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Marine redox evolution in the early Cambrian Yangtze shelf margin area: evidence from trace elements, nitrogen and sulphur isotopes

Part of: From Snowball Earth to the Cambrian Explosion: Evidence from China

Published online by Cambridge University Press:  22 March 2017

GUANG-YI WEI ,
HONG-FEI LING ,
DA LI ,
WEI WEI ,
DAN WANG ,
XI CHEN ,
XIANG-KUN ZHU ,
FEI-FEI ZHANG  and
BIN YAN
GUANG-YI WEI
Affiliation:
State Key Laboratory for Mineral Deposits Research, School of Earth Science and Engineering, Nanjing University, Nanjing 210023, China
HONG-FEI LING*
Affiliation:
State Key Laboratory for Mineral Deposits Research, School of Earth Science and Engineering, Nanjing University, Nanjing 210023, China
DA LI
Affiliation:
State Key Laboratory for Mineral Deposits Research, School of Earth Science and Engineering, Nanjing University, Nanjing 210023, China
WEI WEI
Affiliation:
State Key Laboratory for Mineral Deposits Research, School of Earth Science and Engineering, Nanjing University, Nanjing 210023, China
DAN WANG
Affiliation:
MLR Key Laboratory of Isotope Geology, State Key Laboratories of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
XI CHEN
Affiliation:
State Key Laboratory for Mineral Deposits Research, School of Earth Science and Engineering, Nanjing University, Nanjing 210023, China
XIANG-KUN ZHU
Affiliation:
MLR Key Laboratory of Isotope Geology, State Key Laboratories of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
FEI-FEI ZHANG
Affiliation:
School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-6004, USA
BIN YAN
Affiliation:
MLR Key Laboratory of Isotope Geology, State Key Laboratories of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
*
†Author for correspondence: [email protected]
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Abstract

Nitrogen is an essential element for biological activity, and nitrogen isotopic compositions of geological samples record information about both marine biological processes and environmental evolution. However, only a few studies of N isotopes in the early Cambrian have been published. In this study, we analysed nitrogen isotopic compositions, as well as trace elements and sulphur isotopic compositions of cherts, black shales, carbonaceous shales and argillaceous carbonates from the Daotuo drill core in Songtao County, NE Guizhou Province, China, to reconstruct the marine redox environment of both deep and surface seawater in the study area of the Yangtze shelf margin in the early Cambrian. The Mo–U covariation pattern of the studied samples indicates that the Yangtze shelf margin area was weakly restricted and connected to the open ocean through shallow water flows. Mo and U concentrations, δ15Nbulk and δ34Spy values of the studied samples from the Yangtze shelf margin area suggest ferruginous but not sulphidic seawater and low marine sulphate concentration (relatively deep chemocline) in the Cambrian Fortunian and early Stage 2; sulphidic conditions (shallow chemocline and anoxic photic zone) in the upper Cambrian Stage 2 and lower Stage 3; and the depression of sulphidic seawater in the middle and upper Cambrian Stage 3. Furthermore, the decreasing δ15N values indicate shrinking of the marine nitrate reservoir during the middle and upper Stage 3, which reflects a falling oxygenation level in this period. The environmental evolution was probably controlled by the changing biological activity through its feedback on the local marine environment.

