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Questioning a widespread euxinia for the Furongian (Late Cambrian) SPICE event: indications from δ13C, δ18O, δ34S and biostratigraphic constraints

Published online by Cambridge University Press:  20 May 2015

THOMAS WOTTE  and
HARALD STRAUSS
THOMAS WOTTE*
Affiliation:
Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Strasse 49a, D-50674 Köln, Germany
HARALD STRAUSS
Affiliation:
Institut für Geologie und Paläontologie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 24, D-48149 Münster, Germany
*
†Author for correspondence: thomas.wotte@uni-koeln.de
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Abstract

Results from a high-resolution study of δ13Ccarb, δ18Ocarb, δ34SCAS, δ34SCRS and elemental concentrations (Ca, Fe, Mg, Mn and Sr) in the Furongian Kyrshabakty section, southern Kazakhstan, are reported here. The investigated interval covers the Drumian to Jiangshanian stages of the Cambrian Period, respectively the regional Ptychagnostus atavus to Ivshinagnostus ivshini-Irvingella major trilobite zones. δ13Ccarb data include the Steptoean positive carbon isotope excursion (SPICE) with a local peak value of +5‰. The onset of SPICE corresponds to the Kormagnostus simplex – Glyptagnostus stolidotus zones and pre-dates the base of the Paibian Stage/Furongian Series. δ34SCAS data already increase during the Lejopyge armata biozone culminating in three positive excursions prior and after the SPICE maximum. Differences in onset, peak values and shape of the δ13Ccarb and/or δ34SCAS excursions at Kyrshabakty, but also in almost all sections characterized by the SPICE, are pointing towards Furongian seawater that was low in sulphate concentration and heterogeneous in its carbonate carbon and sulphate sulphur isotopic composition. The occurrence of benthic faunal elements in almost all SPICE-related sections strongly supports oxygenated conditions at the seafloor, therefore excluding widespread anoxia or euxinia. Regional anoxic conditions are most probable. A positive δ18Ocarb excursion parallel to the SPICE could probably be explained by a decline in seawater pH associated with a sea-level rise. Again, no euxinic conditions would be mandatory for explaining the SPICE event.

Keywords

CambrianSPICEsulphurcarbonoxygenKazakhstan
Type
Original Articles
Information
Geological Magazine , Volume 152 , Issue 6 , November 2015 , pp. 1085 - 1103
Copyright
Copyright © Cambridge University Press 2015 

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References

Ahlberg, P., Axheimer, N., Babcock, L. E., Eriksson, M. E., Schmitz, B. & Terfelt, F. 2009. Cambrian high-resolution biostratigraphy and carbon isotope chemostratigraphy in Scania, Sweden: first record of the SPICE and DICE excursions in Scandinavia. Lethaia 42, 2–16.CrossRefGoogle Scholar
Ahlberg, P., Szaniawski, H., Clarkson, E. N. K. & Bengtson, S. 2005. Phosphatic olenid trilobites and associated fauna from the Upper Cambrian of Västergötland, Sweden. Acta Palaeontologica Polonica 50, 429–40.Google Scholar
Alexeiev, D. V., Cook, H. E., Buvtyshkin, V. M. & Golub, L. Y. 2009. Structural evolution of the Ural–Tian Shan junction: A view from Karatau ridge, South Kazakhstan. Comptes Rendus Geoscience 341, 287–97.Google Scholar
