新疆西南天山下侏罗统软沉积物变形研究
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摘要
新疆西南天山乌恰地区早侏罗世软沉积物变形位于湖相砂岩中;由地震触发的软沉积物变形有三个层位,位于下侏罗统康苏组的顶部。变形主要类型为负载(load)、球-枕(ball-and-pillow)、滴状体(droplet)、锥形体(cusps)、液化均一层(homogeneous layer)和液化不整合(liquefied unconformity)。三个变形层位反映乌恰地区早侏罗世末曾连续发生过三次强地震;变形类型机制不同反映三次地震强度有别。乌恰下侏罗统处于中亚塔拉斯—费尔干纳巨型走滑断裂控制的拉分盆地中,断裂走滑伴随地震直接诱发软沉积物变形;古地震震级为Ms6.5～7。
Early Jurassic soft-sediment deformation occuring within lacustrine sandstone is distributed mainly in the Wuqia region,SW Tianshan Mountains,Xinjiang.Triggered by earthquakes,soft-sediment deformation was found to occur in three layers of the Lower Jurassic Kangsu Formation.The main styles of deformation structures contain load cast,ball-and-pillow,droplet,cusps,homogeneous layer,and liquefied unconformity.Three deformation layers reflect that the Wuqia region had undergone three strong earthquakes at the end of Early Jurassic.The differences of deformation mechanisms may represent varying magnitudes of earthquakes.During the Late Jurassic,the Wuqia area was located at the pull-apart basin controlled by significant Talas—Ferghana strike-slip fault in central Asia,accompanied by the soft-sediment deformation induced by the earthquakes.It is suggested in this paper that the magnitudes of the paleoseisms may range from 6.5 to 7.
Early Jurassic soft-sediment deformation occuring within lacustrine sandstone is distributed mainly in the Wuqia region,SW Tianshan Mountains,Xinjiang.Triggered by earthquakes,soft-sediment deformation was found to occur in three layers of the Lower Jurassic Kangsu Formation.The main styles of deformation structures contain load cast,ball-and-pillow,droplet,cusps,homogeneous layer,and liquefied unconformity.Three deformation layers reflect that the Wuqia region had undergone three strong earthquakes at the end of Early Jurassic.The differences of deformation mechanisms may represent varying magnitudes of earthquakes.During the Late Jurassic,the Wuqia area was located at the pull-apart basin controlled by significant Talas—Ferghana strike-slip fault in central Asia,accompanied by the soft-sediment deformation induced by the earthquakes.It is suggested in this paper that the magnitudes of the paleoseisms may range from 6.5 to 7.
引文
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罗金海,周新源,邱斌,杨其林,尹宏,李建立.2004.塔拉斯干纳断裂对喀什凹陷的控制作用.新疆石油地震,25(6):584～587
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乔秀夫,李海兵.2008.枕,球-枕构造:地层中古地震记录.地质论评,54(6):721～730
乔秀夫,李海兵.2009.沉积物的地震及古地震效应.古地理学报,11(6):593～610
Gibert L,Alfaro P,Garcia-Tortosa F J,Scott G.2011.Superposed deformed beds produced by single earthquakes(Tecopa Basin,California):Insights into paleoseismology.Sadimentary Geology,235:148～159
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Moretti M,Pieri P,Tropeano M.2002.Late Pleistocene soft-sediment deformation structure interpreted as seismites in paralic deposits inthe city of Bari(Apulian foreland southern Italy).In:Ettensohn FR,Rast N,Brett C E,eds.Ancient Seismites:Boulder,Colorado.Geological Society of America Spcial Paper,359:75～85
Moretti M,Sabato L.2007.Recognition of trigger mechanisms for soft-sediment deformation in the Pleistocene lacustrine deposits of theSant Acrangelo Basin(Southern Italy):Seismic shock vsoverloading Sedimentary Geology,196:31～45
Obermeier S F.1996.Use of liquefaction-induced features for paleoseismic analysis——An overview of how seismic liquefactionfeatures can be distinguished from other features and how theirregional distribution and properties of source sediment can be used toinfer the location and strength of Holocene paleo-earthquakes.Engineering Geology,44:1～76
Owen G.1995.Soft-sediment deformation in Upper proterozolc Torridonian sandstone(Applecross Formation)at Torridon,Northwest Scotland.J.Sediment.Res.,A65:495～504
Sobel E R,Arnaud N.2000.Cretaceous—Paleogene basaltic rocks of the Tuyon basin,NW China and the Kyrgyz Tian Shan:the trace ofsmall plume.Lithos,50:191～215.
李廷栋,等.2006.中国西部及邻区地质图.北京:地质出版社
刘颖,谢君裴.1984.沙土震动液化.北京:地震出版社.
罗金海,周新源,邱斌,杨其林,尹宏,李建立.2004.塔拉斯干纳断裂对喀什凹陷的控制作用.新疆石油地震,25(6):584～587
乔秀夫,宋天锐,高林志,李海兵,彭阳,张传恒,章雨旭.2006.地层中地震记录(古地震).北京:地质出版社,1～263
乔秀夫,李海兵,王思恩,郭宪璞,司家亮,宗文明.2008.新疆境内塔拉斯—费尔干纳断裂早侏罗世走滑的古地震证据.地质学报,82(6):721～730
乔秀夫,李海兵.2008.枕,球-枕构造:地层中古地震记录.地质论评,54(6):721～730
乔秀夫,李海兵.2009.沉积物的地震及古地震效应.古地理学报,11(6):593～610
Gibert L,Alfaro P,Garcia-Tortosa F J,Scott G.2011.Superposed deformed beds produced by single earthquakes(Tecopa Basin,California):Insights into paleoseismology.Sadimentary Geology,235:148～159
Kuenen P.1958.Experiments in Geology.Trans.Geol.Soc.Glasgow,23:1～28
Moretti M,Alfaro P,Caselles O,Canas J A.1999.Modelling seismites with a digital shaking table.Tectonophysics,304:369～383
Moretti M,Pieri P,Tropeano M.2002.Late Pleistocene soft-sediment deformation structure interpreted as seismites in paralic deposits inthe city of Bari(Apulian foreland southern Italy).In:Ettensohn FR,Rast N,Brett C E,eds.Ancient Seismites:Boulder,Colorado.Geological Society of America Spcial Paper,359:75～85
Moretti M,Sabato L.2007.Recognition of trigger mechanisms for soft-sediment deformation in the Pleistocene lacustrine deposits of theSant Acrangelo Basin(Southern Italy):Seismic shock vsoverloading Sedimentary Geology,196:31～45
Obermeier S F.1996.Use of liquefaction-induced features for paleoseismic analysis——An overview of how seismic liquefactionfeatures can be distinguished from other features and how theirregional distribution and properties of source sediment can be used toinfer the location and strength of Holocene paleo-earthquakes.Engineering Geology,44:1～76
Owen G.1995.Soft-sediment deformation in Upper proterozolc Torridonian sandstone(Applecross Formation)at Torridon,Northwest Scotland.J.Sediment.Res.,A65:495～504
Sobel E R,Arnaud N.2000.Cretaceous—Paleogene basaltic rocks of the Tuyon basin,NW China and the Kyrgyz Tian Shan:the trace ofsmall plume.Lithos,50:191～215.
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