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Conodonts, radiolarians and ostracodes in the Permian E-Lert Formation, Loei Fold Belt, Indochina Terrane, Thailand

journal contribution
posted on 2023-05-18, 09:40 authored by Burrett, C, Udchachon, M, Thassanapak, H, Chitnarin, A
Conodonts are rare in the Permian carbonates of Indochina but abundant conodonts and ostracodes have been obtained from turbiditic limestones of the Permian E-Lert Formation along with radiolarians from overlying cherts, all deposited on the margins of the interplatform Nam Duk Basin. Conodonts are typically Tethyan and are very similar to faunas from Sicily and south China. They include Hindeodus gulloides, Pseudohindeodus oertlii, Mesogondolella siciliensis and Sweetognathus subsymmetricus which indicate a probable late Kungurian – Roadian age range although a Wordian age cannot be excluded. M. siciliensis, which has a high blade and small cusp supposedly typical of warm-water conodonts, is found in deep (<500 m) carbonate turbidites in Thailand and in very deep deposits in Oman and Sicily, but generally not in shallow-water tropical limestones in Thailand, Oman and Sicily. The chert sequence yields a radiolarian fauna consisting of 11 confidently assigned species of which Albaillella asymmetrica, A. sinuata, Tormentum delicatum and Latentifistula patagilaterata suggest a latest Kungurian – earliest Roadian age, deposited at a palaeodepth of c. 500 m. Ostracodes consist of 16 genera and 23 species which belong to Shivaella, Paraberounella, Carinaknightina, Paraparchites, Shemonaella, Bairdia, Cryptobairdia, Bairdiacypris?, Spinocypris, Pseudobythocypris, Baschkirina, Microcheilinella, Basslerella, Polycope and Cyathus, of which Shivaella elertensis sp. nov. Chitnarin is newly described. The ostracodes are a palaeoecologically mixed assemblage comprising external platform and deeper-water forms, suggesting that the limestone turbidites were deposited on the proximal part of the slope. Cyathus caperata and C. elliptica show a palaeobiogeographic link to south China.


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Geological Magazine








School of Natural Sciences


Cambridge Univ Press

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