A Preliminary Report on New Ediacaran Fossils from Iran

Alcheringa: An Australasian Journal of Palaeontology

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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

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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@senckenberg.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 rifting and collision of the Iranian and Ara- Proto-Tethys. Jafari et al. (2007) reported a similar depo- bian plates from the west-southwest; this in turn affected sitional histories from the Elborz Mountains of northern the African, Indian and Eurasian plates during Mesozoic Iran where the Soltanieh Formation (comprising the to Tertiary times (Alavi 2004). Central Iran is a particu- Koushk Series and overlying Heshem Shales) recorded larly complicated structural zone, and incorporates regressive marine dolostones and shales of Neoprotero- sedimentary rocks of Neoproterozoic to Quaternary age, zoic through to Cambrian age. Jafari et al. (2007) pointed which have been modified by orogenies, metamorphism out that the presence of Chuaria and Vendotaenia in the and magmatic episodes that obscure their regional Soltanieh Formation provided clear correlation with Neo- boundaries. Stöcklin (1968)defined Central Iran as bor- proterozoic strata in Newfoundland, Arizona, China and dered by the Elborz Mountains to the north, the Lut Africa. Up-sequence units of the Barut, Lalun and Mila Block in the east, and Sanandaj-Sirjan in the south-south- formations of Central Iran also have equivalents in the west. Nabavi (1976) also considered the northern part of Dezu, Dahu and Kalshaneh formations in the Elborz the Lut Block to be included within Central Iran. Mountains. This reflect successive regressive sequences Nogol-E-sadat et al. (1993) subsequently extended the and a transition from marine to deltaic sediments during northeastern margin of this region and presented new middle Cambrian to early Ordovician (Jafari et al. 2007). ALCHERINGA NEW EDIACARANS FROM IRAN 233

Fig. 3. Geological map of the Chahmir locality area after Soheili & Mahdavi (1991). The green rectangle indicates the 2015 Iranian–Australian expedition area.

Fig. 4. Dargazin locality of the 2015 Iranian–Australian expedition. A, Stratigraphy; B, Fossiliferous outcrop.

Geological setting and age documented by Rajabi et al. (2012), and have been The 2015 Iranian–Australian ﬁeld program focused on known to produce well-preserved late Neoproterozic and sedimentary rock outcrops east of Bafq. These are within early Cambrian fossils. Localities associated with the the Koushk Mine (Fig. 2) and Chahmir (Fig. 3) areas Koushk Mine, here referred to as the Wedge and 234 PATRICIA VICKERS-RICH et al. ALCHERINGA

Fig. 5. Dargazin locality Ediacaran fossils recovered by the 2015 Iranian–Australian expedition. A, B, Possible holdfast structure. B–E, H, Per- simedusites. F, Corumbella. G, Namalia-like form.

Dargazin sections, lie on the Esfordi 1:100 000 map Jafarzadeh 1994). The Tashk Formation is a 2000 m (Soheili & Mahdavi 1991). Chahmir is on the Behabad thick weakly metamorphosed to stratiﬁed sedimentary 1:100 000 map (Mahdavi 1996). Bafq is in the central and volcanic/volcaniclastic sequence. The overlying part of the Kashmar-Kerman structural zone (Ramezani 1500−2000 m of the LCVSS consists of unaltered & Tucker 2003), otherwise termed the Posht-e-Badam interbedded intermediate to felsic volcanic and sedimen- Block (Alavi 1991, Rajabi et al. 2012), and records sec- tary micro-conglomerates, sandstones, volcaniclastics, tions within the Zarigan-Chahmir Basin. These are char- pyritic black siltstones, shales, dolomitic limestones, and acterized by thick, ﬁne-grained siliciclastic sediments dolomites (Haghipour 1974, Rajabi 2008). These rocks and volcanics from the lower Cambrian volcano- have traditionally been considered ‘Precambrian’ (Huck- sedimentary sequence (LCVSS), and are equivalent to riede et al. 1962), although, recent geochronology has the ‘Rizu Series’ or Esfordi Formation in the central part dated the local volcanic to the early Cambrian (528.2 ± of the Zarigan-Chahmir lithotectonic domain (Rajabi 0.8 Ma: Ramezani & Tucker 2003, Rajabi et al. 2012). et al. 2012). ‘Precambrian’ strata of the Tashk Formation The LCVSS is unconformably overlain by early Cam- (Koushk Series) in the Zarigan-Chahmir Basin discon- brian red sandstones and conglomerates of the Lalun and formably overlie late Neoproterozoic metamorphic rocks Dahu formations in Zarigan and Chahmir, as well as of the Boneh-Shurow Basement Complex (Förster & Bafq to the west. ALCHERINGA NEW EDIACARANS FROM IRAN 235

