塔东地区主要不整合面剥蚀量的恢复及成因机制

RESTORATION OF TOTAL THICKNESS ERODED BY MAIN UNCONFORMITIES IN TADONG AREA,TARIM BASIN AND GENETIC MECHANISMS

地层剥蚀量的恢复对于构造演化史研究和油气勘探至关重要。通过对高分辨率地震数据的精细解释,在塔东地区识别出9个不整合面,其中与周缘造山作用相关的不整合面包括:志留系与上奥陶统、上泥盆统与前上泥盆统、三叠系与前三叠系、侏罗系与前侏罗系、古近系与白垩系、新近系与古近系等6个主要不整合面。基于平衡剖面技术,通过趋势厚度法,恢复了塔东地区主要不整合面的剥蚀厚度。研究表明:受天山造山带和阿尔金造山带俯冲、碰撞造山运动的影响,志留系与上奥陶统、上泥盆统与前上泥盆统之间不整合面产生的剥蚀作用主要发生在塔东低凸起和若羌凹陷,并且后者的剥蚀作用最强;三叠系与前三叠系之间不整合面产生的剥蚀作用主要发生在孔雀河斜坡一带;侏罗系与前侏罗系之间不整合面产生的剥蚀作用在塔东低凸起、若羌凹陷和孔雀河斜坡等地区都比较强;古近系与白垩系、新近系与古近系之间不整合面产生的剥蚀作用在塔东地区均发生,但整体剥蚀厚度不大。

Total thickness restoration of eroded strata is an important task for tectonic reconstruction and hydrocarbon exploration. In this study, nine unconformities have been identified in the Tadong area by seismics, of which six major ones are closely related to the orogenic processes in the peripheral mountains of the basin, which includes the unconformities between Silurian and Upper Ordovician, between Upper Devonian and Pre-Upper Devonian, between Triassic and Pre-Triassic, between Juras- sic and Pre-Jurassic, between Paleogene and Cretaceous, and between Neogene and Paleogene. Using balanced sections, the total eroded thickness of the main unconformities is reconstructed by the meth- od of trend thickness for the Tadong area of Tarim Basin. The result suggests that the denudation is strongly controlled by the subduction and collision of the Tianshan and the Altyn Tagh orogenic belts. The denudations between the Silurian and the Upper Ordovician, and between the Upper Devonian and the Pre-Upper Devonian occurs mainly on the Tadong Uplift and the Ruoqiang Depression, and the denudation between the Upper Devonian and the Pre-Upper Devonia is more intensive. On the contrary, the denudation between the Triassic and the Pre-Triassic is on the Kongquehe Slope. The denudation between the Jurassic and the Pre-Jurassic also mainly occurs on the Tadong Uplift,in the Ruoqiang depression and on the Kongquehe slope. The denudation between the Paleogene and the Cretaceous, and the one between the Neogene and the Paleogene occur as well in the Tadong area with weaker denudation.