Álvaro, J. J., Bauluz, B., Subías, I., Pierre, C. & Vincaїno, D. 2008. Carbon chemostratigraphy of the Cambrian-Ordovician transition in a midlatitude mixed platform, Montagne Noire, France. GSA Bulletin 120, 962–75.Google Scholar
Babcock, L. E., Peng, S., Geyer, G. & Shergold, J. H. 2005. Changing perspectives on Cambrian chronostratigraphy and progress toward subdivision of the Cambrian System. Geosciences Journal 9, 101–6.CrossRefGoogle Scholar
Banner, J. L. & Hanson, G. N. 1990. Calculation of simultaneous isotopic and trace element variations during water–rock interaction with applications to carbonate diagenesis. Geochimica et Cosmochimica Acta 54, 3123–37.CrossRefGoogle Scholar
Boyce, W. D. & Knight, I. 2005. Cambrian macrofossils from the Phillips Brook and North Brook anticlines, western Newfoundland. Current Research, Newfoundland and Labrador Department of Natural Resources, Geological Survey, Report 05–1, 39–62.Google Scholar
Brand, U. & Veizer, J. 1980. Chemical diagenesis of a multicomponent carbonate system. 1: Trace elements. Journal of Sedimentary Petrology 50, 1219–36.Google Scholar
Canfield, D. E., Raiswell, R., Westrich, J. T., Reaves, R. C. & Berner, R. A. 1986. The use of chromium reduction in the analysis of reduced inorganic sulphur in sediments and shales. Chemical Geology 54, 149–55.Google Scholar
Chen, J., Chough, S. K., Han, Z. & Lee, J.-H. 2011. An extensive erosion surface of a strongly deformed limestone bed in the Gushan and Chaomidian formations (late Middle Cambrian to Furongian), Shandong Province, China: sequence-stratigraphic implications. Sedimentary Geology 233, 129–49.CrossRefGoogle Scholar
Chen, J., Chough, S. K., Lee, J.-H. & Han, Z. 2012. Sequence-stratigraphic comparison of the upper Cambrian Series 3 to Furongian succession between the Shandong region, China and the Taebaek area, Korea: high variability of bounding surfaces in an epeiric platform. Geosciences Journal 16, 357–79.CrossRefGoogle Scholar
Cook, H. E., Taylor, M. E., Zhemchuzhnikov, S. V., Apollonov, M. K., Ergaliev, G. K., Sargaskaev, Z. S. & Dubinina, S. V. 1991. Comparison of two Early Paleozoic carbonate submarine fans: Western United States and southern Kazakhstan, Soviet Union. In Paleozoic Paleogeography of the Western United States (eds Cooper, J. D. & Stevens, C. H.), pp. 847–72. SEPM, Pacific Section 67.Google Scholar
Cowan, C. A., Fox, D. L., Runkel, A. C. & Saltzman, M. R. 2005. Terrestrial-marine carbon cycle coupling in ~500-m.y.-old phosphatic brachiopods. Geology 33, 661–4.Google Scholar
Denison, R. E., Koepnick, R. B., Burke, W. H. & Hetherington, E. A. 1998. Construction of the Cambrian and Ordovician seawater 87Sr/86Sr curve. Chemical Geology 152, 325–40.Google Scholar
Derry, L. A. 2010. A burial diagenesis origin of Ediacaran Shuram–Wonoka carbon isotope anomaly. Earth and Planetary Science Letters 294, 152–62.Google Scholar
Elrick, M., Rieboldt, S., Saltzman, M. R. & McKay, R. M. 2011. Oxygen-isotope trends and seawater temperature changes across the Late Cambrian Steptoean positive carbon-isotope excursion (SPICE event). Geology 39, 987–90.Google Scholar
Ergaliev, G. K. 1980. Middle and Upper Cambrian trilobites from Malyi Karatau. Alma-Ata: Akademiya Nauk Kazakhskoi SSR, Alma-Ata, 211 pp. (in Russian).Google Scholar
