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Towards a consistent Oxfordian/Kimmeridgian global boundary: current state of knowledge

Wierzbowski A., Atrops F., Grabowski J., Hounslow M., Matyja B. A., Olóriz F., Page K., Parent H., Rogov M. A., Schweigert G., Villaseñor A. B., Wierzbowski H., Wright J. K.

Volumina Jurassica

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2016

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Vol. 14, no. 1

15--49

EN

New data are presented in relation to the worldwide definition of the Oxfordian/Kimmeridgian boundary, i.e. the base of the Kimmeridgian Stage. This data, mostly acquired in the past decade, supports the 2006 proposal to make the uniform boundary of the stages in the Flodigarry section at Staffin Bay on the Isle of Skye, northern Scotland. This boundary is based on the Subboreal-Boreal ammonite successions, and it is distinguished by the Pictonia flodigarriensis horizon at the base of the Subboreal Baylei Zone, and which corresponds precisely to the base of the Boreal Bauhini Zone. The boundary lies in the 0.16 m interval (1.24–1.08 m) below bed 36 in sections F6 at Flodigarry and it is thus proposed as the GSSP for the Oxfordian/ Kimmeridgian boundary. This boundary is recognized also by other stratigraphical data – palaeontological, geochemical and palaeomagnetic (including its well documented position close to the boundary between magnetozones F3n, and F3r which is placed in the 0.20 m interval – 1.28 m to 1.48 m below bed 36 – the latter corresponding to marine magnetic anomaly M26r). The boundary is clearly recognizable also in other sections of the Subboreal and Boreal areas discussed in the study, including southern England, Pomerania and the Peri-Baltic Syneclise, Russian Platform, Northern Central Siberia, Franz-Josef Land, Barents Sea and Norwegian Sea. It can be recognized also in the Submediterranean-Mediterranean areas of Europe and Asia where it correlates with the boundary between the Hypselum and the Bimmamatum ammonite zones. The changes in ammonite faunas at the boundary of these ammonite zones – mostly of ammonites of the families Aspidoceratidae and Oppeliidae – also enables the recognition of the boundary in the Tethyan and Indo-Pacific areas – such as the central part of the Americas (Cuba, Mexico), southern America, and southern parts of Asia. The climatic and environmental changes near to the Oxfordian/Kimmeridgian boundary discussed in the study relate mostly to the European areas. They show that very unstable environments at the end of the Oxfordian were subsequently replaced by more stable conditions representing a generally warming trend during the earliest Kimmeridgian. The definition of the boundary between the Oxfordian and Kimmeridgian as given in this study results in its wide correlation potential and means that it can be recognized in the different marine successions of the World.

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The Oxfordian ammonite genus Passendorferia Brochwicz Lewiński and the Tethyan subfamily Passendorferiinae Meléndez: origin and palaeobiogeography

Mendez G., Atrops F., Bello J., Brochwicz-Lewiński W., Darpa C., Fozy I., Perez-Urresti I., Ramajo J., Sequeiros L.

Volumina Jurassica

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2009

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Vol. 7, no. 1

113-134

EN

The Oxfordian ammonite group Passendorferiinae (known as "Mediterranean perisphinctids") forms a group of perisphinctids characterized by strongly evolute serpenticone coiling and subcircular to subquadrate whorl section, and forms a lateral divergent branch of the main stem Perisphinctidae. They originated probably from Late Callovian Grossouvriinae (Alligaticeras) and spread mainly in the Mediterranean (Tethyan) Province along the southern margin of Tethys, occasionally reaching the outer areas of epicontinental platforms. Their particular morphological features make them somewhat homoeomorphic with Tethyan Kimmeridgian Nebrodites. The phyletic link might be represented by the genus Geyssantia Meléndez, known from the Late Oxfordian Planula Chronozone. Separate biogeographic distribution in relation to the Perisphinctinae might reflect a progressive differentiation of western Tethyan faunas at the Callovian-Oxfordian boundary and at the onset of the Middle Oxfordian Transversarium Chronozone. Their rapid evolution gives them a biostratigraphic value similar to that of the Perisphinctinae. At the turn of the Middle-Late Oxfordian they gave rise to early Ataxioceratinae (Orthosphinctes), which replaced the Perisphinctinae in epicontinental areas, and colonised the marginal epicontinental blocks of northern Tethys. The taxonomy of this group is based upon the recognition of sexual dimorphism, using a single generic and specific name for both (M) and (m), and hence rejecting the use of former subgeneric ames for both dimorphs. A new species within this line: Passendorferia nodicostata sp. nov. from the Plicatilis Biozone (Paturattensis Subbiozone) is defined and described for the first time.

