Stratigraphic overview of the Ediacaran and Cambrian from the Anti ...

International Meeting September 15-24th 2014, Ouarzazate, Morocco

Stratigraphic overview of the Ediacaran and Cambrian from the Anti-Atlas, Morocco Léa Devaere, Sébastien Clausen and J. Javier Álvaro (eds.)

(cover photo: Issafen valley, western Anti-Atlas)

Devaere, L., Clausen, S. and Álvaro, J.J. (Eds.). 2014. Stratigraphic overview of the Ediacaran and Cambrian from the Anti-Atlas, Morocco. University Lille 1, France. ISBN: 978-2-9601543-0-6 (paperback). ISBN: 978-2-9601543-1-3 (PDF) Dépot Légal : 09/2014 Impresssion : Université Lille 1, 59655 Villeneuve d’Ascq, France, 09/2014. This book has been freely provided to the participants of the international meeting held in Ouarzazate, Morocco, September 15-24th, 2014. No commercial value.

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International Meeting

Organizing Committee J. Javier Álvaro, Centre of Astrobiology, Torrejón de Ardoz, Spain Mohammed Benharref, CAP-Ressources, Casablanca, Morocco Sébastien Clausen, University Lille 1, France Léa Devaere, University Lille 1, France Hassan Ezzouhairi, University Chouaib Doukkali, El Jadida, Morocco Abderrahman Soulaimani, University Cadi-Ayyad, Marrakech, Morocco Samuel Zamora, Geological Survey of Spain (IGME), Zaragoza, Spain

Sponsors CAP Ressources, Morocco Geological Survey of Spain (IGME) International Subcomission on Cambrian Stratigraphy International Subcomission on Ediacaran Stratigraphy Managem, Morocco University Lille 1, France

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Table of contents 1. List of participants

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2. Meeting in Ouarzazate (16 -18 September) 2.1- Timetable for presentations 2.2- List of posters 2.3- Abstracts of presentations 3. Guide to Field Excursion 3.1- 19th September: South of Taroudant STOP 1: Tabia Member (Adoudou Formation) at Walkadi, northern rim of Igherm inlier STOP 2: Taguedit Bed of Tabia Member (Adoudou Formation) at Im-n-Tal’at, southern rim of Ouaouafengha inlier STOP 3: Lie-de-vin, Igoudine and Amouslek formations at Tiout stratotype, western Anti-Atlas STOP 4: Open quarry of the Issafen Formation at Amagour, western Anti-Atlas 3.2- 20th September: from Taroudant to Ouarzazate STOP 5: Angular discordance of the Ouarzazate/Adoudou contact, southern Sirwa massif STOP 6: Angular discordance of the Ouarzazate/Adoudou contact at Tizi-n-Tifourt STOP 7: Assif n-Warhmoud Conglomerates STOP 8: Double angular discordance at Tizi n’Taghatine, southern Sirwa inlier STOP 9: Diamictites of the Tiddiline Formation at the Bou Azzer-El Graara inlier 3.3- 21st September: from Ouarzazate to Agdz STOP 10: Alkaline lake embedded in the Ouarzazate Supergroup at Amane n’Tourhart, western Saghro inlier STOP 11: Oued Da’ra caldera, Ouarzazate Supergroup, western Saghro inlier STOP 12: Adoudou and Lie-de-vin formations at Tizi n’Tinfifit jbel, central Anti-Atlas STOP 13: Asrir, Jbel Wawrmast and Jbel Afraou formations at Ourika Wawrmast stratotype, central Anti-Atlas 3.4- 22nd September: from Agdz to Alnif STOP 14: Bab n’Ali volcano in the vicinity of Berkik, central Anti-Atlas STOP 15: Bab n’Ali volcano at homonymous site, central Anti-Atlas 3.5- 23rd September: from Alnif to Ouarzazate

7 7 9 10 42 41 41 44 46 50 53 53 54 55 56 56 59 59 61 64 66 68 68 70 72

STOP 16: Open quarry of the Brèche à Micmacca Member 72 crossing the “telesto level” at Assemame, central Anti-Atlas STOP 17: Open quarry of the Brèche à Micmacca Member 76 at Tizi n'Telgane, central Anti-Atlas STOP 18: Open quarry of the Tarhoucht Member (Morocconus notabilis Zone) 80 at Tizi n'Telgane, central Anti-Atlas 3.6- References

