枕、球—枕构造:地层中的古地震记录
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摘要
枕状构造(pillow)与球—枕构造(ball-and-pillow)、负载构造(load))是地层中的软沉积物变形构造,它们在形态、产状、变形机制等方面是不同的。枕状构造是砂层中一组呈"凹"形弯曲的变形沉积体,它的原始层平行于枕状体的底面,顶面则是一个平直的截切面。枕状构造是由于层状砂层强烈液化向上覆软沉积砂层流动、穿刺,使之弯曲褶皱,在原地固定位置形成,因此枕状构造在一个层内是沿岩层走向呈现一系列相间隔的向形和很窄的背形。形成球—枕构造与负载构造的软沉积层包括细砂单元与上覆粗砂单元。他们的变形机制与砂层的液化作用有关。下伏细粒砂单元具强的液化变形而上覆粗砂单元为弱变形层。上覆粗砂单元(比重大)在下伏细砂单元(比重小)之上形成一个不稳定重力驱动系统,地震发生时的剪切力使重的粗砂(弱液化)陷落下沉至下伏细粒单元(强液化)中成负载构造和球—枕构造。球—枕体位于细砂层的不同位置,表明他们是下沉穿越细砂层单元为异地沉积体。形成枕、球—枕及负载体的软沉积物液化变形机制不同,但液化作用的触发机制是强地震。这些液化变形构造在实验室砂层的振动液化模拟实验中也已得到证实。地层中的枕状构造及球—枕、负载构造代表一次Ms>5的古地震灾变事件。古地震往往是沿着某些古地震断裂分布,是古地震断裂活动的表现。本文将举例讨论我国古老地层中的某些枕状构造、球—枕与负载构造,并简述当时发震的构造背景。
Pillow structure and ball-and-pillow structure are the soft-sediment deformation within strata.They are different in morphological feature,mode of occurrence and mechanism of deformation.Pillow structure consists of a suit of deformed concave upward bodies made of silt and sand whose original layering bent round parallel the basal surface and it truncated at the top surface.The formation of pillows was initiated by the liquefaction of some definite layers within package of layered sand that was forced to fold as a result of upward flow of the liquefied sand at more or less regularly spaced sites.For these reason,the pillows occur intervals across single layered sand beds to forming a series of laterally connected synform(width)and antiforms(narrows).Soft-sediment layer of load,ball-and-pillow involves the fine sand unit and the overlying coarse sand unit.The mechanism of deformation is related to liquefaction and fluidization processes.The fine-sand unit displays active liquefied deformation features while the overlying sands show mainly passive deformation feature(hydraplastic deformation).The superposition of coarse-grained sand(heavy)on fine-grained sand(light)represents a driving force system related to gravitational instability.The heavy sand may sink into the light sands forming load cast,ball-and-pillow and they retained primary lamination of the overlying coarse sand unit.The ball-and-pillow are located different position in the fine sand indicating that they dropped through the fine sand unit.Liquefaction and fluidization was triggered by a strong paleo-seismic event.Pillow and load,ball-and-pillow structure are similar to those obtained experimentally at liquefied sand subjected to shaking.Deformation of pillow,ball-and-pillow,load structures represent a paleo-seismic records of Ms>5 within strata originating along some paleo-seismic fault.Some ancient examples of China are discussed in this paper.
Pillow structure and ball-and-pillow structure are the soft-sediment deformation within strata.They are different in morphological feature,mode of occurrence and mechanism of deformation.Pillow structure consists of a suit of deformed concave upward bodies made of silt and sand whose original layering bent round parallel the basal surface and it truncated at the top surface.The formation of pillows was initiated by the liquefaction of some definite layers within package of layered sand that was forced to fold as a result of upward flow of the liquefied sand at more or less regularly spaced sites.For these reason,the pillows occur intervals across single layered sand beds to forming a series of laterally connected synform(width)and antiforms(narrows).Soft-sediment layer of load,ball-and-pillow involves the fine sand unit and the overlying coarse sand unit.The mechanism of deformation is related to liquefaction and fluidization processes.The fine-sand unit displays active liquefied deformation features while the overlying sands show mainly passive deformation feature(hydraplastic deformation).The superposition of coarse-grained sand(heavy)on fine-grained sand(light)represents a driving force system related to gravitational instability.The heavy sand may sink into the light sands forming load cast,ball-and-pillow and they retained primary lamination of the overlying coarse sand unit.The ball-and-pillow are located different position in the fine sand indicating that they dropped through the fine sand unit.Liquefaction and fluidization was triggered by a strong paleo-seismic event.Pillow and load,ball-and-pillow structure are similar to those obtained experimentally at liquefied sand subjected to shaking.Deformation of pillow,ball-and-pillow,load structures represent a paleo-seismic records of Ms>5 within strata originating along some paleo-seismic fault.Some ancient examples of China are discussed in this paper.
