Title: Widespread delayed mixing in early to middle Cambrian marine shelfal settings
Constraining the timing and motivation of CSR in global view
https://doi.org/10.1016/j.palaeo.2014.01.024
wWillie Wei-Lun Chen
Department of Geoscience, National Taiwan University
Previous view
Introduction
Initial view:ㄇalong with CE
ㄇInitial view:ㄇalong with
C-E transition
- Began along with the rapid diversification of infauna(Precambrian-Cambrian transition), or even occurred in late Neoproterozoic
- Marked by the appearance of the index fossil, three-dimensional burrow Treptichnus pedum and the disappearance of widespread matground structures (( Seilacher and Pflüger, 1994,)
- classic and cited by many publications
Subsequent study: gradual, protracted process
Subsquent study: gradual, protracted process
- Tommotian (McIlroy and Logan, 1999)
- Between Tommotian and Atdabanian(Droser and Bottjer, 1988)
- Base of Atdabanian(Droser et al., 2002)
Paucity: rapid and conspicuous
Study Area
1. lower Cambrian Wood Canyon Formation (Great Basin,US)
2. lower to middle Cambrian Pioche (and correlative Bright Angel Shale) Formations (Great Basin,US)
3. lower Cambrian Torreárboles Sandstone (Guadalajara, Spain)
4. lowermost Cambrian Chapel Island Formation(Newfoundland, Canada)
ㄘHypothesis
Diplocraterion parallelum, Mángano and Buatois(2017)
hypothesis
Deep-tiered trace fossils found in the period, are belong to suspension feeding metazoa
less efficient on increased advection of bottom-waters into the substrate
The progress of CSR may pushed by the emergence of Trilobite in Cambrian series 2
Rusophycus radialis,
Mángano and Buatois(2016)
Over 450 m of section , comprising over 24,300 discrete beds, were examined, and data were collected
method and criteria
- choose heterolithic succession
importance of facies
six ichnofossils criteria:
1) bedding thickness
2) fabric disruption
3) depth of bioturbation
4) bioglyphic preservation
5) the paleobiological and paleoecological complexity of trace fossil assemblages
6) surficially produced physical sedimentary structure
References
References
- Seilacher, A., Pflüger, F., 1994. From biomats to benthic agriculture: a biohistoric revolution.
- McIlroy, Duncan, and Graham A. Logan. "The impact of bioturbation on infaunal ecology and evolution during the Proterozoic-Cambrian transition." Palaios 14.1 (1999): 58-72.
- Droser, Mary L., and David J. Bottjer. "Trends in depth and extent of bioturbation in Cambrian carbonate marine environments, western United States." Geology 16.3 (1988): 233-236.
References
- Droser, Mary L., Sören Jensen, and James G. Gehling. "Trace fossils and substrates of the terminal Proterozoic–Cambrian transition: implications for the record of early bilaterians and sediment mixing." Proceedings of the National Academy of Sciences 99.20 (2002): 12572-12576.
- Mángano, M. Gabriela, and Luis A. Buatois. "The Cambrian revolutions: Trace-fossil record, timing, links and geobiological impact." Earth-science reviews 173 (2017): 96-108.