82 research outputs found

    PERMIAN BRACHIOPODS FROM KARAKORUM (PAKISTAN) PART. 3.

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    Late Wordian (Guadalupian) brachiopods from Member 2 of the Panjshah Formation in the Karakorum (N Pakistan) are described. The brachiopod assemblage, dated by the associated fusulinids and conodonts, consists of 29 genera (3 of which are questionable and 1 unidentifiable) of the orders Productida, Orthida, Rhynchonellida, Athyridida, Spiriferida and Terebratulida. Hunzininae, a new subfamily of the Spiriferellidae is proposed; it includes Darbandia n. gen., with type species D. vagabunda n. sp. and Elivina chapursani n. sp. A third new species is assigned to the genus Anchorhynchia of the family Wellerellidae: A. cimmerica n. sp.A quantitative biostratigraphic analysis demonstrates two major faunal changes in the Elivina chapursani- Chapursania tatianae Assemblage Zone of the upper part of Member 2, which are not strictly linked to lithological changes. This biozone is correlated with the brachiopod faunas of the Gnishik Formation of Armenia and those of the basal Takhtabulak Formation of SE Pamir.The faunal elements of the Elivina chapursani- Chapursania tatianae Assemblage Zone are an admixture of wide-ranging, Tethyan (particularly abundant), Gondwanan and endemic (Cimmerian) genera, representing a transitional fauna and a biostratigraphic tool for intercontinental correlation, which are particularly problematic in this time interval. The Panjshah transitional fauna demonstrates the persistence of the Transhimalayan Province of the Cimmerian Region into the late Guadalupian, which originated at the end of the Cisuralian and occupied Armenia, Central Afghanistan, Karakorum and SE Pamir. It provides also some insights into the biodiversity pattern before the mass extinction at the end of the Guadalupian, and suggests that this event was as rapid as the end- Permian mass extinction, at least in Central Asia.&nbsp

    PERMIAN BRACHIOPODS FROM KARAKORUM (PAKISTAN) PT. 2

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    MIDDLE TRIASSIC BRACHIOPODS FROM VAL PARINA, BERGAMASC ALPS, ITALY

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    The Middle Triassic Esino Limestone of Val Parina yields a rich brachiopod fauna associated with bivalves, gastropods, corals, and ammonoids. The brachiopod fauna of the Esino Limestone includes ubiquitous species (P. fragilis, A. aff. posterior, M. mentzeli, D. cf. dinarica, L. praepunctata and A. angustaeformis), species exclusive to the back reef (T. cf. intervallata, A. aff. ladina and A. aff. raxana) and species exclusive to the shelf margin (C. aff. altaplecta, V. vivida, A. aff. dilatata, H. aff. ambitiosa, T. trigonella, M. ampla, A. aff. canaliculata). The age of the Val Parina brachiopods spans from latest Anisian to Late Ladinian. &nbsp

    CHITRALINA UNDULATA GEN. N. SP. N. (FORAMINIFERIDA) FROM THE LATE PERMIAN OF KARAKORUM (PAKISTAN)

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    Chitralina undulata  gen. n. sp. n. (Foraminiferida) has been found for the first time in the Permian successions of Karakorum (Pakistan). Biostratigraphic analysis based on fusulinids, brachiopods, conodonts and small foraminifers pointed out that Chitralina undulata gen. n. sp. n. occurs from the Kubergandian to the Late Murgabian-Midian. Morphologically, Chitralina undulata gen. n. sp. n., is comparable to Rectostipulina quadrata  Jenny-Deshusses, 1985, differing from it by means of the thickness and composition of the test and for the presence of marked longitudinal costae. The stratigraphic range of Rectostipulina quadrata spans the Midian-Dorashamian time-interval. The new genus Chitralina is very similar to the Permian genus Giraliarella Crespin, differing from it by means of the absence of transverse growth constrictions. The new family Chitralinidae fam. n., is also described  herein

