Terminal Cambrian and Early Ordovician (Tremadocian) Conodonts from Eastern Alborz, North-Central Iran

Alcheringa: An Australasian Journal of Palaeontology

ISSN: 0311-5518 (Print) 1752-0754 (Online) Journal homepage: http://www.tandfonline.com/loi/talc20

Terminal Cambrian and Early Ordovician (Tremadocian) conodonts from Eastern Alborz, north-central Iran

Hadi Jahangir, Mansoureh Ghobadi Pour, Alireza Ashuri & Arash Amini

To cite this article: Hadi Jahangir, Mansoureh Ghobadi Pour, Alireza Ashuri & Arash Amini (2015): Terminal Cambrian and Early Ordovician (Tremadocian) conodonts from Eastern Alborz, north-central Iran, Alcheringa: An Australasian Journal of Palaeontology, DOI: 10.1080/03115518.2016.1118298

To link to this article: http://dx.doi.org/10.1080/03115518.2016.1118298

Published online: 14 Dec 2015.

Submit your article to this journal

Article views: 2

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

Download by: [Gazi University] Date: 17 December 2015, At: 08:12 Terminal Cambrian and Early Ordovician (Tremadocian) conodonts from Eastern Alborz, north-central Iran

HADI JAHANGIR, MANSOUREH GHOBADI POUR*, ALIREZA ASHURI and ARASH AMINI

HADI JAHANGIR,MANSOUREH GHOBADI POUR,ALIREZA ASHURI &ARASH AMINI, XX.XX.2015. Terminal Cambrian and Early Ordovician (Tremadocian) conodonts from Eastern Alborz, north-central Iran. Alcheringa ##, ###-###. ISSN 0311-5518.

Uppermost Cambrian (Furongian) and Lower Ordovician (Tremadocian) deposits of eastern Alborz in northern Iran contain several successive low- to moderate-diversity conodont associations including 13 genera and 19 species of euconodonts, paraconodonts and protoconodonts, which define six biozones: 1, the Proconodontus muelleri;2,Eoconodontus notchpeakensis;3,Cordylodus andresi;4,Cordylodus proavus;5,Paltodus deltifer; and 6, Paroistodus proteus zones. With the exception of Cordylodus andresi, which is otherwise known from Baltoscandia and from the Oaxaquia terrane (Mexico), all index-taxa are geographically widespread, allowing long-range correlation within the Cold Domain or the North Atlantic Province, and in particular with Baltica. Invasion of euconodonts in the Alborz region, defined by the first occurrence of Proconodontus muelleri, coincides closely with a steady rise in sea level and termination of carbonate sedimentation, whereas the transition from the Proconodontus muelleri to Eoconodontus notchpeakensis zones occurs during a highstand interval unlike in Laurentian sequences. The interval corresponding to the Cordylodus andresi and Cordylodus proavus zones, and the transition from the Paltodus deltifer to Paroistodus proteus zones coincided with unstable sea levels and the formation of shoal complexes. The lower boundary of the Floian Stage can be provisionally placed slightly below the first documented occurrence of Acodus sp. cf. A. kechikaensis, somewhat below the second unit of andesitic lava flows in the Simeh-Kuh section.

Hadi Jahangir [[email protected]] and Alireza Ashuri [[email protected]] Department of Geology, Faculty of Sciences, Ferdowsi University, Azadi Square, Mashhad 91775-1436, Iran; Mansoureh Ghobadi Pour* [[email protected]; [email protected]] and Arash Amini [[email protected]], Department of Geology, Faculty of Sciences, Golestan University, Gorgan 49138-15739, Iran. *Also affiliated with Department of Geology, National Museum of Wales, Cathays Park, Cardiff CF10 3NP, UK. Received 13.7.2015; revised 18.10.2015; accepted 6.11.2015.

Key words: Terminal Cambrian, Ordovician, Tremadocian, conodonts, Alborz, Iran.

CAMBRIAN (Furongian) conodonts have been known elements from the Deh-Molla section (Tables 1–3). from the Alborz region of northern Iran for more than However, the assemblages are diverse taxonomically 40 years; however, they have not been the focus of and include 13 genera and 20 species (Fig. 2). research since the pioneering publication by Müller The conodont fauna of the Simeh-Kuh section, (1973). Hence, the application of conodonts to the which represents the most complete Furongian to Lower lower Palaeozoic biostratigraphy of the region has been Ordovician sedimentary succession in the Alborz Downloaded by [Gazi University] at 08:12 17 December 2015 limited. Apart from a few preliminary reports on their region, was chosen as the major target of our study. presence in Lower to Middle Ordovician successions of The Furongian succession in Deh-Molla is important the eastern Alborz Mountains (Ghobadi Pour 2006, because, in addition to the Proconodontus muelleri, Ghobadi Pour et al. 2011a, b), Ordovician conodonts Eoconodontus notchpeakensis and Cordylodus andresi were practically unknown from the region. Only zones, it also preserves the Cordylodus proavus Zone recently has more comprehensive information on the (Fig. 2). Furongian conodont distributional data from late Tremadocian conodonts from the Deh-Molla section the Mila-Kuh section derive mainly from the paper by been published (Jahangir et al. 2014). This study aims Müller (1973). Our important supplementary informa- to analyse the taxonomic composition and stratigraphic tion supports the proposed conodont zonation for the distribution of terminal Cambrian (Furongian) and Early Furongian to Lower Ordovician (Tremadocian) succes- Ordovician (Tremadocian) conodont assemblages from sion of the Alborz region. the Simeh-Kuh, Mila-Kuh and Deh-Molla sections in Traditionally, the middle Cambrian to Ordovician the eastern Alborz Mountains, Semnan Province, Iran succession in the Alborz Mountains has been subdi- (Fig. 1). The conodont yield from the studied succes- vided into the middle to upper Cambrian Mila Forma- sions is fairly low; only 334 conodont elements were tion with the type section at Mila-Kuh introduced by recovered from the Simeh-Kuh section and 109 Stöcklin et al.(1964), and the Ordovician Lashkarak Formation with its type section in Alam-Kuh introduced by Gansser & Huber (1962); however, the relationships © 2015 Association of Australasian Palaeontologists http://dx.doi.org/10.1080/03115518.2016.1118298 between these two lithostratigraphic units have 2 HADI JAHANGIR et al. ALCHERINGA

Fig. 1. Geographic setting of the uppermost Cambrian to Lower Ordovician (Tremadocian) conodont-bearing localities in the Alborz Mountains of Iran.

remained unresolved, and the position of the Cambrian– Material and methods fi Ordovician boundary has not been de ned. As recently The studied samples were dissolved in dilute (10–15%), demonstrated by Ghobadi Pour et al.(2011c), the buffered acetic acid and after treatment, the residue was fi Lashkarak Formation, as originally de ned by Gansser handpicked without using heavy liquid separation. & Huber (1962), can be applied to the Middle and Almost all the identified taxa are figured; the specimens Upper Ordovician deposits of the Alborz Mountains. Its were photographed using a LEO 1450VP scanning elec- lower boundary coincides with the regional disconfor- tron microscope (SEM) at the University of Mashhad. mity at the base of the Darriwilian, which is traceable However, for some euconodonts, the outline of the Downloaded by [Gazi University] at 08:12 17 December 2015 across the Alborz region. basal cavity is diagnostic and thus can not be seen or The validity of the Mila Formation was questioned shown on figures from a SEM. For such specimens, by Geyer et al.(2014), because it is homonymous with photographs using transmitted light were taken using a ‘ ’ the Mila Formation introduced one year earlier by Canon EOS60D digital camera mounted on an Olympus Assereto (1963). The latter unit, as originally desig- binocular microscope. nated, also includes Devonian deposits. Instead, Geyer Thirty-seven limestone samples, each about 1.5 kg, et al.(2014) proposed to assign the Furongian part of were collected from the Simeh-Kuh and Deh-Molla sec- the Cambrian succession in the Alborz Mountains to tions. With a few exceptions, the source rocks are fi the newly de ned Deh-Molla Formation with its type mainly tempestites, or in some cases, shell beds in a section at Shahmirzad. However, the position of the siliciclastic succession. The conodont specimens are upper boundary of this lithostratigraphic unit is also usually complete or only slightly fragmented, but they uncertain and, according to our observations, the strati- are very delicate and fragile; thus many were recovered graphic interval corresponding to Mila Formation mem- broken during the course of preparation. The specimens ber 5 in the Mila-Kuh section is absent at Shahmirzad. are glossy black, dark-brown to light-brown, but Therefore, pending a general revision of the early translucent, when observed in transmitted light. Figured Palaeozoic lithostratigraphy of the Alborz region, we specimens are housed in the Azad University, avoid assignment of the Cambrian (Furongian) and Khorosgan Branch, Esfahan, Iran, under accession Lower Ordovician succession exposed at Simeh-Kuh to numbers AEU/L 5000–5099. any existing formal lithostratigraphic unit. ALCHERINGA CAMBRIAN–ORDOVICIAN CONODONTS FROM IRAN 3

Fig. 2. Stratigraphic columns of the Cambrian–Ordovician boundary beds at Mila-Kuh, Simeh-Kuh and Deh-Molla showing the levels of fossil assemblages and stratigraphic ranges of selected conodont, trilobite and brachiopod species.

Simeh-Kuh section (2006) and revised herein (Fig. 2). It rests on a thick The Simeh-Kuh section is located in the eastern Alborz unit of light-grey bioclastic limestones including bra- Range, northeastern Iran, about 13 km northwest of the chiopod shell beds consisting mainly of disarticulated city of Damghan with its base at 36°12′42.9″N, 54°13′ billingsellid shells and echinoderm limestones, which 36.1″E, and 1382 m above sea level (Fig. 1). According represent the stratigraphic equivalent of member 3 of to the published 1:100 000 scale geological map (Alavi the Mila Formation. A moderately diverse micromor- & Salehi-Rad 1975), the sedimentary rocks exposed in phic linguliform brachiopod assemblage including Dactylotreta lamellosa Popov et al. 2009c, Dictyonina?

Downloaded by [Gazi University] at 08:12 17 December 2015 the Simeh-Kuh area were dated as Devonian. Aghaba- balu (1999) was the first to recognize the presence of sp. Dictyonina sp. cf. D. perforata Palmer, 1954, Otten- Ordovician strata at Simeh-Kuh while collecting bra- byella hyrcanica Popov et al., 2009c, Sadracarta deli- chiopods from the Lower Carboniferous Mobarak catus (Holmer et al., 2001), Siphonobolus sp. and Formation exposed nearby. The existence of the almost Tapuritreta angusta Popov et al., 2009c was docu- continuous middle Cambrian to Middle Ordovician sed- mented by Popov et al. (2009c) from the uppermost 10 imentary succession in the area was first documented m of the limestone unit, but no conodont occurrences by Ghobadi Pour (2006), who also introduced a bios- have yet been documented. tratigraphic subdivision of the Tremadocian part of the succession based on trilobites. Subsequent studies Cambrian, Furongian (Ghobadi Pour et al. 2006, 2007, 2011c, 2015, Popov et al. 2008, 2009a, b, c) revealed rich late Cambrian to Unit L1. This unit consists of laminated dark-grey argil- mid-Ordovician trilobite, and linguliform and rhyn- lites and silty argillites with numerous beds (0.05–0.15 chonelliform brachiopod faunas in the area. Those stud- m thick) of fine-grained sandstones with hummocky ies also provided good accounts of the geology and cross-bedding and several beds of bioclastic limestone stratigraphy of the Simeh-Kuh area. (0.05–0.30 m thick) representing distal tempestites; in The sampled part of the Simeh-Kuh section total 24.25 m thick. The proportion of fine-grained corresponds to the informal units L1 to L11 of the sandstones to argillites increases to 25% within the original description of the succession of the Cambrian– interval from 13.16 m to 20.70 m above the base of the Ordovician boundary beds given by Ghobadi Pour unit. The uppermost part of the unit (20.70–23.85 m) 4 HADI JAHANGIR et al. ALCHERINGA

comprises mainly brownish-grey fine-grained and silty

sandstones with hummocky cross-bedding, which con- 5 tain numerous trilobite fragments. Conodonts were recovered from the limestone beds at 2.60–2.90 m (sample SK4/1), 4.60–4.65 m (sample SK4/2), 7.93– 8.10 m (sample SK4/4), 10.2–10.10 m (sample SK4/6) and 11.35 m (sample SK4/7) above the base of the unit (Fig. 2; Table 1). The trilobite Mictosaukia sp. has been identified from samples SK4/8 (at 17.60–18.24 m above the base of the unit) and SK4/10 (at 22.74–23.55 m above the base of the unit). Unit L2A. This unit consists of two grey to brownish- grey bioclastic limestone beds (the lower one is up to 0.60 m thick, and the upper one is up to 0.07 m thick) separated by intercalated siltstones and fine-grained sand- stones about 2.40 m thick. The total thickness of the unit

is 3.37 m. Sample SK4/12, taken 0.55–0.60 m from the 13 base of the unit, contains the conodonts Cordylodus andresi Viira & Sergeeva in Kaljo et al., 1986, Eoconodontus notchpeakensis, Phakelodus elengatus, Proconodontus muelleri, Prooneotodus gallatini and 2 Westergaardodina sp. cf. W. bicuspidata. Unit L2B. This unit incorporates 1.40 m of coarse- to medium-grained quartzose sandstones, overlain by a 0.90 m-thick bed of pebbly conglomerate, which is suc- ceeded by 6.70 m of siltstones and sandstones; the total thickness is up to 8.0 m. A sandstone bed at 6.20–6.40 m above the base of the unit contains Skolithos burrows.

