Several grabens were developed within Jianghan Basin and their formation and evolution are essential to accumulation of oil and gas in the basin. With an emphasis on the Yuan’an Graben and Nanzhang Graben in northwestern Jianghan Basin and in combination with detailed field observation and measurement of faulting deformation, this study analyzed in detail the tectonic deformation of the northwestern graben zone of Hanjiang Basin and established the stress field sequences. Based on the regional structures and superimposed deformation features in this area, the evolution history of the grabens in Jianghan Basin can be divided into four main stages: 1) Late Cretaceous to Paleogence, the grabens formed in Jianghan Basin due to an NEE-SWW-trending extension; 2) late Paleogence, the grabens deformed strongly by the E- W-striking tectonic compression; 3) Neogene, controlled by NE-SW-trending extension and NW-SE- striking extension in turn, the grabens were extended again; and 4) Late Neogene, dextral-slip activation occurred in the grabens due to NE-SW-striking compression. The establishment of the structural deformation sequence of Hanjiang basin since Late Cretaceous provides structural and geological evidence for probing into the tectonic evolution of Hanjiang Basin during the late stage and reformation of oil and gas accumulation.
