Abstract: This paper probes into the characteristics of the Cenozoic Jiuxi basin from its present tectonic stress field, decollement surface, kinematic feature, sedimentary structure and structural model. It is suggested that the Cenozoic Jiuxi basin is piggyback basin on the north Qilian nappe, where the structural and sedimentary features are all controlled by the thrusting intensity of the north Qilian nappe. Also, this paper makes a brief analysis of the relationship between such a basin and hydrocarbon accumulation.

Key words: Jiuxi basin, piggyback characteristic, nappe, hydrocarbon accumulation