Hostname: page-component-8448b6f56d-m8qmq Total loading time: 0 Render date: 2024-04-24T00:05:45.627Z Has data issue: false hasContentIssue false
  • English
  • Français

Integrated Cambrian biostratigraphy and carbon isotope chemostratigraphy of the Grönhögen-2015 drill core, Öland, Sweden

Published online by Cambridge University Press:  28 May 2018

PER AHLBERG ,
FRANS LUNDBERG ,
MIKAEL ERLSTRÖM ,
MIKAEL CALNER ,
ANDERS LINDSKOG ,
PETER DAHLQVIST  and
MICHAEL M. JOACHIMSKI
PER AHLBERG*
Affiliation:
Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden
FRANS LUNDBERG
Affiliation:
Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden
MIKAEL ERLSTRÖM
Affiliation:
Geological Survey of Sweden, Kiliansgatan 10, SE-223 50 Lund, Sweden
MIKAEL CALNER
Affiliation:
Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden
ANDERS LINDSKOG
Affiliation:
Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden
PETER DAHLQVIST
Affiliation:
Geological Survey of Sweden, Kiliansgatan 10, SE-223 50 Lund, Sweden
MICHAEL M. JOACHIMSKI
Affiliation:
GeoZentrum Nordbayern, Friedrich-Alexander University of Erlangen-Nürnberg, Schloßgarten 5, D-91054 Erlangen, Germany
*
†Author for correspondence: per.ahlberg@geol.lu.se
Get access Rights & Permissions [Opens in a new window]

Abstract

The Grönhögen-2015 core drilling on southern Öland, Sweden, penetrated 50.15 m of Cambrian Series 3, Furongian and Lower–Middle Ordovician strata. The Cambrian succession includes the Äleklinta Member (upper Stage 5) of the Borgholm Formation and the Alum Shale Formation (Guzhangian–Tremadocian). Agnostoids and trilobites allowed subdivision of the succession into eight biozones, in ascending order: the uppermost Cambrian Series 3 (Guzhangian) Agnostus pisiformis Zone and the Furongian Olenus gibbosus, O. truncatus, Parabolina spinulosa, Sphaerophthalmus? flagellifer, Ctenopyge tumida, C. linnarssoni and Parabolina lobata zones. Conspicuous lithologic unconformities and the biostratigraphy show that the succession is incomplete and that there are several substantial gaps of variable magnitudes. Carbon isotope analyses (δ13Corg) through the Alum Shale Formation revealed two globally significant excursions: the Steptoean Positive Carbon Isotope Excursion (SPICE) in the lower–middle Paibian Stage, and the negative Top of Cambrian Excursion (TOCE), previously referred to as the HERB Event, in Stage 10. The δ13Corg chemostratigraphy is tied directly to the biostratigraphy and used for an improved integration of these excursions with the standard agnostoid and trilobite zonation of Scandinavia. Their relations to that of coeval successions in Baltoscandia and elsewhere are discussed. The maximum amplitudes of the SPICE and TOCE in the Grönhögen succession are comparable to those recorded in drill cores retrieved from Scania, southern Sweden. The results of this study will be useful for assessing biostratigraphic relations between shale successions and carbonate facies on a global scale.

