辽西朝阳地区晚侏罗世逆冲断裂及同构造沉积盆地系统

Late Jurassic Thrusting and Syntectonic Sedimentary Basin Systems in the Chaoyang Region,Western Liaoning

位于晚侏罗世燕山冲断带前缘拗陷盆地群东段的辽西金岭寺—羊山盆地和北票盆地,形成于同沉积期的板内挤压变形。两个盆地横断面均显示出北西翼岩层陡立或倒转而南东翼平缓、以及同期碎屑堆积北西翼厚而南西翼薄的特点,具有典型的不对称结构。分别位于两个盆地北西侧的雷家营子和凤凰山逆冲断裂带控制了它们的形成和演化。砾石成分统计分析显示,晚侏罗世土城子时期碎屑物质主要来源于辽西的西北部,即“内蒙地轴”上,是响应逆冲推覆活动的产物。两条断裂带及其所控制的盆地,构成了背驮式盆地—构造系统,清楚地反映出这一时期的逆冲推覆扩展总体上指向SE方向。辽西地区土城子期盆地的形成和沉积充填是区域地壳缩短或增厚的重要方式之一。

The Jinlingsi Yangshan Basin （ab. Jin-Yang Basin） and Beipiao basin in west Liaoning Province, as east segment of the foreland-style basin group of the Yanshan thrust belt, are syntectonic under intraplate deformation during Irate Jurassic Tuchengzi time. The both basins have characteristics of asymmetric profiles, erection or inversion on the northwest limb of the basins near the thrust belts and gentler on the southeast limb toward the direction of ＂foreland＂. And the thickness of strata on the northwest limb is thicker （-2800m）,while becomes thinner （-1100m） toward the southeast limb （i. e. the Jin-Yang Basin）. The Leijiayingzi and Fenghuangshan thrust belts closed up the northwest limb of the basins controlled on formation and evolution of the both basins respectively. Analysis of sedimentary provenance from conglomerates shows clastics mainly derived from the northwest region of western Lioaning, namely the ＂Inner Mongolian Axis＂. Accumulation of thick clastic deposition within the basins is the product responded to thrusting. The both thrusts and correlative basins constitute a piggyback-style thrust-basin sequence, which clearly reveal the thrust propagation basically towards the southeast during that time. The formation and sedimentary accumu of shortening and thickening of regiona ation of the Late Jurassic Tuchengzi basins is important as one way crust in western Liaoning.