    PERMIAN BRACHIOPODS FROM KARAKORUM (PAKISTAN). Pt.1

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    Five brachiopod associations were collected in the Permian successions of N Karakorum (Pakistan). The aim of this work is to describe the two oldest brachiopod assemblages. The oldest association has been assembled in the Asselian-Early Sakmarian Gircha  Fm. It has been named Trigonotreta lyonsensis/Punctospirifer afghanus assemblage and it is characterized by low diversity and dominance of spiriferids, indicating cold climate conditions. The  second assemblage was collected  in the Sakmarian Lupghar Fm., Mb.1 of Upper Hunza valley and in the Sakmarian  Lashkargaz  Fm., Mb. 1 of Baroghil and Lashkargaz (Chitral). It has beennamed Hunzina electa gen. n. sp. n. assemblage and it is characterized by higher diversity than the oldest one, indicating warmer climate conditions. Furthermore Hunzina electa gen. n. sp. n. represents a marker in almost all the stratigraphic sections of N Karakorum. In the appendix two new genera, one new subgenus and nine new species of brachiopods collected in the Bolorian to Murgabian-Midian of Northern  Karakorum are named and described

    Lower and Middle Triassic foraminifera from the Eros Limestone, Hydra Island, Greece

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    Abstract. The systematics and stratigraphic ranges (constrained by conodont dating) of abundant and well preserved foraminiferal faunas from six sections in the Lower and Middle Triassic Eros Limestone of central and western Hydra (Argolis Peninsula, Greece) are described. A joint analysis of the conodonts, foraminifera and bivalves has enabled the Scythian and Anisian stages to be recognized with some certainty within the Eros Limestone carbonate platform. The foraminifera have affinities with those of many other Tethyan localities, in particular the Dinarides, Balkans, Carpathians and the Southern Alps

    ULTRASTRUCTURE OF SOME PERMIAN AND TRIASSIC SPIRIFERIDA AND ATHYRIDIDA (BRACHIOPODA)

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    Twelve species of Permian and Triassic Spiriferida and Athyridida from various localities and formations have been analysed in order to provide new data on the uhrastructure of these brachiopods. Ultrastructural analysis of the genus Tetractinella has provided new elements (e.g. the thickness of the secondary layer, the transverse profile of the secondary layer fibres and their thickness) that enable distinction between the species T. trigonella and T. hexagonalis. Ultrastructural features, such as the shape and the dimensions of the secondary layer fibres, have also led to the ultrastructural differentiation of three species of the genus Trigonotreta (Trigonotreta sp., T. stokesi and T. lyonsensis). Furthermore the ultrastructure of Clavigera bisulcata, Elivina tibetana, Spiriferella rajah, Spirelytha petaliformis, Martinia tschernyschewi and Mentzelia mentzeli has been investigated for the first time and new dtta on "Retzia" beneckei are provided

    LATE CARBONIFEROUS BRACHIOPODS FROM KARAKORUM, PAKISTAN

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    Carboniferous rocks from North Karakorum display sharp lateral variations in lithology and thickness suggesting accumulation in half-grabens during continental rifting between the Karakorum block and northern Gondwana. Different Carboniferous successions, belonging to distinct tectonic units, have been detected. Thin, poorly fossiliferous successions of arenites and crinoidal limestones contrast with very thick terrigenous-carbonate successions comprising two distinct fossiliferous horizons. The lower fossiliferous horizon yielded brachiopods (Pustula sp., Rhipidomella sp., Choristites sp., Martiniopsis sp., Afghanospirifer sp., Gypospirifer sp., Composita sp.) of Bashkirian age. The upper fossiliferous horizon, lying about 90 m above the former, contains corals, crinoids and brachiopods (Densepustula cf. losarensis, Dowhatania sulcata n. sp., Brachythyris sp., Rhipidomella sp., Septacamera dowhatensis, Alispirifer middlemissi) of Moscovian to Kasimovian age. The Carboniferous brachiopods of North Karakorum are similar to those collected in the Late Carboniferous of Central Afghanistan, Himalaya (Manang, Spiti, Tibet), and Lhasa Block (Xainza area).&nbsp
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