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1

New dimorphic species of the genus Rollierites Jeannet from southern Poland

Jain Sreepat, Mazur Marek

Annales Societatis Geologorum Poloniae

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2021

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Vol. 91, No. 4

405--418

EN

A new ammonite assemblage from the lower beds of the Ogrodzieniec Quarry (southern Poland), the only Callovian section in the middle part of the Polish Jura Chain, is described. It includes the presence of Kosmoceras rotundum (Quenstedt), followed by the first example of co-occurring micro- and macroconchs in the genus Rollierites (R. biplicatum sp. n.) and above it, the association of Euaspidoceras sp. and Peltoceratoides (Parawedekindia) gerberi Prieser. Both R. biplicatum sp. n. (m and M; microconch and macroconch) and K. rotundum are assigned to the late Callovian Lamberti Zone. P. (P.) gerberi characterizes the early Oxfordian Cordatum Zone. This is the first record of the genus Rollierites from Poland. This study extends the upper age limit of the middle Callovian Rollierites up to the late Callovian Lamberti Zone. On the basis of morphological and stratigraphical data, it is tentatively proposed that the origin of the early–middle Oxfordian Tornquistes may be in the middle–late Callovian Rollierites, rather than the previously proposed late Callovian Pachyceras. However, this is speculation, as the present data set is insufficient.

2

Late Jurassic facies succession of the Kleszczów Graben area (southern border of the Łódź Depression, peri-Tethyan shelf, central Poland)

Olchowy Piotr, Krajewski Marcin, Felisiak Ireneusz

Geological Quarterly

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2019

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Vol. 63, No. 4

657--682

EN

Numerous fully cored boreholes completed in the last years in central Poland (Kleszczów Graben area, southern border of the Łódź Depression) enabled the researchers to obtain new sedimentological data on the Oxfordian-Tithonian continuous sedimentary record in the Polish part of the northern Tethys shelf. Twenty-two facies were distinguished in the sedimentological succession. The facies represent the outer-, mid- and inner-ramp environments, including evaporitic episodes and palaeosols. The facies document that the Oxfordian-Lower Kimmeridgian (up to Hypselocyclum) carbonate ramp has evolved to the Upper Kimmeridgian-Tithonian carbonate-siliciclastic ramp. Among the Kimmeridgian deposits, numerous hardgrounds, tidal channel deposits and gravity flow sediments were identified. The Kleszczów Graben sedimentary succession is discussed along with the lithostratigraphical units known from the adjacent regions of southern and central Poland.

3

Detailed biostratigraphy of the Middle Callovian – lowest Oxfordian in the Mikhaylov reference section (Ryazan region, European part of Russia) by ammonites

Kiselev D. N., Rogov M. A.

Volumina Jurassica

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2018

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Vol. 16, no 1

73--186

EN

Study of the sections near the Mikhaylov (Ryazan region) has made it possible to improve the infrazonal subdivision of the Middle Callovian – Lower Oxfordian of the European Russia by ammonites. The Athleta Zone is the most complete in the studied sections. A sequence of kosmoceratid biohorizons (phaeinum, proniae, rowlstonense and kuklikum) is established here, as well as infrazonal units based on a phylogenetic sequence of species of the genus Funiferites. A study of the paleobiodiversity and frequency of occurrence of ammonites at different intervals of the section showed that the ammonite assemblages of the Athleta Zone are Sub-Boreal or Sub-Tethyan, while in the Lamberti Zone they are Boreal, and in the Lower Oxfordian they are Arctic. It is also shown that the change in ammonite composition in the sections coincides with the cycles of transgressions and regressions of Boreal basins. New species and subspecies of the ammonites Funiferites allae compressum, Cadoceras (Eichwaldiceras) intermedium, Brightia (B.) lominadzei, B. (B.) progzhellensis, B. (B.) eccentrtica, B. (Glyptia) canaliculata stankevitchae, Zieteniceras rarecostatum are described.

4

Sedimentary successions in the Middle-Upper Oxfordian reef deposits from the southern part of the Kraków-Częstochowa Upland (Southern Poland)

Krajewski M., Olchowy P., Rudziński D.

