龙门山构造带南段晚第四纪河流阶地和构造地貌分析

《龙门山构造带南段晚第四纪河流阶地和构造地貌分析》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、腹陆区。在永富断裂两侧，坡度和起伏度都是一个高值区，而地形上，则呈下降趋势。但是，对于地形剖面，在五龙断裂和陇东断裂之间存在一个峰值，但相应地该段起伏度和坡度变化则较平缓。而对小关子断裂和五龙断裂之间，起伏度、坡度和地形都为高值区，局部受到河流的影响为低值。（4）在地形剖面上，五龙断裂和小关子断裂（双石-大川断裂）之间地势明显隆起，尤其是在p2条带剖面上最为明显，且地形变化规律与起伏度、坡度一致。而SK/L剖面也有类似的规律，R2~R4河流横跨五龙断裂和小关子断裂，在二者之间，SL/K值有明显升高，意味着河道变陡。而岩性变化与SL/K值变化不一致，说明SL/K值变化的主要原因是构造活动。

2、这可能暗示，在五龙断裂和小关子断裂之间，发育有隐伏构造，其活动导致了上覆的阶地拱曲变形、河道变陡和高地貌。在小关子断裂之下，阶地趋于平缓，说明小关子断裂（双石-大川断裂）对褶皱变形有一定的控制作用。龙门山构造带南段的隐伏断层和小关子断裂的活动性应引起重视。关键字：龙门山南段、河流阶地、地貌参数、隐伏构造5万方数据AbstractLongmenshanThrustBelt(LTB)locatesbetweentheTibetplateauandSichuanBasin.SinceMesozoicperiod,therewereatleasttwoshorteningeventsthatma

3、detheLBTatypicalthrustbelt.The2008Ms8WenchuanearthquakeindicatesthattheLBTisanactiveseismiczone.AfterWenchuanearthquake,somestudiesshowedthattheCoulombstressincreasedintheSouthLTB,whichmeanstheseismichazardlevelintheSLBTincreased.In2013,aMs7.0earthquakeshockedLushanCountyseemsconfirmedthispoint.T

4、heLushanearthquakehappenedintheforelandareaofLTBandsomestudiesshowthatareaisstillhighinearthquakehazard.ButthestudiesofthisareaarerareandshowthatYanjing–WulongFaultwereactiveinlatePleistoceneandShuangshi-DachuanFaultoccurredanearthquakeinHoloceneandproducedsurfacerupture.Fluvialterraceisagreatobj

5、ectforactivetectonicstudy.Bymeansofmeasuringthedeformationstyles(offset,title,warpandetal.),wecaninformedtheactivetectoniccharactersofthestudyarea.IntheSouthLTB,QingyijiangRivercutsacrossLongmenshaninitsupperstreamandgeneratefourterraceswhichprovideagoodopportunityforthisstudy.Throughmeasurethete

6、rracealtitudeandheightabovetheriverprecisely,andincombinewithgeomorphicindexextractedfromDEM,thisconclusionsaregenerated:(1)MostofthefluvialterracescrosstheupperstreamofQingyijiangRiverarepreservedinthesmallbasinsofLongdong,Wulong,MupingandLingguanandonlyfourterracescanbedistinguished.T1isaggrada

7、tionalterraceandthesedimentarystructureisclear,thegravelaresub-roundedwithsandylens.T2~T4arecoveredbyslopedepositandsoilandthefluvialdepositwereexhausted.UpperWulong,theterraceaboveriverbedis3~5m,10m,30mand80mrespectiv