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1. List of participants • AHLBERG Per, Department of Earth and Ecosystem Sciences, GeoBiosphere Science Centre, Lund University, Sölvegatan SE-12, 223 62 Lund, Sweden, [email protected] • AHN Soo Yeun, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China, [email protected] • ÁLVARO J. Javier, Centro de Astrobiología (INTA-CSIC), Ctra. de Torrejón a Ajalvir km 4, 28850 Torrejón de Ardoz, Spain, [email protected] • BABCOCK Loren E., School of Earth Sciences, The Ohio State University, Columbus, Ohio 43210, USA and Department of Geology, Lund University, Sölvegatan SE-12, 223 62 Lund, Sweden, [email protected] • BAGNOLI Gabriella, Dipartimento di Scienze della Terra, Università di Pisa, via Santa Maria 53, 56126 Pisa, Italy; [email protected] • BASSETT-BUTT Lewis, Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, SE-75236, Uppsala, Sweden, [email protected] • BENHARREF Mohammed, CAP-Ressources, 56-Résidence Sanaa, Rue El Fourat, 20330Casablanca, Morocco, [email protected] • BETTS Marissa J., Department of Biological Sciences, Macquarie University, Sydney, 2109, Australia, [email protected] • BROCK Glenn A., Department of Biological Sciences, Macquarie University, Sydney, 2109, Australia, [email protected] • BUTLER Aodhàn D., Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, SE-75236, Uppsala, Sweden, [email protected] • CHEN Zhe, State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China, [email protected] • CLAUSEN Sébastien, UMR 8217 Géosystèmes CNRS – Université Lille 1, avenue Paul Langevin, 59655 Villeneuve d’Ascq, France, [email protected] • DAHL Tais, Natural History Museum, University of Copenhagen, Oster Voldgade 5-7, DK-1350, Copenhangen, Denmark, [email protected] • DEVAERE Léa, UMR 8217 Géosystèmes CNRS – Université Lille 1, avenue Paul Langevin, 59655 Villeneuve d’Ascq, France, [email protected] • ERIKSSON Mats E., Department of Geology, Lund University, Sölvegatan SE-13, 223 62 Lund, Sweden, [email protected] • ESTEVE Jorge, Center of Biology, Geosciences and Environment, University of West Bohemia, Klatovska 51, 306 14 Pilsen, Czech Republic, [email protected] • EZZOUHAIRI Hassan, Département de Géologie, Université Chouaib Doukkali, 24000 El Jadida, Morocco, [email protected] • FU Dongjing, State Key Laboratory of Continental Dynamics, Early Life Institute and Department of Geology, Northwest University, Xi’an 710069, China, [email protected] • GAINES Robert R., Geology Department, Pomona College, 185 E. Sixth Street, Claremont, CA 91711, USA, [email protected] • GOZALO Rodolfo, Departamento de Geología, Universitat de València, C/ Dr. Moliner 50, 46100 Burjassot, Spain, [email protected] • HAMOUMI Naima, Odyssée (Océanologie-Dynamique des Séries Sédimentaires-Environnement), Faculty of Sciences, Mohammed V-Agdal University, B.P: 1014, Rabat, Morocco, [email protected] • HAN Jian, State Key Laboratory of Continental Dynamics, Early Life Institute and Department of Geology, Northwest University, Xi’an 710069, China, [email protected] • HENRIET Pierre, Renard Centre of Marine Geology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium, [email protected] • HOLMER Lars E., Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, SE-75236, Uppsala, Sweden, [email protected] • JACQUET Sarah M., Department of Biological Sciences, Macquarie University, Sydney, 2109, Australia, [email protected] • KIHM Ji-oon, Division of Polar Earth-System Sciences, Korea Polar Research Institute, 6 Songdomirae-ro, Yeonsu-gu, Incheon 406-840, Korea, [email protected] • KRUSE Pierre, Northern Territory Geological Survey, PO Box 3000, Darwin, NT, 0801, Australia, [email protected] • KUNLI Luo, CAS, Institute of Geographical Sciences and Natural Resource Research, Chinese Academy of Sciences, 11A Datun Road, Beijing 100101, China, [email protected] • LEI Shu, State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China, [email protected] • LI Guoxiang, State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China, [email protected]

