| 陆相断陷盆地层序形成动力学及层序地层模式 |
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| 引用本文： | 冯有良,李思田,解习农.陆相断陷盆地层序形成动力学及层序地层模式[J].地学前缘,2000,7(3):119-132. |
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| 作者姓名： | 冯有良 李思田 解习农 |
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| 作者单位： | 中国地质大学,武汉,430074 |
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| 基金项目： | 国家自然科学基金资助项目!(49872045) |
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| 摘 要： | 文中认为 :陆相断陷盆地层序形成的动力学机制源于全球构造事件导致的区域构造应力场、地幔隆升产生的岩石圈拉张伸展而导致的不同级别的幕式构造运动以及由构造、冰川消融作用和地球旋转而产生的气候旋回。基准面的变化是构造、气候的函数 ,对于地史时期的滨海盆地 ,基准面就是相对海平面。不同级别的基准面变化旋回形成不同级别的层序 ,表现为盆地的裂陷旋回期相当于海平面变化旋回的超周期组 ,形成构造层序 ;裂陷幕和气候的二级旋回相当于海平面旋回的超周期 ,形成层序组 ;幕式断陷作用和气候的三级旋回形成层序。断陷盆地一个典型层序形成的模式是 :由于湖水体积的有限性 ,一次断陷和掀斜运动就能产生构造坡折并使湖水体积再分配 ,湖水向主断层和构造坡折之间可容空间增大的区域流动 ,造成基准面下降 ,产生陆上暴露、下切水道、水下冲积扇、废弃型三角洲及扇三角洲构成低位域 (LST)。构造宁静期 ,在气候等因素的作用下 ,湖水将趋于恢复断陷前的位置 ,使基准面 (湖平面 )升高 ,形成湖浸和河流退积作用形成的破坏型三角洲 ,深湖、浊积扇及浅湖构成湖扩张体系域 (EST)。当湖平面达到最高并趋于稳定 ,由于断陷使流域地形变陡 ,大量碎屑物入湖形成以三角洲前积体为主的高位体系域 (HST)。叠加在三级基准?
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| 关 键 词： | 陆相断陷盆地 层序形成动力学 层序地层 |
DYNAMICS OF SEQUENCE GENERATION AND SEQUENCE STRATIGRAPHIC MODEL IN CONTINENTAL RIFT-SUBSIDENCE BASIN |
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| FENG You-Liang,LI Si-tian,XIE Xi-nong.DYNAMICS OF SEQUENCE GENERATION AND SEQUENCE STRATIGRAPHIC MODEL IN CONTINENTAL RIFT-SUBSIDENCE BASIN[J].Earth Science Frontiers,2000,7(3):119-132. |
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| Authors: | FENG You-Liang LI Si-tian XIE Xi-nong |
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| Abstract: | With comparison of dynamic mechanics between eustasy and basin evaluating and filling, as well as combination with sequence stratigraphy research in typical rift subsidence basin, this paper shows that the dynamics of sequence forming in rift subsidence basin was due to regional stress field resulted from globe tectonic events, episode movement in different grade resulted from lithosphere extension because of mantel uplifting, and climate circles because of glacial solving and earth spinning. Base level was the function of tectonic movements and climate circles,and base level for coastal basin in geological history was relative sea level. The circles of base level in different grades produced different grade sequences, which showed that rifting circle of basin was corresponding to superperiod sets(supersequence sets) of eustasy to produce tectonic sequence, the second grade circles of climate and tectonic episode was corresponding to superperiod of eustasy to result in sequence sets, episode faulting and climate circles in grade three resulted in sequences. A typical sequence model in rift subsidence basin is showed as follows: because water volume of lake was finite, tilting and faulting produced structural break and redistributed the lake water toward increasing accommodation space area between main fault and structure break, and base level fell to generate lowstand system (LST),characterized by incised channels, subaqueous fans, turbidity fans, abandoned deltas and fan deltas . In the inactive epoch of faulting, lake level, affected by climate, treaded to recover position before faulted and rose rapidly to produce lacustrine expanding systems tract(EST) characterized by lacustrine facies expanding, delta being destroyed, and fluvial retreating,deep lake, turbidity fans, destroyed deltas and shallow lake consisting of lacustrine expanding systems tract, developed . When the lake level arrived at summit and treaded to stable, because faulting made topography steep, and sedimentary was supplied enough, highstand systems tract (HST) characterized by delta was generated .Milankovotch climate circles on the third order base level circles resulted in high frequency sequences such as from 4 to 6 grade sequences. In different sequence sets and systems tract, component of third order sequences was different,which was controlled by climate,tectonic movement and ratio rate between sedimentary being supplied and accommodation being created. |
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| Keywords: | continental faulted basin dynamics of sequence forming sequence stratigraphy$ |
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