Keywords

Yangtze shelf marginearly Cambrianlocal redox conditionnitrogen cyclebiological feedback
Type
Original Articles
Information
Geological Magazine , Volume 154 , Issue 6: THEMATIC ISSUE: From Snowball Earth to the Cambrian Explosion: Evidence from China , November 2017 , pp. 1344 - 1359
Copyright
Copyright © Cambridge University Press 2017 

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References

Ader, M., Sansjofre, P., Halverson, G. P., Busigny, V., Trindade, R. I. F., Kunzmann, M. & Nogueira, A. C. R. 2014. Ocean redox structure across the Late Neoproterozoic Oxygenation Event: a nitrogen isotope perspective. Earth and Planetary Science Letters 396, 1–13.CrossRefGoogle Scholar
Algeo, T. J., Luo, G. M., Song, H. Y., Lyons, T. W. & Canfield, D. E. 2015. Reconstruction of secular variation in seawater sulfate concentrations. Biogeosicences 12 (7), 2131–51.CrossRefGoogle Scholar
Algeo, T. J. & Lyons, T. W. 2006. Mo–total organic carbon covariation in modern anoxic marine environments: implications for analysis of paleoredox and paleohydrographic conditions. Paleoceanography 21 (1), PA1016. doi: 10.1029/2004PA001112.CrossRefGoogle Scholar
Algeo, T. J. & Rowe, H. 2012. Paleoceanographic applications of trace-metal concentration data. Chemical Geology 324–325, 6–18.CrossRefGoogle Scholar
Algeo, T. J. & Tribovillard, N. 2009. Environmental analysis of paleoceanographic systems based on molybdenum–uranium covariation. Chemical Geology 268 (3–4), 211–25.CrossRefGoogle Scholar
Anbar, A. D. & Knoll, A. H. 2002. Proterozoic ocean chemistry and evolution: a bioinorganic bridge? Science 297 (5584), 1137–42.CrossRefGoogle ScholarPubMed
Berner, E. K. & Berner, R. 1996. Global environment: water, air and geochemical cycles. Upper Saddle River, NJ: Prentice Hall, 376 pp.Google Scholar
Calvert, S. 2004. Beware intercepts: interpreting compositional ratios in multi-component sediments and sedimentary rocks. Organic Geochemistry 35, 981–7.CrossRefGoogle Scholar
Canfield, D. E. 2001. Biogeochemistry of sulfur isotopes. Stable Isotope Geochemistry 43, 607–36.CrossRefGoogle Scholar
Canfield, D. E. 2004. The evolution of the earth surface sulfur reservoir. American Journal of Science 304, 839–61.CrossRefGoogle Scholar
Canfield, D. E. 2005. The early history of atmospheric oxygen: homage to Robert M. Garrels. Annual Review of Earth and Planetary Sciences 33, 1–36.CrossRefGoogle Scholar
Canfield, D. E., Poulton, S. W. & Narbonne, G. M. 2007. Late-Neoproterozoic deep-ocean oxygenation and the rise of animal life. Science 315 (5808), 92–5.CrossRefGoogle ScholarPubMed
Chen, X., Ling, H. F., Vance, D., Shields-Zhou, G. A., Zhu, M. Y., Poulton, S. W., Och, L. M., Jiang, S. Y., Li, D., Cremonese, L. & Archer, C. 2015. Rise to modern levels of ocean oxygenation coincided with the Cambrian radiation of animals. Nature Communications 6, 7142. doi: 10.1038/ncomms8142.CrossRefGoogle ScholarPubMed
Cheng, M., Li, C., Zhou, L., Algeo, T. J., Zhang, F. F., Romaniello, S., Jin, C. S., Lei, L. D., Feng, L. J. & Jiang, S. Y. 2016. Marine Mo biogeochemistry in the context of dynamically euxinic mid-depth waters: a case study of the lower Cambrian Niutitang shales, South China. Geochimica et Cosmochimica Acta 183, 79–93.CrossRefGoogle Scholar
Cremonese, L., Shields-Zhou, G., Struck, U., Ling, H.-F., Och, L., Chen, X. & Li, D. 2013. Marine biogeochemical cycling during the early Cambrian constrained by a nitrogen and organic carbon isotope study of the Xiaotan section, South China. Precambrian Research 225, 148–65.CrossRefGoogle Scholar