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• LI Yong, College of Earth Science and Land Resources, Educational Ministry Key Laboratory of Geological Resources and Geological Engineering of Western China, Chang'an University, Xi'an 710054, China, [email protected] • MAACHA Lhou, Managem, Twin Center, Tour A, Angle Boulevards Zerktouni et Al Massira Al Khadra, BP 5199, Casablanca, Morocco, [email protected] • McCOLLUM Linda, Department of Geology, Eastern Washington University, Cheney, WA 990042439, USA, [email protected] • MENÉNDEZ Silvia, Museo Geominero (IGME), Ríos Rosas 23, 28003 Madrid, Spain, [email protected] • MILLER James F., Geography, Geology and Planning, Missouri State University, 901 S. National Avenue, Springfield, MO 65897, USA, [email protected] • NIELSEN Arne T., Natural History Museum, University of Copenhagen, Øster Voldgade 5-7, DK 1350, Copenhagen, Denmark, [email protected] • PALACIOS Teodoro, Área de Paleontología, Universidad de Extremadura, E-06006 Badajoz, Spain, [email protected] • PARK Tae-Yoon, Division of Polar Earth-System Sciences, Korea Polar Research Institute, 6 Songdomirae-ro, Yeonsu-gu, Incheon 406-840, Korea, [email protected] • PENG Jin, College of Resources and Environment Engineering, Guizhou University, Guiyang 50025, China, [email protected] • PENG Shanchi, State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China, [email protected] • PROKOPENKO Maria G., Geology Department, Pomona College, 185 E. Sixth Street, Claremont, CA 91711, USA, [email protected] • PYEMONT Brett, Syndey, Australia, [email protected] • SCHOLTEN Peter G., USA, [email protected] • SMITH Patrick M., Department of Biological Sciences, Macquarie University, Sydney, 2109, Australia, [email protected] • SOULAIMANI Abderrahmane, Département de Géologie, Faculté des Sciences Semlalia, Université Cadi-Ayyadi, PO. Box 2390, 40000 Marrakesh, Morocco, [email protected] • SUNDBERG Frederick, Show Low High School, 500 W. Old Linden Rd., Show Low, AZ 85901, USA, [email protected] • TOPPER Timothy P., Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, SE-75236, Uppsala, Sweden, [email protected] • WALDE Detlef Hans G., University of Brasília, Institute of Geosciences, Campus Universitário Darcy Ribeiro, 70910-970, Brasília-DF, Brazil; [email protected]; • WANG Haizhou, Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, SE-75236, Uppsala, Sweden, [email protected] • WINKLER Wilfred, Geologisches Institut, ETH Zürich, Sonneggstrasse 5, 8092 Zürich, Switzerland, [email protected] • YANG Yuning, State Key Laboratory of Continental Dynamics, Early Life Institute and Department of Geology, Northwest University, Xi’an 710069, China, [email protected] • YIN Zongjun, State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China, [email protected] • ZAMORA Samuel, Museo Geominero, Instituto Geológico y Minero de España, Manuel Lasala 44 9ºB, 50006 Zaragoza, Spain, [email protected] • ZHANG Xingliang, State Key Laboratory of Continental Dynamics, Early Life Institute and Department of Geology, Northwest University, Xi’an 710069, China, [email protected] • ZHANG Zhifei, State Key Laboratory of Continental Dynamics, Early Life Institute and Department of Geology, Northwest University, Xi’an 710069, China, [email protected] • ZHAO Fangchen, State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China, [email protected] • ZHAO Yuanlong, College of Resources and Environment Engineering, Guizhou University, Guiyang 550003, China, [email protected] • ZHOU Chuanming, Key Laboratory of Economic Stratigraphy and Palaeogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, [email protected] • ZHU Maoyan, State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China, [email protected] • ZHU Xuejian, State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China, [email protected] • ŻYLIŃSKA Anna, Faculty of Geology, University of Warsaw, Żwirki i Wigury Str. 93, 02-089 Warszawa, Poland, [email protected]

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2. Meeting in Ouarzazate (16-18th September) 2.1. Timetable for presentations 16th September. Morning 9.00 9.30 -