Lower Ordovician, Tremadocian Unit L3. This unit consists of dark-grey argillaceous siltstones and silty argillites with subsidiary beds of fi

ne-grained sandstones varying from 0.05 to 0.80 m in 2121 211 1 1 thickness; total unit thickness is 14.9 m. Argillites at 2.7–3.10 m above the base of the unit (Fig. 2; samples SK4/16, A1/3) contain abundant trilobites, including Downloaded by [Gazi University] at 08:12 17 December 2015 31 1 Asaphellus inflatus Lu, 1962, Chungkingaspis sinensis 21 212 (Sheng, 1958), Conophrys simehensis Ghobadi Pour, 2006 and Dactylocephalus mehriae Ghobadi Pour, 2006. 21 112 Unit L4. This unit includes dark-grey argillites with 22 25414281 1 2121 212 31 12 1 1 1 a bed of dark-brown limestone up to 0.60 m thick with several sandstone and limestone beds upsequence at 3.52–4.70 m, 4.64–4.70 m, 8.30–8.85 m and 12.0– 12.10 m above the base of the unit; total unit thickness is 13.85 m. Sample SK4/19, taken at 3.52–3.72 m from the base of the unit, contains the conodonts Monocosto- . W. ligula dus sp., Paltodus deltifer pristinus Viira, 1970, . W. bicuspidata Paroistodus numarcuatus Lindström, 1955 and sp. sp. cf sp. cf

Drepanoistodus sp., together with the linguliform bra- . F. dayangchaensis chiopod Dactylotreta batkanensis Popov & Holmer,

1994. A calcareous ironstone bed at 4.64–4.70 m from sp. cf the base of the unit (sample SK4/20) contains the con- Quantitative distribution of conodont elements from the Cambrian (Furongian) of the Simeh-Kuh section. odonts Paltodus deltifer pristinus, Drepanoistodus sp. and Paroistodus numarcuatus (Table 2). The uppermost Table 1. Conodont taxaCordylodus andresi SC4/1 SC4/2 SC4/3 SC4/4 SC4/4A SC4/5 SC4/6 SC4/7 SC4/8 SC4/9 SC4/11 SC4/12 Westergaardodina Eoconodontus notchpeakensis Furnishina Furnishina furnishi Furnishina tortilis Phakelodus elengatus Phakelodus tenuis Problematoconites Proconodontus muelleri Proconodontus serratus Proconodontus transitans Prooneotodus gallatini Prooneotodus rotundatus Westergaardodina Downloaded by [Gazi University] at 08:12 17 December 2015 ALCHERINGA

Conodont taxa Element SC4/19 SC420 SC4/23 SC4/29 SC4/31 SC4/32 SC4/33 SC4/34 SC4/35 SC4/36 Acodus sp. cf. A. kechikaensis 1 Acodus sp. cf. A. triangularis Pa 1 122 Pb 13 M 122126 Sa 12 2 Sb 211124 Sc 1 1 2 3 Sd 324155 Cornuodus sp. 1 Drepanodus arcuatus Pa 11 21 Pb 11 M21 Sa1 21512 23CAMBRIAN Sc2 14 5151 Sd1 23511334 Drepanoistodus sp. cf. D. nowlani Pa 2 2

M1 – Kallidontus sp. 5 IRAN FROM CONODONTS ORDOVICIAN P21 S21 Monocostodus sevierensis E1 Paltodus deltifer pristinus drepanodiform 1 1 oistodiform 6 4 1 Paltodus subaequalis M 1 Paroistodus numarcuatus M 21221 Paroistodus proteus Pa 4 1 Pb 1 1 1 2 M 23 1214 Semiacontiodus sp. 1 1 Triangulodus sp. cf. T. larapintinensis 1 Table 2. Quantitative distribution of conodont elements from the Ordovician (Tremadocian) of the Simeh-Kuh section. 6 HADI JAHANGIR et al. ALCHERINGA

limestone bed at 12.0–12.10 m above the base of the and Kallidontus sp., whereas matrix in the oolitic unit (Fig. 2; sample SK4/23) contains the conodonts ironstone at the top of the unit (Fig. 2; sample SK4/33) Drepanodus arcuatus Pander, 1856, Drepanoistodus sp. contains Acodus sp. cf. A. triangularis, Drepanodus cf. D. nowlani Ji & Barnes, 1994 and Paltodus deltifer arcuatus, Drepanoistodus sp. and Paroistodus proteus. pristinus Viira, 1970, the linguliform brachiopods Disarticulated valves of Protambonites hooshangi Dactylotreta batkanensis and Eurytreta sp., and the and Tarfaya jafariani occur through the entire unit trilobite Psilocephalina lubrica Hsü, 1948. The overly- (sample B0). ing argillites within the interval 12.1–13.0 m (sample Unit L11. This unit incorporates olive-grey to dark- B3/1) contain a rich trilobite assemblage of the grey siltstone, totalling 30.4 m in thickness. Three beds Psilocephalina lubrica Association characterized in of bioclastic and argillaceous limestone occur within the detail by Ghobadi Pour (2006). unit. The lowermost bed at 13.65–13.70 m (Sample Unit L5. This dark-grey argillite incorporates a dis- SK4/34) contains Acodus sp. cf. A. triangularis, Drepan- tinctive bed of tuffaceous sandstone about 1.0 m thick odus arcuatus, Drepanoistodus sp. and Paroistodus pro- with reverse-graded bedding; total unit thickness is 17.6 teus). The second bed at 23.9–24.0 m above the base of m. The interval from 1.0 to 1.25 m above the base of the unit (sample SK4/35) yielded Acodus sp. cf. A. trian- the unit (sample B3/2) contains trilobites of the Psilo- gularis, Drepanodus arcuatus, Drepanoistodus sp. The cephalina lubrica Association characterized in detail by uppermost limestone bed at 30.2–30.3 m (Fig. 2; sample Ghobadi Pour (2006). SK4/36) contains the conodonts Acodus sp. cf. A. Unit L6. This unit is an andesite volcanic lava flow, kechikaensis Pyle & Barnes, 2002, Acodus sp. cf. A. tri- up to 2 m thick. angularis, Cornuodus sp., Drepanodus arcuatus, Palto- dus subaequalis Pander, 1856, Paroistodus proteus and Unit L7. Intercalated grey to greenish-grey siltstones, Triangulodus sp. cf. T. larapintinensis Crespin, 1943. argillaceous siltstones and sandy siltstones, constitute The lower 13.5 m below the first limestone bed contain this 16.8 m-thick unit. Abundant trilobites (Vachikaspis the abundant trilobites Asaphellus fecundus Ghobadi insueta Ghobadi Pour, 2006) and brachiopods (Tarfaya Pour et al., 2007, Damghanampyx ginteri Ghobadi Pour jafariani Popov et al., 2009b) occur between 6.5 and et al., 2007 and Taihungshania miqueli (Bergeron 1894) 7.4 m from the base of the unit (sample B-4). Another and the brachiopods Polytoechia hecatompylensis Popov fossiliferous interval at 10.25–10.50 m above the base et al., 2009b, Paralenorthis semnanensis Popov et al., of the unit (sample SK4/26) contains the trilobites 2009b, Ranorthis cheshmehaliana Popov et al., 2009b Kayseraspis sp. and Psilocephalina lubrica. and Xinanorthis qoomesensis Popov et al., 2009b Unit L8. This unit comprises cross-bedded and (sample ‘T’). Argillites at about 0.5 m above this parallel-bedded, medium- to fine-grained sandstone with limestone bed contain the trilobites Asaphellus fecundus, channels infilled by bioclastic limestones rich in bra- Apatokephalus sp., Damghanampyx ginteri, Euloma sp. chiopod coquinas representing disarticulated shells of and the brachiopod Paralenorthis semnanensis (Ghobadi Protambonites hooshangi Popov et al., 2009b and Pour 2006, Ghobadi Pour et al. 2007, Popov et al. Tarfaya jafariani (sample C1/A); unit thickness is 2.33 2009b). The measured interval of the Simeh-Kuh section m. A conodont sample taken from the impure limestones is topped by a unit of andesitic volcanics up to 1.5 m at 2.25–2.30 m above the base of the unit (sample thick. SK4/29) contains Drepanodus arcuatus, Drepanoistodus Downloaded by [Gazi University] at 08:12 17 December 2015 During the Cambrian (Furongian) and Early Ordovi- sp. cf. D. nowlani, Paroistodus numarcuatus and Parois- cian, the Alborz region was probably part of a small todus proteus Lindström, 1955. peri-Gondwanan terrane situated in temperate latitudes Unit L9. This unit is composed of dark-grey argilla- somewhere between the western Gondwana margin and ceous siltstones, totalling about 8.9 m in thickness. South China (Ghobadi Pour 2006, Ghobadi Pour & Trilobites (Kayseraspis sp. and Psilocephalina lubrica) Popov 2009). For most of the Cambrian and Early to are present at 7.9–8.9 m above the base of the unit mid-Ordovician, the area was tectonically stable, and (sample SK4/30). sedimentary characteristics were probably influenced Unit L10. This is a unit of cross-bedded and parallel- mainly by eustatic sea-level changes (Ghobadi Pour bedded, medium- to fine-grained sandstone and impure et al. 2011c). Net sedimentation rates through that time limestone with abundant brachiopod coquinas. A pebbly were low in the eastern Alborz region. In particular, conglomerate up to 0.8 m thick and lenses of oolitic they were of the order of 10–15 mm per millennium for ironstone occur at the top; total unit thickness is 2.85 m. the Tremadocian interval in Simeh-Kuh. The early to An impure limestone at 1.0 m from the base (Fig. 2; mid-Furongian strata in eastern Alborz are represented sample SK4/31) contains the conodonts Acodus sp. cf. A. by echinoderm limestones and brachiopod shell beds triangularis Ding in Wang, 1993, Kallidontus sp., accumulated in carbonate shoal systems. The first Paroistodus proteus (Lindström, 1955) and Oneotodus appearance of euconodonts in the area (base of unit L1 variabilis Lindström, 1955. Sample SK4/32, taken at 1.3 in Simeh-Kuh) coincided with a conspicuous sea-level m from the base of the unit contains Acodus sp. cf. A. rise, during which continuous carbonate sedimentation triangularis, Drepanodus arcuatus, Drepanoistodus sp. had mainly ceased and was replaced by fine siliciclastic ALCHERINGA CAMBRIAN–ORDOVICIAN CONODONTS FROM IRAN 7

sedimentation well below the seasonal storm wave base. mehriae in the lowermost part of the argillaceous unit No progradational or retrogradational patterns can be overlying topmost Cambrian Cruziana-bearing sand- recognized, probably owing to an extremely low supply stones. Ghobadi Pour et al.(2011b) and Jahangir et al. of siliciclastic sediment. Subsidiary limestone beds in (2014) documented the occurrence of conodonts charac- the uppermost Furongian are mainly distal tempestites. teristic of the Paltodus deltifer Zone in the Tremadocian The proportion of tempestite beds increases in the upper part of the succession. 10 m of unit L1 suggesting progressive shallowing of The uppermost part of the Cambrian succession was the sea during the upper part of the Eoconodontus outlined briefly by Ghavidel-Syooki (2006) and notchpeakensis Zone. The first occurrence of Cordylo- Ghobadi Pour et al.(2011a, b, c), who described mainly dus andresi Viira & Sergeyeva in Kaljo et al., 1986 is the Ordovician sequence. The Cambrian (Furongian) from the shell beds (unit L2A) suggesting a shallow succession was partly characterized by Popov et al. marine environment affected by seasonal storms. The (2011), who described a moderately diverse Furongian overlying sandstone unit contains Skolithos trace fossils rhynchonelliform brachiopod fauna, and by Jahangir suggesting deposition in the peritidal zone. et al.(2014), who reported the presence of the Procon- The beginning of the Ordovician coincided closely odontus muelleri and Eoconodontus notchpeakensis with sharp changes in sedimentation patterns. Deposi- conodont zones and early reprsentatives of Cordylodus tion of fine clastic sediments, argillites and siltstones in the area. Subsequent studies revealed a succession of was characteristic of most of the Tremadocian. Thin terminal Cambrian euconodont zones identical to those tempestite beds of fine-grained sandstones and bioclastic described from Simeh-Kuh, and in addition, the Cordy- limestones occur sporadically through the succession. In lodus proavus Zone was recognized. the absence of conodonts in the lowermost part of the In Deh-Molla, fossiliferous Furongian deposits are Ordovician succession, the lowermost Tremadocian is separated from the basal Ordovician by a barren unit of defined by the occurrence of the Asaphellus inflatus– quartzose sandstone, totalling up to 100 m thick, with a Dactylocephalus trilobite association, which is charac- bed of polymict conglomerate at the top, and with teristic of the basal Tremadocian in South China abundant Cruziana ichnofossils. A conodont-bearing (Ghobadi Pour 2006, Kebria-ee Zadeh et al. 2015). The interval between this sandstone unit and underlying bio- occurrence of trilobites typical of the olenid, nileid and clastic limestones with brachiopod shell beds is very raphiophorid biofacies suggests depositional environ- condensed and is only about 16 m thick (Fig. 2). ments of the outer shelf below seasonal storm wave Conodonts of the Proconodontus muelleri Zone base (Benthic Assemblage 4−5). There were two were recovered from the two lowermost limestone beds remarkable interruptions at the beginning of the Parois- within the intervals 0.21–0.31 m (Fig. 2; sample todus proteus Conodont Zone with a short term sea- DM-A/1) and 3.02–3.07 m (Fig. 2; sample DM-A/2) level fall resulting in accumulation of quartzose sands above the base of the measured profile. In addition to rich in brachiopod coquinas, probably within shoal the eponymous species, the assemblage includes Fur- complexes (units L8 and L10). Two minor episodes of nishina furnishi Müller, 1959, Furnishina tortilis intraplate volcanism in the latest Tremadocian are evi- Müller, 1959, Phakelodus tenuis, Proconodontus serra- dent from the presence of andesitic lava flows; however, tus, Prooneotodus gallatini (Müller, 1959), Prooneoto- there is no sign of a significant increase in tectonic dus rotundatus (Druce & Jones, 1971) and