Keywords

carbon isotope excursiontrilobitesagnostoidsBorgholm FormationAlum Shale FormationScandinavia
Type
Original Article
Information
Geological Magazine , Volume 156 , Issue 6 , June 2019 , pp. 935 - 949
Copyright
Copyright © Cambridge University Press 2018 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Ahlberg, P. 2003. Trilobites and intercontinental tie points in the Upper Cambrian of Scandinavia. Geologica Acta 1, 127–34.Google Scholar
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. & Terfelt, F. 2012. Furongian (Cambrian) agnostoids of Scandinavia and their implications for intercontinental correlation. Geological Magazine 149, 1001–12.CrossRefGoogle Scholar
Álvaro, J. J., Ahlberg, P., Babcock, L. E., Bordonaro, O. L., Choi, D. K., Cooper, R. A., Ergaliev, G. Kh., Gapp, I. W., Ghobadi Pour, M., Hughes, N. C., Jago, J. B., Korovnikov, I., Laurie, J. R., Lieberman, B. S., Paterson, J. R., Pegel, T. V., Popov, L. E., Rushton, A. W. A., Sukhov, S. S., Tortello, M. F., Zhou, Z. & Żylińska, A. 2013. Chapter 19. Global Cambrian trilobite palaeobiogeography assessed using parsimony analysis of endemicity. In Early Palaeozoic Biogeography and Palaeogeography (eds Harper, D. A. T. & Servais, T.), pp. 273–96. Geological Society of London, Memoirs no. 38.Google Scholar
Andersson, A., Dahlman, B., Gee, D. G. & Snäll, S. 1985. The Scandinavian Alum Shales. Sveriges geologiska undersökning Ca56, 1–50.Google Scholar
Axheimer, N. & Ahlberg, P. 2003. A core drilling through Cambrian strata at Almbacken, Scania, S. Sweden: trilobites and stratigraphical assessment. GFF 125, 139–56.CrossRefGoogle Scholar
Axheimer, N., Eriksson, M. E., Ahlberg, P. & Bengtsson, A. 2006. The middle Cambrian cosmopolitan key species Lejopyge laevigata and its biozone: new data from Sweden. Geological Magazine 143, 447–55.CrossRefGoogle Scholar
Azmy, K. 2018. Carbon-isotope stratigraphy of the uppermost Cambrian in eastern Laurentia: implications for global correlation. Geological Magazine, published online 12 February 2018. doi: 10.1017/S001675681800002X.CrossRefGoogle Scholar
Babcock, L. E., Peng, S. C. & Ahlberg, P. 2017. Cambrian trilobite biostratigraphy and its role in developing an integrated history of the Earth system. Lethaia 50, 381–99.CrossRefGoogle Scholar
Bagnoli, G. & Stouge, S. 2014. Upper Furongian (Cambrian) conodonts from the Degerhamn quarry road section, southern Öland, Sweden. GFF 136, 436–58.CrossRefGoogle Scholar
Belt, T. 1867. On some new trilobites from the Upper Cambrian rocks of North Wales. Geological Magazine 4, 294–95.CrossRefGoogle Scholar
Bergström, J. & Ahlberg, P. 1981. Uppermost Lower Cambrian biostratigraphy in Scania, Sweden. Geologiska Föreningens i Stockholm Förhandlingar 103, 193–214.CrossRefGoogle Scholar
Bergström, J. & Gee, D. G. 1985. The Cambrian in Scandinavia. In The Caledonide Orogen – Scandinavia and Related Areas (eds Gee, D. G. & Sturt, B. A.), pp. 247–71. Chichester: John Wiley and Sons.Google Scholar
Boeck, C. 1838. Uebersicht der bisher in Norwegen gefundenen Formen der Trilobiten. In Gaea Norvegica (ed. Keilhau, B. M.), pp.138–45. Christiania (Oslo): Johan Dahl.Google Scholar
Brasier, M. D. 1993. Towards a carbon isotope stratigraphy of the Cambrian System: potential of the Great Basin succession. In High Resolution Stratigraphy (eds Hailwood, E. A. & Kidd, R. B.), pp. 341–50. Geological Society of London, Special Publication no. 70.Google Scholar
Brünnich, M. T. 1781. Beskrivelser over trilobiten, en dyreslægt og dens arter med en ny arts aftegning. Nye Samling af det kongelige Danske Videnskabers Selskabs Skrifter 1, 384–95.Google Scholar