Salutation words on behalf of the organizers. Neoproterozoic stratigraphic architecture of South China. ZHU et al. 9.45 - Ediacaran fossils in marine limestone from Dengying Formation, China. CHEN et al. 10.00 - Neoproterozoic-Cambrian evolution of the Corumbá region (Mato Grosso do Sul State, Brazil). WALDE et al. 10.15 - The stratigraphic complexity of the middle Ediacaran Shuram anomaly in South China. ZHOU et al. 10.30 - Coffee and tea break. Poster session. 11.00 - Cloudinids and the Cambrian stem-group cnidarians. PARK et al. 11.15 - Ancestral animals from the Ediacaran Doushantuo phosphorite, South China. YIN et al. 11.30 - Ediacaran-Cambrian phosphorites from the western margins of Gondwana and Baltica. ÁLVARO et al.. 11.45 - An abrupt change in the nitrogen cycle and redox conditions of surface environments in Ediacaran-Cambrian as recorded in Carbonate Associated Nitrate (CAN). PROKOPENKO and GAINES. 12.00 - Pervasive patterns of unusual chemical sedimentation and transient ocean chemistry at the dawn of the Phanerozoic. GAINES and PETERS. 12.15 - Distribution pattern and evolution of selenium and arsenic across the Ediacaran to Cambrian interval in Qinling Mountain China. KUNLI and SHIXI. 16th September. Afternoon 15.00 - Global ocean oxygenation in the Early Cambrian. DAHL. 15.15 - Basal Cambrian acritarchs from the Yangtze Platform and their biostratigraphic significance. AHN and ZHU. 15.30 - New data from the basal Cambrian of Sonora State (Mexico) and their contribution to the knowledge of the earliest skeletal microfossils of Laurentia. DEVAERE et al. 15.45 - Attachment and life strategies of brachiopods in the Burgess Shale. TOPPER et al. 16.00 - Upper Lower Cambrian (Series 2, Stage 4) mickwitziid stem linguliform brachiopods from Svalbard and the Guanshan Lagerstätte, South China. HOLMER et al. 16.15 - Oldest glosselline linguliform brachiopods from the lower Cambrian of Yunan, China. WANG et al. 16.30 - Coffee and tea break. Poster session. 17.00 - The linguloid brachiopod “Lingulellotreta malongensis” from Chengjiang and Guanshan faunas in Eastern Yunnan, China and its implications for correlations of the traditional lower Cambrian. ZHANG et al. 17.15 - Echinoderms from Morocco reveal unexpected diversity from the Cambrian Series 2-3 boundary interval. ZAMORA and SMITH. 17.30 - A Chengjiang-type fossil assemblage from the Hongjingshao Formation (Cambrian Stage 3) at Chenggong, Kunming, China. ZHAO et al. 17.45 - Shiny black tubules from the Furongian of Sweden - first record of Sphenothallus from the Cambrian of Baltica. STEWART et al.

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17th September. Morning 9.00 -

Proposed reassessment of the Cambrian GSSP. BABCOCK et al. 9.15 - Watsonella crosbyi and the base of Terreneuvian, Cambrian Stage 2 in South Australia. BROCK et al. 9.30 - Defining the base of the Cambrian Stage 2. LI. 9.45 - FAD of trilobites marks the largest phase of the Cambrian explosion: a discussion on defining the Cambrian Series 2 and Stage 3. ZHANG. 10.00 - Restudy on Ovatoryctocara Tchernysheva, 1962 from the lower part of Kaili Formation, Balang, Jianhe County, Guizhou Province, China. ZHAO et al. 10.15 - Corynexochid trilobite taxonomy for the Cambrian Balang Formation South China and their implication for stratigraphy. PENG et al. 10.30 - Coffee and tea break. Poster session. 11.00 - The Early/Mid Cambrian Hawke Bay Event in Scandinavia: A major sea level fall overprinted by epeirogenic uplift. NIELSEN and SCHOVSBO. 11.15 - Problems with selecting a GSSP for the Stage 3 Series 5 Cambrian boundary. MCCOLLUM. 11.30 - The concept of Lotagnostus americanus and a Chinese candidate section for the GSSP defining the base of provisional Cambrian Stage 10. PENG et al. 11.45 - Alternatives for dividing Cambrian Stage 10 into substages. MILLER. 12.00 - Reassessment of lower Cambrian molluscan biostratigraphy from South Australia. JACQUET et al. 17th September. Afternoon 15.00 - First record of Bailiaspis tuberculata Lake, 1940 in the Iberia Chains (NE of Spain) in the Mediterranean Region. CHIRIVELLA et al. 15.15 - Intraspecific variation in paradoxid trilobites from the Cambrian Series 3 of Purujosa (North Spain). ESTEVE. 15.30 - Biostratigraphy of the Cambrian Pertaoorrta Group, Amadeus Basin, Northern Territory, Australia. SMITH et al. 15.45 - Fossils, rocks and Cambrian clocks: lower Cambrian biostratigraphy of the Arrowie Basin, South Australia. BETTS et al. 16.00 - Coffee and tea break. Poster session 16.30 - Ontogeny of Eccaparadoxides and Hydrocephalus from the Skryje-Týřovice Basin (Barrandian area, Czech Republic). LAIBL et al. 16.45 - The first dorsal-eyed bivalved arthropod and its significance for the early arthropod evolution. FU et al. 17.00 - Enrolment in Strenuella polonica Czarnocki, 1926 (Trilobita, Cambrian Series 2) from the Holy Cross Mountains, Poland. ŻYLIŃSKA. 17.15 - Cambrian enrolled trilobites from north China. ESTEVE and YUAN.

