We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Geochemical characteristics of the Ediacaran Dengying Formation in South Qinling: implications for the dolomitization mechanism of dolomites and the terminal Ediacaran paleoenvironment.
- Authors
Liu, Sicong; Zheng, Deshun; Sun, Jiangtao; Li, Yu
- Abstract
The dolomite explosion in the terminal Ediacaran period has great geological significance for understanding the paleoenvironmental evolution of the Precambrian-Cambrian transition. However, dolomite origins remain controversial. Abundant dolomites in the Ediacaran Dengying Formation in the northern Yangtze Block provide a window for solving the problem. In this paper, the genesis of dolomites and the paleoenvironment of the terminal Ediacaran were studied by facies, trace elements (including rare earth elements, REEs), and carbon, oxygen, and strontium isotopes of the Dengying Formation in the Xichuan area of South Qinling, Northern Yangtze Block. The results indicate that the Dengying Formation was deposited on a carbonate platform, and four types of dolomite (i.e., micro-crystalline dolomite, fine-medium crystalline dolomite, brecciated dolomite, and saddle dolomite) are identified. According to the differences in the ∑REEs, δ13C, Z value and 87Sr/86Sr values in different types of dolomite, it is concluded that micro-crystalline dolomite mainly formed in the early diagenetic stage, fine-medium crystalline dolomite in the middle diagenetic stage, and saddle dolomite in the late diagenetic stage, while brecciated dolomite formed in the epigenetic stage. Moreover, it is determined that the dolomitization models for the Dengying Formation include the seepage-reflux, mixed water, burial, and hydrothermal dolomitization models. In addition, micro-crystalline dolomite has a Sr/Ba value far greater than 1, the Z value is usually greater than 125, δEu is positive, V/(V + Ni) is less than 0.74, and δ13C is positive, indicating that the Dengying Formation dolomite was deposited in a shallow water environment with high salinity, weak oxidation, and dry and warm climate. By comparing the characteristics of dolomite in other parts of the world in the same period, it indicates that the global climate warmed up, the ocean appeared oxygenation process, and extensive retrogression events occurred in the Precambrian-Cambrian boundary.
- Publication
Arabian Journal of Geosciences, 2021, Vol 14, Issue 22, p1
- ISSN
1866-7511
- Publication type
Article
- DOI
10.1007/s12517-021-08508-y