鄂尔多斯盆地早白垩世剥蚀地层厚度恢复研究

DENUDATION THICKNESS RESTORATION OF EARLY CRETACEOUS STRATA IN THE ORDOS BASIN

鄂尔多斯盆地下白垩统为中生代盆地演化末期最晚沉积的地层,也是自鄂尔多斯盆地发育以来后期遭受剥蚀改造最为强烈的地层,残存范围最小。通过对全盆八百二十余口钻井现存中生代地层厚度及岩性的统计,从中选取了313口井读取声波时差值,采用声波时差和地层对比趋势法相结合进行剥蚀厚度估算,同时利用联井剖面对比法对整个盆地的恢复厚度进行对比验证。在此基础之上,恢复了早白垩世盆地原始沉积厚度,初步探讨了盆地原始沉积面貌,基本确定了盆地原始沉积边界,从而进一步加深了对晚白垩世以来盆地强烈构造变动的认识,对多种能源矿产同盆共存富集规律的研究具一定的启示。

Lower Cretaceous rocks are the youngest sediments formed during the late Mesozoic basinevolvement in the Ordos Basin. They are also the strata with most intensive denudation and smallest distribution area since the development of the Ordos Basin. The numerical value of mudstone interval transit time in 313 exploration wells are selected through the statistics of thickness and lithology in the Mesozoic strata from 820 wells in the Ordos Basin. The thickness evaluation of denudation stratum is estimated by using interval transit time integrated with stratigraphic correlation. At the same time, the restoration thickness is contrasted and verified through cross section. The original strata of Lower Cretaceous in the Ordos Basin are backstripped, the original sedimentary environment is discussed, and the original basin sedimentation boundary in the early Cretaceous is determined. The understanding of the basin＇s intensive diastrophism since the late Cretaceous has been strengthened. Results from this study has implications for the exploration of mineral and petroleum resources in the basin.