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Conodont biostratigraphy and biofacies across the Devonian-Carboniferous boundary in the Kule section (Uzbekistan)

Narkiewicz Katarzyna, Corradini Carlo, Abdiev Nuriddin, Narkiewicz Marek

Geological Quarterly

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2021

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Vol. 65, No. 1

art. no. 17

EN

New conodont data provide further constraints on the occurrence of the Devonian-Carboniferous boundary in the Kule section through the carbonate Novchomok Formation (Kitab Reserve, Uzbekistan). The stratigraphically condensed section includes the interval from the uppermost Famennian Pseudopolygnathus granulosus-lowermost Protognathodus kockeli zones to the middle Tournaisian Siphonodella crenulata Zone. In addition to revision of earlier published taxonomic and biostratigraphic data, two previously unreported taxa are described: Polygnathus sp. n. A and a peculiar form probably representing a new genus (gen. et sp. indet.). The biofacies analysis documents a succession of polygnathid, siphonodellid-polygnathid, polygnathid-siphonodellid to polygnathid-bispathodid, and again polygnathid-siphonodellid biofacies. The generic composition of the samples and relative abundance of Polygnathus purus reflect deep marine environments of the continental slope and rise.

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The mid-Frasnian subsidence pulse in the Lublin Basin (SE Poland) : sedimentary record, conodont biostratigraphy and regional significance

Narkiewicz K., Narkiewicz M.

Acta Geologica Polonica

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2008

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Vol. 58, no. 3

287-301

EN

Most of the thickness of Frasnian sediments in the central segment of the Lublin Basin, i.e. up to 300 metres, is represented by a single transgressive-regressive Cycle VIa, developed in the carbonate-sulphate platform facies. The age of the transgressive part falls into the interval between the upper part of theUpper hassi Zone and the jamieae Zone, whereas the upper boundary runs between the upper part of the Lower rhenana Zone and the lower part of the Upper rhenana Zone. Basin architecture and conodont biostratigraphic data confirm the tectonic nature of the cycle, which represents a short-termincrease in Frasnian subsidence and depositional rates. Based on the conodont data, it is plausible that the onset of the tectonic subsidence in the Lublin Basin and the incipient Pripyat Graben rifting correspond closely in age. They can thus be attributed to the common tectonic mechanism of regional extension in the south-west part of the East European Platform. The lack of any Late Devonian magmatic activity in the Lublin Basin and the synchronous development of this basin with the Pripyat Graben favour the idea that intraplate stresses were the primary factors controlling subsidence in both depocentres during the mid Frasnian to Famennian. The hypothetical mantle plume could have merely amplified the effects of crustal extension in the Pripyat Graben, thus facilitating a typical rift development.

3

New upper Givetian to basal Frasnian conodont faunas from the Tafilalt (Anti-Atlas, Southern Morocco)

Aboussalam Z.S., Becker R.T.

Geological Quarterly

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2007

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Vol. 51, No 4

345-374

EN

Conodont faunas, mostly from previously unsampled sections of the Tafilalt (eastern Anti-Atlas, Morocco) and spanning the upper Givetian to basal Frasnian, include first records of species for the region and NW Gondwana as well as new taxa: "Ozarkodina" maroccanica n. sp., Polygnathus aequidivisus n. sp., Po. dengleri sagitta n. ssp., Po. jorfensis n. sp., Po. saevus n. sp., Po. tafilensis n. sp., and Schmidtognathus longicavus n. sp. The morphology of Tortodus subsymmetricus n. sp. suggests relation ships of Tortodus with Frasnian ancyrognathids. Other taxa are described in open nomenclature: Po. cristatus n. ssp., Icriodus aff. I. symmetricus, Skeletognathus aff. Sk. norrisi, and enigmatic supposed Pb elements (Gen. et sp. indet.). Ctenopolygnathus lanei Kuzmin (1995) is emended and distinctive morphotypes are recognized in Ct. angustidiscus and Po. collieri. Mesotaxis falsiovalis Sandberg et al. (1989) is a subjective junior synonym of the widely over looked M. guanwushanensis (Tian, 1988). There vised regional lithostratigraphy and conodont sequences allow to refine the upper Givetian zonation. The former Upper disparilis Zone is subdivided into succes sive Po. dengleri sagitta and Po. dengleri dengleri subzones. The basalmost Frasnian Ancyrodella rotundiloba pristina Zone (= MN 1 Zone) is preserved as a thin, condensed lime stone just at one locality (Bine Jebilet). The over lying Frasnes Event Beds (Lower Styliolinites) seem to fall in the subsequent Ad. rotundiloba soluta Zone (MN 2 Zone). Records of rare taxa, such as Po. paradecorosus, Po. Pollocki Morphotype 1, old est Po. webbi, Ct. angustidiscus, and Ct. lanei may be help ful for correlation into distant areas or shallower facies.