Geological Quarterly

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2018

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Vol. 62, No. 3

653--668

EN

The sedimentary succession of the largest example of an Upper Oxfordian reef located in the southern part of the Polish sector of the northern Tethys shelf is described. Detailed sampling of exposures enabled characterization of the full succession of facies and microfacies diversity, documenting the reef evolution. The succession studied represents the maximum development of Upper Jurassic reefs in Poland corresponding to the upper Transversarium and the Bifurcatus zones, and followed by drowning of the carbonate platform in the lower Bimmamatum Zone. The reef succession comprises three types of facies, in which eight important microfacies types were distingushed, reflecting several stages of reef development. Mid-ramp, microbial-sponge frame-reefs represent a transgressive depositional sequence, up to tens of metres thick. A microbial-Crescentiella-ooid and ooid-intraclast-bioclast facies form numerous, decimetre- to metre-scale, sequences corresponding to higher-order, transgressive/regressive sea level changes. These facies represent a mid-inner ramp setting when sedimentation was dominated by bioclasts and non-skeletal grains (mainly ooids, oncoids, aggregate grains and intraclasts). The grains were stabilized by microbialites and cemented in early diagenesis, which created grain-dominated, microbial-cement supported reefs. As a result, both the mid-ramp, microbial-sponge frame-reefs and the shallow-water, grain-dominated, microbial-cement supported reefs form extensive, strongly lithified Oxfordian reef complexes in the Kraków-Częstochowa Upland.

5

Electrical resistivity tomography (ERT) and sedimentological analysis applied to investigation of Upper Jurassic limestones from the Krzeszowice Graben (Kraków Upland, southern Poland)

Woźniak T., Bania G., Mościcki W. J., Ćwiklik M.

Geological Quarterly

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2018

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Vol. 62, No. 2

287--302

EN

This paper highlights the application of shallow non-invasive geophysics (electrical resistivity tomography) supported by sedimentological analysis applied to the investigation, description and interpretation of Upper Jurassic limestones exposed in the abandoned quarry near the village of Tomaszowice (Kraków Upland, southern Poland). Within this site, on the northern margin of the Krzeszowice Graben, a facies diversity of Upper Jurassic limestones can be observed. Field exposures were analysed to broadly characterize these Upper Jurassic limestones in terms of facies and microfacies development. Three facies types, including pelitic limestones, bedded limestones and carbonate gravity-flow deposits, composed of numerous microfacies, have been distinguished. ERT study using a dipole-dipole array has been carried out, along 5 parallel 110 m long profiles and along a perpendicular 110 m long profile, north of the Tomaszowice Quarry wall. The use of ERT in combination with the geological data allowed characterization and description of the geology at the research site as well as the determination of the lithological composition and internal architecture of the subsurface. Furthermore, the ERT interpretation results indicated the presence of a series of a secondary faults closely linked with the Krzeszowice Graben. The distribution of the gravity-flow deposits reflects the fault zone pattern of the graben and Late Jurassic fault activity.

6

Comments on the identification of Ammonites planula Hehl in Zieten, 1830 (Upper Jurassic, SW Germany)

Schweigert G., Kuschel H.

Volumina Jurassica

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2017

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Vol. 15, no 1

1--16

EN

Ammonites planula Hehl in Zieten, 1830 is the type species of the Late Jurassic ammonite genus Subnebrodites Spath, 1925 and the index species of the well-established Planula Zone of the Submediterranean Province. Recently, Enay and Howarth (2017) classified this stratigraphically important ammonite species as a ʻnomen dubiumʼ and considered it to be the possible macroconch counterpart of Idoceras balderum (Oppel, 1863). These authors claimed “Subnebrodites planula Spath, 1925” instead of Ammonites planula (Hehl in Zieten, 1830) to be the type species of Subnebrodites. However, their nomenclatorial acts are based on erroneous assumptions. For future taxonomic stability we here propose a neotype for Ammonites planula (Hehl in Zieten, 1830) and a lectotype for Ammonites planula gigas Quenstedt, 1888. In addition, dimorphism within the stratigraphically much younger Idoceras balderum (Oppel) is demonstrated showing that there is no morphological resemblance and no closer relationship with Ammonites planula (Hehl in Zieten, 1830).

