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Notes on the evolution of the ammonite families Aulacostephanidae and Cardioceratidae and the stratigraphy of the uppermost Oxfordian and lowermost Kimmeridgian in the Staffin Bay sections (Isle of Skye, Northern Scotland)

Wierzbowski A., Matyja B. A., Wright J. K

Volumina Jurassica

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2018

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Vol. 16, no 1

27--50

EN

Detailed study of all the ammonite collections gathered by the authors in the Staffin Bay sections has resulted in minor changes in the distribution of ammonite taxa, and slight modification of the position of the Oxfordian/Kimmeridgian boundary. Most significant is the discovery of Pictonia (Triozites) cf. seminudata which results in the placing of the stage boundary 0.16 m below the level formerly proposed. This study discusses the evolution of the Subboreal family Aulacostephanidae, and the Boreal family Cardioceratidae, indicating changes in the patterns of individual development in the evolution of both families in terms of heterochrony. The Oxfordian/ Kimmeridgian boundary interval shows major morphological changes in both ammonite families which were released from phylogenetic constraints by heterochrony, closely related to changes in environmental conditions.

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Dinoflagellate cyst assemblages across the Oxfordian/Kimmeridgian boundary (Upper Jurassic) at Flodigarry, Staffin Bay, Isle of Skye, Scotland – a proposed GSSP for the base of the Kimmeridgian

Barski M.

Volumina Jurassica

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2018

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Vol. 16, no 1

51--62

EN

Examination of seven ammonite-calibrated palynological samples across the Oxfordian/Kimmeridgian boundary in the Flodigarry sections at Staffin Bay, Isle of Skye, northern Scotland, has revealed dinoflagellate cyst assemblages in general terms in line with previous contributions. The sparse occurrence of Emmetrocysta sarjeantii, Perisseiasphaeridium pannosum and Senoniasphaera jurassica slightly above the proposed Oxfordian/Kimmeridgian boundary may be used as a palynological approximation of the base of the Kimmeridgian. The high abundance of tests resembling modern zygnemataceous chlorophycean alga Spirogyra in two samples above the Oxfordian/Kimmeridgian boundary horizon is probably associated with increased eutrophication and possible association with ‟green tides”. This bloom is proposed as a palynofloral proxy event for the boundary in the Flodigarry section. According to previous studies, various eutrophication events may have a correlation potential in Subboreal Europe.

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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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Ammonite biostratigraphy in the Polish Jura sections (central Poland) as a clue for recognition of the uniform base of the Kimmeridgian Stage

Wierzbowski A., Matyja B.

Volumina Jurassica

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2014

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Vol. 12, no. 1

45--98

EN

The ammonite succession in the stratigraphical interval from the Bifurcatus Zone, through the Hypselum Zone, up to the lower part of the Bimammatum Zone corresponding to a large part of the Submediterranean Upper Oxfordian is studied in several sections of the Polish Jura in central Poland. The sections have yielded numerous ammonites of Submediterranean–Mediterranean affinity, but also, some of Boreal and Subboreal character. The co-occurrence of ammonites of different bioprovinces makes possible the correlation between the different zonal schemes – especially between the Subboreal/Boreal zonations and the Submediterranean/Mediterranean zonation. The correlation shows that the boundary of the Pseudocordata and Baylei zones (Subboreal) and its equivalent – the boundary of the Rosenkrantzi and Bauhini zones (Boreal), currently proposed as the primary standard of the Oxfordian-Kimmeridgian boundary within its GSSP at Staffin Bay (Isle of Skye, Scotland), runs in the Submediterranean/Mediterranean Upper Oxfordian near the base of the Bimammatum Zone. This discovery removes the main obstacle against the formal recognition of the Staffin Bay section as representing the uniform base of the Kimmeridgian Stage in the World and its GSSP. The ammonite taxa recognized are commented on and/or described, and suggestions on their taxonomical and phylogenetical relations are given in the palaeontological part of the study. A new taxon is established: Microbiplices anglicus vieluniensis subsp. nov.

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The Middle Oxfordian to lowermost Kimmeridgian ammonite succession at Mikhalenino (Kostroma District) of the Russian Platform, and its stratigraphical and palaeobiogeographicai importance

Głowniak E., Kiselev D., Rogov M., Wierzbowski A., Wright J.

