一幕完整的前陆盆地构造演化的地层记录:库车坳陷下白垩统
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摘要
位于库车坳陷东部天山山前KZ露头的下白垩统为一套前渊带的充填沉积,包括卡普沙良群和巴什基奇克组两个粗-细-粗的沉积旋回,每个旋回底部的亚格列木组和巴什基奇克组底部均发育一套砾质粗碎屑沉积体。塔北隆起为前隆单元。从天山山前至塔北隆起,地层几何形态从卡普沙良群北厚南薄的强不对称楔型转变为巴什基奇克组北薄南厚的弱不对称楔型,且塔北隆起北斜坡带地震剖面显示卡普沙良群地层南部剥蚀强烈,而巴什基奇克组地层剥蚀位于北部,总体反映盆地由卡普沙良群时期北部沉降、南部抬升转变为巴什基奇克组时期北部抬升、南部沉降的构造反转现象,分别与前陆盆地逆冲构造活动期、宁静期的基底变形特征相一致。因此,卡普沙良群、巴什基奇克组两个的沉积旋回分别为逆冲构造活动期、宁静期的盆地充填记录,两个旋回底部的砾质粗碎屑沉积体分别为逆冲活动开始(岩石圈挠曲沉降)、逆冲活动停滞(岩石圈回弹隆升)的沉积响应。总之,库车坳陷下白垩统记录了一幕完整的前陆盆地构造演化过程。
The Lower Cretaceous of outcrop KZ in the front of Tianshan Mountains,the eastern Kuqa Depression consists of foredeep-filling deposition.Two depositional cycles are identified to have developed respectively in Kapushaliang Group and Bashenjiqike Formation.At the bottom of each cycle,coarse gravelly sediments developed respectively in Yageliemu Formation and the bottom of Bashenjiqike Formation.The Tabei Uplift was the forebulge,from the front of Tianshan Mountains to the Tabei Uplift,Kapushaliang Group appears to be much asymmetric thinning toward south,In contrast,Bashenjiqike Formation is slightly asymmetric,thickening toward south.Moreover,in the seismic profile on the north slope of Tabei Uplift,southern Kapushaliang Group is more violently denuded,but northern Bashenjiqike Formation is denuded.This indicates the northern area subsided with the uplifting in the southern area in Kapushaliang Group,and the northern area reversely uplifted with the reverse subduction of the southern area in Bashenjiqike Formation.This tectonic reversal is accordant with lithosphere deformation from the thrust to the quiescence of foreland basin.Accordingly,the cycle at Kapushaliang Group developed during thrusting;the other at Bashenjiqike Formation during quiescence.The coarse gravelly sediment of Yageliemu Formation is a response to thrust renewing;the other at the bottom of Bashenjiqike Formation a resporse to lithosphere rebounding.In conclusion,the Lower Cretaceous in Kuqa Depression recorde a whole episode of foreland basin tectonic evolution.
The Lower Cretaceous of outcrop KZ in the front of Tianshan Mountains,the eastern Kuqa Depression consists of foredeep-filling deposition.Two depositional cycles are identified to have developed respectively in Kapushaliang Group and Bashenjiqike Formation.At the bottom of each cycle,coarse gravelly sediments developed respectively in Yageliemu Formation and the bottom of Bashenjiqike Formation.The Tabei Uplift was the forebulge,from the front of Tianshan Mountains to the Tabei Uplift,Kapushaliang Group appears to be much asymmetric thinning toward south,In contrast,Bashenjiqike Formation is slightly asymmetric,thickening toward south.Moreover,in the seismic profile on the north slope of Tabei Uplift,southern Kapushaliang Group is more violently denuded,but northern Bashenjiqike Formation is denuded.This indicates the northern area subsided with the uplifting in the southern area in Kapushaliang Group,and the northern area reversely uplifted with the reverse subduction of the southern area in Bashenjiqike Formation.This tectonic reversal is accordant with lithosphere deformation from the thrust to the quiescence of foreland basin.Accordingly,the cycle at Kapushaliang Group developed during thrusting;the other at Bashenjiqike Formation during quiescence.The coarse gravelly sediment of Yageliemu Formation is a response to thrust renewing;the other at the bottom of Bashenjiqike Formation a resporse to lithosphere rebounding.In conclusion,the Lower Cretaceous in Kuqa Depression recorde a whole episode of foreland basin tectonic evolution.
引文
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[2]李勇,王成善,曾允孚.造山作用与沉积响应[J].矿物岩石,2000,20(2):49-56.
[3]汪泽成,刘和甫,熊保贤,等.从前陆盆地充填地层分析盆山耦合关系[J].地球科学:中国地质大学学报,2001,26(1):33-39.
[4]Jordan T E.Thrust Loads and Foreland Basin Evolution,Gre-taceous,Western United States[J].AAPG Bulletin,1981,6:2 506-2 520.
[5]林畅松,刘景彦,张燕梅,等.库车坳陷第三系构造层序的构成特征及其对前陆构造作用的响应[J].中国科学:D辑,2002,32(3):177-183.
[6]贾进华.前陆盆地层序地层学研究简介[J].地质科技情报,1995,14(1):23-28.
[7]刘少峰.前陆盆地挠曲过程模拟的理论模型[J].地学前缘,1995,2(3):69-77.
[8]Flemings P B,Jordan T E.Stratigraphic Modeling of ForelandBasins:Interpreting Thrust Deformation and LithosphericRheology[J].Geology,1990,18:430-434.
[9]Quinlan G M,Beaumont C.Appalachian Thrusting,Lithos-pheric Flexure and Paleozoic Stratigraphy of Eastern Interior ofNorth America[J].Canadian Journal Earth Sciences,1984,21:973-996.
[10]Beaumont C,Quinlan G M,Hamilton J.Orogeny and Stratig-raphy:Numeral Model of the Paleozoic in the Eastern Interiorof North American[J].Tectonics,1988,7(3):389-416.
[11]肖建新,林畅松,刘景颜.塔里木盆地北部库车坳陷白垩系层序地层与体系域特征[J].地球学报,2002,23(5):453-458.
[12]贾进华.库车坳陷白垩纪巴什基奇克组沉积层序与储层研究[J].地学前缘,2000,7(3):133-143.
[13]王家豪,王华,陈红汉,等.库车坳陷前渊带层序地层分析———以白垩系卡普沙良群为例[J].地质科技情报,2005,24(1):25-29.
[14]贾进华,顾家裕,郭庆银,等.塔里木盆地克拉通气田白垩系储层沉积相[J].古地理学报,2001,3(3):67-75.
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