| Paleogeomorphology plays an important controlling role in the spatial distribution characteristics of
sedimentation. Based on the structural restoration of 16 typical north-south geological profiles by using balanced crosssection techniques, the pre-Cretaceous paleogeomorphology in Kuqa Depression has been reconstructed, and its control
effect on sedimentation has been analyzed. Firstly, based on the calculation of the shortening amount of the balanced
profile, the northern boundary of the pre-Cretaceous sedimentary basin in Kuqa Depression is calculated. Then, based on
the restored thickness data of the Cretaceous stratum, the pre-Cretaceous paleogeomorphology of Kuqa Depression is
mapped. Finally, a paleogeological map of the Kuqa Depression at the end of the Jurassic is compiled based on the
restored balanced profile, and the controlling effect of paleogeomorphology on sedimentation is analyzed. The results
show that: (1) The north-south geological profile of the Kuqa Depression has a structural shortening amount ranging from
3.74 to 26.02 km since the Early Cretaceous, with a structural shortening rate ranging from 3.76% to 24.74%. The
structural deformation is mainly concentrated in the mountainous areas of the southern Tianshan Mountains. Based on the
calculation according to the angle between the geological profile and the normal to the structural strike, the current basin
boundary has shifted southwards by a minimum of 3.70 km and a maximum of 25.19 km compared to the pre-Cretaceous
boundary. (2) The pre-Cretaceous paleogeomorphology is characterized by alternating uplift and depression, which can be
divided into Wensu uplift, Baicheng low uplift, central subsidence area, Yangxia slope, and Yangdong low uplift from
west to east. The uneven structural compression stress on the north and south sides of the Kuqa Depression, as well as the
lithological differences in the internal sedimentary strata, led to the occurrence of east-west zoning characteristics of
paleogeomorphology. (3) Paleogeomorphology controls the development of two sets of sedimentary systems in the Early
Cretaceous Yageliemu Formation in Kuqa Depression. The northern sedimentary system develops fan delta on the east
and west sides of the depression, and braided river delta in the middle of the depression. In the northern sedimentary
system, the Kelasu structural belt is the favorable development area of structural hydrocarbon reservoirs, and the
Yiqikelike structural belt and Yangxia sag are the favorable development areas of stratigraphic-lithologic hydrocarbon
reservoirs. The southern sedimentary system develops mainly small near-source fan deltas, and stratigraphic lithologic
reservoirs. |