Volumina Jurassica

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2010

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Vol. 8, no. 1

5-48

EN

The Mikhalenino section on the Russian Platform has yielded numerous ammonites from the Middle and Upper Oxfordian and lowermost Kimmeridgian, collected bed by bed. The ammonites belong mostly to the Boreal family Cardioceratidae, but also to the Subboreal family Aulacostephanidae; additionally at some levels there were collected various Submediterranean ammonites (Perisphinctidae, Oppeliidae and Aspidoceratidae). The co-occurrence of ammonites representative of different faunal provinces makes possible recognition of the Boreal, Subboreal, and partly also Submediterranean standard zonations. In consequence, it is possible to make a close correlation between these zonal schemes. The Oxfordian/Kimmeridgian boundary at the Pseudocordata/Baylei zonal boundary of the Subboreal zonal scheme corresponds precisely to the Rosenkrantzi/Bauhini zonal boundary. This boundary of the stages defined well faunistically in the Flodigarry section (Isle of Skye, Scotland) and proposed as a candidate for the uniform Oxfordian/Kimmeridgian boundary, can be also recognized in the Russian section studied. The boundary can be traced in the Mikhalenino section using the same criteria as used at Staffin: the appearance of the first representatives of Pictonia [M]–Prorasenia [m] (Subboreal), and the first appearance of Amoeboceras (Plasmatites) (Boreal). This indicates the large correlation potential of the boundary defined in this way. The research on the Mikhalenino section has provided the new palaeontological findings described in this study. These include the first discovery in the territory of the Russian Platform of ammonites of the genera/subgenera Decipia, Vineta and Pomerania (Pachypictonia). Two new species: Decipia (?) kostromensis sp. nov., and Pictonia mesezhnikovi n. sp. are described.

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A potential stratotype for the Oxfordian/Kimmeridgian boundary: Staffin Bay, Isle of Skye, UK

Wierzbowski A., Coe A., Hounslow M., Matyja B., Ogg J., Page K., Wierzbowski H., Wright J.

Volumina Jurassica

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2006

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Vol. 4, no. 1

17-33

EN

A coastal exposure of the Staffin Shale Formation at Flodigarry, Staffin Bay, Isle of Skye, Scotland, UK fulfils the criteria for definition as the Global Stratotype Section and Point (GSSP) for the base of the Kimmeridgian Stage (Upper Jurassic). This marine shale succession was deposited during a long-term transgression, and is part of a complete, relatively well-expanded stratigraphic succession. A rich fauna of ammonites above and below the Oxfordian/Kimmeridgian boundary allows recognition of the Evoluta Subzone (Pseudocordata Zone) and Rosenkrantzi Subzone (Rosenkrantzi Zone) of the Subboreal and Boreal uppermost Oxfordian, and the Densicostata Subzone (Baylei Zone) and the Bauhini Zone of the Subboreal and Boreal lowermost Kimmeridgian). A suitable level for the boundary is thus marked by the replacement of the Subboreal Ringsteadia (M)/Microbiplices (m) by Pictonia (M)/Prorasenia (m), and by the first appearance of Boreal Amoeboceras (Plasmatites). Detailed study of the microfossils reveals an excellent dinoflagellate succession. A variety of stratigraphically important dinoflagellates are found, the assemblages being intermediate in character between Boreal and Subboreal ones. The magnetostratigraphic data, though rather troublesome to extract, shows a polarity pattern which can be confidently correlated to other UK boundary sections. The upper boundary of a normal magnetozone falls at, or very near, the proposed Oxfordian/Kimmeridgian boundary. The 87Sr/86Sr ratio at the boundary, based on an analysis of belemnites, lies between 0,70689 and 0,70697, averaging 0.70693. Matching worldwide trends, no distinct change in the ratio is seen across the boundary. A lack of variations in the carbon isotope composition of belemnites across the Oxfordian/Kimmeridgian boundary does not indicate perturbation in the global carbon cycle. However, high ?13C values and their scatter suggest the influence of local fractionation affecting isotope composition of dissolved inorganic carbon (DIC) in the partly isolated Boreal sea. A fall in the belemnite ?18O values in the Upper Oxfordian and Lower Kimmeridgian compared to the Mid Oxfordian suggests a slight rise in seawater temperature.

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Boreal and Subborreal ammonites in the Submediterranean uppermost Oxfordian in the Bielawy section (northern Poland) and their correlation value

Matyja B., Wierzbowski A.

Acta Geologica Polonica

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2002

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Vol. 52, nr 4

411-421

EN

The youngest deposits exposed in the Bielawy Quarry (Kujawy area, northern Poland) yielded both Submediterranean ammonites, making possible recognition of the uppermost Submediterranean Oxfordian, and Subboreal-Boreal ammonites, indicative of some parts of the Subboreal/Boreal lowermost Kimmeridgian. This makes possible closer correlation of the different zonal schemes that appear to be important in discussion of the uniform Oxfordian/Kimmeridgian boundary and recognition of its GSSP. The upper part of the Submediterranean Planula Subzone yields Boreal Amoeboceras of the Plasmatites group, indicative of the Boreal Bauhini Zone. Moreover, the lowermost part of the Submediterranean Galar Subzone corresponding to the wenzeli horizon yields Boreal Amoeboceras of the Amoebites group (such as Amoeboceras bayi BIRKELUND & CALLOMON), indicative of the lowermost part of the Boreal Kitchini Zone, as well as late representatives of the genus Pictonia, described here as Pictonia kuiaviensis sp. nov., allowing correlation with the upper part of the Subboreal Baylei Zone.