鄂尔多斯盆地伊陕斜坡东北部榆林地区中生代沉降史分析

Analysis on Mesozoic subsidence history of northeast Yishan slope of Ordos basin

通过对伊陕斜坡东北部中生代被剥蚀地层的估算来模拟该区三叠纪以来的沉降史,采用PRA公司的Basin-Mod 1-D软件,应用回剥技术模拟榆林地区的沉降史,并绘制沉降史曲线。研究结果表明二叠纪以来研究区的沉降主要经历了4期沉降和4期抬升,早白垩世沉降幅度最大,沉降速率达到57.00 m/Ma;晚白垩世发生了三叠纪以来最强烈的一期全盆抬升剥蚀事件,研究区最大剥蚀厚度超过1 100 m。从早侏罗世开始,受燕山运动逐渐增降的影响,盆地沉积中心自东向西迁移退缩,最终于燕山中期到达吕梁山以西,并在其东部发生构造掀斜抬升,形成现在鄂尔多斯盆地的构造格局。

The eroded stratum is used to estimate the subsidence history of that area after Triassic in Mesozoic of northeast area in Yishan slope.The BasinMod 1-D software of the PRA company is adopted,and the backstripping technology is used to simulate the subsidence history of Yulin area.Moreover the curve of subsidence history is protracted.The result shows that there are 4 stages of subsidence and 4 stages of uplift in the research area since Permian.The subsidence range was most severe in lower Cretaceous with the speed of subsidence as 57.00 m/Ma;the strongest uplift subsidence event in whole basin was happened in Late Cretaceous since Triassic with the largest subsidence thickness up to 1 100 m. Due to the effect of gradually uplifting during the Yanshan movement,the subsidence center is transferred from east to west since early Jurassic and finally to the west of the L(?)liang Mountains.The structural tilt-lift occurred at east L(?)liang Mountains,resulting in the present structural framework of Ordos basin.