Downloaded by [Gazi University] at 08:12 17 December 2015 activity within the region until the beginning of the Westergaardodina sp. cf. W. ligula Müller, 1959. The Darriwilian. first documented appearance of Eoconodontus nothch- pealensis is at 4.28 m (Fig. 2; sample DM-A/3), whereas the first documented appearance of Cordylodus Deh-Molla section andresi is at 12.96 m of the measured section (Fig. 2; The sampled Cambrian (Furongian) section in the samples DM-A/4, DM-A/4A). The conodont-bearing Deh-Molla area (geographic coordinates of the zero samples were recovered from seven fossiliferous layers point 36°21′17.88″ N; 54°44′47.94″ E, altitude 1682 m) (Table 3, samples DM-A/3, DM-A/3A to DM-A/3F) in is situated about 1 km northeast of the Qalyankesh the lower 4 m within the interval assigned to the Mountain and at 3.7 km east of the entrance to the Eoconodontus nothchpealensis Zone, whereas the upper Shahrud University mine, which is approximately 8.5 4.7 m are barren. With the exception of the lowermost km north of Kalat-e Molla village (Fig. 1). The terminal sample, Eoconodontus nothchpealensis is very rare Cambrian to Ordovician succession in the area was first through the interval, whereas the transitional eucon- documented by Ghavidel-Syooki (2006). Subsequently, odont species Proconodontus muelleri and Proconodon- Ghobadi Pour et al.(2011a, b, c) described Tremado- tus serratus Miller, 1969 are relatively common. The cian ostracods and selected brachiopod taxa from the remainder of the assemblage comprises protoconodont Ordovician part of the succession and defined the Cam- and paraconodont species with long stratigraphic ranges brian–Ordovician boundary based on the appearance of (Table 3). the characteristic trilobite association with Asaphellus Conodonts of the Cordylodus andresi Zone have inflatus, Chungkingaspis sinensis and Dactylocephalus been recovered from three samples (Fig. 2; Table 3; 8 HADI JAHANGIR et al. ALCHERINGA

samples DM-A/4, DM-A/4A−DM-A/4C). The thickness of the interval assigned to this zone does not exceed 0.95 m. The associated conodont assemblage is of extremely low diversity; it includes Phakelodus tenuis, Prooneotodus gallatini, Prooneotodus rotundatus and Westergaardodina sp. cf. W. ligula. The transition to the Cordylodus proavus Zone 12 13 occurs at 13.9 m above the base of the measured inter- val (Fig. 2; sample DM-A/4D). The eponymous species has been recovered from three additional fossiliferous 4352 beds at 14.6−14.7 m (Fig. 2; sample DM-A/4E) and at 15.5−15.7 m above the base of the measured section (Fig. 2; samples DM-A/4F, DM-A/4G). The associated 1 assemblage is represented by a few species of proto- and paraconodonts that are transitional from the lower units, including Furnishina tortilis, Phakelodus elenga- tus, Phakelodus tenuis, Prooneotodus gallatini and Westergaardodina sp. cf. W. bicuspidata. The available trilobite data (Popov et al. 2011) sug- gest that all sampled intervals are within the Alborsella Zone of Kushan (1973). Conodont residuals contain

31 4 also linguliform microbrachiopods and sparse sclerites of the palaeoscolecide Milaculum (Sample DM-A/1), which require further study.

Mila-Kuh section

11 Mila-Kuh is situated about 50 km west-southwest of Damghan, about 6.5 km southwest of Tuyeh village, and about 5 km northwest of the road connecting Sem- nan to Damghan (Fig. 1; 35°58′54″ N, 53°48′44″ E). The original description of the Mila Formation by Stöcklin et al.(1964) remains the primary published source of information on the Cambrian stratigraphy of the area. However, the uppermost argillaceous unit of member 5 of the Mila Formation (Stöcklin et al. 1964) is dated as Early Ordovician (Tremadocian; Kebria-ee Zadeh et al. 2015).

Downloaded by [Gazi University] at 08:12 17 December 2015 Despite a low conodont yield, Müller’s(1973) study 21 provided data on the successive appearances of eucon- odont species in Mila-Kuh that agree well with the pat- tern evident in Simeh-Kuh and Deh-Molla sections. 71 Bioclastic limestones with brachiopod shell beds, assigned by Stöcklin et al.(1964) to the ‘Mila Forma- 11 31 1 1 1 2 2 tion Member 3’, lack conodonts. According to Müller (1973) all conodont-bearing samples came from ‘Mila Formation Member 4’, consisting of grey argillaceous 21251 1423212 1 2 1 1 2 2 1 1 1 2 1 1 2 and nodular limestones, siltstones and sandstones total- ling up to 90 m thick (Fig. 2). The lowermost con- odont-bearing bed (Fig. 2; sample 2270) at 5 m above the base of ‘Mila Formation Member 4’ contains only para- and protoconodonts. The euconodont Proconodon- .W.ligula . W. bicuspidata tus serratus appears in sample 2271 taken 1 m higher sp. cf sp. cf in the section, whereas the first documented occurrence of Proconodontus muelleri Miller, 1969 is 7 m above Quantitative distribution of conodont elements from the Cambrian (Furongian) of the Deh-Molla section. the base of ‘Mila Formation Member 4’ (Fig. 2; sample 2272). Eoconodontus notchpeakensis occurs Westergaardodina Proconodontus muelleri Proconodontus serratus Prooneotodus gallatini Prooneotodus rotundatus Phakelodus tenuis Westergaardodina Phakelodus elengatus Cordylodus proavus Eoconodontus notchpeakensis Furnishina furnishi Furnishina tortilis Conodont taxaCordylodus andresi DM-A/1 DM-A/2 DM-A/3 DM-A/3A DM-A/3B DM-A/3C DM-A/3D DM-A/3ETable 3. DM-A/3F DM-A/4 DM-A/4A DM-A/4B DM-A/4C DM-A/4D DM-A/4E DM-A/4F DM-A/4G ALCHERINGA CAMBRIAN–ORDOVICIAN CONODONTS FROM IRAN 9

sporadically in the beds higher than 8.4 m above the Lower Ordovician of tropical carbonate platform base of the unit (Fig. 2; sample 2274) with only four successions (e.g., Miller 1969, 1980, Miller et al. 2003, specimens recovered from the whole succession accord- 2006) in the Tropical Domain (Zhen & Percival 2003) ing to Müller (1973, pp. 12, 13). Cordylodus proavus is not applicable to the Alborz Region. However, a appears in relative abundance at 41 m above the base ‘simplified’ conodont zonal scheme with coarser bios- of ‘Mila Formation Member 4’ (Fig. 2; sample 2281), tratigraphic resolution, comparable with that of the Cold but no Cordylodus andresi has yet been recorded. As in Domain, and in particular of the Baltoscandian Province Deh-Molla, conodonts co-occur with trilobites character- sensu Zhen & Percival (2003) is proposed. istic of the Alborsella Zone (Kushan 1973, Müller The Proconodontus muelleri Zone is the lowermost 1973). biostratigraphic zone recognized in the succession. It is defined by the first occurrence of the eponymous taxon at the base of unit L1. Proconodontus serratus Conodont biostratigraphy (Fig. 4E) is the only other euconodont taxon in the The first conodont biozonation of the Cambrian−Ordovi- assemblage; background components of the fauna are cian boundary beds in Iran was compiled by Müller represented mainly by paraconodont taxa with long (1973). It was a composite and generally low-resolution stratigraphic ranges, including Furnishina sp. cf. F. biostratigraphic scheme based on two conodont succes- dayangchaensis (Fig. 4L, M), Prooneotodus gallatini sions documented through the Mila Formation (Alborz (Fig. 4Q, R), Prooneotodus rotundatus (Fig. 4S, U), Mountains, northern Iran) and the Derenjal Formation Westergaardodina sp. cf. W. bicuspidata (Fig. 4H, I) (Derenjal Mountains, Tabas region, east-central Iran). and Westergaardodina sp. cf. W. ligula (Fig. 4J, K). Conodont faunas younger than the Cordylodus proavus Within eastern Alborz, this biozone is recognizable in Zone were unknown in the Alborz Mountains at that the lower part of member 4 of the Mila Formation in time. The Furongian to Tremadocian conodont biostrati- the Mila-Kuh section (samples 2271 and 2272; Müller graphic succession of the Tabas region was recently 1973) and Deh-Molla section (Fig. 2; samples DM/A1 revised by Ghaderi et al. (2009; Fig. 3). and DM/A2). Despite the low taxonomic diversity (13 genera and The Eoconodontus notchpeakensis Zone is recog- 20 species) and relatively low conodont yield in the nized in the Simeh-Kuh section by the first occurrence processed samples, the new data are sufficient to con- of the eponymous taxon at 5.0 m above the base of the struct a conodont-based biostratigraphic scheme for the unit L1 (Fig. 2, sample SK4/3). The associated assem- late Furongian and Tremadocian of the Alborz region. blage includes transitional species of the euconodonts The conodont zonation developed for the Furongian to Proconodontus serratus and Proconodontus muelleri. Downloaded by [Gazi University] at 08:12 17 December 2015

Fig. 3. Chrono- and lithostratigraphic summary chart of the uppermost Cambrian to Lower Ordovician (Tremadocian) strata of Eastern Alborz showing correlation with the conodont zonations of central Iran, Baltica and Laurentia (mainly after Miller et al. 2003, 2011, Cooper & Sadler 2012 and Peng et al. 2012 with emendations). Sea-level curve for Baltoscandia modified from Nielsen (2004). North Atlantic conodont biozones are mainly after Kaljo et al.(1986), Viira (2011) and Männik & Viira (2012). 10 HADI JAHANGIR et al. ALCHERINGA Downloaded by [Gazi University] at 08:12 17 December 2015

Fig. 4. A, B, Proconodontus muelleri Miller, 1969; A, AEU/L 5000, outer lateral view, sample SK4/1; B, AEU/L 5001, posterior view, sample SK4/1; C, D, Eoconodontus notchpeakensis (Miller, 1969), sample SK4/3; C, AEU/L 5003, M-element, outer lateral view; D, AEU/L 5004, M-element, outer lateral view; E, Proconodontus serratus Miller, 1969, sample SK4/1, outer lateral view. F, G, Cordylodus andresi Viira & Sergeyeva in Kaljo et al., 1986, sample SK4/12; F, AEU/L 5005, outer lateral view; G, AEU/L 5006, outer lateral view. H, I, Westergaardodina sp. cf. W. bicuspidata Müller, 1959, sample SK4/2; I, AEU/L 5007, upper view; H, AEU/L 5008, lateral view; J, K, Westergaardodina sp. cf. W. ligula Müller, 1959, sample SK4/2; J, AEU/L 5009, lateral view; K, AEU/L 5010, upper view. L, M, Furnishina sp. cf. F. dayangchaensis Chen & Gong, 1986, sample SK4/2; L, AEU/L 5011, anteriolateral view; M, AEU/L 5012, outer posterolateral view. N, O, Furnishina tortilis Müller, 1959, sample SK4/3; N, AEU/L 5013, inner lateral view; O, AEU/L 5014, posterior view. P, Furnishina furnishi Müller, 1959, sample SK4/4, anterior view. Q, R, Prooneotodus gallatini (Müller, 1959), sample SK4/3; Q, AEU/L 5015, outer lateral view; R, AEU/L 5016, outer posterolateral view. S, U, Prooneotodus rotundatus (Druce & Jones, 1971), AEU/L 5017, outer lateral view, sample SK4/7; U, AEU/L 5019, posterior view, sample SK4/3. T, Proconodontus transitans Szaniawski & Bengtson 1998, sample SK4/3, AEU/L 5018, outer lateral view. V, Phakelodus tenuis (Müller, 1959); sample SK4/7, AEU/L 5020, outer lateral view. W, Phakelodus elengatus (Müller, 1955), sample SK4/7, AEU/L 5021, outer lateral view. Scale bars = 100 μm. ALCHERINGA CAMBRIAN–ORDOVICIAN CONODONTS FROM IRAN 11

Proconodontus transitans (Fig. 4T) first appears at the Lindström has not been recovered from the Simeh-Kuh base of this zone. There is also a moderately diverse section; however, it occurs in the Deh-Molla section paraconodont fauna including Furnishina furnishi (Ghobadi Pour et al. 2011b, Fig. 3J, K). (Fig. 4P), Furnishina tortilis (Fig. 4N, O), Prooneotodus The Paroistodus proteus Zone is defined by the first gallatini, Problematoconites sp. and Westergaardodina occurrence of the eponymous species near the top of unit sp. cf. W. ligula (Fig. 4J, K). The protoconodonts L8 (Fig. 2, sample SK4/29). The associated conodont Phakelodus elengatus (Fig. 4V) and Phakelodus tenuis assemblage includes Drepanodus arcuatus (Fig. 7K–S), (Fig. 4W) appear only in the upper part of the zone Drepanoistodus sp. cf. D. nowlani and Paroistodus (Fig. 2, sample SK4/5). Within eastern Alborz the numarcuatus. The assemblage diversifies upsequence Eoconodontus notchpeakensis Zone was recognized by with Acodus sp. cf. A. triangularis, Kallidontus sp. and Müller (1973; samples 2772, 2774, 2777, 3859) in mem- Oneotodus variabilis Lindström, 1955 documented from ber 4 of the Mila Formation in the Mila-Kuh section and the samples SK4/31 and SK4/32 (Fig. 2, unit L10), is also present in the Deh-Molla section (Fig. 2). whereas Acodus sp. cf. A. kechikaensis, Cornuodus sp., The Cordylodus andresi Zone is defined in Paltodus subaequalis and Triangulodus sp. cf. T. larap- Simeh-Kuh by the first occurrence of the eponymous intinensis appear in the uppermost part of the sampled species, which is the earliest yet known representative succession (sample SK4/36), just below the second layer of the Cordylodus lineage, in unit L2A (Fig. 2, sample of lava flows (Fig. 2). Acodus sp. cf. A. triangularis is SK4/12). The associated conodont assemblage contains the most common species in the middle and upper part up to six species that persist from the Eoconodontus of the unit. notchpeakensis Zone. Cordylodus sp. reported by Jahangir et al. (2014) from sample DM/A4 of the Deh-Molla section is now assignable to Cordylodus Faunal affinities and conodont-based andresi (Fig. 2; Table 3). Accordingly, this biostrati- graphic unit is also present in Deh-Molla. correlation The Cordylodus proavus Zone is absent in the The Cambrian (Furongian) conodont fauna of the Simeh-Kuh section, but it was well documented by Alborz region is dominated by paraconodont species Müller (1973; samples 2284, 2286, 2287) in the upper with long stratigraphic ranges, whereas biostratigraphi- part of member 4 of the Mila Formation in the Mila- cally informative euconodonts are represented by a few Kuh section, but no Cordylodus specimens assignable sparse cosmopolitan species; hitherto, they are the only to Cordylodus andresi have been documented so far taxa valuable for biostratigraphic subdivision and corre- from Mila-Kuh. Cordylodus proavus (Fig. 5F–J, 6C–F) lation of the Iranian succession on a global scale. The has been recovered recently from the uppermost part of conodont faunas are characteristic of the Cold Domain the Furongian succession in the Deh-Molla section sensu Zhen & Percival (2003), and in particular of the (Fig. 2), where it succeeds Cordylodus andresi. Furongian faunas of Baltoscandia (Kaljo et al. 1986, The Paltodus deltifer Zone is defined by the first Müller & Hinz 1991, Szaniawski & Bengtson1998, occurrence of Paltodus deltifer pristinus (Fig. 7C–F) in Bagnoli & Stouge 2014) and the Oaxaquia terrane, sample SK4/19 taken from a limestone bed at the base of which was probably part of the Gondwanan domain in unit L4 in the Simeh-Kuh section where it occurs together the early Palaeozoic (Landing et al. 2007, fig. 11). fi

