川中古隆起构造演化特征及其与早寒武世绵阳－长宁拉张槽的关系

摘要

根据早寒武世绵阳－长宁拉张槽的发现，为深化对四川盆地基础地质的认识开展相关构造演化研究。通过震旦系顶界古构造恢复，对比分析拉张槽分布范围与各期川中古隆起分布范围，研究了古隆起演化与拉张槽的关系。以拉张槽和古隆起为主体可将四川盆地划分为12个区域。认为川中地区的隆起是伴随着早寒武世拉张槽由隆起转换为凹陷演化形成的，川西南地区在晚震旦世拉张槽隆升剥蚀阶段已具有雏形。拉张槽东西两侧是相互独立的构造区域，印支期（晚三叠世）古隆起与拉张槽具有北东向联合古隆起特征。此后演化特征仍具有差异性，特别是喜马拉雅期至今的演化过程中，川西南地区的隆升幅度远大于川中地区，致使现今构造特征表现为震旦系顶界构造川西南与川中分别位于同一隆起构造的高点和斜坡位置。因此，绵阳－长宁拉张槽对震旦系－下古生界原生油气地质条件的控制和川中古隆起对震旦系－下古生界古今油气藏的形成、调整和保存具有控制作用。%In the light of the findings of the early Cambrian Mianyang-Changning intracratonic sag, this paper makes a study related to the structure and evolution for further knowing the basic geology in Sichuan Basin.Based on the palaeotectonic reconstruction of the top of the Sinian strata and by comparing the ranges of the intracratonic sag and the paleouplift at various stages,the present paper deciphers the relationship between the Mianyang-Changning intracratonic sag and the Central Sichuan paleouplift.The result shows that Sichuan Basin can be classified into 12 areas based on the evolutionary characteristics of the intracratonic sag and the paleouplift.The paper proposes that the Central Sichuan paleouplift formed with the evolution of the Cambrian intracratonic sag.The east side and west side of the intracratonic sag are independent tectonic regions,and only during Late Triassic period,they jointed a paleouplift.Their present structural features are the Southwest Sichuan uplift and the Central Sichuan uplift,respectively,especially resulting from the differential evolutions after the Himalayan period.Therefore,the Mianyang-Changning intracratonic sag controls the primary oil and gas geological conditions and the Central Sichuan paleouplift controls the formation,adjustment and preservation of the oil and gas reservoirs of the Lower Paleozoic-Sinian strata.