古地貌恢复技术方法及其研究意义——以鄂尔多斯盆地侏罗纪沉积前古地貌研究为例

THE WAY AND IMPLICATIONS OF REBUILDING PALAEOGEOMORPHOLOGY Taking the research of palaeogeomorphology of the Ordos Basin before Jurassic deposition as example

古地形地貌是控制一个盆地后期沉积相发育与分布的一个主要因素 ,同时在一定程度上控制着后期油藏的储盖组合。同现在地貌一样 ,古地貌形态受到了所处的区域构造位置、气候、基准面变化及构造运动等因素综合作用的影响。鄂尔多斯盆地侏罗系发育在由印支运动主幕所造成的三叠纪顶部不整合接触面上 ,早侏罗世沉积特点主要受控于沉积前古地形地貌 ,因此开展侏罗纪沉积前古地貌恢复工作及探讨古地貌对后期油气藏关系对于寻找侏罗系油田具有重要的指导意义。作者主要是从沉积学角度出发 ,通过对鄂尔多斯盆地侏罗纪沉积前古地形地貌的恢复研究 ,进一步对古地貌恢复从方法上进行了研究 。

Palaeogeomorphology is one of the main factors. It controls not only the development and distribution of the late sedimentary facies but also the assemblage of reservoirs and capping formations. Just like the modern geomorphology, it is influenced by the tectonic position, climate, base level, and so on. Rebuilding the palaeogeomorphology is a complex work. The Jurassic sedimentary strata of the Ordos Basin develops upon the denudation surface generated during the Indosinian orogeny, and their characteristics are being controlled by palaeogeomorphology. Therefore, the renewing work of the palaeogeomorphology of Ordos before Jurassic deposition can efficiently direct the exploration of the Jurassic oil reservoir. The palaeogeomorphology of the Ordos Basin shows that the northern and western parts are high but the southern and eastern parts are low in the basin. It includs five palaeogeomorphologic units, that is, highland, valley plain, hilly area depression area and palaeo river. The paper mainly discusses the ways of rebuilding palaeogeomorphology and its relationship with the late oil reservoir through rebuilding the palaeogeomorphology of the Ordos Basin before Jurassic.