摘要
通过对钻井岩芯的详细观察和描述,发现在塔里木盆地满加尔坳陷晚奥陶世开阔陆棚相—盆地相沉积地层中,存在各种各样的、复杂的软沉积物变形构造,主要有液化流动构造,包括液化砂岩脉、液化角砾岩、底劈构造及水塑性卷曲变形与震积不整合等。特别是在满加尔坳陷与卡塔克隆起结合部塔中Ⅰ号断层的下降盘,发现存在米级软沉积物变形构造,以软沉积物布丁变形构造为主,变形构造的上、下均发育不等厚的未变形沉积层。这些变形构造的形成与震积作用有关,发育在晚奥陶世不同时期。在晚奥陶世早期,古地震记录表现出拉张应力作用的结果,且由早至晚古地震应力有逐渐增强的趋势。发现的多幕次的古地震记录表明,中加里东运动在满加尔坳陷及周缘表现明显,塔中Ⅰ号断裂是该时期古地震的主控断裂,其活动具有周期性和多旋回的特点,表现为多期次的由弱到强再结束的特征,且在不同部位有差异。晚奥陶世塔中Ⅰ号断裂带的地震活动影响着该区古构造和古沉积的发育。
The varied and complex styles of soft-sediment deformation structures are well preserved in Late Ordovician deposits of Manjiaer depression and its adjacent areas in the Tarim basin in northwestern China.A large variety of ductile and brittle deformation structures were observed in drilled well cores sediments of the continental shelf-basin facies deposition in Late Ordovician.They contain liquefied sand veins,liquefied breccia,diaper-like structure,hydroplastic convolutions,and seismic unconformity and so on.Especially,the extensive meter-scale horizon of soft-sediment deformation was observed in the joints of Katake uplift and Manjiaer depression,presence of the seismites sequence combination of mainly boudinage-like soft-sediment deformation structure and little liquefied sand vein and breccia,formed during unconsolidation by shear-extensional regional tectonic setting. The deformations layers interval characterized by unreformed beds with different thickness.These structure deformations resulted from the seismic deposited,the deformational characteristics presented extentional environment,and the paleostress intensity increased from early to late in the earlier Late Ordovician.The multi paleo-seismic records were association with multiphase of activities of the main earthquake fault.The Paleo-seismic records indicate that the Tazhong fault 1was an active earthquake fault during the Late Ordovician;the nature and activity of this fault varied with different phases and their positions.They were responded to the Caledonian movement on Manjiaer depression and its surrounding.The paleo-seism of the Tazhong fault 1affected evolution of paleotectonics and paleosediments in the Late Ordovician.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2010年第12期1805-1816,共12页
Acta Geologica Sinica
基金
中国石化股份有限公司科技开发部项目“塔里木盆地构造背景、盆山动力学及油气前景”(编号YPH08110)资助成果
关键词
软沉积物变形构造
震积作用
震积岩成因
晚奥陶世
满加尔坳陷
塔里木盆地
soft-sediment deformation structure
seismic deposition
paleo-seismogenesis
the Late Ordovician
Manjiaer depression
Tarim Basin