Ergaliev, G. K. 1981. Upper Cambrian biostratigraphy of the Kyrshabakty section, Malyi Karatau, southern Kazakhstan. In Short Papers for the Second International Symposium on the Cambrian System (ed. Taylor, M. E.), pp. 82–88. US Geological Survey Open-file Report 81–743.Google Scholar
Ergaliev, G. K. 1992. On palaeogeography of Karatau (southern Kazakhstan) in Middle Cambrian to Early Ordovician. Proceedings of Academy of Sciences, Republic of Kazakhstan, Series Geology 6, 51–6 (in Russian).Google Scholar
Ergaliev, G. K. & Ergaliev, F. G. 2004. Stages and zones of the Middle and Upper portions of Cambrian of Malyi Karatau for the Project of International Stratigraphic Chart. In Geology of Kazakhstan (ed. Daukeev, S. Zh.), pp. 36–52. Almaty: Kazakhstan Geological Society (in Russian).Google Scholar
Ergaliev, G. K. & Ergaliev, F. G. 2008. Middle and Upper Cambrian Agnostida of the Aksai National Geological Reserve, South Kazakhstan (Kyrshabakty River, Malyi Karatau Range). Almaty: Gylym Press, 376 pp. (in Russian with English abstract, introduction and figure captions).Google Scholar
Ergaliev, G. K., Zhemchuzhnikov, V. G., Ergaliev, F. G., Bassett, M. G., Popov, L. E. & Holmer, L. 2009. Field Excursion Guide of the 14th International Field Conference of the Cambrian Stage Subdivision Working Group, International Subcommission on Cambrian Stratigraphy, Malyi Karatau Range, Southern Kazakhstan, 71 pp.Google Scholar
Freeman, R. J. & Sitt, J. H. 1996. Upper Cambrian and lowest Ordovician articulate brachiopods from the Arbuckle and Wichita Mountains, Oklahoma. Journal of Paleontology 70, 355–72.CrossRefGoogle Scholar
Geyer, G. & Shergold, J. 2000. The quest for internationally recognized divisions of Cambrian time. Episodes 23, 188–95.Google Scholar
Gill, B. C., Lyons, T. W. & Frank, T. D. 2008. Behavior of carbonate-associated sulfate during meteoric diagenesis and implications for the sulfur isotope paleoproxy. Geochimica et Cosmochimica Acta 72, 4699–711.Google Scholar
Gill, B. C., Lyons, T. W. & Saltzman, M. R. 2007. Parallel, high-resolution carbon and sulphur isotope records of the evolving Paleozoic marine sulphur reservoir. Palaeogeography, Palaeoclimatology, Palaeoecology 256, 156–73.Google Scholar
Gill, B. C., Lyons, T. W., Young, S. A., Kump, L. R., Knoll, A. H. & Saltzman, M. R. 2011. Geochemical evidence for widespread euxinia in the Later Cambrian ocean. Nature 469, 80–3.Google Scholar
Glumac, B. & Walker, K. R. 1998. A Later Cambrian positive carbon-isotope excursion in the southern Appalachians: Relation to biostratigraphy, sequence stratigraphy, environments of deposition, and diagenesis. Journal of Sedimentary Research 68, 1212–22.Google Scholar
Grant, R. E. 1965. Faunas and Stratigraphy of the Snowy Range Formation (Upper Cambrian) in Southwestern Montana and Northwestern Wyoming. Geological Society of America, Memoir no. 96, 171 pp.Google Scholar
Green, P. M. & Balfe, P. E. 1980. Stratigraphic drilling report – GSQ Mt Whelan 1 and 2. Queensland Government Mining Journal 81, 162–78.Google Scholar
Holmer, L. E., Popov, L. E., Koneva, S. P. & Bassett, M. G. 2001. Cambrian–Early Ordovician brachiopods from Malyi Karatau, the Western Balkhash Region, and Tien Shan, Central Asia. Special Papers in Palaeontology 65, 1–180.Google Scholar