Emerson, S. R. & Huested, S. S. 1991. Ocena anoxia and the concentrations of molybdenum and vanadium in seawater. Marine Chemistry 34 (34): 177–96.CrossRefGoogle Scholar
Feng, L., Li, C., Huang, J., Chang, H. & Chu, X. 2014. A sulfate control on marine mid-depth euxinia on the early Cambrian (ca.529–521Ma) Yangtze platform, South China. Precambrian Research 246, 123–33.CrossRefGoogle Scholar
Fike, D. A., Grotzinger, J. P., Pratt, L. M. & Summons, R. E. 2006. Oxidation of the Ediacaran ocean. Nature 444 (7120), 744–7.CrossRefGoogle ScholarPubMed
Godfrey, L. V. & Falkowski, P. G. 2009. The cycling and redox state of nitrogen in the Archaean ocean. Nature Geoscience 2 (10), 725–9.CrossRefGoogle Scholar
Goldberg, E. D. 1963. Mineralogy and chemistry of marine sedimentation. In Submarine Geology (ed. Shepard, F. P.), pp. 436–66. New York: Harper and Row.Google Scholar
Goldberg, T., Poulton, S. & Strauss, H. 2005. Sulfur and oxygen isotope signatures of late Neoproterozoic to early Cambrian sulfate, Yangtze Platform, China: diagenetic constraints and seawater evolution. Precambrian Research 137 (3–4), 223–41.CrossRefGoogle Scholar
Goldberg, T., Strauss, H., Guo, Q. & Liu, C. 2007. Reconstructing marine redox conditions for the Early Cambrian Yangtze Platform: evidence from biogenic sulfur and organic carbon isotopes. Palaeogeography Palaeoclimatology Palaeoecology 254 (1–2), 175–93.CrossRefGoogle Scholar
Guo, Q., Shields, G. A., Liu, C., Strauss, H., Zhu, M., Pi, D., Goldberg, T. & Yang, X. 2007. Trace element chemostratigraphy of two Ediacaran–Cambrian successions in South China: implications for organosedimentary metal enrichment and silicification in the Early Cambrian. Palaeogeography, Palaeoclimatology, Palaeoecology 254 (1–2), 194–216.CrossRefGoogle Scholar
Habicht, K. S., Gade, M., Thamdrup, B., Berg, P. & Canfield, D. E. 2002. Calibration of sulfate levels in the Archean ocean. Science 298, 2372–4.CrossRefGoogle ScholarPubMed
Habicht, K. S., Salling, L., Thamdrup, B. & Canfield, D. E. 2005. Effect of low sulfate concentrations on lactate oxidation and isotope fractionation during sulfate reduction by Archaeoglobus fulgidus strain Z†. Applied and Environmental Microbiology 71 (7), 3770–7.CrossRefGoogle ScholarPubMed
Haq, B. U. & Schutter, S. R. 2008. A chronology of Paleozoic sea-level changes. Science 322 (5898), 64–8.CrossRefGoogle ScholarPubMed
Harrison, A. G. & Thode, H. G. 1958. Mechanism of the bacterial reduction of sulfate from isotope fractionation studies. Transactions of the Faraday Society 54, 84–92.CrossRefGoogle Scholar
Higgins, M. B., Robinson, R. S., Husson, J. M., Carter, S. J. & Pearson, A. 2012. Dominant eukaryotic export production during ocean anoxic events reflects the importance of recycled NH4 + . Proceedings of the National Academy of Sciences of the United States of America 109, 2269–74.CrossRefGoogle ScholarPubMed
Holland, H. D. 2006. The oxygenation of the atmosphere and oceans. Philosophical Transactions of the Royal Society B Biological Sciences 361 (1470), 903–15.CrossRefGoogle ScholarPubMed
Holser, W., Schidlowski, M., Mackenzie, F. & Maynard, J. 1988. Biogeochemical cycles of carbon and sulfur. Chemical Cycles in the Evolution of the Earth. Chichester: John Wiley & Sons, 105–74.Google Scholar
Jiang, S., Chen, Y., Ling, H., Yang, J., Feng, H. & Ni, P. 2006. Trace- and rare-earth element geochemistry and Pb–Pb dating of black shales and intercalated Ni–Mo–PGE–Au sulfide ores in Lower Cambrian strata, Yangtze Platform, South China. Mineralium Deposita 41 (5), 453–467.CrossRefGoogle Scholar
