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A Preliminary Report on New Ediacaran Fossils from Iran

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A Preliminary Report on New Ediacaran Fossils from Iran Alcheringa: An Australasian Journal of Palaeontology ISSN: 0311-5518 (Print) 1752-0754 (Online) Journal homepage: http://www.tandfonline.com/loi/talc20 A preliminary report on new Ediacaran fossils from Iran Patricia Vickers-Rich, Sara Soleimani, Farnoosh Farjandi, Mehdi Zand, Ulf Linnemann, Mandy Hofmann, Siobhan A. Wilson, Raymond Cas & Thomas H. Rich To cite this article: Patricia Vickers-Rich, Sara Soleimani, Farnoosh Farjandi, Mehdi Zand, Ulf Linnemann, Mandy Hofmann, Siobhan A. Wilson, Raymond Cas & Thomas H. Rich (2018) A preliminary report on new Ediacaran fossils from Iran, Alcheringa: An Australasian Journal of Palaeontology, 42:2, 230-243, DOI: 10.1080/03115518.2017.1384061 To link to this article: https://doi.org/10.1080/03115518.2017.1384061 View supplementary material Published online: 26 Nov 2017. Submit your article to this journal Article views: 117 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=talc20 A preliminary report on new Ediacaran fossils from Iran PATRICIA VICKERS-RICH , SARA SOLEIMANI, FARNOOSH FARJANDI, MEHDI ZAND, ULF LINNEMANN, MANDY HOFMANN, SIOBHAN A. WILSON, RAYMOND CAS and THOMAS H. RICH VICKERS-RICH, P., SOLEIMANI, S., FARJANDI, F., ZAND, M., LINNEMANN, U., HOFMANN, M., WILSON, S.A., CAS,R.&RICH, T.H. June, 2018. A preliminary report on new Ediacaran fossils from Iran. Alcheringa 42, 230–243. ISSN 0311–5518. Recent exploratory field mapping of marine sedimentary sequences in the Koushk Mine locality of the Bafq region in Central Iran, and on the northern slopes of the Elborz Mountains south of the Caspian Sea, has yielded large complex body and trace fossils of Neoproterozoic–early Cam- brian age. The recovered specimens resemble the previously documented Precambrian discoidal form Persimedusites, and a the tubular morphotype Corumbella, which is a novel occurrence for Iran and otherwise only recorded before from Brazil and the western USA. Additional enigmatic traces can not yet be interpreted unequivocally, but suggest that future work may uncover more unusual Ediacaran fossils from various localities in Central Iran. Patricia Vickers-Rich* [[email protected], [email protected]], Faculty of Science, Swinburne University of Technology, Melbourne (Haw- thorn), Victoria 3122, Australia; Sara Soleimani [[email protected]], Palaeontology Department, Geological Survey of Iran, Tehran, Iran; Farnoosh Farjandi [[email protected]], Department of Geochemical Exploration, Geological Survey of Iran, Tehran, Iran; Mehdi Zand [[email protected]], Geology Department, Bafq Mining Company, Koushk Mine, Yazd, Iran. Ulf Linnemann [ulf.linnemann@senck- enberg.de], and Mandy Hofmann [[email protected]], Senckenberg Naturhistorische Sammlungen, Dresden, Museum für Mineralo- gie und Geologie, Sektion Geochronologie, Koenigsbruecker Landstrasse 159, D-01109, Dresden, Germany; Siobhan A. Wilson [[email protected]], School of Earth, Atmosphere and Environment, Monash University, Melbourne (Clayton), Victoria 3800, Australia; Raymond Cas [[email protected]], School of Earth, Atmosphere and Environment, Monash University, Melbourne (Clayton), Victoria 3800, Australia; Thomas H. Rich† [[email protected]], Museum Victoria, Exhibition Gardens, PO Box 666, Melbourne, Victoria, 3001 Australia. *Also affiliated with: School of Earth, Atmosphere and Environment, Monash University, Melbourne (Clayton), Victoria 3800, Australia; School of Environmental Sciences, Deakin University, Melbourne (Burwood), Victoria, Australia 3125; Palaeontology Department, Museum Victoria, Carlton Gardens, PO Box 666, Melbourne, Victoria 3001, Australia. †Also affiliated with: School of Earth, Atmosphere and Environment, Monash Univer- sity, Melbourne (Clayton), Victoria 3800, Australia; Faculty of Science, Swinburne University of Science and Technology, Melbourne (Hawthorn), Victoria 3122, Australia. Received 7.12.2016; revised 19.6.2017; accepted 17.8.2017. Key words: Neoproterozoic, Yazd region, Koushk Mine, Corumbella, Persimedusites. THE FIRST RECORDS of Neoproterozoic metazoan longer considered to be metazoan traces, and Hamdi fossils from Iran were published by Stöcklin et al. et al. (1989) specifically questioned identification of the (1972), who noted that ‘the Infracambrian of North Iran ‘Rizu series’ finds. Nevertheless, Stöcklin (1968) noted has yielded stromatolites and other problematic fossils a lead isotope age of 760–595 ± 120 Ma (Huckriede (Stöcklin 1968). In the lower part of the sequence, a et al. 1962) for a synsedimentary cherty dolomite and distinct shale marker traceable from the Central Elborz acidic volcanic ore deposit in the ‘Rizu Series’, which