引文
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陈肇夏,何信昌,谢凯旋,罗伟,林卓雄,张徽正,童鉴水,林启文,陈政恒,杨昭男,李希元.2000.台湾地质图(比例尺五十万分之一).“经济部中央地质调查所”.
冯先岳.1989.地震振动液化变形研究.内陆地震,3(4):299～307.
何春荪,1986.台湾地质概论,台湾地质图说明书.台北:“经济部中央”地质调查所:1～164.
和政军,宋天锐,丁孝忠,张巧大,孟祥化,葛明.2000.燕山中元古代裂谷早期同沉积断裂活动及其对事件沉积的影响.古地理学报,2(3):83～91.
李海兵,戚学祥,朱迎堂,杨经绥,Tapponier P,史连昌,王永文.2004.2001年东昆仑地震(Ms=8.1)不对成的同震地表破裂构造.地质学报,78(5):633～660.
李海兵.2006.下寒武统大林子组中的软沉积物变形构造.见:乔秀夫,等.地层中地震记录(古地震).北京:地质出版社,161～181.
梁定益,宋志敏,赵崇贺,聂泽同.2002.河北省白石山中元古代地震遗迹的发现.地质通报,21(10):625～630.
林朝宗.2004.台湾的地质现象,第三辑.台北:经济部中央地质调查所,1～157.
刘颖,谢君裴.1984.沙土振动液化.北京:地震出版社.
乔秀夫,高林志.1986.华北地台上一个值得注意的含盐层位.见:中国地质科学院地质研究所所刊,15号.北京:地质出版社,66～69.
～69.乔秀夫,宋天锐,高林志,彭阳,李海兵,高劢,宋彪,张巧大.1994.碳酸盐岩振动液化地震序列.地质学报,68(1):16～34.
乔秀夫,宋天锐,李海兵,高林志.1996.辽东半岛南部震旦系—下寒武统成因地层.北京:科学出版社,1～174.
乔秀夫,高林志,彭阳,李海兵.2001.古郯庐带沧浪铺阶地震事件、层序及构造意义.中国科学(D辑),31(11):911～918.
乔秀夫,宋天锐,李海兵.2002a.是地震液化泄水成因,不是“渗流管”构造.科学通报,47(14):1118～1120.
乔秀夫,高林志,彭阳.2002b.古郯庐带新元古界——灾变、层序、生物.北京:地质出版社,1～128.
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,高林志.2007.燕辽裂陷槽中元古代古地震与古地理.古地理学报,9(4):337～352.
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.
张传恒,刘典波,张传林,王自强.2006.新疆博格达地区早二叠世软沉积物变形构造:弧后碰撞前陆盆地地震记录.地学前缘,13(14):255～266.
Cojan I,Thiry M.1992.Seismicallyinduced deformation structuresin Oligocene shallow-marine and eolian coastal sands(ParisBasin).Tectonophysics,206:79～89.
Guiraud M,Plaziat J C.1993.Seismites in the fluviatile Bimasandstones:identification of Paleoseisms and discussion of theirmagnitudes in a Cretaceous synsedimentary strike-slip basin(Upper Benue,Nigeria).Tectonophysics,225:493～522.
Kuenen P.1953.Significant feature of graded bedding.Bull.Am.Assoc.Pterol.Geologist,37:1044～1066.