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18th September. Morning 9.00 -

Shedding light on the tommotiid stem-brachiopod transition with multi-scalar X-ray computed tomography. BUTLER et al. 9.15 - Peeking into Cambrian ‘Orsten’ arthropods using Synchrotron Radiation X-ray Tomographic Microscopy. ERIKSSON et al. 9.30 - Polyfocal photos of microfossils using petrographic microscopes. MILLER et al. 9.45 - Designing a Moroccan Mound Heritage Route. HENRIET et al. 10.00 - Workshop of International Subcommission on Ediacaran Stratigraphy. 10.45 - Coffee and tea break. 11.15 - Workshop of International Subcommission on Cambrian Stratigraphy.

2.2. List of posters BASSETT-BUTT et al.The fauna of the Middle Cambrian Nelson Limestone: A biostratigraphic and evolutionary approach. LIÑÁN et al. The lower Cambrian (Ovetian) Agraulidae from Spain and the oldest trilobite records. HOLMER et al.The Early Cambrian of Antarctica: Faunas and chemostratigraphy of the Shackleton Limestone. MENÉNDEZ et al.Late Ovetian (Cambrian Series 2, Stage 3) archaeocyathan biostratigraphy from Spain. PALACIOS. A pilot proposal of a Middle Cambrian (Series 3) acritarch biozonation in northwestern Gondwana. PALACIOS et al.Acritarchs from the Hanford Brook Formation (New Brunswick, Canada), and their implications for acritarch zonation across the Cambrian Series 2-3 transition. PARK et al.Biostratigraphy of the Cambrian Spur Formation at Eureka Spur, northern Victoria Land, Antarctica: a preliminary report. PENG.Invalid Cambrian chronostratigraphic units: the Changqingian and the Jinanian stages proposed by Yuan and others. ZHU. A new aglaspidid (Arthropoda) species from the Furongian Series (Cambrian) of China.

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2.3. Abstracts of presentations

Basal Cambrian acritarchs from the Yangtze Platform and their biostratigraphic significance Soo Yeun AHN and Maoyan ZHU Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, China; [email protected]; [email protected]

In the Yangtze Platform (South China), well-developed successions of mixed carbonatesiliciclastic deposits spanning the terminal Neoproterozoic through lower Palaeozoic provide extensive data for global chronostratigraphic correlation of this critical time interval. Chronostratigraphy of the basal Cambrian System of the Yangtze Platform is largely dependent on the biostratigraphy of skeletal metazoan fossils. However, acanthomorphic acritarchs have been reported from the same time interval and have been suggested as a prospective biostratigraphic tool other than small shelly fossils (SSFs) in South China. To test temporal relationships between the two fossil groups, the microfossils from the chert layers of the lower Yanjiahe Formation, Yangtze Gorges area, and the Daibu Member of the Zhujiaqing Formation, eastern Yunnan Province, have been examined. The new data demonstrates that a distinct Asteridium-Heliosphaeridium-Comasphaeridium (AHC) acritarch assemblage corresponds to the Anabarites trisulcatus-Protohertzina anabarica (A-P) Zone, the first SSFs Zone representing the lower Meishucunian Stage of South China. The acritarch assemblage is dominated by the genus Asteridium and Heliosphaeridium, and associates with other acritarchs and microfossils. The synchronicity of the two fossil assemblages indicates that the AHC assemblage can also be used as a significant biostratigraphic tool in the basal Cambrian System in the Yangtze Platform. This, together with the chemostratigraphic records of South China, can represent the evolutionary snapshot of the early Cambrian, and potentially serve as an important intercontinental tie point of a key interval of the Cambrian System.

Ediacaran-Cambrian phosphorites from the western margins of Gondwana and Baltica J. Javier ÁLVARO1, Graham A. SHIELDS2, Per AHLBERG3, Sören JENSEN4 and Teodoro PALACIOS4 1

Centro de Astrobiología (INTA/CSIC), Torrejón de Ardoz, Spain; [email protected] Department of Earth Sciences, University College London, UK; [email protected] 3 GeoBiosphere Science Centre, Department of Geology, Lund University, Sweden; [email protected] 4 Área de Paleontología, Facultad de Ciencias, Universidad de Extremadura, 06006 Badajoz, Spain; [email protected]; [email protected] 2

