Basement Structures Have Crucial Influence On Rift Development: Insights From the Jianghan Basin, Central China

Crustal heterogeneity has a fundamental influence on rift development; however, the detailed architecture of structures within crystalline basement is commonly poorly understood, resulting in the exact manner in which basement structures control rift development being rather enigmatic. The Jianghan Basin evolved on a crystalline basement covered by thick prerift strata, providing an excellent opportunity to unravel the enigma. Using extensive 2‐D and 3‐D seismic, borehole and field data from the Jianghan Basin in combination, we investigate the deformation characteristics of basement structures and unravel their relationship with the overlying rift basin. A most striking feature of the basement structures in the Jianghan Basin is that prerift strata near the major rift‐related fault planes in the hanging walls are older than these in the footwalls and for most faults prerift strata in the hanging walls become increasingly older while approaching the fault planes, suggesting that these rift‐related faults have reactivated preexisting thrusts or thrusts associated with unroofed folds through negative structural inversion. All the major rift‐related faults have very high Dmax/L ratios (0.11–0.66) compared to typical normal faults, likely resulting from either constant length fault model or low frictional strength. By unraveling the prerift deformation intensity and structural division of basement structures in the Jianghan Basin, we propose that basement structures not only have crucial influence on rift geometry but also control rift localization. The reactivation of multidirectional basement structures and multidirectional extension with rift localization in the Jianghan Basin provides yet unrecognized insights into the development of tripartite rift systems.