Fig. 6. Wedge locality of the 2015 Iranian–Australian expedition. A, Stratigraphy; B, Fossiliferous outcrop with C, enlargement of surface material.

Stratigraphy and sedimentology granitic, given their association with quartz exhibiting undulose extinction (?plutonic) and minor muscovite Lithologically, the Koushk field sites are dominated by inclusions. rhyodacites, rhyolites, dolomites, green tuffs, dark The fossil-bearing beds at Chahmir (Fig. 10) include shales and acidic volcanic rocks of the Tashk Formation a ferruginous quartzose mudstone with angular quartz (Koushk Series). At Dargazin they are about 31 m thick grains in an iron oxide rich altered clay matrix (Fig. 8). with fossiliferous light grey shales, altered grey-green to The iron oxide overprint makes it impossible to yellow shales, and black-grey shales. Some massive sul- determine provenance, although some larger, probably fide mineralization also contains pyritic intercalations non-volcanogenic quartz grains show undulose extinc- and green to brown tuffs. These beds are collectively tion and vacuoles that suggest plutonic or vein sources. overlain by dolstones (Fig. 4). Trace fossils were found A slight lamination fabric appears to be an epiclastic, in the thin-bedded shales, and are preserved as flattened fine-grained mudstone that lacks relic glass shards and impressions, often with a black mineralized coating, or is thus not tuffaceous. three-dimensional tubes with a yellow-orange outer Another fossiliferous unit at Chahmir comprises coating (Fig. 5). black, finely laminated and possibly carbonaceous The Wedge section comprises 140 m of blackish- quartz mudstone. Petrographic/provenance features are grey shales, fossil-bearing light grey shales and consistent with other deposits, but there are no lamina- sandstones interbedded with tuff and dolomitic tuffs tions or definitive bedding horizons (Rajabi et al. 2008). overlain by dolomites (Fig. 6). Enigmatic tubular and Both Persimedusites and tubular Corumbella-like struc- discoidal macrofossils are preserved as flattened (with tures were recovered in epirelief and hyporelief (Fig. 11). black mineralized encrustations) and three-dimensional specimens (Figs 7, 8). Coarse siltstones host Persime- dusites-like impressions. The Wedge sample 3 (Fig. 9) Mineralogy also contains a small (2–3%) angular, fresh twinned pla- gioclase indicative of rapid transport and deposition in We collected six samples of mineralized encrustations an arid climate. The source of these grains was likely coating the fossils, together with matrix from both the 236 PATRICIA VICKERS-RICH et al. ALCHERINGA

Fig. 7. Wedge locality Ediacaran fossils recovered by the 2015 Iranian–Australian expedition. A, Namalia-like form. B, D,?Persimedusites. C, E, F, Corumbella. G, Algae-like branching structure. H, Possible trace fossils.