7

Biostratigraphy, geochemistry and sedimentology of Middle to Late Jurassic strata in the Strážovce section (Strážovské vrchy Mts), Krížna Nappe of the Central Carpathians, Slovakia

Michalík J., Bąk M., Lintnerová O., Méres Š

Volumina Jurassica

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2017

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Vol. 15, no 1

161--178

EN

The Jurassic / Lower Cretaceous sequence of the Strážovce section has been deposited in the central, axial part of the Zliechov Basin. Its most characteristic part – the Ždiar Formation consists of bedded siliceous radiolarian limestones and radiolarites. The radiolar¬ian assemblage typical of the North Tethyan Bioprovince lived during mid Oxfordian – Early Kimmeridgian in a warm upper part of the well stratified water column, partially near to the thermocline. Radiolarian abundance decreases upwards. Productivity decrease is quanti¬fied by the share of biogenic SiO2 as well as by high EFSi values during sedimentation of both the Ždiar and Jasenina formations. The geochemical data indicate relatively stable volume of the siliciclastic component of the rocks and a felsic character comparable to the Average Shale. The chemically homogeneous sedimentary signal indicates values of both CPA and EF ≤ 1 of Ti, Zr, Fe, Na, K, Rb, V and U. The values of EF > 1 signal enrichment of elements with affinity to carbonate minerals (Sr, Mn, P, Y, and Mg). Metal enrichment (Cu, Zn and Ni) indicates metal mobilization from other sources or due to carbonate diagenesis. In comparison to the Average Shale, decreased ΣREE´s and negative Cech and Euch anomalies could be regarded as a typical deep sea water signal. The differentiated REE record of higher calcareous beds of the Jasenina Fm. suggests basinal dysoxic conditions. The “bell-shape” of curves (normalized to shale) indicate that REEs were slightly affected by carbonate diagenesis. The Oxfordian / Kimmeridgian siliceous sedimentation in the Zliechov Basin was influenced probably more by monsoon-controlled input of land derived weathered material than by hydrothermal fluids from the bottom rifts.

8

Selected Oxfordian brachiopods from Zalas (Cracow Upland, Poland)

Radwańska U.

Acta Geologica Polonica

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2017

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Vol. 67, no. 3

433--440

EN

Small brachiopods of the families Craniidae Menke, 1828 and Thecidellinidae Elliott, 1958 were selected from the Oxfordian sequence which lies transgressively upon a Variscan rhyodacite laccolite exposed at Zalas in the Cracow Upland, southern Poland, a site which is well-known due to various kinds of ubiquitous fossils. The craniids include three species: Craniscus bipartitus (Münster in Goldfuss, 1837), Craniscus tripartitus (Münster in Goldfuss, 1837) and Craniscus antiquior (Jelly, 1843), and the thecidellinids – two species: Rioultina zalasensis sp. nov. and Rioultina wapiennensis Krawczyński, 2008. The species described herein indicate tropical or subtropical waters, and a moderately (?) deep character of the sea basin at Zalas.

9

On the typological basis of Perisphinctes Waagen, 1869 and the leading modern ammonite superfamily Perisphinctoidea Steinmann, 1890

Callomon J. H., Wright J. K.

Volumina Jurassica

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2016

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Vol. 14, no. 1

1--14

EN

A re-examination of the type specimen of Ammonites biplex Sowerby, 1821 shows that the reasons previously given for rejecting this species as the type species of Perisphinctes, to be replaced by Amm. variocostatus Buckland, 1836 (Hemming, 1954), were unfounded. Fortunately, the replacement, based on a macroconch type, is a better representative of the genus than its originally validly designated microconch, Ammonites biplex. The decision in Opinion 303 (Hemming, 1954) is therefore a good one but arrived at for the wrong reasons. It should be left unchanged.

10

Pressure dissolution features in Oxfordian microbial-sponge buildups with pseudonodular texture, Kraków Upland, Poland

Matyszkiewicz J., Kochman A.