Hurtgen, M. T., Halverson, G. P., Arthur, M. A. & Hoffman, P. F. 2006. Sulfur cycling in the aftermath of a 635-Ma snowball glaciation: evidence for a syn-glacial sulfidic deep ocean. Earth and Planetary Science Letters 245, 551–70.Google Scholar
Hurtgen, M. T., Pruss, S. B. & Knoll, A. H. 2009. Evaluating the relationship between the carbon and sulfur cycles in the later Cambrian ocean: An example from the Port au Port Group, western Newfoundland, Canada. Earth and Planetary Science Letters 281, 288–97.CrossRefGoogle Scholar
Jacobsen, S. B. & Kaufman, A. J. 1999. The Sr, C and O isotopic evolution of Neoproterozoic seawater. Chemical Geology 161, 37–57.CrossRefGoogle Scholar
Jaffrés, J. B. D., Shields, G. A. & Wallmann, K. 2007. The oxygen isotope evolution of seawater: A critical review of a long-standing controversy and an improved geological water cycle model for the past 3.4 billion years. Earth-Science Reviews 83, 83–122.Google Scholar
Kampschulte, A., Bruckschen, P. & Strauss, H. 2001. The sulphur isotopic composition of trace sulphates in Carboniferous brachiopods: implications for coeval seawater, correlation with other geochemical cycles and isotope stratigraphy. Chemical Geology 175, 149–73.Google Scholar
Kampschulte, A. & Strauss, H. 2004. The sulphur isotopic evolution of Phanerozoic seawater based on the analysis of structurally substituted sulphate in carbonates. Chemical Geology 204, 255–86.Google Scholar
Kaufman, A. J., Jacobsen, S. B. & Knoll, A. H. 1993. The Vendian record of C- and Sr-isotopic variations: implications for tectonics and paleoclimate. Earth and Planetary Science Letters 120, 409–30.CrossRefGoogle Scholar
Kaufman, A. J. & Knoll, A. H. 1995. Neoproterozoic variations in the C-isotopic composition of seawater: stratigraphic and biogeochemical implications. Precambrian Research 73, 27–49.Google Scholar
Kim, S.-T., Hillaire-Marcel, C. & Micci, A. 2006. Mechanisms of equilibrium and kinetic oxygen isotope effects in synthetic aragonite at 25°C. Geochimica et Cosmochimica Acta 70, 5790–801.Google Scholar
Koneva, S. P. & Ushatinskaya, G. T. 2010. New brachiopod species from the order Acrotretida from the Cambrian of central Kazakhstan. Paleontological Journal 44, 632–43.Google Scholar
Kouchinsky, A., Bengtson, S., Gallet, Y., Korovnikov, I., Pavlov, V., Runnegar, B., Shields, G., Veizer, J., Young, E. & Ziegler, K. 2008. The SPICE carbon isotope excursion in Siberia: a combined study of the upper Middle Cambrian–lowermost Ordovician Kulyumbe River section, northwestern Siberian Platform. Geological Magazine 145, 609–22.Google Scholar
Kruse, P. D., Jago, J. B. & Laurie, J. R. 2009. Recent developments in Australian Cambrian biostratigraphy. Journal of Stratigraphy 33, 35–47.Google Scholar
Kump, L. R. & Arthur, M. A. 1999. Interpreting carbon-isotope excursions: carbonates and organic matter. Chemical Geology 161, 181–98.Google Scholar
Kump, L. R., Arthur, M. A., Patzkowsky, M. E., Gibbs, M. T., Pinkus, D. S. & Sheehan, P. M. 1999. A weathering hypothesis for glaciation at high atmospheric pCO2 during the Late Ordovician. Palaeogeography, Palaeoclimatology, Palaeoecology 152, 173–87.CrossRefGoogle Scholar
Kurtz, V. E. 1971. Upper Cambrian Acrotretidae from Missouri. Journal of Paleontology 45, 53–5.Google Scholar