Wedge and Dargazin localities. Processing included gypsum and an alunite mineral (likely natroalunite) were hand-grinding in an agate mortar and pestle, then adher- also detected, and probably derived from weathering of ence to a zero background quartz plate using a small Na- and K-rich albite and muscovite during oxidation of drop of anhydrous ethanol. Powder X-ray diffraction sedimentary Fe-sulﬁde minerals, such as pyrite. The (XRD) patterns were collected using a Bruker D8 white-coloured mineral coating was composed of Advance Eco X-ray diffractometer in the Monash X-ray natroalunite with minor amounts of jarosite minerals Platform in Melbourne. A Cu source was operated at (potassium natrojarosite and perhaps hydroniumjarosite), 40 kV and 25 Ma over an angular range from 3 to 70° gypsum and kaolinite (a weathering product of albite and 2θ, with a step size of 0.01° 2θ and counting time of muscovite). It also contained quartz, albite and muscovite 2.8 s/step. Mineral identiﬁcation was undertaken from originating from the host rock. The grey-coloured min- the ICDD PDF-2 database using the DIFFRACplus EVA eral encrustations were similar in composition to the v.2 package (Bruker AXS). matrix, but were not crystalline, and thus be amorphous The Wedge section host rock was found to be domi- inorganic phase or organic matter. nated by quartz, with minor albite and muscovite consis- The Dargazin and Wedge section rocks are compara- tent with the petrological observations from thin-sections ble in composition, but the Daragzin sample contains (Supplementary Online Table S1). Trace abundances of minor amounts of natrojarosite and hydronium jarosite ALCHERINGA NEW EDIACARANS FROM IRAN 237

Fig. 8. Wedge locality biogenic traces recovered by the 2015 Iranian–Australian expedition. A, Hollow? trace structure with B, associated clay casts.

Fig. 9. Matrix thin-sections recovered by the 2015 Iranian–Australian expedition. A, B, Wedge locality; C, D, Chahmir locality. Scale bars equate between A, B and C, D. without detectable natroalunite. The yellow-coloured reducing sedimentary conditions. The sulfate minerals mineral crusts comprise natrojarosite and hydronium- are oxidative weathering products of Fe-sulfide miner- jarosite (Fig. 12). No residual sulfides or Fe-oxyhydrox- als, albite and muscovite, and likely originated from ide were found in the XRD patterns. However, the sulfur-reducing bacteria during early diagenesis. Interac- presence of alunite, jarosites, gypsum and kaolinite evi- tion with oxidized ground water or later exhumation dences oxidative weathering of Fe-sulfides in the pres- would have induced oxidative weathering of the ence of detrital minerals of probable granitic origin. original pyrite to form the secondary alunite–jarosite– This suggests that the deposition occurred under gypsum–kaolinite assemblage. 238 PATRICIA VICKERS-RICH et al. ALCHERINGA

Fig. 10. Chahmir locality of the 2015 Iranian–Australian expedition. A, Stratigraphy; B, Fossiliferous outcrop with C, enlargement of surface outcrop.

Geochronology 204Pb signal, together with a model Pb composition Zircon concentrates were separated from ca 1–2kg (Stacey & Kramers 1975), was also carried out if samples using standard methods. Final selection of the necessary. zircon grains for U–Pb dating was achieved by hand- Raw data were corrected for background signal, picking under a binocular microscope. Zircons of all common Pb, laser induced elemental fractionation, grainsizes and morphological types were selected, instrumental mass discrimination, and time-dependant mounted in resin blocks and polished to half their thick- elemental fractionation of Pb/Th and Pb/U using a cus- ness. The stratigraphic time-scale of Gradstein et al. tom Excel spreadsheet program developed by Axel (2012) was used to constrain stratigraphical ages. Gerdes (Johann Wolfgang Goethe-University Frankfurt, Zircons were analysed at the GeoPlasma Lab, Frankfurt am Main, Germany). Reported uncertainties Senckenberg Naturhistorische Sammlungen Dresden. were propagated by quadratic addition of the external LA-SF (Sector Field) ICP-MS techniques were used to reproducibility obtained from the standard zircon GJ-1 examine U, Th, and Pb isotopes on a Thermo-Scientific (ca 0.6% and 0.5–1% for the 207Pb/206Pb and Element 2 XR sector field ICP-MS coupled to a RESO- 206Pb/238U, respectively) during individual analytical LUTION Excimer Laser System from ESI (wave- sessions, and the within-run precision of each analysis. length = 193 nm). This instrument was equipped with a Concordia diagrams (2σ error ellipses) and Concordia LAURIN S-155 ablation cell with a space capacity for ages (95% confidence level) were produced using Iso- 20 mounts. Each analysis consisted of 15 s background plot/Ex 2.49 (Ludwig 2001) and frequency and relative acquisition, followed by 25 s data acquisition using a probability plots using AgeDisplay (Sircombe 2004). laser spot-size of 25 and 35 μm respectively. During The 207Pb/206Pb age was taken for interpretation for all measurement the fluence was set in a range of 4–4.5 J/ zircons > 1.0 Ga (see Gerdes & Zeh 2006 for analytical cm2 with a 6 Hz repletion rate. A common Pb correc- protocols and data processing). Zircons showing a tion based on the interference and background-corrected degree of concordance in the range of 90–101% were ALCHERINGA NEW EDIACARANS FROM IRAN 239

