Role of paleoenvironment conditions and microbial activities in spatiotemporal distribution of ‘Orsten’-type biota: evidence from the early Cambrian of the Three Gorge area, South China The 5th International Conference of Geobiology

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Role of paleoenvironment conditions and microbial activities in spatiotemporal distribution of ‘Orsten’-type biota: evidence from the early Cambrian of the Three Gorge area, South China

ID：244 View Protection：ATTENDEE Updated Time：2025-05-21 16:51:23 Hits：239 Poster Presentation

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Abstract

The Ediacaran–Cambrian transition marks a major biological revolution characterized by the rapid emergence of diverse metazoan phyla and the establishment of metazoan-dominated ecosystems, as evidenced by globally distributed exceptional fossil assemblages. Among these, ‘Orsten’-type preservation provides unique insights into meiofaunal communities typically underrepresented in other taphonomic modes. From the Ediacaran to Ordovician, two key trends coincide with the diversification of ‘Orsten’-preserved meiofaunal organisms: (1) a progressive decline in fossil fidelity of the ‘Orsten’-preservation and (2) a spatial migration of environments favoring preservation from shallow to relatively deep marine settings, with a critical transition possibly occurring during Cambrian Series 2, Stage 3. To investigate the drivers of this shift, we analyzed two sections deposited synchronously during Cambrian Series 2, Stage 3 under contrasting water depths, namely Changkan (shallow) and Qiaojiaping (deep) sections of the eastern Three Gorges area, South China. Both sections yield abundant cuticular fossils associated with microbial assemblages, with six and five distinct microbial morphotypes identified in the Shuijingtuo and Shipai formations, respectively. Integrated paleontological and geochemical data (Mo-EF vs. U-EF) suggest that the observed contrasts in fossil abundance, diversity, and fidelity between the two sections reflect divergent paleoredox conditions, opposing pore-water phosphorus enrichment trends, and fundamentally distinct microbial roles in preservation pathways. Broader analysis implies that the spatiotemporal migration of ‘Orsten’-type preservation reflects multidirectional feedback mechanisms, including: (1) marine oxygenation episodes; (2) altering dissolved phosphorus reservoirs in water column and pore-water; and (3) biological innovations such as “substrate revolution” and “culture revolution” brought by grazing pressure, which suppressed microbial mat proliferation while enhancing biomixing. These processes may have shoaled the oxygen penetration depth, diversified microbial decomposer communities, and intensified microbial engagement in diagenetic phosphorus cycling. Ultimately, sustained environmental perturbations and ventilated irrigation regimes reshaped microbial mediation of taphonomy, facilitating the rise of modern marine ecosystems. The spatiotemporal evolution and eventual decline of ‘Orsten’-type preservation thus record a transformative interplay between biosphere evolution and Earth system dynamics during the Cambrian radiation

Keywords

‘Orsten’-type preservation, Doushantuo-type preservation, microbes, Lagerstätte, taphonomy

Speaker

Ying Wu

student Chengdu University of Technology

Submission Author

Ying Wu Chengdu University of Technology

Lei Zhang Chengdu University of Technology

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Important Date

Conference Date

Jun 10

2025

to

Jun 13

2025
Apr 15 2025

Draft paper submission deadline

Organized By

State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (CUG, Wuhan)

Contact Information

Yizhou Huang
yi******@cug.edu.cn
186********

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