沉积过程对被动大陆边缘构造热演化影响研究

Influence of surface processes on tectono-thermal evolution of rifted margins

在被动大陆边缘形成过程中,沉积过程会促进岩石圈挠曲均衡调整和产生沉积热披覆效应,影响大陆边缘结构和热演化过程,是被动大陆边缘伸展破裂机制研究和油气盆地烃源岩演化的重要控制因素。本文总结了被动大陆边缘构造热演化研究进展,分析了沉积过程对其构造热演化的影响。多种地质证据表明,沉积-剥蚀过程会通过调整裂谷体系中的负载分布和地壳后续变形等,对裂谷断层发育、大陆边缘形态及对称性、裂后异常构造沉降和岩浆作用等有重要影响。然而,目前被动大陆边缘形成过程数值模拟研究仍较少考虑二维(2D)或三维(3D)剥蚀-沉积过程,不能较好地恢复沉积盆地热史和生烃史。通过耦合2D或3D沉积过程的岩石圈构造演化模型,可以对被动大陆边缘构造热演化带来新的、全面的认识。

Tectono-thermal modelling is one of the key means in exploring the continental rifted margins.During rifting,erosion and sedimentation will modulate the distribution of loading and deformation of the crust,and thus influence the tectono-thermal evolution of passive continental margins.Surface processes are important controlling factors of rifting process and the evolution of hydrocarbon source rocks in oil and gas basins.We summarized the tectono-thermal evolution of passive continental margins,and showed two mechanism of the impact of surface processes:flexural isostatic balance of the lithosphere and thermal blanketing effect of sediments.Multiplesourced geological evidence suggests that the surface process has a significant impact on the development of rift faults,the morphology and symmetry of continental margins,post-rift anomalous tectonic subsidence,and magmatism,by adjusting the load distribution and subsequent crustal deformation in the rift system.However,current numerical modeling studies on the formation of passive continental margins still rarely consider 2D or 3D surface processes,which limits their ability to accurately reconstruct the thermal history and hydrocarbon generation history of sedimentary basins.By coupling the lithospheric tectonic evolution model with 2D or 3D surface processes,a new and comprehensive understanding of the tectono-thermal evolution of passive continental margins can be brought.