STUDY ON THE SEQUENCE STRATIGRAPHY OF SINIAN GANJINGZI FORMATION IN DALIAN REGION, LIAONING PROVINCE

The Ganjingzi Formation of Dalian region is an important Neoproterozoic stratigraphic horizon in Liaoning Province where lots of carbonate rocks are developed. Based on the classical sequence stratigraphy theory, through the comprehensive analysis of field survey sections, the sequence stratigraphy of Sinian Ganjingzi Formation in Dalian is studied, and 5 sequence boundaries are identified, which are further divided into 4 third-order sequences, 15 parasequence formations and 55 parasequences. The sedimentary facies of carbonate rocks can be divided into restricted platform and open platform subfacies, and subdivided into lagoon, tidal flat, low-energy subtidal and shoal microfacies. The regional tectonics and astronomical cycles are used to discuss the environmental evolution of Ganjingzi Formation. It is believed that process went through restricted platform→open platform→restricted platform. Under the influence of low-amplitude tectonic uplift and subsidence at the end of Yangtze cycle, 5 short times of exposures took place during the late Nanguanling period-Ganjingzi period in Dalian area, which formed 5 sequence boundaries. Meanwhile, effected by periodic astronomical cycles, the high-frequency cycles of parasequences are formed. The study on the sequence stratigraphy and sedimentary evolution of Ganjingzi Formation in Dalian region provides a basis for the oil-gas exploration in southeastern Liaoning Province.