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The ammonite faunas of the Callovian/Oxfordian boundary interval in Europe and their relevance to the establishment of an Oxfordian GSSP

Melendez G., Page K., Wright J., Atrops F.

Volumina Jurassica

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2006

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Vol. 4, no. 1

185-185

EN

The latest Callovian and Early Oxfordian represent one of the most dynamic intervals in the history of Jurassic Ammonoidea and is characterized by one of the highest levels of mixing of Boreal, Submediterranean and even Mediterranean faunas. In particular the massive expansion of Boreal Cardioceratidae from their original “home” in Arctic areas as far south as South East France, brings them into contact with Mediterranean-style faunas rich in Phylloceratidae. This so-called “Boreal Spread” (after J. H. Callomon) provides the framework within which high-resolution inter-bioprovincial correlations are possible and hence the context for a sucessful GSSP designation for the base of the Oxfordian Stage within Europe (and hence the beginning of the Upper Jurassic). Associated with the Cardioceratidae, however, is a great variety of Perisphinctina, including Aspidoceratidae, Periphinctidae, Grossouvridae and rarer Pachyceratidae as well as frequent Hecticoceratidae and rarer Phylloceratidae. The latter groups are much more abundant in southern areas (Tethyan Realm), but the Aspidoceratidae do persist well into the Boreal Realm. Crucially, several groups of the Perisphinctina persist beyond Europe and therefore provide tantalising indications that a truly global correlation of any GSSP established in Europe will ultimately be possible. The current paper will review the stratigraphical, taxonomic and palaeobiogeographical context and significance of the trans Callovian/Oxfordian boundary faunas within Europe, building on recent results from the UK and France. Conclusions will be drawn concerning the appropriate – or convenient – level at which the place the Callovian-Oxfordian in Europe and its potential interpretation elsewhere. Such conclusions are highly relevant to the eventual establishment of an Oxfordian GSSP.

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On the origin and palaeobiogeographic spread of Oxfordian ammonite genus Passendorferia and Tethyan subfamily Passendorferiinae Melendez

Melendez G., Atrops F., Bello J., Brochowicz-Lewiński W., D'Arpa C., Fozy I., Perez-Urresti I., Sequeiros L.