Jin, C. S., Li, C., Algeo, T. J., Planavsky, N. J., Cui, H., Yang, X. L., Zhao, Y. L., Zhang, X. L. & Xie, S. C. 2016. A highly redox-heterogeneous ocean in South China during the Early Cambrian (~529–514 Ma): implications for a local “Cambrian Explosion”. Earth and Planetary Science Letters 441, 38–51.CrossRefGoogle Scholar
Jin, C. S., Li, C., Peng, X. F., Cui, H., Shi, W., Zhang, Z.H., Luo, G. M. & Xie, S. C. 2014. Spatiotemporal variability of ocean chemistry in the early Cambrian, South China. Science China Earth Science 57, 579–91.CrossRefGoogle Scholar
Jones, D. S. & Fike, D. A. 2013. Dynamic sulfur and carbon cycling through the end-Ordovician extinction revealed by paired sulfate-pyrite δ34S. Earth and Planetary Science Letters 363, 144–55.CrossRefGoogle Scholar
Kikumoto, R., Tahata, M., Nishizawa, M., Sawaki, Y., Maruyama, S., Shu, D.G., Han, J., Komiya, T., Takai, K. & Ueno, Y. 2014. Nitrogen isotope chemostratigraphy of the Ediacaran and Early Cambrian platform sequence at Three Gorges, South China. Gondwana Research 25, 1057–69.CrossRefGoogle Scholar
Lehmann, B., Nägler, T. F., Holland, H. D., Wille, M., Mao, J., Pan, J., Ma, D. & Dulski, P. 2007. Highly metalliferous carbonaceous shale and Early Cambrian seawater. Geology 35 (5), 403–6.CrossRefGoogle Scholar
Li, C., Cheng, M., Algeo, T. J. & Xie, S. C. 2015. A theoretical prediction of chemical zonation in early oceans (>520 Ma). Science in China D (Earth Sciences) 58 (11), 1901–9.CrossRefGoogle Scholar
Li, C., Love, G. D., Lyons, T. W., Fike, D. A., Sessions, A. L. & Chu, X. 2010. A stratified redox model for the Ediacaran ocean. Science 328 (5974), 80–3.CrossRefGoogle ScholarPubMed
Li, C., Love, G. D., Lyons, T. W., Scott, C. T., Feng, L., Huang, J., Chang, H., Zhang, Q. & Chu, X. 2012. Evidence for a redox stratified Cryogenian marine basin, Datangpo Formation, South China. Earth and Planetary Science Letters 331–332, 246–56.CrossRefGoogle Scholar
Li, Z., Bogdanova, S. V., Collins, A. S., Davidson, A., De Waele, B., Ernst, R. E., Fitzsimons, I. C. W., Fuck, R. A., Gladkochub, D. P., Jacobs, J., Karlstrom, K. E., Lu, S., Natapov, L. M., Pease, V., Pisarevsky, S. A., Thrane, K. & Vernikovsky, V. 2008. Assembly, configuration, and break-up history of Rodinia: a synthesis. Precambrian Research 160 (1–2), 179–210.CrossRefGoogle Scholar
Ling, H.-F., Chen, X., Li, D., Wang, D., Shields-Zhou, G. A. & Zhu, M. 2013. Cerium anomaly variations in Ediacaran – earliest Cambrian carbonates from the Yangtze Gorges area, South China: implications for oxygenation of coeval shallow seawater. Precambrian Research 225, 110–27.CrossRefGoogle Scholar
Lyons, T. W., Anbar, A. D., Severmann, S., Scott, C. & Gill, B. C. 2009. Tracking Euxinia in the ancient ocean: a multiproxy perspective and proterozoic case study. Annual Review of Earth and Planetary Sciences 37 (1), 507–34.CrossRefGoogle Scholar
Lyons, T. W., Reinhard, C. T. & Planavsky, N. J. 2014. The rise of oxygen in Earth's early ocean and atmosphere. Nature 506 (7488), 307–15.CrossRefGoogle ScholarPubMed
Och, L. M. & Shields-Zhou, G. A. 2012. The Neoproterozoic oxygenation event: environmental perturbations and biogeochemical cycling. Earth-Science Reviews 110 (1–4), 26–57.CrossRefGoogle Scholar
Och, L. M., Shields-Zhou, G. A., Poulton, S. W., Manning, C., Thirlwall, M. F., Li, D., Chen, X., Ling, H., Osborn, T. & Cremonese, L. 2013. Redox changes in Early Cambrian black shales at Xiaotan section, Yunnan Province, South China. Precambrian Research 225, 166–89.CrossRefGoogle Scholar