Buchardt, B., Nielsen, A. T. & Schovsbo, N. H. 1997. Alunskiferen i Skandinavien. Geologisk Tidsskrift 1997 (3), 1–30.Google Scholar
Calner, M., Ahlberg, P., Lehnert, O. & Erlström, M. (eds) 2013. The Lower Palaeozoic of southern Sweden and the Oslo Region, Norway. Field Guide for the 3rdAnnual Meeting of the IGCP project 591. Sveriges geologiska undersökning Rapporter och meddelanden 133, 1–96.Google Scholar
Cocks, L. M. & Fortey, R. A. 1998. The Lower Palaeozoic margins of Baltica. GFF 120, 173–9.CrossRefGoogle Scholar
Cocks, L. M. & Torsvik, T. H. 2005. Baltica from the late Precambrian to mid-Palaeozoic times: the gain and loss of a terrane's identity. Earth-Science Reviews 72, 39–66.CrossRefGoogle Scholar
Egenhoff, S. O., Fishman, N. S., Ahlberg, P., Maletz, J., Jackson, A., Kolte, K., Lowers, H., Mackie, J., Newby, W. & Petrowsky, M. 2015. Sedimentology of SPICE (Steptoean positive carbon isotope excursion): a high-resolution trace fossil and microfabric analysis of the middle to late Cambrian Alum Shale Formation, southern Sweden. Geological Society of America Special Paper 515, 87–102.CrossRefGoogle Scholar
Erlström, M. 2016. Litologisk och geokemisk karaktärisering av berggrundsavsnitt på södra Öland – resultat från kärnborrning vid Grönhögen. SGU-rapport 15, 1–37.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.CrossRefGoogle ScholarPubMed
Hammer, Ø. & Svensen, H. H. 2017. Biostratigraphy and carbon and nitrogen geochemistry of the SPICE event in Cambrian low-grade metamorphic black shale, southern Norway. Palaeogeography, Palaeoclimatology, Palaeoecology 468, 216–27.CrossRefGoogle Scholar
Henningsmoen, G. 1957. The trilobite family Olenidae with description of Norwegian material and remarks on the Olenid and Tremadocian Series. Skrifter utgitt av Det Norske Videnskaps–Akademi i Oslo, I. Matematisk–Naturvidenskapelig Klasse 1957 (1), 1–303.Google Scholar
Høyberget, M. & Bruton, D. L. 2008. Middle Cambrian trilobites of the suborders Agnostina and Eodiscina from the Oslo Region, Norway. Palaeontographica Abteilung A 286, 1–87.CrossRefGoogle Scholar
Høyberget, M. & Bruton, D. L. 2012. Revision of the trilobite genus Sphaerophthalmus and relatives from the Furongian (Cambrian) Alum Shale Formation, Oslo Region, Norway. Norwegian Journal of Geology 92, 433–50.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.CrossRefGoogle Scholar
Lake, P. 1919. A monograph of British Cambrian trilobites, Pt. V. Monographs of the Palaeontographical Society 71, 89–120.CrossRefGoogle Scholar
Landing, E., Westrop, S. R. & Adrain, J. M. 2011. The Lawsonian Stage – the Eoconodontus notchpeakensis FAD and HERB carbon isotope excursion define a globally correlatable terminal Cambrian stage. Bulletin of Geosciences 86, 621–40.CrossRefGoogle Scholar
Lehnert, O., Ahlberg, P., Calner, M. & Joachimski, M. M. 2013. The Drumian Isotopic Carbon Excursion (DICE) in Scania, southern Sweden – a mirror of the onset of the Marjumiid Biomere at a time of increased primary production? In Proceedings of the 3rd IGCP 591 Annual Meeting – Lund, Sweden, 9–19 June 2013 (eds Lindskog, A. & Mehlqvist, K.), pp. 172–4. Lund: Lund University.Google Scholar
Li, D. D., Zhang, X. L., Chen, K, Zhang, G., Chen, X. Y., Huang, W., Peng, S. C. & Shen, Y. 2017. High-resolution C-isotope chemostratigraphy of the uppermost Cambrian stage (Stage 10) in South China: implications for defining the base of Stage 10 and palaeoenvironmental change. Geological Magazine 154, 1232–43.CrossRefGoogle Scholar