Volumina Jurassica

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2006

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Vol. 4, no. 1

240-241

EN

Oxfordian ammonite group Passendorferiinae (known as "Mediterranean Perisphinctids") form a lateral divergent branch of the main stem of Perisphinctidae, originating probably from Late Callovian Grossouvriinae (Alligaticeras) and spreading mainly in the Mediterranean (Tethyan) Province during the Early, Middle and Late Oxfordian. This morphologically homogeneous group is characterized by the evolute serpenticone coiling with sub-circular to subquadrate whorl section. Ribbing "simple" radial, is formed by mostly single and symmetrically bifurcate ribs, turning into thicker, straight, "columnar" ribs, slightly elevated on the ventral margin in adult stage of macroconchs. All these features make them strongly homoeomorphic with Tethyan Kimmeridgian Nebrodites, with which they have been often mistaken. The phyletic link might be represented by the genus Geyssantia Melendez, from Late Oxfordian Planula Chronozone. Microconchs, 80 to 120 mm Dm are isocostate, densely ribbed, lappeted and, show typically the development of parabolic nodes at the final part of adult phragmocone. Macroconchs 240 to over 320 mm Dm, slightly variocostate, show thick uniform columnar ribs in adult stage. Two main genera are so far recognized, evolving independently during Early and Middle Oxfordian: Passendorferia Brochwicz Lewiński, known from Lower Oxfordian early Cordatum Chronozone to Upper Oxfordian, Bimammatum-(?)Hauffianum Chronozone, characterized by extremely evolute serpenticone inner whorls with subcircular whorl section leading to subquadrate middle and outer whorls, and Sequeirosia Melendez, known mainly from the Middle Oxfordian characterized by more involute serpenticone coiling with subquadrate whorl section from early inner whorls. Passendorferiinae colonised and spread mainly on the southern margin of Tethys, being autochthonous in epioceanic carbonate platforms of western Tethys, from Hungary to southern Alps, Sicily, North Africa or Betic ranges, and reaching occasionally the external deeper areas of shallow epicontinental platforms at the northern margin of Tethys. This separate biogeographic distribution with respect to Perisphinctinae probably reflects a progressive extensional block differentiation of western Tethys at the Callovian-Oxfordian boundary and at the onset of Middle Oxfordian Transversarium Chronozone. Their rapid evolution provides them a biostratigraphic value similar to that of Perisphinctinae. At the turn of Middle-Late Oxfordian they gave rise to early Ataxioceratinae (Orthosphinctes), which would replace the Perisphinctinae and colonise the marginal epicontinental blocks of northern Tethys.

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New studies on perisphinctids from the Lower Tithonian (Hybonotum Zone) of S Germany and SE France

Scherzinger A., Atrops F., Schweigert G.

Volumina Jurassica

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2006

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Vol. 4, no. 1

244-245

EN

New extensive collections from the Hybonotum Zone of Liptingen (SW Germany), Canjuers (Dpt. Var, France) and Crussol (Dpt. Ardeche, France), together with already published material from Laisacker (Franconia, S Germany, Schairer & Barthel 1981) give deep insights in ontogeny, intraspecific variation, dimorphism, and evolution of several Late Jurassic perisphinctid ammonite genera, as a basis for future revisions. In older studies perisphinctids were often problematic due to little material, erroneous interpretations of type species, incompletely or poorly preserved specimens, disregarding of dimorphism, and widespread homeomorphism. After our recent study the perisphinctids are much more diverse than previously thought. A correlation with French biohorizons established in the Paris and Aquitaine basins is possible due to the occurrence of Gravesia M+m and Tolvericeras M+m?, especially at Liptingen. Besides the two latter genera we can distinguish five other dimorphic pairs which are coupled as follows: Lithacoceras Hyatt (M) + Silicisphinctes Schweigert & Zeiss (m); group of "Virgatosphinctes" eystettensis Schneid (M) + Subplanites group A (m); Euvirgalithacoceras Zeiss, Schweigert & Scherzinger (M) + Subplanites group B, S. rueppellianus sensu Schairer & Barthel non Quenstedt (m); Hegovisphinctes Zeiss, Schweigert & Scherzinger (M) + group of "Torquatisphinctes" filiplex Schairer & Barthel non Quenstedt (m); Hoelderia Ohmert & Zeiss (M) + group of "Subdichotomoceras" sp. in Schairer & Barthel 1981, pl. 5, fig. 4 only (m). Some of these dimorphic pairs can be recognized also in SE Spain (Calanda area) and in the Balkans (Bulgaria, Croatia) and thus permit correlations across the Submediterranean Province. The rich perisphinctid fauna, together with other excellently preserved ammonites underlines the potential of the French sections as key sections for long-distance and high time-resolution correlations as well as the understanding of the Kimmeridgian-Tithonian transition.