First Ordovician chitinozoans from Indian Gondwana — New evidence from the Shiala Formation

Sinha, H. N.; Vandenbroucke, Thijs R.A.; Verniers, Jacques

doi:10.1016/j.revpalbo.2011.07.006

Cited by 15 publications

(2 citation statements)

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“…of the Hope Shales in the UK (Jenkins 1967), which is now considered L. megaesthonica , corresponding to mid-Darriwilian, recorded from Sweden (Eisenack 1955, 1968; Grahn 1980; Grahn et al 1996), Estonia (Eisenack et al 1976; Nõlvak et al 2019), and France (Paris 1981). Likewise, Conochitina chydaea has been recorded from many localities, including the lower Hope Shales (lower Darriwilian) in Shropshire, England (Jenkins 1967); Middle Ordovician (Darriwilian, based on the Darriwilian Pterograptus elegans Zone), the Cape Cormorant Formation ( Cyathochitina jenkinsi Zone), western Newfoundland, Canada (Albani et al 2001); Middle Ordovician (Darriwilian) in southern Europe and northern Africa (Gutiérrez-Marco et al 2013; Vaz 2014); and Middle–Late Ordovician (Shiala Formation), India (Sinha et al 2011). Based on the chronostratigraphical calibration proposed for the chitinozoan biozones (Paris 1990, 1996; Webby et al 2004; Videt et al 2010), S. formosa and its associated chitinozoan taxa confirm a Darriwilian age (stage slice upper Dw2 and lower Dw3 and time slice upper 4b and lower 4c) for the samples MG-MHP 219 to MG-MHP 221 of the Lashkarak Formation, northern Iran (Figure 4 and Table 2).…”

Section: 2 Acritarch Biostratigraphymentioning

confidence: 99%

Peri-Gondwanan acritarchs and chitinozoans from the Lower–Middle Ordovician Lashkarak Formation in the Alborz Mountain Ranges, northern Iran: regional stratigraphical significance and palaeogeographical implications

Ghavidel‐Syooki

Piri-Kangarshahi

2023

Palynology

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The Lashkarak Formation (Lower-Middle Ordovician) in the Gerdkuh locality, 10 km west of Damghan city, northern Iran, has been found to contain acritarchs and chitinozoans. This study aimed to understand these chitinozoan and acritarch successions as well as brachiopods in this part of the Alborz Mountains, in a novel manner. Ninety-seven surface samples from this succession were collected and analysed. Thirty samples yielded well-preserved palynomorph taxa such as acritarchs, chitinozoans, and scolecodonts, as well as graptolite remains. In total, 53 taxa were identified among the acritarchs (38 species belonging to 21 genera) and chitinozoans (15 species belonging to 10 genera). Although scolecodonts and graptolite remains were also observed, they were not studied in detail. The palynological analyses revealed the presence of several diagnostic acritarchs in the Lashkarak Formation, including Vulcanisphaera simplex, Arbusculidium filamentosum, Coryphidium bohemicum, Dactylofusa velifera, Striatotheca mutua, Arkonia virgata, and Orthosphaeridium ternatum. These acritarchs allowed the recognition of five acritarch assemblage zones. Similarly, seven chitinozoan biozones were recognised: Eremochitina brevis, Desmochitina ornensis, Belonechitina henryi, Cyathochitina protocalix, Cyathochitina calix, Siphonochitina formosa, and Laufeldochitina clavata. These findings confirm the inclusion of the Alborz Mountains in the peri-Gondwana palaeoprovince during the Early-Middle Ordovician. The co-occurrence of the acritarch and chitinozoan taxa with previously identified brachiopods allowed for the establishment of a more detailed Early-Middle Ordovician biozonation, demonstrating their potential usefulness for global chronostratigraphy. Based on palynological and brachiopod assemblages, a shallow marine inner shelf setting is suggested for the Early-Middle Ordovician at the Gerdkuh locality. Moreover, in this study, four new morphotype species were erected, consisting of one new chitinozoan (Cyathochitina gerdkuhensis sp. nov.) and three new acritarchs (Baltisphaeridium razii sp. nov., Navifusa alborzensis sp. nov., and Orthosphaeridium iranense sp. nov.). However, Othosphaeridium cf. ternatum was left in open nomenclature. HIGHLIGHTSPalynomorphs from the Lower-Middle Ordovician (Lashkarak Formation) were recorded from the Alborz Mountains. 15 chitinozoan species (10 genera) were recorded from the Lashkarak Formation, S. Caspian Sea. 38 acritarch taxa (21 genera) were identified, indicating the N. Gondwanan Domain. The diagnostic acritarch taxa are Arbusculidium, Coryphidium, Striatotheca, and Arkonia. Chitinozoan biozones are E. brevis, D. ornensis, B. henryi, C. protocalix, C. calix, S. formosa, and L. clavata. Baltisphaeridium razii sp. nov., Navifusa alborzensis sp. nov., Cyathochitina gerdkuhensis sp. nov., and Orthosphaeridium iranense sp. nov. is recorded for the first time. A major hiatus corresponds to the Late Ordovician, Silurian, and Early-Middle Devonian.