Kurtz, V. E. 1975. Franconian (Upper Cambrian) trilobite faunas from the Elvins Group of southeast Missouri. Journal of Paleontology 49, 1009–43.Google Scholar
Lindsay, J. F., Kruse, P. D., Green, O. R., Hawkins, E., Brasier, M. D., Cartlidge, J. & Corfield, R. M. 2005. The Neoproterozoic–Cambrian record in Australia: A stable isotope study. Precambrian Research 143, 113–33.CrossRefGoogle Scholar
Marenco, P. J., Corsetti, F. A., Kaufman, A. J. & Bottjer, D. J. 2008. Environmental and diagenetic variations in carbonate associated sulfate: an investigation of CAS in the Lower Triassic of the western USA. Geochimica et Cosmochimica Acta 72, 1570–82.Google Scholar
McCrea, J. M. 1950. On the isotopic chemistry of carbonates and a paleotemperature scale. The Journal of Chemical Physics 18, 849–57.Google Scholar
Miller, J. F., Evans, K. R. & Dattilo, B. F. 2012. The great American carbonate bank in the miogeocline of western central Utah: Tectonic influences on sedimentation. In The Great American Carbonate Bank: The Geology and Economic Resources of the Cambrian–Ordovician Sauk Megasequence of Laurentia (eds Derby, J. R., Fritz, R. D., Longacre, S. A., Morgan, W. A. & Sternbach, C. A.), pp. 769–854. AAPG, Memoir no. 98.Google Scholar
Miller, J. F., Evans, K. R., Kurtz, V. E. & Repetski, J. E. 2013. Biostratigraphy and sequence stratigraphy of Cambrian and lowest Ordovician strata in Missouri. In Paleozoic Succession in Missouri, Part 1 (revised), Cambrian System (eds Mulvany, P. S. & Thompson, T. L.), pp. 13–24. Missouri Geological Survey, Report of Investigations 70.Google Scholar
Montañez, I. P., Banner, J. L., Osleger, D. A., Borg, L. E. & Bosserman, P. J. 1996. Integrated Sr isotope variations and sea-level history of Middle to Upper Cambrian platform carbonates: implications for the evolution of Cambrian seawater 87Sr/86Sr. Geology 24, 917–20.2.3.CO;2>CrossRefGoogle Scholar
Montañez, I. P., Osleger, D. A., Banner, J. L., Mack, L. E. & Musgrove, M. L. 2000. Evolution of the Sr and C Isotope Composition of Cambrian Oceans. GSA Today 10, 1–7.Google Scholar
Ng, T. W., Yuan, J. L. & Lin, J. P. 2014. The North China Steptoean positive carbon isotope excursion and its global correlation with the base of the Paibian Stage (early Furongian Series), Cambrian. Lethaia 47, 153–64.Google Scholar
Palmer, A. R. 1954. The faunas of the Riley Formation in central Texas. Journal of Paleontology 28, 709–86.Google Scholar
Palmer, A. R. 1965. Trilobites of the late Cambrian Pterocephaliid biomere in the Great Basin, United States. US Geological Survey, Professional Paper no. 493, 106 pp.Google Scholar
Palmer, A. R. 1981. Subdivision of the Sauk sequence. In Short Papers for the 2nd International Symposium on the Cambrian System (ed. Taylor, M. E.), pp. 160–2. United States Geological Survey, Open-File Report 81–743.Google Scholar
Peng, S., Babcock, L. E. & Cooper, R. A. 2012. The Cambrian Period. In The Geological Time Scale 2012, Volume 2 (eds Gradstein, F. M., Ogg, J. G., Schmitz, M. D. & Ogg, G. M.), pp. 437–488. Elsevier.CrossRefGoogle Scholar
Peng, S., Babcock, L. E., Robison, R. A., Lin, H., Rees, M. N. & Saltzman, M. R. 2004. Global standard stratotype-section and point (GSSP) of the Furongian Series and Paibian Stage. Lethaia 37, 365–79.CrossRefGoogle Scholar
