1,721,004 research outputs found
A Silurian conodont zonation from late Llandovery to end Pridoli in Sardinia
No full textThe standard Late Llandovery - Top Pridoli conodont zonation between the top of the celloni Zone and the latest Pridoli detorta Zone is revised on the basis of data from the Silurian System of Sardinia. Fifteen biointervals have been recognized; among them, one zone is here newly named (Oz. exc. hamata) and three more zones (K. crassa, K. v. variabilis interval Zone and Pe. latialata), proposed and sporadically used in some previous biozonations, are reintroduced. The scheme provided for Sardinia fits well in other part of the world, like the Cellon section
Bimineralic (calcareous and phosphatic) skeleton in Late Ordovician Bryozoa from Sardinia: Geological implications.
No full textThe study of Palaeozoic Bryozoa from the Upper Ordovician of Sardinia was carried out by integrating the traditional thin section description with the SEM observation of single zooecia or zoarial remnants, isolated by acid acetic technique. This technique was made possible by the presence of a bimineralic (calcareous and phosphatic) skeleton,which is interpreted as the result of the mineralization of the membranous part of the cryptocyst originally very rich in phosphorus. The frequent records of phosphatic bodies in Bryozoa lead us to hypothesize the possibility that some Bryozoa secrete,at least in the Palaeozoic, a phosphatic skeleton in response to particular environmental conditions. The deposition of calcium phosphate occurred in the zooecial cavity owing to the change in chemical conditions between the regeneration and degeneration phases
Conodont stratigraphy of a highly tectonised Silurio-Devonian Section in the San Basilio area (SE Sardinia)
No full textSeveral conodont species belonging to five "late Silurian biozones (Ancoradella ploeckensis, Polygnathoides siluricus,
Ozarkodina crispa, Ozarkodina remscheidensis, Oulodus elegans detortus) and four Early and Late Devonian biozones (delta, pesavis,
kitabicus-excavatus and Late rhenana) allow a better interpretation of stratigraphy and tectonics of the San Basilio area in western Gerrei.
Frasnian sediments are documented for the first time in SE Sardinia.
[Stratigrafia a conodonti di una sezione forremente tettonizzata di eta Siluriano-Devoniano nell'area di San Basilio
(Sardegna SE)] - Grazie alla biostratigrafia a conodonti viene interpretata la complessa tettonica di una sezione nell'area di San Basilio
(Sardegna sud-orientale) e viene ricostruita la successione originaria. Sono documentate cinque biozone a conodonti del Siluriano superiore
(Ancoradella eioeckensis, Polygnathoides siluricus, Ozarkodina crispa, Ozarkodina remscheidensis, Oulodus elegans detortus), tre del
Devoniano Injeriore (delta, pesavis e kitabicus-excavatus) una del Devoniano Superiore (Late rhenana). Vengono inoltre documentati per la
prima volta sedimenti frasniani nel Sud-Est della Sardegna
The Ichnofossil Genus Paradictyodora Olivero, Buatois & Scasso (2004) from the Pliocene of the Northern Apennines, Italy.
No full textThe ichnospecies Paradictyodora flabelliformis is reported for the first time from the Pliocene "Argille Azzurre Formation" of Northern Italy. The orizon has an older age and is deeper than the shallow-water protected shoreface enviroment where the type specimens have been found. A narrow tubular structure exceptionally preserved on the specimen studied possibly supports the tellinid bivalve model instead of the Arenicola model fro the origin of the trace fossil
Upper Tremadoc–Lower Arenig? Anisograptid–Dichograptid fauna from the Cabitza Formation (Lower Ordovician, SW Sardinia, Italy)
No full textThe discovery of the anisograptid graptolite Araneograptus murrayi (Hall, 1865), the dichograptids Clonograptus (Clonograptus) cf. rigidus
(Hall, 1858) and Clonograptus (Clonograptus) cf. multiplex (Nicholson, 1868) and of two unassigned species of Didymograptus in the Late
Tremadoc–Early Arenig? sediments of the Fluminese area (SW Sardinia) adds new data on the biostratigraphy and palaeoecological setting of the
Cabitza Formation, as well as on the paleobiogeographical distribution of these taxa
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