Downloaded by [Gazi University] at 08:12 17 December 2015 with the trilobite Psilocephalina lubrica. The underlying Close af nities between these three faunas are also units, L2B and L3, totalling 23.9 m in thickness, lack car- supported by a cluster analysis (Jahangir et al. 2014, bonates, and the siliciclastic rocks exposed within this fig. 5). The lowermost biostratigraphic unit based on interval were not suitable for processing conodonts. The euconodonts in the Simeh-Kuh section is the Procon- list of other conodont taxa, which occur together with odontus muelleri Zone, whereas equivalents of the Pro- Paltodus deltifer pristinus, includes Drepanoistodus sp., conodontus tenuiserratus and Proconodontus Monocostodus sp. (Fig. 7A, B) and Paroistodus numar- posterocostatus zones, recognized at the base the Furon- cuatus (Fig. 7T, U). This zone is also represented in the gian conodont biostratigraphic succession of Laurentia Deh-Molla section (Ghobadi Pour et al. 2011b, Jahangir (Miller et al. 2003), are not represented in the Alborz et al. 2014) by more diverse conodont assemblages, region. The same is true for Baltoscandia and the Oax- including Paltodus quinqucostatus Müller, 1964, Rosso- aquia terrane. Szaniawski & Bengtson (1998) intro- dus sp. cf. R. beimadaonsis Chui & Zhang in An et al., duced the Proconodontus transitans Subzone at the 1983, Scandodus sp. cf. S. furnishi and Variabiloconus base of the euconodont succession of Baltoscandia, sp. cf. V. variabilis Lindström, 1955, Drepanoistodus sp. although they considered the eponymous taxon as the cf. D. nowlani, Drepanoistodus sp., Monocostodus sp. earliest representative of the proconodont lineage. They (Fig. 7A, B) and Paroistodus numarcuatus (Fig. 7T, U) also argued that the first documented occurrence of Pro- appear in the uppermost limestone sample of unit L4 conodontus muelleri is diachronous on different conti- (SK4/23) at Simeh-Kuh within the stratigraphic interval nents; however, this argument lacks sufficient evidence. assigned to this zone (Fig. 2). Units L5 and L7 comprise It is likely that the Proconodontus lineage evolved orig- exclusively siliciclastic rocks. Paltodus deltifer deltifer inally in the epicratonic seas of the Tropical Domain 12 HADI JAHANGIR et al. ALCHERINGA Downloaded by [Gazi University] at 08:12 17 December 2015

Fig. 5. A–E. Cordylodus andresi Viira & Sergeyeva in Kaljo et al., 1986; A, AEU/L 5022, outer lateral view, sample DMA/4A; B, AEU/L 5023, outer lateral view, sample DMA/4B; C, AEU/L 5024, anteriobasal view, sample DMA/4A; D, AEU/L 5025, outer lateral view, sample DMA/4; E, AEU/L 5026, outer lateral view, sample DMA/4. F–J, Cordylodus proavus Müller, 1959; AEU/L 5027, outer lateral view, sample DMA/4D; G, AEU/L 5028, outer lateral view, sample DMA/4E; H, AEU/L 5029, outer lateral view, sample DMA/4G; I, AEU/L 5030, posterior view; sample DMA/4G; J, AEU/L 5031, outer lateral view; sample DMA/4F. Scale bars = 100 μm.

(e.g., epeiric seas of Laurentia and the Australasian sec- Alborz region, the euconodont invasion closely coin- tor of Gondwana) and only later migrated into the Cold cides with a steady sea-level rise. This transgressive Domain. Nevertheless, the Proconodontus muelleri event is also recognized at the beginning of the Procon- Zone is the earliest globally recognized biostratigraphic odontus muelleri Zone in the Lawson Cove Section of unit established on this euconodont lineage. In the Laurentia (Miller et al. 2003), but it is not detectable in ALCHERINGA CAMBRIAN–ORDOVICIAN CONODONTS FROM IRAN 13

Fig. 6. Fig. A–D, Cordylodus andresi Viira & Sergeyeva in Kaljo et al., 1986; A, AEU/L 5032, outer lateral view, sample DMA/4A; B, AEU/L 5033, inner lateral view, sample DMA/4B; C, D, AEU/L 5034, outer lateral view, sample SK-4/12; E–G, Cordylodus proavus Müller, 1959; E, AEU/L 5035, outer lateral view; sample DMA/4D; F, AEU/L 5036, outer lateral view, sample DMA/4E; G, AEU/L 5037, inner lateral view, sample DMA/4G. Scale bars = 100 μm. Downloaded by [Gazi University] at 08:12 17 December 2015 the Scandinavian Alum Shale Formation, which accu- suggested that, if the base of the Global Cambrian mulated in a deep water environment. Stage 10 is placed at the first appearance datum (FAD) Proconodontus serratus occurrs in all three studied of the Lotagnostus americanus agnostoid trilobite Zone, sections at or near the base of the Proconodontus muel- it will be located within the lower part of the Procon- leri Zone, but in the conodont succession of Laurentia odontus muelleri conodont Zone, if synonymy of the it appears not earlier than in the Eoconodontus notch- Swedish specimens assigned to Lotagnostus trisectus peakensis Zone (Miller et al. 2003). It is possible that (Salter, 1864) and Lotagnostus americanus (Billings, Proconodontus serratus evolved in the faunas of the 1860) suggested by Peng & Babcock (2005) is valid Cold Domain and only later migrated to the Tropical (for an opposing view, see Landing et al. 2007). In the Domain, as documented for Cordylodus (Bagnoli & Furongian succession of the Alborz region, the FAD of Stouge 2014). On the other hand, Eoconodontus notch- Proconodontus muelleri is close to the base of the local peakensis is a relatively rare taxon in the studied suc- Alborsella trilobite Zone; however, precise correlation cession, and its full range may not be adequately between the conodont and trilobite zonations of Iran documented. Nevertheless, the observed first appear- requires further study. ances of euconodont species in all three studied sections The succeeding Eoconodontus notchpeakensis Zone are used as the primary criterion for definition of the is another globally recognized biostratigraphic unit. The base of this biostratigraphic unit. FAD of the eponymous species is considered to be a Based on correlation of the Baltoscandian conodont possible alternative for placement of the base of Cam- and trilobite successions, Bagnoli & Stouge (2014) brian Stage 10 (Miller et al. 2011). Global correlation 14 HADI JAHANGIR et al. ALCHERINGA Downloaded by [Gazi University] at 08:12 17 December 2015

Fig. 7. A, B, Monocostodus sp., sample SK4/19; A, AEU/L 5038, E-element, inner lateral view; B, AEU/L 5039, E-element, posterior view. C–F, Paltodus deltifer pristinus Viira, 1970; C, AEU/L 5040, M-element, inner lateral view, sample SK4/19; D, AEU/L 5041, M-element, inner lateral view, SK4/19; E, AEU/L 5042, S-element outer lateral view, sample Sk-4/23; F, AEU/L 5043, S-element, posterior view, sample Sk-4/23. G–J, Drepanoistodus sp. cf. D. nowlani Ji & Barnes, 1994; G, AEU/L 5044, Pa-element, inner lateral view, sample SK4/23; H, AEU/L 5045, Pa-element, posterior view, sample SK4/23; I, AEU/L 5046, M-element, outer lateral view, sample Sk-4/29; J, AEU/L 5047, M-element, inner posterolateral view, sample Sk-4/29. K–S, Drepanodus arcuatus Pander, 1856; K, AEU/L 5048, Pa-element, outer lateral view, sample SK4/23; L, AEU/L 5049, Pb-element, outer lateral view, sample SK4/23; M, AEU/L 5050, M-element, inner lateral view, sample SK4/31; N, AEU/L 5051, Sa-element, outer lateral view, sample SK4/36; O, AEU/L 5052, Sa-element; basal view, sample SK4/36. P, AEU/L 5053, Sc-element, basal view, sample SK4/34; Q, AEU/L 5054, Sc-element, outer lateral view, sample SK4/34. R, AEU/L 5055, Sd-element, outer lateral view, sample SK4/36; S, AEU/L 5056, Sd-element, posterior view, sample SK4/36. T, U, Paroistodus numarcuatus Lindstrom, 1955, T, AEU/L 5057, M-element, outer lateral view, sample SK4/31; U, AEU/L 5058, M-element, basal view, sample SK4/31. Scale bars = 100 μm. ALCHERINGA CAMBRIAN–ORDOVICIAN CONODONTS FROM IRAN 15

of the Eoconodontus notchpeakensis Zone has been The Cordylodus proavus Zone has not been recog- discussed in great detail by Landing et al.(2007) and nized in the Simeh-Kuh section; however, conodonts Miller et al.(2011). characteristic of this zone were documented by Müller The Cordylodus andresi Zone is a newly intro- (1973) from member 4 of the Mila Formation at duced biostratigraphic unit for the Iranian conodont Mila-Kuh (Fig. 2). This suggests the presence of a hia- succession. The Furongian specimens of Alborz con- tus at the base of the overlying cross-bedded Cruziana- firm to the strict concept of Cordylodus andresi as rec- bearing sandstone unit deposited within nearshore shoal ognized by Viira et al.(1987). It is likely, that systems, which represents a distinct marker bed at the specimens from the Oaxaquia Terrane assigned by top of the Cambrian succession traceable across eastern Landing et al.(2007)toCordylodus andresi also Alborz (Kebria-ee Zadeh et al. 2015). belong to the species, but the schematic illustrations of The base of the Ordovician at the Simeh-Kuh section the basal cavity in that study are not adequate to prove coincides closely with a significant drowning event and their taxonomic affiliation (Bagnoli & Stouge 2014). invasion of the Asaphellus inflatus—Dactylocephalus There is good evidence that Cordylodus andresi sensu trilobite association, which is typical of coeval succes- stricto precedes the FAD of Cordylodus proavus in sions in northern Iran (Ghobadi Pour 2006, Kebria-ee Baltoscandia (Kaljo et al. 1986, Viira et al. 1987, Zadeh et al. 2015). No conodonts have been recovered Bagnoli & Stouge 2014); however, existing data on from this stratigraphic interval owing to the complete the FAD of Cordylodus andresi in relation to the base absence of limestone beds. of the Eoconodontus notchpeakensis Zone are contro- The Paltodus deltifer Zone in Simeh-Kuh is coeval versial. In Baltoscandia, Eoconodontus notchpeakensis with the Baltoscandian Paltodus deltifer Zone as is rare and usually co-occurs with Cordylodus andresi, defined by Löfgren (1997a), and with the Paltodus del- whereas the appearance of the latter species coincides tifer Zone of the eastern Cordillera, Argentina (Zeballo with a regression (Bagnoli & Stouge 2014). Landing et al. 2005, Voldman et al. 2013, Zeballo & Albanesi et al.(2007) reported that in the Yudachica Member of 2013). The latter region has been assigned by Zeballo the Oaxaquia Terrane Cordylodus andresi occurs et al.(2008) to the Cold Domain of the Shallow-Sea slightly below the FAD of Eoconodontus notchpeaken- Realm sensu Zhen & Percival (2003). However, only sis and concluded that the Cordylodus andresi Zone Paltodus deltifer pristinus and Accodus arcuatus are represents the stratigraphic equivalent of the shared between the mid-Tremadocian faunas of Alborz Eoconodontus notchpeakensis Zone of the Laurentian and the eastern Cordillera, whereas Drepanoistodus carbonate platform. Subsequently, this correlation was nowlani appears in both regions in the upper part of the challenged by Miller et al.(2011) in their discussion Paltodus deltifer Zone. Another distinctive feature of of Eoconodontus notchpeakensis as an index taxon for the Argentinean fauna is the early occurrence of the Global Cambrian Stage 10. In the Laurentian con- Kallidontus (Voldman et al. 2013, Zeballo & Albanesi odont succession of Utah (Miller et al. 2003, 2011), 2013), which is otherwise unknown in the Tremadocian the Eoconodontus notchpeakensis Subzone of the faunas of the Cold Domain, but appears in the Alborz Eoconodontus Zone corresponds mainly to the interval region in the overlying Paroistodus proteus Zone. It is of the Red Tops Lowstand, but in the Simeh-Kuh likely that Kallidontus evolved originally in the Cold section there is no sign of any significant sea-level fall Domain and only later migrated to the Tropical Domain

