摘要
解放后,随着石油普查的开展,发现在平缓单斜的鄂尔多斯断块西缘地腹存在一个狭长的断褶带。但只是在七十年代以来,特别是近几年来,由于地震勘探的开展才对它的全貌有了较深入的认识。我们称其为鄂尔多斯断块西缘断裂带(以下简称断裂带)。它北起桌子山,经陶乐、马家滩、甜水铺、平凉而达陇县、千阳一带,长近600公里(图1)。仅北端的桌子山有大面积前中生代地层出露,大部分地区被白垩系及新生界覆盖。
Abstract
Along the west edge of Ordos fault block,there is a bunch of zigzag faults which,in fact.comprises part of the great N-S treading tectonic belt running through central China.This belt is inherited from the basement,which control-ling the formation and deformation of its sedimentary covers.During the period when tension stress prevailed,the fault belt took the form of normal fault with its west side seriously subsiding in the Paleozoic stage,but its east side subsided in the Mesozoic.In the period of compression,i.e.at the late stage of its tectonic cycle,it took the from of eastwards thrust-ing with some folds accompanied.The deformation caused by the Caledonian Orogeny was not quite violent,while intensive imbricate thrust faults were formed by the Yanshanian Orogeny during Late Jurassic.Compressed by the Siberian and Indian plates unequally both from the north and south during the Yanshanian Orogeny,Ordos area was subjected to clock-wise rotation enhanced by Alashan fault block squeezing toward it from the west.So this results in the above mentioned tectonic deformation along the west edge of Ordos fault block.It is concluded that this fault belt possesses better prospects for petroleum exploration due to the existence of source rocks on its both sides and good preservation condition along the fault belt and its eastern area.
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