Fig. 11. Chahmir locality Ediacaran fossils recovered by the 2015 Iranian–Australian expedition. A, D, G, Corumbella. B, Part, and C, counterpart showing algae-like branching structures. E,?Persimedusites. F, indeterminate biogenic structure. classiﬁed as concordant because of error ellipse overlap ages fell in the range of 1012 ± 26 Ma and 1249 with the Concordia. Th/U ratios were obtained from the ± 32 Ma. Palaeoproterozoic zircon grains ranged from LA-ICP-MS measurements of investigated zircon 1788 ± 42 Ma to 2496 ± 42 Ma. Archaean zircons were grains. U and Pb content and Th/U ratio were found to range from 2515 ± 27 Ma to 3321 ± 14 Ma. calculated relative to the GJ-1 zircon standard, and are The complete zircon pattern therefore suggests a typical accurate to approximately 10%. Analytical results of eastern Gondwanan provenance, with the ﬁnal sedimen- U–Th–Pb isotopes and calculated U–Pb ages are tation time frame younger than 581 ± 8.6 Ma. This presented in the Supplementary Tables S2 and S3. result places the Iranian Ediacaran-type macrofossils as Zircon ages from the Wedge section locality ranged the oldest yet on record (Pu et al. 2016). from 577 ± 16 Ma to 3321 ± 14 Ma (Fig. 13). Of the Zircon ages from the Chahmir locality ranged from 117 analysed grains, 68 zircons were concordant in a 537 ± 11 Ma to 2344 ± 31 Ma. Only 20 of 60 analysed range of 90 to 101%. A maximum age of sedimentation zircon grains went concordant in a range of 90–101%. is given by a Concordia age of 581 ± 8.6 Ma calculated The majority of all zircon grains fell within an Edi- from the three youngest zircons (n = 3). Most zircon acaran time frame (Fig. 14), although a few grains ages were Neoproterozoic with pronounced peaks at ca could be of earliest Cambrian age but with error overlap 600 Ma, 750 Ma and 950 Ma. Mesoproterozoic zircon across the Ediacaran–Cambrian boundary (537 ± 11 Ma, 240 PATRICIA VICKERS-RICH et al. ALCHERINGA

Fig. 12. Powder X-ray diffraction pattern for yellow precipitate from Dargazin locality samples.

540 ± 13 Ma). Some late Ediacaran zircons also over- lapped the Ediacaran–Cambrian boundary, and provide early Cambrian ages (541 ± 11 Ma to 547 ± 12 Ma). A number of older zircons reﬂect Cryogenian (n = 1) and Tonian (n = 2) ages. Three zircons are Palaeoprotero- zoic in age. Mesoproterozoic and Archaean zircon grains did not occur in these samples. The Concordia age of the youngest zircons (540.7 ± 4.8 Ma) reﬂects a maximum age of sedimentation at younger than 540.7 ± 4.8 Ma, but with an error range that would not pre- clude an Ediacaran age. No samples from the Dargazin section localities were dated.