Downloaded by [Gazi University] at 08:12 17 December 2015 from the base of the Proconodontus muelleri Zone to of the Shallow-Sea Realm, where it occurs in the upper- the base of the Cordylodus? andresi Zone. most Tremadocian to Floian stages of eastern Laurentia Remarkably, the FAD of Cordylodus? andresi in south- (Pyle & Barnes 2002). ern Sweden occurs at a time of sea-level fall of similar In the Simeh-Kuh section (Fig. 2), the FAD of Palto- magnitude to that observed at Simeh-Kuh. In dus deltifer pristinus closely coincides with the FAD of Baltoscandia, this is usually explained by tectonically Psilocephalina lubrica, which is the eponymous taxon of induced uplift (Artyushkov et al. 2000; Bagnoli & the local trilobite zone (Ghobadi Pour et al. 2015). Stouge 2014, p. 3). It is also possible that the sea-level The base of the Paroistodus proteus Zone at Simeh- fall during the Red Tops Lowstand might also have Kuh corresponds to the maximum sea-level fall and is been tectonically induced, and the significance of local probably synchronous with the Ceratopyge Regressive and regional tectonics in sea-level changes observed in Event (Nielsen 2004), which was followed by an abrupt Laurentia during the Furongian is underestimated. The sea-level rise and invasion of the Asaphellus fecundus– Cordylodus? andresi Zone is probably broadly coeval Taihungshania miqueli trilobite association, characteris- with the Cambrooistodus minutus Biozone. This tic of the raphiophorid biofacies (Ghobadi Pour et al. uncertainty can be resolved only when the position of 2007, 2015). This zone is widely recognized in the HERB carbon isotope excursion in the Iranian Baltoscandia (Löfgren 1997b, Nõlvak et al. 2006). Furongian succession is identified. Nevertheless, the Ghobadi Pour et al.(2007) reported the occurrence of new data from Iran are significant for evaluating the Drepanoistodus sp. aff. D. amoenus in the lower part of criteria used for defining the Global Cambrian Stage the Paroistodus proteus Zone of the Simeh-Kuh section, 10 lower boundary. where it co-occurs with the biogeographically indicative 16 HADI JAHANGIR et al. ALCHERINGA

trilobite Taihungshania miqueli (Bergeron, 1894), other- 1998 Proconodontus muelleri Miller; Szaniawski & wise known from the Mediterranean peri-Gondwanan Bengtson, p. 17, pl. 2, figs 4–17, fig. 4g–k. belt. However, Drepanoistodus sp. D. aff. amoenus is 2002 Proconodontus muelleri Miller; Pyle & Barnes, not represented in the samples of the present study; p. 57, pl. 12, figs 21, 22. therefore, none of the conodont subzones introduced by 2014 Proconodontus muelleri Miller; Jahangir et al., pl. Löfgren (1997b) for the Paroistodus proteus Zone in 1, fig. 7. Baltoscandian conodont succession can be recognized at Simeh-Kuh. Nevertheless, the occurrence of Acodus sp. Material. Simeh-Kuh section: 17 specimens from sam- – cf. A. kechikaensis in the uppermost limestone bed ples SK4/1 SK4/3, SK4/5, SK4/6, SK4/9, SK4/12; (Fig. 2; sample SK4/36) below the volcanic unit sug- Deh-Molla section: 11 specimens from samples DM-A/ – gests a lowermost Floian age for the uppermost part the 1 A/3, DM-A/3A, DM-A/3C, DM-A/3E. described succession. In the ‘Atlantic Realm’ zonation Remarks. The Proconodontus muelleri elements from proposed by Pyle & Barnes (2002) for western Canada, Simeh-Kuh are typical of the taxon, as re-defined by the base of the Acodus kechikaensis Zone is located Szaniawski & Bengtson (1998). They are gently slightly above the lower boundary of the Floian. recurved, laterally compressed simple cones with an Acodus triangularis was known previously from the extremely deep basal cavity extending to the tip of the Honghuayuan Formation of South China, where it is cusp. A slight lateral curvature of the cusp is character- confined to the lower part of the Floian Stage. At istic, as are sharp, keeled anterior and posterior margins, Simeh-Kuh, Acodus sp. cf. A. triangularis is the most and smooth lateral faces. The basal outline is oval to common taxon in the middle and upper part of the lacriform. Only broad morphotypes compressed from Paroistodus proteus Zone. If it co-occurs with one side are represented. The nearly geniculate and Drepanoistodus sp. aff. D. amoenus in samples SK-4/ rounded specimens reported for this taxon were not 31, SK-4/32 and SK-4/34, the appearance of the former observed in this study. species in Alborz in the uppermost Tremadocian sug- gests diachroneity of FADs. Proconodontus serratus Miller, 1969 (Fig. 4E) 1969 Proconodontus milleri serratus Miller; p. 438, pl. Systematic palaeontology 66, figs 1–4. Although all the identified taxa are illustrated (Figs 1980 Proconodontus serratus Miller; Miller, p. 31, pl. fi fi 4–9), species represented by low numbers are not 1, g. 13, text- g. 4D. described, or are only briefly discussed in this section, 1991 Proconodontus serratus Miller; Müller & Hinz, fi – fi – because they do not provide new information on the p. 56, pl. 42, gs 17 21, pl. 43, gs 1 3, 6, 7, text- fi morphology or systematics of the taxon. More extensive g. 22a (more complete synonymy). discussion and descriptions are provided for species that 1998 Proconodontus serratus Miller; Szaniawski & fi – fi are new for the region, and for taxa that require taxo- Bengtson, p. 18, pl. 1, gs 1 3, 7, pl. 4, gs 9, 10, – nomic or morphological clarification. 13, 17 19. The taxonomy of conodonts accepted in the paper 2014 Proconodontus serratus Miller; Jahangir et al., pl. fi follows the most recent concepts on multi-element 1, g. 8.

Downloaded by [Gazi University] at 08:12 17 December 2015 apparatuses. All elements are described using the con- Material. Simeh-Kuh section: 22 specimens from sam- ventional orientation and notation scheme (Clark et al. ples SK4/1–SK4/8; Deh-Molla section: 12 elements 1981, Sweet 1988). from samples DM-A/1–A/3, DM-A/3C and DM-A/3E.

Class CONODONTA Eichenberg, 1930 Remarks. Specimens from Simeh-Kuh have all the major Order EUCONODONTA Müller & Hinz, 1991 features of the species. They are gently and evenly Family PROCONODONTIDAE Lindström, 1970 recurved, with keeled anterior and posterior margins and Proconodontus Miller, 1969 with a serrated posterior keel except for the apical part.

Type species. Proconodontus muelleri Miller, 1969. Eoconodontus Miller, 1980 Type species. Eoconodontus notchpeakensis (Miller, Proconodontus muelleri Miller, 1969 (Fig. 4A, B) 1969) fi 1969 Proconodontus muelleri Miller; p. 437, pl. 66, gs Eoconodontus notchpeakensis (Miller, 1969) – fi fi 34 40; g. 5h, non pl. 66, gs 31?, 32, 33. (Fig. 4C, D) 1980 Proconodontus muelleri Miller; Miller, p. 2931, pl. 1, fig. 7, text-fig. 4C. 1969 Proconodontus notchpeakensis; Miller, p. 438, 1991 Proconodontus muelleri Miller; Müller & Hinz, text-fig. 5G, pl. 66, figs 21–29. p. 56, pl. 42, figs I, 3–9, non pl. 42, figs 2?, 10?, 1969 Proconodontus carinatus Miller; p. 437, text-fig. 11, 14, 15, 16?. (more complete synonymy) 5I, pl. 66, figs 13–20. ALCHERINGA CAMBRIAN–ORDOVICIAN CONODONTS FROM IRAN 17

1980 Eoconodontus notchpeakensis (Miller); Miller, non 2014 Cordylodus andresi Viira & Sergeeva; pp. 22–23, fig. 3D, E, pl. 1, figs 10–12 (complete Bagnoli & Stouge, p. 18, fig. 11F–M. synonymy). non 1988 Cordylodus andresi Barnes; pp. 410, 411, figs 2002 Eoconodontus notchpeakensis (Miller); Pyle & 13d–f, 14a (=Cordylodus delicatus Pyle & Barnes Barnes, p. 182, pl. 7, figs 1–3 (more complete syn- 2002). onymy). fi 2009 Eoconodontus notchpeakensis (Miller); Tol- Material. Simeh-Kuh section: ve specimens from sam- macheva & Abaimova, pp. 437, 438, figs 4C–G, M; ples SK4/12; Deh-Molla section: eight elements from 9A–C. samples DM-A/4, DM-A/4A and DM-A/4B. 2014 Eoconodontus notchpeakensis (Miller); Jahangir Remarks. The shape of the basal cavity is among the et al., pl. 1, fig. 9. most significant features for discriminating Cordylodus Material. Simeh-Kuh section: four M specimens from species (Miller 1969, 1980, Druce & Jones 1971, samples SK4/3, SK4/5, SK4/12; Deh-Molla section: five Bagnoli et al. 1988). The depth of the basal cavity can P-elements and three S-elements from samples DM-A/3 be seen and photographed in the optical microscope, fi and DM-A/3E. but SEM photographs do not provide suf cient informa- tion for precise discrimination of early members of the Remarks. Miller (1969) described rounded elements of Cordylodus lineage. P. notchpeakensis and later (Miller 1980) assigned them The specimens identified as Cordylodus andresi (together with compressed elements of Proconodontus from Simeh-Kuh have a distinctly recurved cusp and carinatus) to the Eoconodontus multi-element apparatus. large base with a denticulate posterior edge, which car- Since that time, morphotypes of E. notchpeakensis have ries two to four denticles on the cusp and the posterior been described as either drepanodiform and scandodi- processes. Rounded elements have an extensive, deep form (e.g., Landing 1983, Dubinina 2000)oras basal cavity, which extends deep into the tip of the rounded and compressed (e.g., Miller 1980). Zhen & cusp. In the studied specimens, the anterior edge of the Percival (2006) applied a letter designation for these basal cavity curves convexly very near to the edge of morphotypes, which is followed here. the element proper, whereas the posterior edge is Only M-elements of the E. notchpeakensis apparatus smoothly recurved and has distinct extensions beneath are present in the samples from Simeh-Kuh. They are the denticles. Compressed and twisted elements are not laterally compressed and asymmetrical owing to lateral represented in the collection, but the morphology of the deflection of the element inwards, with smooth lateral specimens available allows confident assignation to this faces and the anterior edge being keeled sharply from species. the tip of the cusp to the basal margins. The posterior It is likely that specimens from the Yudachica edge is keeled sharply on the tip of the cusp but Member of the Oaxaquia Terrane, Mexico named becomes weakly keeled to rounded towards the basal Cordylodus? andresi also belong to this species sensu margin. The cusp is infilled with white matter and has stricto. They occur together with Proconodontus the form of a short, slightly recurved, simple cone. The muelleri and very weakly denticulate Proconodontus basal cavity is very deep, but does not reach the tip, ter- serratus, two species that do not range into the Cordy- minating at the bend of the cusp. The S-elements recov- lodus proavus Zone on tropical carbonate platforms of Downloaded by [Gazi University] at 08:12 17 December 2015 ered from the Deh-Molla section are rounded on both Laurentia and North China (Landing et al. 2007), sides and lack a keel. The basal outline is suboval with whereas their occurrence in the Yudachica Member is smooth lateral faces. definitely prior to the FAD of Cordylodus proavus in the middle part of the unit. Family CORDYLODONTIDAE Lindström, 1970 There is confusion about the date when the binomen Cordylodus andresi Viira & Sergeyeva became avail- Cordylodus Pander, 1856 able. Formally, the taxon was defined in a publication Type species. Cordylodus angulatus Pander, 1856. by Viira et al.(1987); however, Szaniawski & Bengtson (1998) suggested that it was available since it was first Cordylodus andresi Viira & Sergeyeva in Kaljo et al., published by Kaljo et al.(1986) without discussion of 1986 (Figs 4F, G; 5A–E; 6A–D) this matter. Indeed, in addition to illustrations, Kaljo et al.(1986, p. 103) provided a written definition that 1986 Cordylodus andresi sp. nov. Viira & Sergeyeva in outlined characters that are purported to differentiate the Kaljo et al., p. 103, pl. 2, figs 1–6, 9, 10. taxon, which meet the requirements of the ICZN (1999, 1987 Cordylodus andresi Viira & Sergeyeva in Viira Arts 11.9, 13.1.1) for new taxa designated between et al.; pp. 147, 148, pl. 1, figs 1–8, pl. 3, figs 1–4; 1960 and 1999. text-fig. 2, 33–59. Recently, after the revision of the types of Cordylo- 2007 Cordylodus andresi Viira & Sergeeva; Landing dus andresi, Bagnoli (personal communication 2015) et al., p. 915, figs 5a–g, 10g, h. came to the conclusion that specimens assigned to 18 HADI JAHANGIR et al. ALCHERINGA

Cordylodus andresi from the Furongian of southern Material. Simeh-Kuh section: 61 specimens from Öland belong to a different, not yet formally defined, samples SK4/19, SK4/29 SK4/31–SK4/36 (Table 2). species. Unlike the types of Cordylodus andresi from the Remarks. This geographically widespread and long- Furongian Maardu Member of north Estonia, they have ranging species is quite abundant in the upper Tremado- prominent keels in the compressed elements and a very cian of Simeh-Kuh where it contributes up to 40% of deep basal cavity that reaches to the tip of the cusp. the conodont elements in individual associations. The morphology of all morphotypes in the collection agrees Family FRYXELLODONTIDAE Miller, 1980 fully with descriptions and illustrations given by Löfgren & Tolmacheva (2003), but Sb-elements were Kallidontus Pyle & Barnes, 2002 not observed.