Peng, S., Babcock, L. E., Zuo, J., Zhu, X., Lin, H., Yang, X., Qi, Y., Bagnoli, G. & Wang, L. 2012. Global standard stratotype-section and point (GSSP) for the base of the Jiangshanian Stage (Cambrian: Furongian) at Duibian, Jiangshan, Zhejiang, Southeast China. Episodes 35, 1–16.Google Scholar
Prokoph, A., Shields, G. A. & Veizer, J. 2008. Compilation and time-series analysis of a marine carbonate δ18O, δ13C, 87Sr/86Sr and δ34S database through Earth history. Earth-Science Reviews 87, 113–33.CrossRefGoogle Scholar
Rieboldt, S. 2011. Cambrian inarticulate brachiopods from Nevada and Texas. Palaeoworld 13, 310.Google Scholar
Rowell, A. J. & Brady, M. J. 1976. Brachiopods and biomeres. Brigham Young University Geology Studies 23, 165–80.Google Scholar
Saltzman, M. R., Cowan, C. A., Runkel, A. C., Runnegar, B., Stewart, M. C. & Palmer, A. R. 2004. The Late Cambrian SPICE (δ13C) event and the Sauk II–Sauk III regression: new evidence from Laurentian basins in Utah, Iowa, and Newfoundland. Journal of Sedimentary Research 74, 366–77.Google Scholar
Saltzman, M. R., Ripperdan, R. L., Brasier, M. D., Lohmann, K. C., Robinson, R. A., Chang, W. T., Peng, S., Ergaliev, E. K. & Runnegar, B. 2000. A global carbon isotope excursion (SPICE) during the Late Cambrian: relation to trilobite extinctions, organic-matter burial and sea level. Palaeogeography, Palaeoclimatology, Palaeoecology 162, 211–23.CrossRefGoogle Scholar
Saltzman, M. R., Runnegar, B. & Lohmann, K. C. 1998. Carbon isotope stratigraphy of Upper Cambrian (Steptoean Stage) sequences of the eastern Great Basin: record of a global oceanographic event. Geological Society of America Bulletin 110, 285–97.Google Scholar
Saltzman, M. R., Young, S. A., Kump, L. R., Gill, B. C., Lyons, T. W. & Runnegar, B. 2011. Pulse of atmospheric oxygen during the late Cambrian. Proceedings of the National Academy of Sciences of the United States of America 108, 3876–81.Google Scholar
Shergold, J. H. 1982. Idamean (Late Cambrian) trilobites, Burke River Structural Belt, western Queensland. Bureau of Mineral Resources, Australia, Bulletin 187, 1–69.Google Scholar
Shergold, J. H. 1993. The Iverian, a proposed Late Cambrian Stage, and its subdivision in the Burke River Structural Belt, western Queensland. BMR Journal of Australian Geology and Geophysics 13, 345–58.Google Scholar
Sial, A. N., Peralta, S., Ferreira, V. P., Toselli, A. J., Aceñolaza, F. G., Parada, M. A., Gaucher, C., Alonso, R. N. & Pimentel, M. M. 2008. Upper Cambrian carbonate sequences of the Argentine Precordillera and the Steptoean C-Isotope positive excursion (SPICE). Gondwana Research 13, 437–52.Google Scholar
Sial, A. N., Peralta, S., Gaucher, C., Toselli, A. J., Ferreira, V. P., Frei, R., Parada, M. A., Pimentel, M. M. & Pereira, N. S. 2013. High-resolution stable isotope stratigraphy of the upper Cambrian and Ordovician in the Argentine Precordillera: carbon isotope excursions and correlations. Gondwana Research 24, 330–48.Google Scholar
Spero, H. J., Bijma, J., Lea, D. W. & Bemis, B. E. 1997. Effect of seawater carbonate concentration on foraminiferal carbon and oxygen isotopes. Nature 390, 497–500.Google Scholar
