ABSTRACT

Accumulating sediments is an inherent attribute of endorheic basins. Overall aggradational stratigraphic architecture can be predicted in endorheic basins, whereas the offlap process can be regarded as an important geological indicator in closed basins. This study theoretically proposes the possible offlap process in endorheic basins, and then explores the actual pattern of the offlap process in the Qaidam basin, the largest endorheic basin in the northern Tibetan Plateau. According to the interpretation of drilling well data and seismic reflection profiles, widespread offlap is identified at all the three boundaries of the Qaidam basin since the late Miocene. The offlap process in endorheic basins is controlled by newborn faults or new isostatic flexures inside the previous basin margin. Interpretation of seismic reflection profiles reflects that the rigid Qaidam block was gradually broken during the India‐Eurasian collision and the plateau progressively expanded from pre-existing mountains to basins.

摘要

沉积物堆积是内流盆地的固有属性。内流盆地的整体加积地层结构可以预测，而闭合盆地的重叠过程可以作为重要的地质指标。本研究从理论上提出了内流盆地可能的错开过程，进而探讨了青藏高原北部最大的内流盆地柴达木盆地的错开过程的实际模式。根据钻井资料和地震反射剖面解释，晚中新世以来柴达木盆地的三个边界都出现了广泛的剥脱。内流盆地的错开过程受新断层或前盆地边缘内新的等静压弯曲控制。