Type species. Kallidontus serratus Pyle & Barnes, Family DREPANOISTODONTIDAE Fåhreaus & Now- 2002. lan, 1978

Kallidontus sp. (Fig. 8E, F, G) Drepanoistodus Lindström, 1971

Material. Simeh-Kuh section: three Pb-elements and Type species. Oistodus forceps Lindström, 1955 three S-elements; samples SK4/31, SK4/32, SK4/36. Drepanoistodus sp. cf. D. nowlani Ji & Barnes, 1994 Remarks. The diagnostic Pb elements of the unnamed (Fig. 7G–J) Iranian species are most similar to the Pb-elements of the Canadian species Kallidontus nodosus (Skoki 2002 Drepanoistodus nowlani Ji & Barnes; Pyle & Formation, Acodus kechikaensis Zone of British Barnes, p. 63, pl. 6, figs 13–15. Columbia), which are characterized by a convex 2007 Drepanoistodus sp. cf. Drepanoistodus nowlani Ji anterior cusp face and a concave posterior cusp face. & Barnes; Zhen et al., p. 132, pl. 2, figs 1–21, pl. However, the specimens from Simeh-Kuh differ in hav- 3, figs 1–9. (synonymy) ing a gently convex posterior cusp face. The S-elements unlike K. nodosus, have strong nodes (not blunt denti- Material. Simeh-Kuh section: Three Pa-elements and cles) along the posterior process and weakly developed two M-elements from samples SK4/23 and SK4/29. transverse ridges. Remarks. This species is represented in the collection Kallidontus gondwanicus Zeballo & Albanesi, 2013 by the Pa- and M-elements. They closely resemble from the Tremadocian Coquiena Formation (Paltodus Drepanoistodus sp. cf. Drepanoistodus nowlani deltifer Zone) of Cordillera Oriental, Argentina is prob- described by Zhen & Nicoll (2009) from the Emanuel ably the earliest documented species of the genus. The Formation of the Canning Basin, Western Australia. At Iranian Kallidontus sp. differs from it in having more Simeh-Kuh, Drepanoistodus sp. cf. D. nowlani is appar- prominent processes and more strongly developed nodes ently restricted to a low-diversity interval in the upper and transverse ridges on Pb-elements, whereas differen- part of the Paltodus deltifer Zone and also occurs in the tiation of the S-element morphotype series in Kallidon- lowermost sample of the Paroistodus proteus Zone. tus gondwanicus is provisional according to Zeballo &

Downloaded by [Gazi University] at 08:12 17 December 2015 Albanesi (2013). It is likely that the Iranian specimens Paltodus Pander, 1856 of Kallidontus belong to a separate, not formally desig- nated species, but the available material is not satisfac- Type species. Paltodus subaequalis Pander, 1856 tory for its detailed description. Paltodus deltifer pristinus Viira, 1970 (Fig. 7C–F) Order PROTOPANDERODONTIDA Sweet, 1988 1970 Drepanodus pristinus Viira, p. 227, text-figs 5, 6, Family DISTACODONTIDAE Bassler, 1925 pl. 1, figs 7, 8. Drepanodus Pander, 1856 1970 Acodus firmus Viira, p. 225, text-fig. 2, pl. 1, fig. 9. 1970 Drepanodus bisymmetricus Viira, p. 226, text-figs Type species. Drepanodus arcuatus Pander, 1856 3, 4, pl. 1, figs 1–5. 1970 Drepanodus aff. subarcuatus Furnish; Viira, pl. 1, Drepanodus arcuatus Pander, 1856 (Fig. 7K–S) figs 18, 19. fi 1856 Drepanodus arcuatus Pander, p. 20, pl. 1, figs 2, 1970 Scandodus varanguensis Viira; p. 230, gs 8, 9, fi 4, 5, 17, 30, ?31. pl. 1, gs 11, 12. 2003 Drepanodus arcuatus Pander; Löfgren & Tol- 1980 Paltodus deltifer pristinus (Viira); Szaniawski, fi – macheva, pp. 211–215, figs 2, 3A–C, E–H, 5K–V, p. 113, pls 16, 17, 18, gs 2, 7 11, 13. 6M–U, 7H–N, 8A–G. (full synonymy) 1997a Paltodus deltifer pristinus (Viira); Löfgren, fi – – 2013 Drepanodus arcuatus Pander; Voldman et al., p. 263, gs 5P Y, 6A G. (source includes p. 305, pl. 3, figs 19–21. synonymy) ALCHERINGA CAMBRIAN–ORDOVICIAN CONODONTS FROM IRAN 19 Downloaded by [Gazi University] at 08:12 17 December 2015

Fig. 8. A–D, Paroistodus proteus Lindström 1955; A, AEU/L 5059, Pa-element, inner lateral view, sample SK4/31; B, AEU/L 5060, Pa-element, outer lateral view, sample SK4/31; C, Pb-element, AEU/L 5061, outer lateral view, sample SK4/34; D, M-element, AEU/L 5062, outer lateral view; sample SK4/36. E–G, Kallidontus sp., E, AEU/L 5063, S-element, sample Sk-4/31; outer anterolateral view; F, Pb-element, AEU/L 5064, outer lateral view, sample SK4/31; G, AEU/L 5065, Pb-element, outer lateral view, sample SK4/31. H, Oneotodus variabilis Lindström, 1955, sample SK4/31, AEU/L 5065, inner anterolateral view. I, J, Acodus sp. cf. A. kechikaensis Pyle & Barnes, 2002, sample Sk-4/36; I, AEU/L 5066, P-element; inner lateral view; J, AEU/L 5067, P-element; basal view. K, Cornuodus sp., sample Sk-4/36; AEU/L 5068, outer lateral view. L, M, Gen. et sp. indet., sample SK4/36; L, AEU/L 5069, posterior view; M, AEU/L 5070, inner lateral view. N, Triangulodus sp. cf. T. larapintinensis Crespin, 1943, sample SK4/36; AEU/L 5071, E-element; inner lateral view. O, Paltodus subaequalis Pander, 1856, sample SK4/36; AEU/L 5072, M-element; inner lateral view. Scale bars = 100 μm. 20 HADI JAHANGIR et al. ALCHERINGA Downloaded by [Gazi University] at 08:12 17 December 2015

Fig. 9. Acodus sp. cf. A. triangularis (Ding in Wang, 1993); A, AEU/L 5073, Pa-element, outer lateral view, sample SK4/36; B, AEU/L 5074, Pa-element, inner lateral view, sample SK4/36; C, AEU/L 5075, Pa-element, outer lateral view showing the fine striae in the area posterior to the outer lateral costa, sample SK4/36; D, AEU/L 5076, Pb-element, outer lateral view, sample SK4/33; E, AEU/L 5077, Pb-element, inner anterolateral view, sample SK4/33; F, AEU/L 5078, M-element, inner lateral view, sample SK4/36; G, AEU/L 5079, outer anterolateral view, sample SK4/36; H, AEU/L 5083, Sa-element, outer lateral view, sample SK4/36; I, AEU/L 5082, M-element, inner lateral view, sample SK4/36; J, AEU/L 5081, M-element, outer lateral view, sample SK4/36; K, AEU/L 5080, M-element, basal inner lateral view, sample SK4/32; L, AEU/L 5084, Sa-element, posterior view, sample SK4/33; M, AEU/L 6000, Sa-element, outer lateral view; N, AEU/L 5085, Sa-element, posterior view, sample SK4/36; O, AEU/L 5086, Sb-element, anterior view, sample SK4/35; P, AEU/L 5087, Sb-element, posterior view, sample SK4/35; Q, AEU/L 5088, Sb-element, outer lateral view, sample SK4/36; R, AEU/L 5089, Sb-element, outer lateral view, sample SK4/36; S, AEU/L 5090, inner posterolateral view, Sb-element, inner posterolateral view, sample SK4/36; T, AEU/L 5091, Sc-element, inner lateral view, sample SK4/35. U, AEU/L 5092, Sc-element, inner posteriolateral view, sample SK4/36. V, AEU/L 5093, Sc-element, basal view, sample SK4/36. W, AEU/L 5094, Sd-element, inner lateral view, sample SK4/35. X, AEU/L 5095, Sd-element, inner lateral view, sample SK4/36. Y, AEU/L 5096, Sd-element, outer lateral view, sample SK4/36. Z, AEU/L 5097, Sd-element, posterior view, sample SK4/36. AA, AEU/L 5098, Sd-element, posterior view, sample SK4/35. AB, AEU/L 5099, Sd-element, basal view, sample SK4/35. Scale bars = 100 μm. ALCHERINGA CAMBRIAN–ORDOVICIAN CONODONTS FROM IRAN 21

2011 Paltodus deltifer pristinus (Viira); Ghobadi Pour Material. Simeh-Kuh section: five Pa-elements, five Pb et al. fig. 3F, H. elements and 13 M-elements from samples SK4/29, SK4/31, SK4/33–SK4/36. Material. Simeh-Kuh section: two drepanodiform and 11 oistodiform elements from samples SK4/19, SK4/20, Remarks. Paroistodus proteus was revised by Löfgren SK4/23. (1997b) as having a septimembrate apparatus. The spe- cies is relatively rare in the studied samples, thus only Remarks. This is the second report of the occurrence of three morphotypes (Pa, Pb, M) have been identified. Paltodus deltifer pristinus from Iran. Previously, Nevertheless, specimens from Simeh-Kuh are very simi- M- and Sa-elements assigned to this taxon were illus- lar to those described from the late Tremadocian to fi trated by Ghobadi Pour et al.(2011b, g. 3F, H) from Floian of Baltoscandia (Löfgren 1997b). the Lower Ordovician (Tremadocian) of the Deh-Molla section. Order PRIONIODONTIDAE Dzik, 1976 The apparatuses of Paltodus deltifer and Paltodus Family ACODONTIDAE Dzik, 1994 deltifer pristinus were illustrated and discussed in detail by Szaniawski (1980) and Löfgren (1997a). The new Acodus Pander, 1856 specimens are almost identical to those previously Type species. Acodus erectus Pander, 1856. described from Baltoscandia. Paltodus deltifer deltifer was not recovered from the Acodus sp. cf. A. kechikaensis Pyle & Barnes, 2002 Simeh-Kuh section, but this subspecies is apparently (Fig. 8I, J) present in the Shirgesht Formation of the Tabas region in north-central Iran (Ghobadi Pour & Turvey 2009, cf. 2002 Acodus kechikaensis Pyle & Barnes, p. 87, pl. fig. 3) and in the Lower Ordovician (Tremadocian) 1, figs 11–17. argillites of the Deh-Molla section (Ghobadi Pour et al. Material. Simeh-Kuh section: a few P elements, sample 2011b, fig. 3G, K). SK4/36. As mentioned by Szaniawski (1980), the conodont elements from the Lower Ordovician (Tremadocian) Remarks. A few specimens from sample SK4/36 are Shirgesht Formation of the Tabas region in east-central assigned to Acodus sp. cf. A. kechikaensis, because they fi Iran identi ed and illustrated by Müller (1973)as have a P-element with a prominent inner lateral costa, Drepanodus subarcuatus Furnish, 1938, Drepanodus which is similar to those described from northeastern suberectus (Branson & Mehl, 1933), Drepanodus British Columbia (Pyle & Barnes 2002) and Wilcox tenuis Moskalenko, 1967, Oistodus inaequalis Pander, pass, Alberta, Canada (Pyle et al. 2003). The 1856 and Ulrichodina sp., at least in part, are closely occurrence of Acodus sp. cf. A. kechikaensis in sample similar to the elements of Paltodus deltifer pristinus, SK4/36 is the earliest indication of the Floian Stage in but their precise taxonomic discrimination requires the conodont succession of the Simeh-Kuh section. further study, and they are not included here in the synonymy list. Acodus sp. cf. A. triangularis (Ding in Wang, 1993) (Fig. 9) Paroistodus Lindström, 1971

Downloaded by [Gazi University] at 08:12 17 December 2015 cf. 1993 Oistodus triangularis Ding; Wang p. 185, pl. Type species. Oistodus parallelus Pander, 1856. 19, figs 1, 2. cf. 2005 Acodus triangularis (Ding); Zhen et al., Paroistodus proteus (Lindström, 1955) emend. p. 307, figs 3–5. Löfgren, 1997b (Fig. 8A–D) Material. Simeh-Kuh section: 53 elements from samples 1955 Drepanodus proteus Lindström; p. 566, pl. 3, figs SK31–SK36 (Table 3). 18–21, text-fig. 2a–f, j. 1997b Paroistodus proteus (Lindström); Löfgren, Remarks. The species was first introduced by Ding fi – – p. 922, text- gs 3H N, 4L AB. (complete (in Wang 1993) based on type material from the synonymy) Honghuayuan Formation of Anhui Province, South 2001 Paroistodus proteus (Lindström, 1955); China. The multi-element concept of Acodus triangu- fi – Tolmacheva et al., g. 4.8 9. laris followed here was proposed by Zhen et al.(2005), 2007 Paroistodus proteus (Lindström, 1955); Zhen who also provided a comprehensive discussion of the fi – et al., p. 136, 137, pl. 5, gs 1 11. affinities of the taxon. The specimens from Simeh-Kuh 2009 Paroistodus proteus (Lindström, 1955); Zhen & are distinctly similar to morphotypes of the septimem- fi – Nicoll, p. 15, g. 8A K. brate Acodus triangularis apparatus as reconstructed by 2015 Paroistodus proteus (Lindström, 1955); Zhen Zhen et al.(2005) on the material from the Early fi – et al., p. 20, g. 13G N. Ordovician Honghuayuan Formation of South China 22 HADI JAHANGIR et al. ALCHERINGA

with the exception of the Sd-elements, which conodonts are yet reported from that stratigraphic completely lack the indistinct denticulation evident on interval owing to the complete absence of carbon- the specimens from South China (Zhen et al. 2005, ates. The base of the Paltodus deltifer Zone coin- fig. 5U, V). Nevertheless, we provisionally consider cides with FAD of the trilobite Psilocephalina them to be conspecific. lubrica, which is the eponymous species of the In Alborz, Acodus sp. cf. A. triangularis appears in local trilobite zone widely recognized in the eastern the uppermost Tremadocian part of the Paltodus deltifer Alborz region (Ghobadi Pour et al. 2015). Another Zone, whereas in South China, they occur in the Tetra- regressive event occurred close to the base of the graptus approximates Zone equivalents suggesting an Paroistodus proteus Zone. It was probably syn- early Floian age (Zhen et al. 2005). chronous with the Ceratopyge Regressive Event. (5) The position of the Floian Stage lower boundary is Triangulodus van Wamel, 1974 poorly constrained in the studied conodont succes- sion, although it can be placed close to the FAD of Type species. Scandodus brevibasis (Sergeeva), sensu Acodus sp. cf. A. kechikaensis in the upper part of Lindström, 1971. the Paroistodus proteus Zone. Triangulodus sp. cf. T. larapintinensis (Crespin, 1943) (Fig. 8N)