Ohkouchi, N., Nakajima, Y., Okada, H., Ogawa, N. O., Suga, H., Oguri, K. & Kitazato, H. 2005. Biogeochemical processes in the saline meromictic Lake Kaiike, Japan: implications from molecular isotopic evidences of photosynthetic pigments. Environmental Microbiology 7, 1009–16.CrossRefGoogle ScholarPubMed
Pinti, D. L., Hashizume, K., Orberger, B., Gallien, J. P., Cloquet, C. & Massault, M. 2007. Biogenic nitrogen and carbon in Fe-Mn-oxyhydroxides from an Archean chert, Marble Bar, Western Australia. Geochemistry, Geophysics, Geosystems 8, Q02007. doi: 10.1029/2006GC001394.CrossRefGoogle Scholar
Piper, D. Z. & Calvert, S. E. 2009. A marine biogeochemical perspective on black shale deposition. Earth-Science Reviews 95 (1–2), 63–96.CrossRefGoogle Scholar
Prokopenko, M., Hammond, D., Berelson, W., Bernhard, J., Stott, L., Douglas, R. 2006. Nitrogen cycling in the sediments of Santa Barbara basin and Eastern Subtropical North Pacific: nitrogen isotopes, diagenesis and possible chemosymbiosis between two lithotrophs (Thioploca and Anammox) – ‘riding on a glider’. Earth and Planetary Science Letters 242, 186–204.CrossRefGoogle Scholar
Redfield, A. C. 1963. The influence of organisms on the composition of seawater. In The Sea (ed. Hill, M. N.), vol. II, pp. 26–77. New York: John Wiley.Google Scholar
Reinhard, C. T., Planavsky, N. J., Robbins, L. J., Partin, C. A., Gill, B. C., Lalonde, S. V., Bekker, A., Konhauser, K. O. & Lyons, T. W. 2013. Proterozoic ocean redox and biogeochemical stasis. Proceedings of the National Academy of Sciences of the United States of America 110 (14), 5357–62.CrossRefGoogle ScholarPubMed
Sahoo, S. K., Planavsky, N. J., Kendall, B., Wang, X., Shi, X., Scott, C., Anbar, A. D., Lyons, T. W. & Jiang, G. 2012. Ocean oxygenation in the wake of the Marinoan glaciation. Nature 489 (7417), 546–9.CrossRefGoogle ScholarPubMed
Scott, C. & Lyons, T. W. 2012. Contrasting molybdenum cycling and isotopic properties in euxinic versus non-euxinic sediments and sedimentary rocks: refining the paleoproxies. Chemical Geology 324–325, 19–27.CrossRefGoogle Scholar
Scott, C., Lyons, T. W., Bekker, A., Shen, Y., Poulton, S. W., Chu, X. & Anbar, A. D. 2008. Tracing the stepwise oxygenation of the Proterozoic ocean. Nature 452 (7186), 456–59.CrossRefGoogle ScholarPubMed
Shen, Y., Zhao, R., Chu, X. & Lei, J. 1998. The carbon and sulfate isotope signature in the Precambrian–Cambrian transition series of the Yangtze Platform. Precambrian Research 89, 77–86.CrossRefGoogle Scholar
Shields-Zhou, G. & Zhu, M. 2013. Biogeochemical changes across the Ediacaran–Cambrian transition in South China. Precambrian Research 225, 1–6.CrossRefGoogle Scholar
Sigman, D., Karsh, K. & Casciotti, K. 2009. Ocean process tracers: nitrogen isotopes in the ocean. Encyclopedia of Ocean Science, 2nd edn. Amsterdam: Elsevier.Google Scholar
Steiner, M., Zhu, M., Weber, B. & Geyer, G. 2001. The Lower Cambrian of eastern Yun-nan: trilobite-based biostratigraphy and related faunas. Acta Palaeontologica Sinica 40 (Suppl.), 63–79.Google Scholar
Strauss, H. 1997. The isotopic composition of sedimentary sulfur through time. Palaeogeography, Palaeoclimatology, Palaeoecology 132, 97–118.CrossRefGoogle Scholar
Strauss, H. 1999. Geological evolution from isotope proxy signals – sulfur. Chemical Geology, 161 (1–3), 89–101.CrossRefGoogle Scholar
Taylor, S. R. & McLennan, S. M. 1985. The Continental Crust: Its Composition and Evolution. Oxford: Blackwell.Google Scholar
Thomazo, C., Ader, M. & Philippot, P. 2011. Extreme 15N-enrichments in 2.72-Gyrold sediments: evidence for a turning point in the nitrogen cycle. Geobiology 9,107–20.CrossRefGoogle ScholarPubMed