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Section: 2 Acritarch Biostratigraphymentioning

confidence: 99%

Peri-Gondwanan acritarchs and chitinozoans from the Lower–Middle Ordovician Lashkarak Formation in the Alborz Mountain Ranges, northern Iran: regional stratigraphical significance and palaeogeographical implications

Ghavidel‐Syooki

Piri-Kangarshahi

2023

Palynology

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“…The greenish-grey silty shale of the lower part of the Shiala succession has yielded well-preserved chitinozoans, melanosclerites, and acritarchs, which suggest Middle to Late Ordovician age whereas, based on calcareous algae, the upper age limit extends into the Middle Silurian. Hence, the Ordovician–Silurian boundary lies within the Shiala Formation (Sinha et al, 1998, 2011; Sinha and Trampisch, 2013; Sinha and Verniers, 2016). On the other hand, Khanna et al (1985) and Bhargava (2008, 2011) assigned a Late Ordovician age to the Yong limestone and placed the Ordovician-Silurian boundary within the Yong Limestone Formation.…”

Section: Geologic Setting and Agementioning

confidence: 99%

A new cryptostome bryozoanPtilotrypafrom the Upper Ordovician Yong Limestone Formation: Tethyan sequence of Kumaun Higher Himalaya, India

et al. 2019

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A new species of the Paleozoic bryozoan genus Ptilotrypa of the order Cryptostomata is described from the lower part of the Yong Limestone Formation, Katian, Upper Ordovician of the Kumaun Tethys Himalaya: Ptilotrypa bajpaii new species. The presence of the genus Ptilotrypa in the Tethyan Himalaya suggests paleogeographic connections to the Upper Ordovician of North America and, consequently, Upper Ordovician age for the lower part of the Yong Limestone Formation. This species displays a reticulate colony shape, which suggests an efficient filtering capacity in an environment with a high primary production. Morphological peculiarities and systematic assignment of the genus Ptilotrypa are discussed.UUID: http://zoobank.org/898276c8-2924-4da2-ae96-3392cb2ebbc3

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Phanerozoic Mass Extinctions and Indian Stratigraphic Records

Prasad

Parmar

2020

Springer Geology

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First Ordovician chitinozoans from Indian Gondwana — New evidence from the Shiala Formation

Cited by 15 publications

References 10 publications

Peri-Gondwanan acritarchs and chitinozoans from the Lower–Middle Ordovician Lashkarak Formation in the Alborz Mountain Ranges, northern Iran: regional stratigraphical significance and palaeogeographical implications

Peri-Gondwanan acritarchs and chitinozoans from the Lower–Middle Ordovician Lashkarak Formation in the Alborz Mountain Ranges, northern Iran: regional stratigraphical significance and palaeogeographical implications

A new cryptostome bryozoanPtilotrypafrom the Upper Ordovician Yong Limestone Formation: Tethyan sequence of Kumaun Higher Himalaya, India

Phanerozoic Mass Extinctions and Indian Stratigraphic Records

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