Identification of recently collected Iranian Ediacaran fossils The 2015 Iranian–Australian expedition detected Edi- acaran fossil morphotypes resembling the described taxa Corumbella, Persimedusites and Namalia. Other trace fossils were also collected, but their identification is uncertain. The Corumbella-like tubular fossils have parallel sides with their length greater than width. They are abundant in the Koushk Mine localities, and have been recovered elsewhere in Ediacaran sequences from the Mato Grosso of Brazil (Babcock et al. 2005, Pacheco et al. 2012, 2015; Supplementary Fig. S1) and western USA (Hagadorn & Waggoner 2000). None of the Ira- Fig. 13. U–Pb ages of detrital zircon grains from the Wedge locality nian specimens are complete, and they have probably Pat 2 sample site (analytic sample 847). A, Combined binned fre- undergone transportation prior to burial. Corumbella is quency and probability density distribution plot of zircon grains in the common in the late Ediacaran, and perhaps early range of 500–1000 Ma. B, Concordia diagram of the youngest zircon Cambrian (Schiffbauer et al. 2016). Other tubular population showing age at 581.0 ± 8.6 Ma. Ediacaran taxa include Conotubus (Cai et al., 2011), Cambrotubulus, Platysolenites, Cloudina, Sinotubulites, et al., 2016, Meyer et al. 2012, Tarhan et al. 2014). and Corumbella (Pacheco et al. 2012,), Wenghuiia Conularids (Ivantsov & Fedonkin 2003, Leme et al. (Wang & Wang, 2008), Palaeoscolex and Maotiansha- 2008) also exhibit annulated morphologies but are more nia (Xian-Guang et al., 2004), Shaanxilithes (Darroch triangular in profile. ALCHERINGA NEW EDIACARANS FROM IRAN 241

Mountains of northwestern Canada (Narbonne et al. 2014). Namalia has also been reported from Namibia (Germs 1968), but re-interpreted as Ernietta (Fedonkin et al., 2007). Peculiar frond-like traces, together with other discoidal structures and trace fossils, were also recovered from the Dargazin section, and Chamir localities, but these might be inorganic and concretionary. Branching structures from the Wedge section and Chahmir localities appear to be algal in origin. Finally, shallow bur- rows associated with ripple marks (Supplementary Fig. S2) were collected from the Elborz Mountains ﬁeld sites of Hamdi et al. (1989).