Kuenen P.1958.Experiments in geology.Trans.Geol.Soc.Glasgow,23:1～28.
Li Haibing,Van der Woerd J,Tapponnier P.2005.Slip rate on theKunlun fault at Hongshuigou,and recurrence time of greatevents comparable to the14/11/2001/,Ms-7.9Kokoxiliearthguake.Earth and Planetary Science Letters,237:285～299.
Moretti M,Pieri P and Tropeano,M.2002.Late Pleistocene soft-sediment deformation structures interpreted as seismites inparalic deposits in the city of Bari(Apulian forland,SouthernItaly).In:Ettensohn F R,Rast Nand Brett C E.eds.AncientSeismites:Boulder.Colorado:Geoloical Society of AmericaSpecial Paper,359:75～85.
Owen G.1996.Experimental soft-sediment deformation:structureformed by the liquefaction of unconsolidated sands and someancient examples.Sedimentology,43:279～293.
Pettijohn F J,Potter P E.1964.Atlas and Glossary of PrimarySedimentary Structures.Berlin:Springer,1～370.
Qiao Xiufu,Song Tianrui,Gao Linzhi,Peng Yang,Li Haibing,Gao Mai,Song Biao,Zhang Qiaoda.1994.Seismic sequence incarbonate rocks by vibrationliquefaction.Acta Gedgloica Sinica(English Edition),7(3):243～265.
Qiao Xiufu,Gao Linzhi,Peng Yang,Li Haibing.2002.Seismicevent,sequence andtectonic significancein Canglangpu StageinPaleo-Tanlu Fault Zone.Science in China(English Edition,Series D),45(9):781～191.
Qiao Xiufu,Gao Linzhi,Peng Yang.2007.Mesoproterozoicearthquake event and breakup of the Sino—Korean Plate.ActaGeologica Sinica(English Edition).81(3):385～397.
Rodriguez M A,Calvo J P,Vicent G,De Gomez-Gras D.2000.Soft-sediment deformation structures interpreted as seismites inlacustrine sediments of the Prebetic Zone,SE Spain,and theirpotential use as indicators of earthquake magnitudes during theLate Miocene.Sedimentary Geology,135:117～135.
Sims J D.1975.Determining earthquake recurrence intervals fromdeformational structures in young lacustrine sediments.Tectonophysics,29:141～152.
Smith B.1916.Ball-or-pillow-form structure in sandstone.Geol.Mag.,3,n.s:146～156.
陈肇夏,何信昌,谢凯旋,罗伟,林卓雄,张徽正,童鉴水,林启文,陈政恒,杨昭男,李希元.2000.台湾地质图(比例尺五十万分之一).“经济部中央地质调查所”.
冯先岳.1989.地震振动液化变形研究.内陆地震,3(4):299～307.
何春荪,1986.台湾地质概论,台湾地质图说明书.台北:“经济部中央”地质调查所:1～164.
和政军,宋天锐,丁孝忠,张巧大,孟祥化,葛明.2000.燕山中元古代裂谷早期同沉积断裂活动及其对事件沉积的影响.古地理学报,2(3):83～91.
李海兵,戚学祥,朱迎堂,杨经绥,Tapponier P,史连昌,王永文.2004.2001年东昆仑地震(Ms=8.1)不对成的同震地表破裂构造.地质学报,78(5):633～660.
李海兵.2006.下寒武统大林子组中的软沉积物变形构造.见:乔秀夫,等.地层中地震记录(古地震).北京:地质出版社,161～181.
梁定益,宋志敏,赵崇贺,聂泽同.2002.河北省白石山中元古代地震遗迹的发现.地质通报,21(10):625～630.
林朝宗.2004.台湾的地质现象,第三辑.台北:经济部中央地质调查所,1～157.
刘颖,谢君裴.1984.沙土振动液化.北京:地震出版社.
乔秀夫,高林志.1986.华北地台上一个值得注意的含盐层位.见:中国地质科学院地质研究所所刊,15号.北京:地质出版社,66～69.