The late Ediacaran-‘mid’ Cambrian occurrences of phosphorites in the western Mediterranean region (West Gondwana) and southern Sweden (NW Baltica) are related to the poleward drift of West Gondwana and the northern drift of Baltica. As a result, these regions crossed subtropical and temperate palaeolatitudes of the southern hemisphere, in which oceanic upwelling and high patterns of organic productivity were the probable source of the phosphorous along their western margins. A parallel SW-NE-trend migration of evaporites and delayed, time transgressive phosphorites point to distal upwelling environments associated with shallower arid conditions. Concentration of hardground-derived phosphate accumulations took place by repeated alternations of low sedimentation rates and condensation, in situ early-diagenetic and microbially mediated precipitation of amorphous francolite and carbonate fluorapatite, winnowing and polyphase reworking of previously phosphatized skeletons and hardgroundderived clasts. Thicker phosphorites of economic importance display a spiculate spongethromboid consortium that points to a distinct benthic community developed on suboxic, slopeto-basinal substrates. The extremely high rare-earth element contents of representative phosphorite samples reflect lengthy scavenging of REE and Y after deposition. Considerable scavenging took place near the seafloor, as evidenced from the rare preservation of primary seawater features, such as Ce depletion and Y enrichment in some samples, and in particular in phosphatized thrombolites. However, reworked basinal phosphorites have lost most of the characteristic features associated with seawater, and are characterized by middle-REE enrichment.

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Proposed reassessment of the Cambrian GSSP Loren E. BABCOCK1,2, Shanchi PENG3, Maoyan ZHU3, Shuhai XIAO4 and Per AHLBERG2 1

School of Earth Sciences, The Ohio State University, Columbus, USA; [email protected] Department of Geology, Lund University, Sweden; [email protected] 3 Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, China; [email protected]; [email protected] 4 Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, USA; [email protected] 2

Since the time of its ratification in 1992, the Cambrian GSSP, 2.3 m above the base of Member 2A (Quaco Road Member) of the Chapel Island Formation, Fortune Head section, Newfoundland, Canada, has been challenged as posing an ambiguous correlation level. Difficulties have been encountered in precisely correlating the horizon coinciding with the GSSP to strata on most paleocontinents, but especially to Siberia and South China (Gondwana). The GSSP point, which was intended to coincide with the base of the Treptichnus pedum (formerly Phycodes pedum or Trichophycus pedum) Ichnozone at the FAD of the trace fossil Treptichnus pedum, occurs above the first appearance of the trace in the stratotype section. Trace fossils of other forms in the stratotype provide a means of bracketing the position of the GSSP, but are imprecise guides for correlation globally. Other chronostratigraphic guides are unavailable at the stratotype because of a dominance of coarse siliciclastic lithologies and metamorphic overprint. To facilitate global correlation of the Cambrian base and ensure nomenclatural stability to the extent possible, discussion of the merits and perceived weaknesses of the Cambrian GSSP is sought. Possible solutions to the problems surrounding the current GSSP definition are addressed in hopes that the global scientific community will actively participate in developing a well-reasoned, practical solution that will stand the test of time.

The fauna of the Middle Cambrian Nelson Limestone: A biostratigraphic and evolutionary approach Lewis BASSETT-BUTT1, Lars E. HOLMER1, Timothy P. TOPPER1 and Christian B. SKOVSTED2 1 Department of Earth Sciences, Uppsala University, Sweden. [email protected]; [email protected]; [email protected] 2 Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden; [email protected]

Since their first description from the Early Cambrian of Siberia in the 1970s, small shelly fossils have come to comprise important biostratigraphic proxies, and record the existence of many enigmatic groups of metazoans. Extensive work has been carried out in sections from the Cambrian Gondwanan supercontinent, but due to the remoteness of localities, the biostratigraphy of Antarctic Cambrian sections is still poorly understood; researchers have relied on Cambrian fossils preserved in erratics or morraine boulders. We present the first inclusive description of a variety of taxa, from many phyla, recovered from rocks collected in-situ from the Middle Cambrian Nelson Limestone, of the Neptune Range in the Pensacola Mountains. Monospecific acrotretids (Prototreta) and botsfordids (Karathele) dominate the phosphatic microfauna, which also includes fragmentary paterinids (e.g Micromitra), rare fragmentary linguilids (Eoobolus), and sponge spicules in vast abundance. The macrofauna contains larger specimens of the same species, as well as billingsellids and protorthids. Enigmatic phosphatic tubes make up a small part of the fauna. More recogniseable small shelly fossils (e.g, chancellorids) are fragmentary and extremely rare. Trilobite fragments were found in high abundance. The fauna displays strong heterogeneity between the levels of the Nelson Limestone. Palaeobiogeographic analysis indicates that the fauna corroborates previously described strong links with South Australia, but also implies a strong link to Himalayan sections. Worker effort and collection bias were found to a have strong effect on the number of taxa described.