Trotter, J. A., Williams, I. S., Barnes, C. R., Lécuyer, C. & Nicoll, R. S. 2008. Did cooling oceans trigger Ordovician biodiversification? Evidence from conodont thermometry. Science 321, 550–4.Google Scholar
Uchikawa, J. & Zeebe, R. E. 2010. Examining possible effects of seawater pH decline on foraminiferal stable isotopes during the Paleocene-Eocene Thermal Maximum. Paleoceanography 25, PA2216, doi: 10.1029/2009PA001864.Google Scholar
Usdowski, E. & Hoefs, J. 1993. Oxygen isotope exchange between carbonatic acid, bicarbonate, carbonate, and water: A re-examination of the data of McCrea (1950) and an expression for the overall partitioning of oxygen isotopes between the carbonate species and water. Geochimica et Cosmochimica Acta 57, 3815–8.Google Scholar
Veizer, J., Ala, D., Azmy, K., Bruckschen, P., Buhl, D., Bruhn, F., Carden, G. A. F., Diener, A., Ebneth, S., Godderis, Y., Jasper, T., Korte, C., Pawellek, F., Podlaha, O. G. & Strauss, H. 1999. 87Sr/86Sr, δ13C and δ18O evolution of Phanerozoic seawater. Chemical Geology 161, 59–88.Google Scholar
Wenger, L. M. & Baker, D. R. 1986. Variations in organic geochemistry of anoxic-oxic black shale-carbonate sequences in the Pennsylvanian of the Midcontinent, U.S.A. Organic Geochemistry 10, 85–92.CrossRefGoogle Scholar
Woods, M. A., Wilby, P. R., Leng, M. J., Rushton, A. W. A. & Williams, M. 2011. The Furongian (late Cambrian) Steptoean Positive Carbon Isotope Excursion (SPICE) in Avalonia. Journal of the Geological Society, London 168, 851–61.Google Scholar
Wotte, T., Álvaro, J. J., Shields, G. A., Brown, B., Brasier, M. & Veizer, J. 2007. C-, O- and Sr-isotope stratigraphy across the Lower–Middle Cambrian transition of the Cantabrian zone (Spain) and the Montagne Noire (France), West Gondwana. Palaeogeography, Palaeoclimatology, Palaeoecology 256, 47–70.Google Scholar
Wotte, T., Shields-Zhou, G. A. & Strauss, H. 2012. Carbonate-associated sulfate: experimental comparisons of common extraction methods and recommendations toward a standard analytical protocol. Chemical Geology 326–327, 132–44.Google Scholar
Wotte, T., Strauss, H., Fugmann, A. & Garbe-Schönberg, D. 2012. Paired δ34S data from carbonate associated sulfate and chromium-reducible sulfur across the traditional Lower–Middle Cambrian boundary of W-Gondwana. Geochimica et Cosmochimica Acta 85, 228–53.Google Scholar
Wotte, T., Strauss, H. & Sundberg, F. A. 2011. Carbon and sulfur isotopes from the Cambrian Series 2–Cambrian Series 3 of Laurentia and Siberia. Museum of Northern Arizona Bulletin 67, 43–63.Google Scholar
Zeebe, R. E. 1999. An explanation of the effect of seawater carbonate concentration on foraminiferal oxygen isotopes. Geochimica et Cosmochimica Acta 63, 2001–7.Google Scholar
Zeebe, R. E. 2001. Seawater pH and isotopic paleotemperatures of Cretaceous oceans. Palaeogeography, Palaeoclimatology, Palaeoecology 170, 49–51.Google Scholar
Zhu, M., Babcock, L. E. & Peng, S. 2006. Advances in Cambrian stratigraphy and paleontology: integrating correlation techniques, paleobiology, taphonomy and paleoenvironmental reconstruction. Palaeoworld 15, 217–22.Google Scholar
Zhu, M., Zhang, J., Li, G. & Yang, A. 2004. Evolution of C isotopes in the Cambrian of China: implications for Cambrian subdivision and trilobite mass extinctions. Geobios 27, 287–301.Google Scholar