Lim, J. N., Chung, G. S., Park, T. Y. & Lee, K. S. 2016. Lithofacies and stable carbon isotope stratigraphy of the Cambrian Sesong Formation in the Taebaeksan Basin, Korea. Journal of the Korean Earth Science Society 36, 617–31.CrossRefGoogle Scholar
Lindskog, A. & Eriksson, M. E. 2017. Megascopic processes reflected in the microscopic realm: sedimentary and biotic dynamics of the Middle Ordovician “orthoceratite limestone” at Kinnekulle, Sweden. GFF 139, 163–83.CrossRefGoogle Scholar
Linnarsson, G. 1875. Öfversigt af Nerikes öfvergångsbildningar. Öfversigt af Kongliga Vetenskapsakademiens Förhandlingar 1875, 3–48.Google Scholar
Lundberg, F., Ahlberg, P., Eriksson, M. E. & Lindskog, A. 2016. Integrated Cambrian stratigraphy of the Tomten-1 drill core, southern Sweden. In Palaeo Down Under 2, Adelaide, 11–15 July 2016 (eds Laurie, J. R., Kruse, P. D., García-Bellido, D. G. & Holmes, J. D.), pp. 76–7. Geological Society of Australia Abstracts no. 117.Google Scholar
Martinsson, A. 1974. The Cambrian of Norden. In Lower Palaeozoic Rocks of the World. 2. Cambrian of the British Isles, Norden, and Spitsbergen (ed. Holland, C. H.), pp. 185–283. London: John Wiley & Sons.Google Scholar
Miller, J. F., Evans, K. R., Freeman, R. L., Ripperdan, R. L. & Taylor, J. F. 2011. Proposed stratotype for the base of the Lawsonian Stage (Cambrian Stage 10) at the First Appearance Datum of Eoconodontus notchpeakensis (Miller) in the House Range, Utah, USA. Bulletin of Geosciences 86, 595–620.CrossRefGoogle Scholar
Miller, J. F., Evans, K. R., Freeman, R. L., Ripperdan, R. L. & Taylor, J. F. 2014. The proposed GSSP for the base of Cambrian Stage 10 at the First Appearance Datum of the conodont Eoconodontus notchpeakensis (Miller, 1969) in the House Range, Utah, USA. GFF 136, 189–92.CrossRefGoogle Scholar
Miller, J. F., Ripperdan, R. L., Loch, J. D., Freeman, R. L., Evans, K. R., Taylor, J. F. & Tolbart, Z. C. 2015. Proposed GSSP for the base of Cambrian Stage 10 at the lowest occurrence of Eoconodontus notchpeakensis in the House Range, Utah, USA. Annales de Paléontologie 101, 199–211.CrossRefGoogle Scholar
Montañez, I. P., Osleger, D. A., Banner, J. L., Mack, L. E. & Masgrove, 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.CrossRefGoogle Scholar
Nielsen, A. T. & Schovsbo, N. H. 2007. Cambrian to basal Ordovician lithostratigraphy in southern Scandinavia. Bulletin of the Geological Society of Denmark 53, 47–92.Google Scholar
Nielsen, A. T. & Schovsbo, N. H. 2011. The Lower Cambrian of Scandinavia: depositional environment, sequence stratigraphy and palaeogeography. Earth-Science Reviews 107, 207–310.CrossRefGoogle Scholar
Nielsen, A. T. & Schovsbo, N. H. 2013. The Cambro-Ordovician Alum Shale revisited: depositional environment, sea-level changes and transient isostatic disturbances. In Proceedings of the 3rd IGCP 591 Annual Meeting– Lund, Sweden, 9–19 June 2013 (eds Lindskog, A. & Mehlqvist, K.), pp. 249–51. Lund: Lund University.Google Scholar
Nielsen, A. T. & Schovsbo, N. H. 2015. The regressive Early-Mid Cambrian ‘Hawke Bay Event’ in Baltoscandia: epeirogenic uplift in concert with eustasy. Earth-Science Reviews 151, 288–350.CrossRefGoogle Scholar
Nielsen, A. T., Weidner, T., Terfelt, F. & Høyberget, M. 2014. Upper Cambrian (Furongian) biostratigraphy in Scandinavia revisited: definition of superzones. GFF 136, 193–7.CrossRefGoogle Scholar
Peng, S. C., Babcock, L. E. & Cooper, R. A. 2012. The Cambrian Period. In The Geologic Time Scale 2012 (eds Gradstein, F. M., Ogg, J. G., Schmitz, M. D. & Ogg, G. M.), pp. 437–88. Oxford: Elsevier.CrossRefGoogle Scholar
