Color changes of Upper Cretaceous stratum and the depositional environment implication in northern Songliao Basin
Liu Ying1,2, Wu Chaodong1,2, Zhang Shun3
1. Key Laboratory of Orogenic Belts and Crustal Evolution of Ministry of Education, Peking University Beijing 100871;
2. The institute of Oil & Gas, Peking University Beijing 100871;
3. Research Institute of Exploration and Development, Petro-China Daqing Oilfield Company Ltd. , Daqing, Heilongjiang 163712
Through the color index analysis of the Upper Cretaceous stratum,and with the evidence of evolution of paleoclimate,ostracods,paleomorphology and provenance analysis to be compared,the characteristics of color in time and space variations were summed up:from Qingshankou Formation to Member 4 of Nenjiang Formation,there are two distinct cycles,which were controlled by paleoclimate; from Member 5 of Nenjiang Formation to Mingshui Formation,the color had complex changes,which were controlled by tectonic activity.The oxidation tint in Member 3 and 4 of Nenjiang Formation is mainly distributed in the eastern and northeastern basin controlled by sedimentary system,which confirmed the main provenances existed in the eastern and northeastern during the deposition of the Member 3 of the Nenjiang Formation and changed to the north from Member 3 to 4 of Nenjiang Formation.The analysis showed that color changes caused by two main factors:the sedimentary media concentration and hydrodynamic conditions.The results show that color index of stratum is mainly decided by the solution concentration and hydrodynamic so as to reflect the environmental changes in time and space,which can be used as an important indicator in the regional study of paleoclimate,basin evolution and paleomorphology reconstruction.