Correspondences between high‐frequency sequences and the Milankovitch Cycles of Dongying Formation in Liaoxi Uplift, Bohai Bay Basin, North‐east China. (26th March 2021)

• Record Type: Journal Article
• Authors: Xia, Shiqiang; Lin, Changsong; Du, Xiaofeng; Li, Hong
• Is Part Of: Geological journal. Volume 56:Number 7(2021)
• Page Start: 3687
• Page End: 3697
• Publication Date: 2021-03-26
• Subjects: Bohai Bay Basin -- Dongying Formation -- high‐frequency sequences -- Liaoxi Uplift -- Milankovitch Cycles; Geology -- Periodicals; 551
• DOI: 10.1002/gj.4130
• Languages: English
• ISSNs: 0072-1050

Abstract

Abstract : The typical wells in Liaoxi Uplift were selected to conduct studies on high‐frequency sequences and their correspondences with the Milankovitch Cycles in Dongying Formation based on integrated analysis of wireline logs and sieve residue logs. The results of well JZ‐E show that 37 ultra‐short‐term cycles, 13 short‐term cycles, 8 mid‐term cycles, and 5 long‐term cycles are identified. Meanwhile, the correspondences between high‐frequency sequences and the Milankovitch Cycles in Dongying Formation were analysed based on GR curve of well JZ‐E and MATLAB procedure. The correspondences indicate that the Milankovitch Cycles are well preserved in Dongying Formation. The thickness of long‐period cycles caused by eccentricity ranges from 2.7963 to 3.9965 m. The thickness of mid‐term cycles caused by obliquity ranges from 1.5081 to 2.1126 m. The thickness of short‐period cycles caused by precessions ranges from 0.5791 to 1.1269 m. There is a good consistency between high‐frequency sequences and the Milankovitch Cycles in Dongying Formation. The mid‐term cycle, short‐term cycle, and ultra‐short‐term cycle of high‐frequency sequence correspond, respectively, to long‐period eccentricity, short‐period eccentricity, and precession cycle of the Milankovitch Cycles. Lacustrine fluctuations caused by the change in Earth's orbit play a major role in controlling high‐frequency sequences. Abstract : The facies distributions within high‐frequency sequence stratigraphic framework with Dongying Formation in Liaoxi Uplift still sparks controversy. Th typical well in Liaoxi Uplift is picked to conduct study on high‐frequency sequences in Dongying Formation. The results of well JZ‐E show that 37 ultra‐short‐term cycles, 13 short‐term cycles, 8 mid‐term cycles, and 5 long‐term cycles are identified. Furthermore, the responses between the Milankovitch Cycles and high‐frequency sequences in Dongying Formation based on GR logs calculated by MATLAB procedure. The responses indicate that the Milankovitch Cycles are well preserved in Dongying Formation. The thickness of long‐period cycles caused by eccentricity ranges from 2.7963 to 3.9965 m, the thickness of mid‐term cycles caused by obliquity cycles ranges from 1.5081 to 2.1126 m and the thickness of short‐period cycles caused by precessions ranges from 0.5791 to 1.1269 m. It shows good consistency between high‐frequency sequences in Dongying Formation and the Milankovitch Cycles. The mid‐term cycle, short‐term cycle and ultra‐short‐term cycle of high‐frequency sequences corresponds respectively to long‐period eccentricity, short‐period eccentricity and precession cycle of the Milankovitch Cycles. Lacustrine level caused by changes of the Earth's orbit plays a major role in controlling high‐frequency sequences.