Peng, S. C., Babcock, L. E., Robison, R. A., Lin, H. L., Rees, M. N. & Saltzman, M. R. 2004. Global Standard Stratotype-section and Point (GSSP) of the Furongian Series and Paibian Stage (Cambrian). Lethaia 37, 365–79.CrossRefGoogle Scholar
Phillips, J. 1848. The Malvern Hills compared with the Palaeozoic districts of Abberley, Woolhope, May Hill, Torthworth, and Usk. Memoirs of the Geological Survey of Great Britain 2, 1–330.Google Scholar
Rasmussen, B. W., Nielsen, A. T. & Schovsbo, N. H. 2015. Faunal succession in the upper Cambrian (Furongian) Leptoplastus Superzone at Slemmestad, southern Norway. Norwegian Journal of Geology 95, 1–22.Google Scholar
Rasmussen, B. W., Rasmussen, J. A. & Nielsen, A. T. 2017. Biostratigraphy of the Furongian (upper Cambrian) Alum Shale Formation at Degerhamn, Öland, Sweden. GFF 139, 92–118.CrossRefGoogle Scholar
Ripperdan, R. L. 2002. The HERB Event: end of Cambrian carbon cycle paradigm? Geological Society of America, Abstracts with Programs 34 (6), 413.Google Scholar
Ripperdan, R. L., Magaritz, M., Nicoll, R. S. & Shergold, J. H. 1992. Simultaneous changes in carbon isotopes, sea level, and conodont biozones within the Cambrian–Ordovician boundary interval at Black Mountain, Australia. Geology 20, 1039–42.2.3.CO;2>CrossRefGoogle 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.CrossRefGoogle Scholar
Saltzman, M. R., Ripperdan, R. L., Brasier, M. D., Lohmann, K. C., Robison, R. A., Chang, W. T., Peng, S. C., 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
Schiffbauer, J. D., Huntley, J. W., Fike, D. A., Jeffrey, M. J., Gregg, J. M. & Shelton, K. L. 2017. Decoupling biogeochemical records, extinction, and environmental change during the Cambrian SPICE event. Science Advances 3 (3), e1602158. doi: 10.1126/sciadv.1602158.CrossRefGoogle ScholarPubMed
Schovsbo, N. H. 2001. Why barren intervals? A taphonomic case study of the Scandinavian Alum Shale and its faunas. Lethaia 34, 271–85.CrossRefGoogle Scholar
Schovsbo, N. H. 2002. Uranium enrichment shorewards in black shales: a case study from the Scandinavian Alum Shale. GFF 124, 107–15.CrossRefGoogle 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.CrossRefGoogle 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.CrossRefGoogle Scholar
Stouge, S., Bagnoli, G. & Azmi, K. 2016. The Cambrian HERB excursion (Furongian) from the Martin Point Formation of the Cow Head Group, western Newfoundland, Canada. In Palaeo Down Under 2, Adelaide, 11–15 July 2016 (eds Laurie, J. R., Kruse, P. D., García-Bellido, D. G. & Holmes, J. D.), p. 56. Geological Society of Australia Abstracts no. 117.Google Scholar
Terfelt, F. 2003. Upper Cambrian trilobite biostratigraphy and taphonomy at Kakeled on Kinnekulle, Västergötland, Sweden. Acta Palaeontologica Polonica 48, 409–16.Google Scholar
Terfelt, F., Ahlberg, P. & Eriksson, M. E. 2011. Complete record of Furongian polymerid trilobites and agnostoids of Scandinavia – a biostratigraphical scheme. Lethaia 44, 8–14.CrossRefGoogle Scholar
Terfelt, F., Eriksson, M. E., Ahlberg, P. & Babcock, L. E. 2008. Furongian Series (Cambrian) biostratigraphy of Scandinavia – a revision. Norwegian Journal of Geology 88, 73–87.Google Scholar
Terfelt, F., Eriksson, M. E. & Schmitz, B. 2014. The Cambrian–Ordovician transition in dysoxic facies in Baltica – diverse faunas and carbon isotope anomalies. Palaeogeography, Palaeoclimatology, Palaeoecology 394, 59–73.CrossRefGoogle Scholar
