148 / 2019-06-05 14:56:28

Meso-Neoproterozoic Sedimentary System and Palaeogeographic Evolution of Typical Aulacogens in North China Craton

Typical Aulacogens, Meso-Neoproterozoic, Lithofacies Palaeogeography, Sedimentary System, North China Craton

The potential of oil and gas resources in the Meso-Neoproterozoic has attracted close attention of the international geological community. Proterozoic high-quality source rocks in other countries also developed in the North China craton basin in China at the same time, indicating that the Meso-Neoproterozoic in North China also has great exploration potential. This paper takes Meso-Neoproterozoic strata in Yanliao Aulacogen and Xiong’er Aulacogen of the north-eastern margin of North China Craton as the research object. Based on 6 field backbone profile measurements and 9 key auxiliary profile observations, the types and characteristics of Meso-Neoproterozoic sedimentary systems and the overall evolution of palaeogeographic environment in the typical aulacogens of North China Craton are systematically studied from the aspects of rock color, rock association type, rock structure, sedimentary structure and geochemistry.
The results shows that: the Meso-Neoproterozoic in the study area can be divided into four major sedimentary systems, seven sedimentary facies: ①Marine clastics sedimentary system includes barrier-type coastal facies, barrier-free coastal facies and neritic shelf facies; ②Marine carbonate sedimentary system mainly includes carbonate platform facies and biohermal facies; ③Marine-continental transitional facies sedimentary system includes fan delta facies; ④Glacial sedimentary system includes glacial facies. According to its sedimentary characteristics, fourteen subfacies and twenty microfacies are further divided. Among them, barrier-free coastal facies, carbonate platform facies and neritic shelf facies are the main sedimentary facies types of Meso-Neoproterozoic in the study area. The lithofacies and palaeogeographic characteristics in different periods of the study area are obviously different. In Mesoproterozoic, the study area sedimentary systems changed from clastic rock sedimentary system of the Changcheng System to carbonate rock sedimentary system of the Jixian System, and then to the coexistence of clastic rock sedimentary system and carbonate rock sedimentary system of the To-be-built System. In Neoproterozoic, the study area changed from clastic rock sedimentary system of the Qingbaikou System to glacial-clastic rock sedimentary system of the Sinian System developed only in Xiong’er aulacogen, and the difference between north and south is obvious.