Conclusions Results from the 2015 Iranian–Australian exploratory field survey (Vickers-Rich et al. 2016) highlight the need for more detailed prospecting and documentation of Ediacaran fossils and localities in Iran. Examples of Corumbella, Persimedusites and Namalia-like forms, as well as algal traces and other biogenic structures are likely Neoproterozoic–early Cambrian in age. Notably, one area near Bafq yielded Cretaceous corals in sediments previously mapped as ‘Precambrian’, which are currently under study (Brian Rosen [The Natural His- tory Museum] pers. comm. 2016). The Iranian Corum- bella material is the first record of this taxon outside the Americas and indicates that more intense prospect- Fig. 14. U–Pb ages of detrital zircon grains from Chahmir locality Pat 1 sample site (analytic sample 858). A, Combined binned frequency ing, especially in previously sampled localities in cen- and probability density distribution plot of zircon grains in the range tral and northwestern Iran, holds excellent prospects for of 500–1000 Ma. B, Concordia diagram of the youngest zircon popu- significant future discoveries. lation showing age at 540.7 ± 4.8 Ma. Acknowledgements The Iranian Persimedusites are disc-shaped with Many thanks to the field team (Gh. Abdi, M. Pahlavani, symmetrical internal lobes and secondary distal M. Mohseni, A. Rezaei) and the people of Dalir and branches (Hahn & Pflug 1980). Arrouy et al.(2016) the Koushk Mine for their hospitality and accommoda- reported Persimedusites-like fossils from the late Neo- tion. Valiollah Ranjbar (Head of Industry and Trade, proterozoic Cerro Negro Formation in Argentina, and Bafq) and the Iranian Embassy (Canberra) provided suggested affinity with Aspidella. However, the Iranian administrative assistance. Field equipment, logistics and Persimedusites lack holdfasts (Gehling et al. 2000, site access were facilitated by the Geological Survey or Tarhan et al. 2015, Kruse & Jago 2016), and have Iran. PrimeSCI! (Monash University) and Swinburne radial branches extending from their centre. Other University of Technology (Melbourne) supported PV-R. disc-shaped late Ediacaran taxa, such as Praecambrid- Robert Smith and Mary Gilroy (Federation University, ium, Wigwamiella, Palaeophragmodictya (Gehling & Ballarat) prepared the thin-sections. Steve Morton Rigby, 1996, see also Fedonkin et al. 2007), early (Monash University) provided superb photography. Cambrian archaeocyathids, and early Palaeozoic Doris Seegets-Villiers (University of Melbourne) proof- tetracorals (e.g., Brooksella, Combophyllum, Tabularia: read and formatted the manuscript; Draga Gelt (Monash Sokolov 1971) lack this repetitive structure. University) and Sally Rogers-Davidson (Museum Victo- Rugoconites enigmaticus (Coutts et al., 2016) does, ria) assisted with figures. Helen Brand (Australian Syn- however, manifest centrally originating branches that chrotron Facility) advised on mineralogy. Soren Jensen broaden towards the periphery and could represent a and Jim Gehling (South Australian Museum) provided comparable taphomorph. comments and access to collections in the South Fragmentary Namalia-like fossils (see Narbonne Australian Museum for comparison. Alex Liu and a et al. 2014) were collected from the Wedge and Darga- second reviewer, as well as Alcheringa Chief Editor zin section localities. These are flat with distinct ribbed Benjamin Kear significantly improved the manuscript. patterning. Namalia is known from the Mackenzie The International Geosciences Program of UNESCO 242 PATRICIA VICKERS-RICH et al. ALCHERINGA and the Australian IGCP Committee contributed GERDES,A.&ZEH, A., 2006. Combined U–Pb and Hf isotope LA- finances for IGCP Project 597, of which this expedition (MC-) ICP-MS analyses of detrital zircons: Comparison with SHRIMP and new constraints for the provenance and age of an to Iran was a part. We thank the Australian IGCP Com- Armorican metasediment in Central Germany. Earth and Plane- mittee for their funding support as well as the UNESCO tary Science Letters 249,47–61. IGCP Board for project IGCP587. GERMS, G.J.B., 1968. Discovery of a new fossil in the Nama System, South West Africa. Nature 219,53–54. GRADSTEIN, F.M., OGG, J.G., SCHMITZ, M.D., OGG, G., eds, 2012. The Disclosure statement geologic time scale 2012. Elsevier 1 & 2, 1144. fl HAGADORN, J.W. & WAGGONER, B., 2000. Ediacaran fossils from the No potential con ict of interest was reported by the authors. southwestern Great Basin, United States. Journal of Paleontology 74, 349–359. doi:10.1666/0022-3360(2000) 074<0349: EFFTSG>2.0CO;2. Funding HAGHIPOUR, A., 1974. Etude géologique de la région de BiabanakBafq (Iran Central), pétrologie et tectonique du socle Précambrien et This work was supported by Patricia Vickers-Rich personal funds; de sa couverture. Université Scientifique et Médicale de Greno- Geological Survey of Iran. ble, Grenoble, 403 pp. (unpublished thesis). HAHN,G.&PFLUG, H., 1980. Ein neuer Medusen-Fund aus dem Jung-Prakämbrium von Zentral-Iran. Senckenbergiana Lethaea Supplemental data 60, 449–461. HAMDI, B., BRASIER, M.D. & ZHIWEN, J., 1989. Earliest skeletal fossils Supplemental data for this article can be accessed here. https://doi.org/ from Precambrian-Cambrian boundary strata, Elburz Mountains, 10.1080/03115518.2017.1384061 Iran. Geological Magazine 126, 283–289. HUCKRIEDE, R., KURSTEN,M.&VENZLAFF, H., 1962. Zur Geologie des ORCID Gebietes zwischen Kerman und Saghand (Iran). Beihefte zum Geologischen Jahrbuch 51, 197 pp. Patricia Vickers-Rich http://orcid.org/0000-0003-1850-8067 IVANTSOV, A.Y.U, & FEDONKIN, M.A., 2003. 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