TY  - JOUR
AV  - restricted
TI  - Integrated Stratigraphy and Mineralogy of the Doushantuo Formation in Weng?an, South China, and Implications for Ediacaran Phosphogenesis
Y1  - 2024/04//
EP  - 503
UR  - https://doi.org/10.1007/s12583-022-1765-3
ID  - discovery10163957
N2  - The Ediacaran?Cambrian Phosphogenic Episode is the Earth?s first true phosphogenic event and resulted in worldwide phosphate deposits, which occurred during the processes of the Neoproterozoic Oxygenation Event. The Ediacaran Doushantuo Formation (ca. 635?551 Ma) of Weng?an area in central Guizhou, South China, contains two economic phosphorite beds (the Lower and Upper Phosphorite Beds). This paper presents a detailed stratigraphic, sedimentological and mineralogical study of multiple outcrop and drill core sections of the Doushantuo Formation across the Weng?an area, and identified 11 lithofacies and 4 types of phosphatic grains. Significant differences in lithofacies and grain types between the upper and lower phosphate deposits are observed, indicating that the two sets of phosphate deposits are the products of two distinct phosphogenic processes. The Lower Phosphorite Bed mainly consists of banded and laminated phosphorites, contains micro-oncoids formed by microbially-mediated precipitation and peloids formed by in-situ chemically oscillating reactions, indicating a biochemical and chemical enrichment of phosphorus to sediments during the Early Ediacaran Period. The Upper Phosphorite Bed is mainly composed of carbonaceous, massive, and stromatolitic phosphorites, contains bioclasts (phosphatized spheroidal fossils), and intraclasts formed by hydrodynamic agitation, suggesting that the major accesses of phosphorus to sediments were the remineralization of organic P. Deposition of the two economic phosphorite beds was controlled by two sea-level cycles. Such differences have also been documented in contemporaneous phosphate-bearing successions in Brazil and Mangolia, indicating a significant shift in global phosphogenic mechanism during the early and middle Ediacaran, which may be due to the changes in redox conditions in seawater, associated with the Neoproterozoic Oxygenation Event. These regional active P-cycle processes could produce more free oxygen, which may have contributed to the upcoming Phanerozoic global oxidation.
SP  - 476
N1  - This version is the author accepted manuscript. For information on re-use, please refer to the publisher?s terms and conditions.
VL  - 35
KW  - phosphorite
KW  -  lithofacies
KW  -  phosphatic grains
KW  -  phosphogenic paragenesis
phosphorus cycle
KW  -  mineralogy
JF  - Journal of Earth Sciences
A1  - Jiao, L
A1  - She, Z
A1  - Papineau, D
A1  - Zhang, Y
A1  - Dodd, MS
A1  - Cao, K
A1  - Chen, Q
ER  -