to Azerbaijan contains abundant small disc-like features has subsequently yielded Ediacaran fossils (see below). which closely resemble Permoria sp. of the Precam- Hahn & Pflug (1980) named a novel Ediacaran brian–Cambrian Vindhyan “System” of India (Pascoe taxon from Iran, Persimedusites chahgazensis, which 1959, p. 498, Pl. w) or Beltanella gilesi Sprigg (?) of they assigned to Scyphozoa. This specimen came from the Upper Valdai series of the Russian platform, which the ‘late Precambrian’ Esfordi Formation outcrops at is just below the Lower Cambrian Baltic Series’. Chahgaz near Koushk in Central Iran. Hahn & Pflug Stöcklin (1968) continued: ‘Another interesting fauna— (1980) suggested that Persimedusites might be compa- containing forms closely resembling Dickinsonia, Sprig- rable with another medusoid, Eulithota found in the late gina and Medusites asteroides of the upper Precambrian Jurassic of Germany, but considered it distinct from the of Australia—recently was discovered by geologists of classical Australian Ediacaran medusoid Rugoconites, the Rio Tinto Company (pers. comm.) in the “Rizu which is ornamented by branching grooves. The Iranian Series” east of Yazd’. Since Stöcklin (1968) and Persimedusites has a counterpart with preserved ridges, Stöcklin et al.(1972), many of these occurrences are no but these do not have a branching pattern (unlike the counterpart of Rugoconites where the grooves are branching). Another key difference was the regularity of fl © 2017 Australasian Palaeontologists ridges in Persimedusites (Hahn & P ug, 1980). https://doi.org/10.1080/03115518.2017.1384061 Published online 26 Nov 2017 ALCHERINGA NEW EDIACARANS FROM IRAN 231 Fig. 1. Tectono-sedimentary regions of Iran after Aghanabati (2004). The red rectangle indicates the 2015 Iranian–Australian expedition area. Hamdi et al.(1989) documented phosphatic tubes of Mountains), as well as tube structures attributable to Hyolithellus, structures resembling Rugatotheca, frag- Hyolithellus, Cambrotubulus and protoconodonts typical ments of the protoconodont Protohertzina and poten- for the Tommotian (Hamdi et al. 1989). Hamdi et al. tially primitive ?monoplacophorans from the Lower (1989) further noted that the biostratigraphical and Dolomite Member of the Soltanieh Formation in north- lithological settings of the Soltanieh Formation are com- ern Iran. The Soltanieh Formation overlies the Kahar patible with those of Tommotian sequences in China, Formation, which is late Neoproterozoic in age based India, Pakistan and Kazakhstan, especially in the preva- on acritarchs (F. Farjandi unpublished data). The Middle lence of phosphorites. These are locally characterized Dolomite Member of the Soltanieh Formation has pro- by strong negative carbon isotope anomalies that reflect duced small shelly fossils (from Dalir in the Elboz the global Tommotian signal. 232 PATRICIA VICKERS-RICH et al. ALCHERINGA Fig. 2. Geological map of the Koushk locality area after Soheili & Mahdavi (1991). The yellow rectangle indicates the 2015 Iranian–Australian expedition area. Ediacaran fossils were recovered from grey to black shale units at the Wedge and Dargazin (Chahgaz) section localities. In late 2015, new discoveries of Ediacaran fossils subzone classification. Aghanabati (2004) alternatively (late Neoproterozoic) representing large complex organ- suggested that Central Iran and Sanandaj-Sirjan consti- isms were made by a joint Iranian–Australian expedi- tuted a larger central domain. Rajabi et al.(2012) recog- tion team working in the Bafq Region of Central Iran. nized that the Zarigan-Chahmir Basin ‘located in the These are described in this paper, together with detailed Posht-e-Badam Block of the Central Iranian Microconti- tectonic, geological, mineralogical and geochronological nent’, hosted zinc–lead sequences consisting of ‘carbona- analysis of the host deposits. Our intention is to provide ceous, fine-grained black siltstone with interlayered a framework for future exploration for Ediacaran fossils rhyolitic tuffs’. The upper part of this volcanolithic suc- in the Iranian region, which is currently being under- cession was of early Cambrian age, and deposited in a taken by different international groups (Vickers-Rich back-arc rift along the microcontinental edge (Rajabi et al. 2016, Vaziri & Laflamme 2016). et al. 2012). Rajabi et al.(2012) additionally stated that the Posht-e-Badam Block ‘developed along the Proto- Tethyan margin of the Gondwanan supercontinent’ and Tectonic setting was created by late Neoproterozoic–early Cambrian The tectonic history of Iran has been influenced by breakup of the Central Iranian Microcontinent, in con- development of the Tethyan region (Fig. 1), especially junction with back-arc rifting linked to emergence of the Gondwanan
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