～69.乔秀夫,宋天锐,高林志,彭阳,李海兵,高劢,宋彪,张巧大.1994.碳酸盐岩振动液化地震序列.地质学报,68(1):16～34.
乔秀夫,宋天锐,李海兵,高林志.1996.辽东半岛南部震旦系—下寒武统成因地层.北京:科学出版社,1～174.
乔秀夫,高林志,彭阳,李海兵.2001.古郯庐带沧浪铺阶地震事件、层序及构造意义.中国科学(D辑),31(11):911～918.
乔秀夫,宋天锐,李海兵.2002a.是地震液化泄水成因,不是“渗流管”构造.科学通报,47(14):1118～1120.
乔秀夫,高林志,彭阳.2002b.古郯庐带新元古界——灾变、层序、生物.北京:地质出版社,1～128.
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,高林志.2007.燕辽裂陷槽中元古代古地震与古地理.古地理学报,9(4):337～352.
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.
张传恒,刘典波,张传林,王自强.2006.新疆博格达地区早二叠世软沉积物变形构造:弧后碰撞前陆盆地地震记录.地学前缘,13(14):255～266.
Cojan I,Thiry M.1992.Seismicallyinduced deformation structuresin Oligocene shallow-marine and eolian coastal sands(ParisBasin).Tectonophysics,206:79～89.
Guiraud M,Plaziat J C.1993.Seismites in the fluviatile Bimasandstones:identification of Paleoseisms and discussion of theirmagnitudes in a Cretaceous synsedimentary strike-slip basin(Upper Benue,Nigeria).Tectonophysics,225:493～522.
Kuenen P.1953.Significant feature of graded bedding.Bull.Am.Assoc.Pterol.Geologist,37:1044～1066.
Kuenen P.1958.Experiments in geology.Trans.Geol.Soc.Glasgow,23:1～28.
Li Haibing,Van der Woerd J,Tapponnier P.2005.Slip rate on theKunlun fault at Hongshuigou,and recurrence time of greatevents comparable to the14/11/2001/,Ms-7.9Kokoxiliearthguake.Earth and Planetary Science Letters,237:285～299.
Moretti M,Pieri P and Tropeano,M.2002.Late Pleistocene soft-sediment deformation structures interpreted as seismites inparalic deposits in the city of Bari(Apulian forland,SouthernItaly).In:Ettensohn F R,Rast Nand Brett C E.eds.AncientSeismites:Boulder.Colorado:Geoloical Society of AmericaSpecial Paper,359:75～85.
Owen G.1996.Experimental soft-sediment deformation:structureformed by the liquefaction of unconsolidated sands and someancient examples.Sedimentology,43:279～293.
Pettijohn F J,Potter P E.1964.Atlas and Glossary of PrimarySedimentary Structures.Berlin:Springer,1～370.
Qiao Xiufu,Song Tianrui,Gao Linzhi,Peng Yang,Li Haibing,Gao Mai,Song Biao,Zhang Qiaoda.1994.Seismic sequence incarbonate rocks by vibrationliquefaction.Acta Gedgloica Sinica(English Edition),7(3):243～265.
Qiao Xiufu,Gao Linzhi,Peng Yang,Li Haibing.2002.Seismicevent,sequence andtectonic significancein Canglangpu StageinPaleo-Tanlu Fault Zone.Science in China(English Edition,Series D),45(9):781～191.
Qiao Xiufu,Gao Linzhi,Peng Yang.2007.Mesoproterozoicearthquake event and breakup of the Sino—Korean Plate.ActaGeologica Sinica(English Edition).81(3):385～397.
Rodriguez M A,Calvo J P,Vicent G,De Gomez-Gras D.2000.Soft-sediment deformation structures interpreted as seismites inlacustrine sediments of the Prebetic Zone,SE Spain,and theirpotential use as indicators of earthquake magnitudes during theLate Miocene.Sedimentary Geology,135:117～135.
Sims J D.1975.Determining earthquake recurrence intervals fromdeformational structures in young lacustrine sediments.Tectonophysics,29:141～152.
Smith B.1916.Ball-or-pillow-form structure in sandstone.Geol.Mag.,3,n.s:146～156.
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