Tribovillard, N., Algeo, T. J., Baudin, F. & Riboulleau, A. 2012. Analysis of marine environmental conditions based on molybdenum uranium covariation: applications to Mesozoic paleoceanography. Chemical Geology 324–325, 46–58.CrossRefGoogle Scholar
Tribovillard, N., Algeo, T. J., Lyons, T. & Riboulleau, A. 2006. Trace metals as paleoredox and paleoproductivity proxies: an update. Chemical Geology 232 (1–2), 12–32.CrossRefGoogle Scholar
Wang, D., Ulrich, S., Ling, H-F., Guo, Q-J., Shields-Zhou, G. A., Zhu, M-Y. & Yao, S-P. 2015. Marine redox variations and nitrogen cycle of the early Cambrian southern margin of the Yangtze Platform, South China: evidence from nitrogen and organic carbon isotopes. Precambrian Research 267, 209–26.CrossRefGoogle Scholar
Wang, X., Shi, X., Jiang, G. & Zhang, W. 2012. New U–Pb age from the basal Niutitang Formation in South China: implications for diachronous development and condensation of stratigraphic units across the Yangtze platform at the Ediacaran–Cambrian transition. Journal of Asian Earth Sciences 48, 1–8.CrossRefGoogle Scholar
Wang, X., Shi, X., Zhao, X. & Tang, D. 2015. Increase of seawater Mo inventory and ocean oxygenation during the early Cambrian. Palaeogeography Palaeoclimatology Palaeoecology 440, 621–31.CrossRefGoogle Scholar
Wedepohl, K. H. 1995. The composition of the continental crust. Geochimica et Cosmochimica Acta 59, 1217–32.CrossRefGoogle Scholar
Wei, W., Wang, D., Li, D., Ling, H. F., Chen, X., Wei, G. Y., Zhang, F. F., Zhu, X. K. & Yan, B. 2016. Evidence from nitrogen isotopes and Mo contents of the Basal Datangpo Formation, northeastern Guizhou, South China. Journal of Earth Science 27 (2), 233–41.CrossRefGoogle Scholar
Xu, L. G., Lehmann, B., Mao, J. W., Nägler, T. F., Neubert, N., Böttcher, M. E. & Escher, P. 2012. Mo isotope and trace element patterns of Lower Cambrian black shales in South China: multi-proxy constraints on the paleoenvironment. Chemical Geology 318–319, 45–59.CrossRefGoogle Scholar
Xu, L. G., Lehmann, B., Mao, J. W., Qu, W. J. & Du, A. D. 2011. Re–Os age of polymetallic Ni-Mo-PGE-Au mineralization in Early Cambrian black shales of South China – a reassessment. Economic Geology 106, 511–22.Google Scholar
Zerkle, A. L., House, C. H., Cox, R. P. & Canfield, D. E. 2006. Metal limitation of cyanobacterial N2 fixation and implications for the Precambrian nitrogen cycle. Geobiology 4, 285–97.CrossRefGoogle Scholar
Zerkle, A. L., Junium, C. K., Canfield, D. E. & House, C. H. 2008. Production of 15N-depleted biomass during cyanobacterial N2-fixation at high Fe concentrations. Journal of Geophysical Research – Biogeosciences 113 (G3). doi: 10.1029/2007JG000651.CrossRefGoogle Scholar
Zhang, X. N., Sigman, D. M., Morel, F. M. M. & Kraepiel, A. M. L. 2014. Nitrogen isotope fractionation by alternative nitrogenases and past ocean anoxia. Proceedings of the National Academy of Sciences of the United States of America 111 (13), 4782–7.CrossRefGoogle ScholarPubMed
Zhu, M., Strauss, H. & Shields, G. A. 2007. From snowball earth to the Cambrian bioradiation: calibration of Ediacaran-Cambrian earth history in South China. Palaeogeography, Palaeoclimatology, Palaeoecology 254, 1–6.CrossRefGoogle Scholar
Zhu, M., Zhang, J., Steiner, M., Yang, A., Li, G. & Erdtmann, B. D. 2003. Sinian-Cambrian stratigraphic framework for shallow- to deep-water environments of the Yangtze Platform: an integrated approach. Progress in Natural Science 13, 951–60.CrossRefGoogle Scholar