Material. Simeh-Kuh section: one Pb-element from sample SK4/36. Acknowledgements Our special thanks to Gabriella Bagnolli for her Remarks. The Pb-element of this species from Simeh- comprehensive and constructive comments, which were Kuh is similar to those described from western New very helpful in improving the manuscript. We are South Wales, Australia, by Zhen et al.(2003) except grateful to two anonymous reviewers for their valuable for the less extended basal-posterior corner. suggestions, which helped to improve the final presenta- tion of the paper. Hadi Jahangir and Alireza Ashuri acknowledge support from the Ferdowsi University, Conclusions Mashhad. Mansoureh Ghobadi Pour and Arash Amini acknowledge support from the Golestan University. (1) The uppermost Cambrian to Lower Ordovician (Tremadocian) conodont biostratigraphic succession is described for the first time from the eastern References Alborz region of northern Iran; 13 genera and 19 AGHABABALU, B., 1999. Biostratigraphy of early Carboniferous species of euconodonts, paraconodonts and proto- brachiopods in north of Damghan area (east of Alborz). M.Sc. conodonts are documented; the Proconodontus thesis, Esfahan University, Esfahan, 190 pp. (unpublished; in muelleri, Eoconodontus notchpeakensis, Cordylodus Persian) andresi zones in the uppermost Furongian and ALAVI,M.&SALEHI-RAD, R., 1975. Geological map of Damghan. Geological map of Iran 1:100,000 Series, Sheet 6862, Geological Cordylodus proavus, Paltodus deltifer and survey of Iran, Tehran. Paroistodus proteus zones in the Tremadocian are AN, T., ZHANG, F., XIANG, W., ZHANG, Y., XU, W., ZHANG, H., JIANG, Downloaded by [Gazi University] at 08:12 17 December 2015 recognized. D., YANG,CH., LIN, L., CUI,ZH.&YANG, X., 1983. The – conodonts of north China and the adjacent regions. Science (2) In general, the conodont fauna from the Cambrian Press, Beijing, 223 pp. (in Chinese with English abstract) Ordovician boundary beds of northern Iran is ARTYUSHKOV, E.V., LINDSTROM,M.&POPOV, L.E., 2000. Relative characterized by low diversity and abundance. sea-level changes in Baltoscandia in the Cambrian and early Nevertheless, the occurrence of a few biostrati- Ordovician: the predominance of tectonic factors and the absence of large scale eustatic fluctuations. Tectonophyisics 320, 375–407. graphically informative eoconodont species enables ASSERETO, R., 1963. The Paleozoic formations in Central Elburz (Iran) relatively precise correlation of the Iranian succes- (Preliminary notes). Rivista Italiana di Paleontologia e sion within the Cold Domain of the Shallow-Sea Stratigrafia69, 503–543. Realm sensu Zhen & Percival (2003) and beyond. BAGNOLI,G.&STOUGE, S., 2014. Upper Furongian (Cambrian) conodonts from the Degerhamn quarry road section, southern (3) Invasion of the euconodonts in the upper Furongian Öland, Sweden. GFF 136, 436–458. (Proconodontus muelleri Zone) of the Alborz BAGNOLI, G., STOUGE,S.&TONGIORGI, M., 1988. Acritarchs and region coincided with a marine transgression and conodonts from the Cambro-Ordovician Furuhäll (Köpingsklint) section (Öland, Sweden). Rivista Italiana Paleontologia termination of continuous carbonate sedimentation, fi – fi Stratigra a94, 163 248. whereas the rst appearance of Cordylodus BARNES, C.R., 1988. The proposed Cambrian-Ordovician global (C. andresi Zone) occurred at the time of a sea boundary stratotype and point (GSSP) in Western Newfoundland, level lowstand. Canada. Geological Magazine 124, 381–414. BASSLER, R.S., 1925. Classification and stratigraphic use of the (4) The base of the Ordovician in the Alborz region – fl consodonts. Geological Society of America Bulletin 36, 218 220. coincided with proliferation of the Asaphellus in a- BERGERON, J., 1894. Notes paleontologiques. I. Crustacés. Bulletin de tus—Dactylocephalus trilobite association, but no la Société Géologique de la France 2, 333–346. ALCHERINGA CAMBRIAN–ORDOVICIAN CONODONTS FROM IRAN 23

BILLINGS, E., 1860. On some new species of fossils from the limestone GHOBADI POUR, M., KEBRIA-EE ZADEH, M.R. & POPOV, L.E., 2011a. near Point Levi, opposite Quebec. Canadian Naturalist and Early Ordovician (Tremadocian) brachiopods from Eastern Alborz Geologist 5, 301–324. Mountains, Iran. Estonian Journal of Earth Sciences 60,65–82. BRANSON, E.B. & MEHL, M.G., 1933. Conodont studies number one. GHOBADI POUR, M., MOHIBULLAH, M., WILLIAMS, M., POPOV, L.E. & University of Missouri Studies 8,5–72. TOLMACHEVA,TYU, 2011b. New, early ostracods from the CHEN,J.&GONG, W., 1986. Conodonts. In Aspects of Cambrian- Ordovician (Tremadocian) of Iran: systematic, biogeographical Ordovician Boundary in Dayangcha, China.CHEN, J., ed., China and palaeoecological significance. Alcheringa 35, 517–529. Prospect Publishing House, Beijing, 93–223. GHOBADI POUR, M., POPOV, L.E., KEBRIA-EE ZADEH, M.R. & BAARS, C., CLARK, D.L., SWEET, W.C., BERGSTRÖM, S.M., KLAPPER, G., AUSTIN, 2011c. Middle Ordovician (Darriwilian) brachiopods associated R.L., RHODES, F.H.T., MÜLLER, K.J., ZIEGLER, W., LINDSTRÖM, M., with the Neseuretus biofacies, eastern Alborz Mountains, Iran. MILLER, J.F. & HARRIS, A.G., 1981. Conodonta. In Treatise on Memoirs of the Association of Australasian Palaeontologists 42, Invertebrate Paleontology, part W, Miscellanea, supplement 2. 263–283. ROBISON, R.A., ed., Geological Society of America, Boulder and GHOBADI POUR, M., POPOV, L.E., HEJAZI, S.H., HOLMER, L.E., University of Kansas, Lawrence, 202 pp. HOSSEINI-NEZHAD, M., RASULI, R., FALLAH,KH,AMINI,A.& COOPER, R.A. & SADLER, P.M., 2012. The Ordovician Period. In The JAHANGIR, H., 2015. Early Ordovician (Tremadocian) faunas and Geologic Time Scale 2012.GRADSTEIN, F.M., OGG, J.G., SCHMITZ, biostratigraphy of the Gerd-Kuh section, eastern Alborz, Iran. M. & OGG, G., eds, Elsevier, Amsterdam, 489–523. Stratigraphy 12,55–61. CRESPIN, I., 1943. Conodonts from the Waterhouse Range, Central HOLMER, L.E., POPOV, L.E., KONEVA, S.P. & BASSETT, M.G., 2001. Australia. Transactions of the Royal Society of South Australia Cambrian–early Ordovician brachiopods from Malyi Karatau, the 67, 231–233. western Balkhash Region, and northern Tien Shan, Central Asia. DRUCE, E.C. & JONES, P.J., 1971. Cambro-Ordovician conodonts from Special Papers in Palaeontology 65,1–180. the Burke River Structural Belt, Queensland. Bureau of Mineral HSÜ, S.C., 1948. Part III, The I-Changian trilobites and other fossils. Resources, Geology and Geophysics, Bulletin 110,1–159. In The I-Chang Formation and the Ichangian fauna. HSÜ,S.& DUBININA, S.V., 2000. Conodonts and zonal stratigraphy of the Cam- MA, C., eds., Contributions from the Institute of Geology 8,1–51. brian–Ordovician boundary beds. Trudy Geologicheskogo Instituta ICZN, 1999. International Code of Zoological Nomenclature, 4th 517, 239. (in Russian) Edition. International Commission on Zoological Nomenclature, DZIK, J., 1976. Remarks on the evolution of Ordovician conodonts. London, 306 pp. Acta Paleontologia Polonica 21, 395–455. JAHANGIR, H., GHOBADI POUR,M.&ASHOURI, A.R., 2014 (1392). DZIK, J., 1994. Conodonts of the Mojcza Limestone. In Ordovician Palaeobiogeography of conodonts from the Alborz Mountains Carbonate Platform Ecosystem of the Holy Cross Mountains. through Cambrian–Ordovician transition. Paleontology (Iran) 1, DZIK, J., OLEMPSCKA,E.&PISERA, A., eds., Palaeontologia 137–148. (In Persian) Polonica 53,43–128. JI,Z.&BARNES, C.R., 1994. Lower Ordovician conodonts of the St. EICHENBERG, W., 1930. Conodonten aus dem Culm des Harzes. George Group, Port au Port Peninsula, western Newfoundland, Paläontologische Zeitschrifl 12,77–182. Canada. Palaeontographica Canadiana 11,1–149. FÅHRÆUS, L.E. & NOWLAN, G.S., 1978. Franconian (Late Cambrian) to KALJO, D., BOROVKO, N., HEINSALU, H., KHAZANOVICH, K., MENS, K., early Champlainian (Middle Ordovician) conodonts from the Cow POPOV, L., SERGEYEVA, S., SOBOLEVSKAYA,R.&VIIRA, V., 1986. Head Group, western Newfoundland. Journal of Paleontology 52, The Cambrian-Ordovician boundary in the Baltic-Ladoga clint 444–471. area. Eesti NSV Teaduste Akadeemia Toimetised. Geoloogia 35, FURNISH, W.M., 1938. Conodonts from the Prairie du Chien (Lower 97–108. Ordovician) beds of the Upper Mississippi Valley. Journal of KEBRIA-EE ZADEH, M.R., GHOBADI POUR, M., POPOV, L.E., BAARS,C.& Paleontology 12, 318–340. JAHANGIR, H., 2015. First record of the Ordovician fauna in GANSSER,A.&HUBER, H., 1962. Geological observations in the Mila-Kuh, eastern Alborz, northern Iran. Estonian Journal of Central Elburz, Iran. Schweizerische Mineralogische und Earth Sciences 64, 121–139. Petrographische Mitteilungen 42, 593–630. KUSHAN, B., 1973. Stratigraphie und trilobiten Fauna in der GEYER, G., BAYET-GOLL, A., WILMSEN, M., MAHBOUBI,A.& Mila-Formation Mittelkambrium-Tremadoc) im Alborz-Gebirge MOUSSAVI-HARAMI, R., 2014. Lithostratigraphic revision of the (N-Iran). Palaeontographica A 144,113–165. middle Cambrian (Series 3) and upper Cambrian (Furongian) in LANDING, E., 1983. Highgate Gorge: Upper Cambrian and Lower northern and central Iran. Newsletters on Stratigraphy 47,21–59. Ordovician continental slope deposition and biostratigraphy, GHADERI, A., AGHANABATIL, A., HAMDI,B.&MILLER, J.F., 2009. Northwestern Vermont. Journal of Paleontology 57, 1149–1188. Downloaded by [Gazi University] at 08:12 17 December 2015 Biostratigraphy of the first and second member of type section of LANDING, E., WESTROP, S.R. & KEPPIE, J.D., 2007. Terminal Cambrian the Shirgesht Formation in north of Tabas with special emphasis and lowest Ordovician succession of Mexican West Gondwana: on conodonts. Journal of Earth Scinces Iran 67, 150–163. biotas and sequence stratigraphy of the Tinu Formation. GHAVIDEL-SYOOKI, M., 2006. Palynostratigraphy and palaeogeography Geological Magazine 144, 909–936. of the Cambro-Ordovician strata in southwest of Shahrud city LINDSTRÖM, M., 1955. Conodonts from the lowermost Ordovician (Kuh-e-Kharbash, near Deh-Molla), Central Alborz, Northern strata of south-central Sweden. Geologiska Foreningens i Iran. Review of Palaeobotany and Palynology 139,81–95. Stockholm Forhandlingar 76, 517–604. GHOBADI POUR, M., 2006. Early Ordovician (Tremadocian) trilobites LINDSTRÖM, M., 1970. A suprageneric taxonomy of the conodonts. from Simeh-Kuh, Eastern Alborz, Iran. In Studies in Palaeozoic Lethaia 3, 427–445. palaeontology. BASSETT, M.G. & DEISLER, V.K., eds., National LINDSTRÖM, M., 1971. Lower Ordovician conodonts of Europe. Museum of Wales Geological Series 25,93–118. Geological Society of America Memoir 127,21–61. GHOBADI POUR,M.&POPOV, L.E., 2009. First report on the occurrence LÖFGREN, A., 1997a. Conodont faunas from the upper Tremadoc at of Neseuretinus and Ovalocephalus in the Middle Ordovician of Brattefors, south-central Sweden, and reconstruction of the Iran. Acta Palaeontologica Polonica 54, 125–133. Paltodus apparatus. GFF 119, 257–266. GHOBADI POUR,M.&TURVEY, S.T., 2009. Revision of some Lower to LÖFGREN, A., 1997b. Reinterpretation of the Lower Ordovician Middle Ordovician leiostegiid and associated trilobites from Iran conodont apparatus Paroistodus. Palaeontology 40, 913–929. and China. Memoirs of the Association of Australasian LÖFGREN,A.&TOLMACHEVA,TYU, 2003. Taxonomy and distribution Palaeontologists 37, 463–480. of the Ordovician conodont Drepanodus arcuatus Pander, 1856, GHOBADI POUR, M., WILLIAMS, M., VANNIER, J., MEIDLA,T.&POPOV, and related species. Paläontologische Zeitschrift 77, 203–221. L.E., 2006. Ordovician ostracods from east-central Iran. Acta LU, Y., 1962. Early Ordovician trilobites. In A Handbook of Index Palaeontologica Polonica 51, 551–560. Fossils of Yangtze District.WANG, Y., ed., Science Press, Beijing, GHOBADI POUR, M., VIDAL,M.&HOSSEINI-NEZHAD, M., 2007. An 42–47. (In Chinese) Early Ordovician trilobite assemblage from the Lashkarak MÄNNIK,P.&VIIRA, V., 2012. Ordovician conodont diversity in the Formation, Damghan area, northern Iran. Geobios 40, 489–500. northern Baltic. Estonian Journal of Earth Sciences 61,1–14. 24 HADI JAHANGIR et al. ALCHERINGA

