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- Title
Burial Dolomitization and Mixed Water Dolomitization in Longwangmiao Formation, Southeastern Sichuan Basin.
- Authors
WANG Yong; SHI ZeJin; MENG XingPing; LIU PeiJie; TIAN YaMing; QING HaiRuo
- Abstract
Based on field investigation and geochemical analysis, it is believed that the dolomites of the Longwangmiao Formation in the Tuhechang and Nanshanping sections, southeast Sichuan Basin, differ from other dolomites in the area, being mainly of reflux seepage origin. Tuhechang dolomite is of burial origin, and the dolomite in Nanshan-ping is of mixed-water origin. The Tuhechang dolomites occur in the lower part of the Longwangmiao Formation, and did not have the geological conditions suitable for forming reflux seepage dolomites. The temperature of inclusions of the Tuhechang dolomites shows a formation temperature higher than 105 °C. Its Mn element and Fe element content are relatively high (average 792.5x10-6 and 3 428.8x10-6 respectively), with good correlation. The average δ18O content is - 8.18‰, which is significantly lower than for dolomites in other sections of the study area. These all reflect a burial environment in the Tuhechang section. The main part of the Nanshanping section lies in a slope facies zone, and did not have the geological conditions for the formation of reflux seepage dolomite. Nanshanping dolomite contains an obviously low value for Na element, and δ18O is also obviously negative, both indicating that it was formed in a low-salinity fluid environment at a relatively low temperature. In addition, Nanshanping dolomite shows obvious U element enrichment, indicating that its formation was related to atmospheric fresh water, and it is therefore a mixed-water dolomite. These two dolomite types have relatively good physical properties, which is highly significant for reservoir development in the southeastern Sichuan Basin.
- Publication
Acta Sedimentologica Sinica, 2021, Vol 39, Issue 6, p1517
- ISSN
1000-0550
- Publication type
Article
- DOI
10.14027/j.issn.1000-0550.2021.065