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Fossils, rocks and Cambrian clocks: lower Cambrian biostratigraphy of the Arrowie Basin, South Australia Marissa J. BETTS1, Glenn A. BROCK1, James B. JAGO2, John R. PATERSON3, Timothy P. TOPPER4, Christian B. SKOVSTED5 and John R. LAURIE6 1

Department of Biological Sciences, Macquarie University, Sydney, Australia; [email protected]; [email protected] 2 School of Natural and Built Environments, University of South Australia, Adelaide, Australia; [email protected] 3 Division of Earth Sciences, School of Environmental and Rural Science, University of New England, Armidale, Australia; [email protected] 4 Department of Earth Sciences, Palaeobiology, Uppsala University, Sweden; [email protected] 5 Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden; [email protected] 6 Eastern and Onshore Petroleum, Geoscience Australia, Canberra, Australia; [email protected]

The Cambrian Period is one of the most underdeveloped parts of the International Geological Timescale. There are many large subdivisions (including two Series and six Stages) still awaiting ratified definitions. A major impediment to the development of the Cambrian timescale and global correlation is the paucity of comprehensive biostratigraphic, lithostratigraphic and chemostratigraphic data, especially from East Gondwana (of which Australia forms a major part). Regional studies are ultimately the key to resolving and calibrating the timescale. In South Australia, the lower Cambrian succession in the Arrowie Basin is well preserved, well exposed and contains rich fossil assemblages. The primary aim of this study is to present composite biostratigraphic data for early Cambrian taxa from ten stratigraphic sections measured through the lower Wilkawillina and Ajax Limestones and the Mernmerna Formation in the Arrowie Basin, South Australia. A decade of concerted systematic sampling - compiled in this project - has revealed that ranges of many early Cambrian shelly fossil taxa are predictable and repeatable across the basin, making them excellent candidates for applied regional biostratigraphic investigations. The succession is dominated by Small Shelly Fossils (SSF) including the tommotiids Dailyatia ajax and D. macroptera, as well as other tommotiids, brachiopods, micromolluscs and bivalved arthropods. Total ranges of these taxa extend from late Terreneuvian, Stage 2 to Series 2, Stage 3, where they partially overlap with the Abadiella huoi trilobite Zone. The helcionellid mollusc Pelagiella subangulata is present in many of the sections providing a proxy for the base of Series 2, Stage 3. Future investigations will focus on integrating the biostratigraphic data with detailed lithostratigraphy, oxygen and carbon chemostratigraphy and radioisotopic dating of interbedded tuffs to further facilitate regional and global correlation.

Watsonella crosbyi and the base of Terreneuvian, Cambrian Stage 2 in South Australia Glenn A. BROCK1, Thomas BROUGHAM1, Christian B. SKOVSTED2, Timothy P. TOPPER3, James B. JAGO4, Marissa J. BETTS1, Sarah M. JACQUET1 and John R. PATERSON5 1 Department of Biological Sciences, Macquarie University, Sydney, Australia; [email protected]; [email protected]; [email protected] 2 Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden; [email protected] 3 Department of Earth Sciences, Palaeobiology, Uppsala University, Sweden; [email protected] 4 School of Natural and Built Environments, University of South Australia, Adelaide, Australia; [email protected] 5 Division of Earth Sciences, School of Environmental and Rural Science, University of New England, Armidale, Australia; [email protected]

The definition of the base of Terreneuvian, Stage 2 of the Cambrian Timescale has recently become a major point of controversy especially related to the reliability and biostratigraphic utility of the micromolluc Watsonella crosbyi. This taxon has a cosmopolitan distribution in subtrilobitic strata in Siberia, South China, Avalonia and West Gondwana (Cadomia) and its cooccurrence with the dextrally coiled shell of Aldanella attleborensis has been promoted as a potential GSSP for the base of Cambrian Stage 2. The occurrence of Watsonella crosbyi in Australia has long been recognized but the lack of formal taxonomic documentation and poorly

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resolved stratigraphic context has led to confusion about the biostratigraphic range and correlation of this taxon in Cambrian East Gondwana. Recent suggestions have even correlated the range of Watsonella crosbyi in South Australia with the Parabadiella huoi trilobite Zone which would confound the utility of this fossil for global correlation in the lower Cambrian. Measurement of new stratigraphic sections on Fleurieu Peninsula, Stansbury Basin, South Australia reveals that Watsonella crosbyi (though rare) is part of an assemblage dominated by micromolluscs including a sinistral form of Aldanella (A. cf. golubevi) as well as univalved species of ?Pelagiella, Bemella, and Parailsanella. The fauna also includes Australohalkieria and coeloscleritophorans including Eremactis and chancelloriids. Stratigraphically, the Watsonella assemblage first appears in the upper part of the Mount Terrible Formation (MTF) a ~92 m thick package of dominantly clastic rocks that rests unconformably above the Ediacaran Wilpena Group in lower part of the Normanville Group. Aldanella is restricted to the upper MTF, but Watsonella crosbyi (and other micromolluscs) range up to the lower half of the Sellick Hill Formation. The overlapping stratigraphic ranges of Watsonella and Aldanella in the upper part of the Mount Terrible Formation are regarded as equivalent to the base of Cambrian stage 2. The underlying 60 m of MTF (with indeterminate hyoliths and tubes) represents sequence package Є1.0 which correlates with a Fortunian Stage. The 240 m stratigraphic range represented by the Watsonella assemblage through the Normanville Group represents a typical pre-trilobitic Stage 2 (Tommotian) equivalent fauna. The fauna predates the FAD of the key (endemic) guide fossil Kulparina rostrata in the middle-upper Sellick Hill Formation, which we have demonstrated to be pre-trilobitic in age in the Arrowie Basin. There is no evidence that trilobites occur in the MTF, nor in the overlying Wangkonda Limestone, Sellick Formation or even the Fork Tree Limestone. The Watsonella fauna in South Australia correlates very well with other occurrences in China, France and Siberia and is thus an excellent marker for correlation of the base of Cambrian Stage 2.