Thickpenny, A. 1984. The sedimentology of the Swedish Alum Shales. In Fine-grained Sediments: Deepwater Processes and Facies (eds Stow, D. A. W. & Piper, D. J. W.), pp. 511–25. Geological Society of London, Special Publication no. 15.Google Scholar
Thickpenny, A. 1987. Palaeo-oceanography and depositional environment of the Scandinavian Alum Shales: sedimentological and geochemical evidence. In Marine Clastic Sedimentology – Concepts and Case Studies (eds Leggett, J. K. & Zuffa, G. G.), pp. 156–71. London: Graham & Trotman.CrossRefGoogle Scholar
Torsvik, T. H. & Cocks, L. M. 2005. Norway in space and time: a centennial cavalcade. Norwegian Journal of Geology 85, 73–86.Google Scholar
Torsvik, T. H. & Cocks, L. M. 2013. Chapter 2. New global palaeogeographical reconstructions for the Early Palaeozoic and their generation. In Early Palaeozoic Biogeography and Palaeogeography (eds Harper, D. A. T. & Servais, T.), pp. 5–24. Geological Society of London, Memoirs no. 38.Google Scholar
Torsvik, T. H. & Cocks, L. M. 2017. Earth History and Palaeogeography. Cambridge: Cambridge University Press, 317 pp.CrossRefGoogle Scholar
Torsvik, T. H. & Rehnström, E. F. 2001. Cambrian palaeomagnetic data from Baltica: implications for true polar wander and Cambrian palaeogeography. Journal of the Geological Society, London 158, 321–9.CrossRefGoogle Scholar
Wærn, B. 1952. Palaeontology and stratigraphy of the Cambrian and lowermost Ordovician of the Bödahamn core. Bulletin of the Geological Institution of the University of Uppsala 34, 223–50.Google Scholar
Wahlenberg, G. 1818. Petrificata telluris svecanae. Nova Acta Regiae Societatis Scientiarum Upsaliensis 8, 1–116.Google Scholar
Weidner, T. & Nielsen, A. T. 2009. The Middle Cambrian Paradoxides paradoxissimus Superzone on Öland, Sweden. GFF 131, 253–68.CrossRefGoogle Scholar
Weidner, T. & Nielsen, A. T. 2013. The late Cambrian (Furongian) Acerocarina Superzone (new name) on Kinnekulle, Västergötland, Sweden. GFF 135, 30–44.CrossRefGoogle Scholar
Westergård, A. H. 1922. Sveriges olenidskiffer. Sveriges geologiska undersökning Ca18, 1–205.Google Scholar
Westergård, A. H. 1936. Paradoxides œlandicus beds of Öland with the account of a diamond boring through the Cambrian at Mossberga. Sveriges geologiska undersökning C394, 1–66.Google Scholar
Westergård, A. H. 1944. Borrningar genom alunskifferlagret på Öland och i Östergötland 1943. Sveriges geologiska undersökning C463, 1–22.Google Scholar
Westergård, A. H. 1946. Agnostidea of the Middle Cambrian of Sweden. Sveriges geologiska undersökning C477, 1–140.Google Scholar
Westergård, A. H. 1947a. Supplementary notes on the Upper Cambrian trilobites of Sweden. Sveriges geologiska undersökning C489, 1–34.Google Scholar
Westergård, A. H. 1947b. Nya data rörande alunskifferlagret på Öland. Sveriges geologiska undersökning C483, 1–12.Google 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.CrossRefGoogle Scholar
Wotte, T. & Strauss, H. 2015. Questioning a widespread euxinia for the Furongian (Late Cambrian) SPICE event: indications from δ13C, δ18O, δ34S and biostratigraphic constraints. Geological Magazine 152, 1085–103.CrossRefGoogle Scholar
Zhu, M. Y., Babcock, L. E. & Peng, S. C. 2006. Advances in Cambrian stratigraphy and paleontology: integrating correlation techniques, paleobiology, taphonomy and paleoenvironmental reconstruction. Palaeoworld 15, 217–22.CrossRefGoogle Scholar
Zhu, M. Y., Zhang, J. M., Li, G. X. & Yang, A. H. 2004. Evolution of C isotopes in the Cambrian of China: implications for Cambrian subdivision and trilobite mass extinctions. Geobios 37, 287–301.CrossRefGoogle Scholar