TS3BW, the tectonic movement of the north part and the middle part of Longmenshan was kind, the south part, alluvial fan sediments found in the Lushan-Iianghekou district