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摘要: 现代层序地层学的理论发展,把沉积过程纳入到地质演化的时空框架中并与地球的多旋回或节律演化结合研究,形成了一套带有革命性的、在等时地层格架中研究沉积作用的新方法,成为了油气资源等沉积矿产预测勘探的重要工具。沉积盆地的沉积充填可划分出与各级沉积旋回相对应的层序地层单元。追踪对比由不整合面或不整合面及其对应的整合面为界的高级别层序地层单元建立的区域性等时地层格架,对盆地构造古地理再造和油气勘探战略性研究至关重要;追踪四、五级等低级别层序地层单元和体系域建立的高精度层序地层格架,可为重点区域或区带的沉积体系和储集体的沉积构成和分布等的解剖提供精细的地层对比基础。依据沉积基准面的变化,从层序内水进到水退的沉积旋回中可划分出正常水退沉积、强制性水退沉积、水进沉积及垂向加积等成因沉积类型。海相或湖相盆地中三级层序地层单元内均可较好地划分出低位、水进、高位及下降体系域。
盆地构造作用、气候变化、海、湖平面升降过程对层序发育的控制作用及沉积响应研究,一直是层序地层学或沉积地质分析领域的研究热点。沉积盆地的层序地层序列演化是盆地地球动力学过程的总体响应。层序地层学把盆地古构造、古地理的变迁纳入到统一的地球演化系统中研究,形成了与区域地球演化史或盆地动力学演化相结合的重要研究领域。多旋回盆地或叠合盆地中多期次的构造变革导致了多个区域性不整合面所分隔的多个构造层序的叠加。注重构造—层序地层的结合分析,揭示盆地的层序地层序列与多期盆地构造作用的成因联系,是构造活动盆地或大型叠合盆地沉积地质演化和油气聚集规律研究的关键。盆地构造作用,如前陆盆地多期次的逆冲挠曲沉降和回弹隆起的构造作用、多幕裂陷过程、多期构造反转等与重要不整合及区域性沉积旋回或层序的形成密切相关;而由气候变化引起的海或湖平面变化是控制高频沉积旋回或低级别层序发育的主要因素。在构造活动盆地中,构造坡折带对沉积体系域和沉积相的发育分布具重要控制作用。-
关键词:
- 层序结构成因沉积类型控制因素沉积盆地
Abstract: 〗aphic unit can be usually classified into several types of genetic deposits, that is, the normal regressive, forced regressive, transgressive and aggradational deposits. Depositional cycle of a third order sThe development of modern sequence stratigraphic theories, integrating the study of depositional process in the time and space configuration and the cyclic or rhythmic evolution of the Earth, has formed a innovative theory for the investigation of depositional facies in chronostratigraphic framework, and became an important prospecting tool for petroleum exploration. Basin fills can be usually divided into different sequence stratigraphic units consistence with different cycles. The regional sequence stratigraphic framework established by collating highorder sequence stratigraphic units confined by major unconformities is very important for the reconstruction of tectonopaleogeography and the strategic evaluation of petroleum exploration, and the high resolution sequence stratigraphic framework erected by tracing the low order, such as the forth or fifth odor sequence stratigraphic units, may provide accurate stratigraphic correlation for the investigation of depositional facies and reservoir distribution along selected districts within a basin. Depositional cycle of a sequence stratigrequence stratigraphic unit can be easily divided into lowstand, transgressive, highstand and falling systems tracts in marine or nonmarine basins.
The control of tectonism, climatic and sea or lake level change on the development of depositional sequences has long been one of the major research themes in sequence stratigraphy or sedimentological geology. The evolution of basin filling sequence is the response to the basin dynamic processes. The combination study of sequence stratigraphy with basin dynamic or regional evolution of the Earth has formed an important research area intaking the study of paleotectonics and paleogeography into the unique time and space system of the Earth evolution. The multiple reformation of the polycyclic or superimposed basins underwent resulted in the stacking of a series of tectonic sequences confined by regional unconformities and it is the key to establish the relationship of the tectonic evolution and the basin filling sequence in order to reveal the sedimentary geological history and petroleum accumulation within a basin. The formation of major unconformities and regional depositional cycles or sequences are commonly attributed to the tectonism, such as the multiple thrust flexural subsidence and rebounding uplift due to denudation, multiple riffing and tectonic reversion; whereas the development of high frequency depositional sequences related to sea or lake level change have be usually interpreted to be controlled by climatic change. In the tectonic actively basins, the structural slopbreak zones have great influence on the development of despositional systems tracts and facies associations.-
Key words:
- sequence architecture
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