MILLER, J.F., 1969. Conodont fauna of the Notch Peak Limestone Iran. Memoirs of the Association of Australasian Palaeontolo- (Cambro-Ordovician) House Range, Utah. Journal of Paleontol- gists 37, 103–122. ogy 43, 413–439. POPOV, L.E., GHOBADI POUR, M., KEBRIA-EE ZADEH, M.-R. & SHAHBEIK, MILLER, J.F., 1980. Taxonomic revisions of some Upper Cambrian and S., 2011. First record of silicified Cambrian (Furongian) Lower Ordovician conodonts with comments on their evolution. rhynchonelliform brachiopods from the Mila Formation, Alborz The University of Kansas, Paleontological Contribution 99,1–44. Range, Iran. Memoirs of the Association of Australasian Palaeon- MILLER, J.F., EVANS, K.R., LOCH, J.D., ETHINGTON, R.L., STITT, J.H., tologists 42, 193–207. HOLMER, L.E. & POPOV, L.E., 2003. Stratigraphy of the Sauk III PYLE, L.J. & BARNES, C.R., 2002. Taxonomy, evolution, and interval (Cambrian–Ordovician) in the Ibex area, western Millard biostratigraphy of conodonts from the Kechika Formation, Skoki County, Utah and central Texas. Brigham Young University Formation, and Road River Group (Upper Cambrian to Lower Geology Studies 47,23–118. Silurian). NRC Research Press, Ottawa, Northeastern British MILLER, J.F., ETHINGTON, R.L., EVANS, K.R., HOLMER, L.E., LOCH, J.D., Columbia, 227 pp. POPOV, L.E., REPETSKI, J.E., RIPPERDAN, R.L. & TAYLOR, J.F., PYLE, L.J., BARNES, C.R. & JI, Z., 2003. Conodont fauna and bios- 2006. Proposed stratotype for the base of the highest Cambrian tratigraphy of the Outram, Skoki, and Owen Creek formations stage at the first appearance datum of Cordylodus andresi, (Lower to Middle Ordovician), Wilcox Pass, Alberta, Canada. Lawson Cove section, Utah, USA. Palaeoworld 15, 384–405. Journal of Paleontology 77, 958–976. MILLER, J.F., EVANS, K.R., FREEMAN, R.L., RIPPERDAN, R.L. & TAYLOR, SALTER, J.W., 1864. Figures and descriptions illustrative of British J.F., 2011. Proposed stratotype for the base of the Lawsonian organic remains. Decade 11, Trilobites (chiefly Silurian). Memoirs Stage (Cambrian Stage 10) at the First Appearance Datum of of the Geological Survey of the United Kingdom,1–64. Eoconodontus notchpeakensis (Miller) in the House Range, Utah, SHENG, X., 1958. Ordovician trilobites of southwestern China. Acta USA. Bulletin of Geosciences 86, 595–620. Palaeontologica Sinica 6, 169–204. [In Chinese with English MOSKALENKO, T.A., 1967. Conodonts from the Tsun’ Stage (Lower summary] Ordovician) of the rivers Moiero and Podkamennaya Tunguska. STÖCKLIN, J., RUTTNER,A.&NABAVI, M.N., 1964. New data on the In New data on the Lower Palaeozoic deposits of the Siberian lower Palaeozoic and Precambrian of North Iran. Geological Platform. IVANOVSKII, A.B. & SOKOLOV B.S., eds., Trudy Instituta Survey of Iran, Reports 1,1–29. geologii i geofiziki Sibirskogo otdeleniya Akademii Nauk SSSR SWEET, W.C., 1988. The Conodonta: morphology, taxonomy, palaeoe- 137,98–116. (in Russian) cology, and evolutionary history of a long-extinct animal phylum. MÜLLER, K., 1959. Kambrische Conodonten. Zeitschrift Deutschen Oxford Press, Clarendon, 212 pp. Geologische Gesellschaft 111, 434–485. SZANIAWSKI, H., 1980. Conodonts from the Tremadocian Chalcedony MÜLLER, K., 1964. Conodonten aus dem unteren Ordovizium von Beds, Holy Cross Mountains (Poland). Acta Paleontologica Polo- Südkorea. Neues Jahrbuch für Geologie und Paläontologie nica 25, 101–121. Abhandlung 119,93–102. SZANIAWSKI,H.&BENGTSON, S., 1998. Late Cambrian euconodonts MÜLLER, K., 1973. Late Cambrian and Early Ordovician conodonts from Sweden. In Proceedings of the Sixth European Conodont from northern Iran. Reports of Geological Survey of Iran 30, Symposium (ECOS VI).SZANIAWSKI, H., ed., Palaeontologia 1–77. Polonica 58, 7–29. MÜLLER,K.&HINZ, I., 1991. Upper Cambrian conodonts from Swe- TOLMACHEVA,T.YU &ABAIMOVA, G.P., 2009. Late Cambrian and Early den. Fossils and Strata 28,1–153. Ordovician conodonts from the Kulumbe River section, northwest NIELSEN, A.T., 2004. Ordovician sea level changes: A Baltoscandian Siberian Platform. Memoirs of the Association of Australasian perspective. In The Great Ordovician Biodiversification Event. Palaeontologists 37, 427–451. WEBBY, B.D., PARIS, F., DROSER, M.L. & PERCIVAL, I.G., eds, TOLMACHEVA,TYU,KOREN’, T.N., HOLMER, L.E., POPOV, L.E. & Columbia University Press, New York, NY, 84–93. RAEVSKAYA, E., 2001. The Hunneberg Stage (Ordovician) in the NÕLVAK, J., HINTS,O.&MÄNNIK, P., 2006. Ordovician timescale in area east of St. Petersburg, north-western Russia. Paläontologis- Estonia: recent developments. Proceedings of the Estonian che Zeitschrift 74, 543–561. Academy of Sciences, Geology 55,95–108. VAN WAMEL, W.A., 1974. Conodont biostratigraphy of the Upper Cam- PALMER, A.R., 1954. The faunas of the Riley Formation in Central brian and Lower Ordovician of northwestern Öland, south-eastern Texas. Journal of Paleontology 28, 709–786. Sweden. Utrecht Micropalaeontological Bulletins 10,1–125. PANDER, C.H., 1856. Monographie der fossilen Fische des silurischen VIIRA, V., 1970. Conodonts of the Varangu Member (Estonian upper Systems der russisch–baltischen Gouvernments. Akademie der Tremadoc). Eesti NSV Teaduste Akadeemia, Keemia-Geoloogia Wissenschaft, St Petersburg, 91 pp. 19, 224–233. (in Russian) Downloaded by [Gazi University] at 08:12 17 December 2015 PENG,S.&BABCOCK, L.E., 2005. Two Cambrian agnostoid trilobites, VIIRA, V., 2011. Lower and Middle Ordovician conodonts from the Agnostotes orientalis (Kobayashi, 1935) and Lotagnostus ameri- subsurface of SE Estonia and adjacent Russia. Estonian Journal canus (Billings, 1860): Key species for defining global stages of of Earth Sciences 60,1–21. the Cambrian System. Geosciences Journal 9, 107–115. VIIRA, V., SERGEEVA,S.&POPOV, L., 1987. Earliest representatives of PENG, S., BABCOCK, L.E. & COOPER, R.A., 2012. The Cambrian Period. the genus Cordylodus (Conodonta) from Cambro-Ordovician In The Geologic Time Scale 2012.GRADSTEIN, F.M., OGG, J.G., boundary beds of North Estonia and Leningrad region. Eesti NSV SCHMITZ,M.&OGG, G., eds, Elsevier, Amsterdam, 438–488. Teaduste Akadeemia Toimetised. Geoloogia 36, 145–153. POPOV, L.E. & HOLMER, L.E., 1994. Cambrian-Ordovician lingulate VOLDMAN, G.G., ALBANESI, G.L., MONALDI, C.R. & ZEBALLO, F., 2013. brachiopods from Scandinavia, Kazakhstan, and South Ural Biostratigraphy of the Santa Rosita Formation (Furongian– Mountains. Fossils and Strata 35,1–156. Tremadocian) in its type area, Eastern Cordillera, NW Argentina. POPOV, L.E., GHOBADI POUR,M.&HOSSEINI, M., 2008. Early to Stratigraphy 10, 301–322. Middle Ordovician lingulate brachiopods from the Lashkarak WANG, C., ed., 1993. Conodonts of the Lower Yangtze Valley—index Formation, Eastern Alborz Mountains, Iran. Alcheringa 32,1–35. to biostratigraphy and organic metamorphic maturity. Science POPOV, L.E., BASSETT, M.G., HOLMER, L.E. & GHOBADI POUR, M., Press, Beijing, 326 pp. 2009a. Early ontogeny and soft tissue preservation in siphonotre- ZEBALLO, F.J. & ALBANESI, G.L., 2013. New conodont species and tide brachiopods: New data from the Cambrian-Ordovician of biostratigraphy of the Santa Rosita Formation (upper Furongian– Iran. Gondwana Research 16, 151–161. Tremadocian) in the Tilcara Range, Cordillera Oriental of Jujuy, POPOV, L.E., GHOBADI POUR, M., BASSETT, M.G. & KEBRIAEE ZADEH, Argentina. Geological Journal 48, 170–193. M.R., 2009b. Billingsellide and orthide brachiopods: New ZEBALLO, F.J., ALBANESI, G.L. & ORTEGA, G., 2005. Conodontes y insights into earliest Ordovician evolution and biogeography from graptolitos de las formaciones Alfarcito y Rupasca (Tremado- Northern Iran. Palaeontology 52,35–52. ciano) del área de Alfarcito, Tilcara, Cordillera Oriental de Jujuy, POPOV, L.E., GHOBADI POUR, M., HOSSEINI,M.&HOLMER, L.E., 2009c. Argentina. Parte 2: Paleontología sistemática. Ameghiniana 42, Furongian linguliform brachiopods from the Alborz Mountains, 47–66. ALCHERINGA CAMBRIAN–ORDOVICIAN CONODONTS FROM IRAN 25

ZEBALLO, F.J., ALBANESI, G.L. & ORTEGA, G., 2008. New late ZHEN, Y.Y., PERCIVAL, I.G. & WEBBY, B.D., 2003. Early Ordovician Tremadocian (Early Ordovician) conodont and graptolite records conodonts from far western New South Wales, Australia. Records from the southern South American Gondwana margin (Eastern of the Australian Museum 55, 169–220. Cordillera, Argentina). Geologica Acta 6, 131–145. ZHEN, Y.Y., LIU,J.&PERCIVAL, I.G., 2005. Revision of two ZHEN,Y.Y.&NICOLL, R.S., 2009. Biogeographic and biostratigraphic prioniodontid species (Conodonta) from the Early Ordovician implications of the Serratognathus bilobatus fauna (Conodonta) Honghuayuan Formation of Guizhou, South China. Records of from the Emanuel Formation (Early Ordovician) of the Canning the Australian Museum 57, 303–320. Basin, Western Australia. Records of the Australian Museum 61, ZHEN, Y.Y., PERCIVAL, I.G., LÖFGREN,A.&LIU, J.B., 2007. 1–30. Drepanoistodontid conodonts from the Early Ordovician ZHEN, Y.Y. & PERCIVAL, I.G., 2003. Ordovician conodont biogeogra- Honghuayuan Formation of Guizhou, South China. Acta phy—reconsidered. Lethaia 36, 357–369. Micropalaeontologica Sinica 24, 125–148. ZHEN, Y.Y. & PERCIVAL, I.G., 2006. Late Cambrian–Early Ordovician ZHEN, Y.Y., ZHANG, Y.D., TANG, Z.C., PERCIVAL, I.G. & YU, G.H., conodont faunas from the Koonenberry Belt of western New 2015. Early Ordovician conodonts from Zhejiang Province, south- South Wales, Australia. Memoirs of the Association of east China and their biostratigraphic and palaeobiogeographic Australasian Palaeontologists 32, 267–285. implications. Alcheringa 39, 109–141. Downloaded by [Gazi University] at 08:12 17 December 2015 本文献由“学霸图书馆-文献云下载”收集自网络，仅供学习交流使用。

学霸图书馆（www.xuebalib.com）是一个“整合众多图书馆数据库资源，

提供一站式文献检索和下载服务”的24 小时在线不限IP 图书馆。 图书馆致力于便利、促进学习与科研，提供最强文献下载服务。

图书馆导航：

图书馆首页 文献云下载 图书馆入口 外文数据库大全 疑难文献辅助工具