摘要
三角洲和海岸平原沉积可以通过在一个广阔区域中能足以判明三维相分布和不整合的岩石记录资料来相互区分。这个区别是建立在分布的基础上,而不是基于象过去那种纯理论上的由海相到河流冲积相的变化。对这两类环境沉积物的区别一般是很难的,甚至是不可能的。如果只是建立在有限资料上,将会导致不准确的结论,甚至可导致错误的相模式,使之引起对地下储层或煤层位置的预测出现问题。作为构造、海平面升降和自循环活动控制海岸平原的相分布模型来说,可被看作是岸线沉积类型之间的统一连续体的端员。以约克盆地中侏罗世的沉积岩为例说明由不确切的定义和不正确相模式的应用可引起的争论。中侏罗世的Ravenscar群在这里被解释为受构造和海平面升降影响的海岸平原沉积。浅海和非海相环境的反复波动被解释为受垂向构造运动和海平面变化引起的,而不是自循环过程所致。
Deltaic and coastal plain deposits can be distinguished from eachother in the rock record where enough data are available to interpret thethree - dimensional distribution of facies and unconformities over a widearea. This distinction is based on the distribution of facies rather thanpurely on a marine-to-alluvial transition as has been the case in the past.The distinction between deposits of the two environments is often verydiffcult or impossible, and if based on limited data may lead to inaccurateand even incorrect models that can cause problems with prediction of reservoirrocks or coal location in the subsurtace. Models of the gross facies distri-bution for tectonically, eustatically and autocyclically controlled coastalplains are seen as the end-members of a continuum be tween coastline depo-sitional styles.The Middle Jurassic sedimentary rocks of the Yorkshire Basin are usedto illustrate the controversy that can arise from imprecise definitions and the application of incorrect facies models. The Middle Jurassic RavensearGroup is interpreted here as the deposits of a tectonically and eustaticallyinfluenced coastal plain. Repeated fluctuations between shallow-marine andnon- marine conditions are interpreted as mainly caused by vertical tecto-nic movements and sea - level changes rather than. by autocyclic processes.
出处
《大庆石油学院学报》
CAS
北大核心
1989年第4期1-10,共10页
Journal of Daqing Petroleum Institute
关键词
岩石
三角洲
海岸平原
储层
delta
coastal plain
facies model
depositional sequence
