关键词: 成因演化, 盆地结构, 新生代, 珠一坳陷, 珠江口盆地

Abstract: Based on investigating the general characteristics of fault systems by using abundant 3D seismic data, this paper clarified the
tectonic evolution vertically and superimposition process of a Cenozoic basin by calculating the fault activity rate, analyzing the
equilibrium section, and combining the distribution characteristics of residual strata. The dynamic mechanism of the development and
transformation of the basin was also discussed. Results show that the Zhu 1 depression of the Pearl River Mouth Basin of this study
underwent four evolution stages: early stage of rifting, late stage of rifting, depression stage and tectonic reactivation stage. In detail,
during the rifting stage (E2w-E2e), due to the rotating extrusion of the Indochina block and the southward subduction of the proto-South
China Sea, the regional stress field changed clockwisely from NW-trending to SN-trending. This resulted in the transformation of basincontrolling
faults from early rifting WE- and NEE-trending into late rifting EW- and NWW-trending. The system of lithosphere
extensional deformation transformed from the wide rift mode to the narrow rift mode. As a result, the isolated half-graben or narrow
graben of the basin structure tended to be connected and extended. While during the post-rifting depression period (E3z-N1z-N1h), the
activity of those faults decreased and stopped. It might because the extensional center of lithosphere had migrated southward to the
spreading center of the South China Sea, and the northern margin of the South China Sea was in a post-rifting thermal subsidence stage
with weak tectonic activities overall. Then during the tectonic activation stage (N1y-N2w-Q), the NWW-trending and pre-existing
subparallel EW-trending faults reactivated, and the conjugate strike-slip fault system is composed of a subparallel EW-trending dextral
strike-slip fault zone and a NW-trending sinistral strike-slip fault zone, and a series of NWW-trending secondary tensile fractures were
formed. It might be due to the NNE-trending extensional stetting caused by the obduction and arc-continent collision of the NWW
movement of the Philippine Sea Plate. Cenozoic tectonic evolution of the Zhu 1 depression revealed by this study not only provides
guidance for regional oil and gas exploration, but also has certain reference implications for the study of evolution of passive continental
margins.

Key words: genetic evolution, basin structure, Cenozoic, Zhu 1 depression, Pearl River Mouth Basin