Shedding light on the tommotiid stem-brachiopod transition with multi-scalar X-ray computed tomography Aodhán D. BUTLER1, Russell GARWOOD2, Michael STRENG1, Zhifei ZHANG3, Tristian LOWE4 and Lars E. HOLMER1 1

Department of Earth Sciences, Palaeobiology, Uppsala University, Sweden; [email protected] 2 University of Manchester, UK; [email protected] 3 State Key Laboratory for Continental Dynamics and Early Life Institute, Northwest University, Xi’an, China; [email protected] 4 Manchester X-Ray Imaging Facility, UK; [email protected]

The fossil record of life on earth is strongly biased towards organisms which have hard parts biomineralised tissues such as shells, teeth or bones. Indeed, we now know that the event termed the Cambrian explosion, once thought of as the initial appearance of life, in fact partially results from the evolution of hard parts and their resulting sudden appearance in the fossil record. This event, 542 million years ago, is immediately preceded by the appearance of a group of problematic microfossils known as the small shelly fauna. Significant progress has been achieved tracing the origin and evolution of Brachiopoda to these plethora of lower Cambrian scleritome taxa. We aim to determine the characters suites linking the putative stemLophotrochozoa to crown brachiopods and other lophotrochozoans. This is achieved by comparing records of exceptional preservation, most conspicuously members of Lagerstätten such as the Burgess Shale type faunas, with more widespread Cambrian stem-brachiopods and small shelly fossils. This determination is crucial to reconstructing the brachiopod stem-group and in polarising character changes associated with the putative transition from scleritome organisms to crown-group brachiopods. Lab-based CT scanning has helped us to characterise the gross anatomy, micro-structure and histology of tommotiid SSF’s, providing the basis for solving the placement of these enigmatic fossils on the tree of life. Major features critically examined include those of fossilised setae, structures commonly found across Lophotrochozoa. Exceptionally preserved examples of which can be found in-situ in both brachiopods and tommotiids implying a close affinity. The addition of 3D microCT and synchrotron tomography data provides novel information on ontogenetic growth trajectories and the arrangement of phosphatised shell structures including so-called 'acrotretid type' columns and the conformation of associated lamellae. CT scanning also reveals exceptionally preserved soft-tissues such as lophophores, mantle canals and digestive organs otherwise not visible without destructive

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sampling of scientifically valuable fossils. Such new data facilitates further critical anatomical comparison of tommotiids including Micrina, Sunnaginia and Eccentrotheca with stem-group brachiopods such as Mickwitzia, Heliomedusa and Setatella. These suggested homologies are of phylogenetic significance, and shed further light on the early evolution and assembly of the lophotrochozoan body plan during the early Cambrian.

Ediacaran fossils in marine limestone from Dengying Formation, China Zhe CHEN1, Chuanming ZHOU1, Shuhai XIAO2, Hong HUA3 and Xunlai YUAN1 1

Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, China; [email protected]; [email protected]; [email protected] 2 Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, USA; [email protected] 3 State Key Laboratory of Continental Dynamics and Department of Geology, Northwest University, Xi’an China; [email protected]

Ediacara-type fossils are central to our understanding of animal evolution on the eve of the Cambrian explosion. Here we report several iconic Ediacaran genera (Hiemalora, Pteridinium, Rangea, and Charniodiscus) and a new annulated tubular fossil (Wutubus annularis [1]), from marine limestone of the 551-541 Ma Dengying Formation in South China. The new discovery of Hiemalora, Pteridinium, Rangea, and Charniodiscus adds to our understanding of the geographic, stratigraphic, environmental, and taphonomic distribution of these Ediacaran genera. The stratigraphic range of Charniodiscus is extended to be