Annales Societatis Geologorum Poloniae

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2016

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Vol. 86, No. 4

355--377

EN

Part of the Oxfordian carbonate buildups in the southern part of the Kraków Upland is developed as pseudonodular limestones, which represent segment reefs. These limestones are composed of connected, rounded-oval to subangular carbonate pseudonodules. The pseudonodules, densely packed within the limestone, fall out easily under mechanical stress. The recently observed texture of pseudonodular limestones resulted from two stages of chemical compaction. During the first stage, in the Late Jurassic, high-amplitude and low-amplitude stylolites and dissolution seams were formed. The sites particularly favourable for the development of high-amplitude stylolites were the boundaries between already lithified fragments of the laminar, rigid microbial-sponge framework. The low-amplitude stylolites formed mainly in the intercalated wackestone-packstone, which was lithified somewhat later; hence, the dissolution seams originated at the contacts between the rigid microbial-sponge framework and the wackestonepackstone. After Early Cretaceous erosion, which decreased the burial load, Late Cretaceous sedimentation enabled the renewal of pressure dissolution. Thus, some low-amplitude stylolites evolved into dissolution seams. In stylolites composed of both low- and high-amplitude segments, dissolution proceeded at the bases of interpenetrating high-amplitude stylolite columns, with the simultaneous transformation of low-amplitude stylolite segments into dissolution seams. These seams, which formed at the initial stage of chemical compaction, were subjected in turn to further pressure dissolution, giving rise to the formation of horsetail structures. The vertical stress field, which triggered the pressure dissolution processes, presumably resulted in the formation of high-angle and vertical incipient tension gashes. At the beginning of the processes, these gashes remained closed. In the Cenozoic, under the extensional regime generated by overthrusting Carpathian flysch nappes, some high-angle and vertical dissolution seams and low-amplitude stylolites opened up, forming deformed dissolution seams and deformed stylolites. Under the same conditions, the high-angle and vertical tension gashes opened up as well. Subsequently, during the exposure period, unloading fractures developed, partly as a result of the opening of some subhorizontal and horizontal dissolution seams and stylolites. The unloading fractures, along with the already existing vertical and high-angle tension gashes, formed the network changing the limestone into pseudonodules of various shapes and sizes. The open spaces between the limestone fragments became local conduits for karst waters.

11

Integrated biostratigraphy of the Jurassic strata of the Wagad Uplift, Kachchh, western India

Rai J., Garg S., Gupta M., Singh A., Pandey D. K., Fürsich F. T., Alberti M., Garg R.

Volumina Jurassica

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2015

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Vol. 13, no. 2

55--80

EN

An integrated study based on calcareous nannofossils, organic-walled dinoflagellate cysts, and ammonites from the Washtawa and Kanthkot formations of the Wagad Uplift have allowed a detailed documentation of the stratigraphic position of these formations within the Oxfordian and Kimmeridgian sediments of the Kachchh Basin, western India. The nannofossil assemblages from the lower part of the Nara Shale Member exposed in the Nara and Washtawa domes, the Kanthkot Ammonite Beds along the Trambau River section, and the Patasar Shale Member exposed along the Trambau River section and the Patasar Tank section in the eastern part of the Wagad Uplift belong to the NJ 14 Cyclagelosphaera margerelli Zone of the Early Oxfordian, the NJ 15a Lotharingius sigillatus Zone of the Middle Oxfordian, and the NJ 15b Cretarhabdus conicus of Early Kimmeridgian age, respectively. Zonation schemes, based on calcareous nannofossils, dinoflagellate cysts, and ammonites were calibrated highlighting their biostratigraphic potential. These studies may represent a reference biochronology for Oxfordian–Kimmeridgian age strata applicable to the Tethyan realm of which India was a part during Late Jurassic times.

12

Microbial laminites with coprolites from Upper Jurassic carbonate buildups (Kraków-Częstochowa Upland, Poland)

Kochman A., Matyszkiewicz J.

Annales Societatis Geologorum Poloniae

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2012

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Vol. 82, No. 4

331–-347

EN

The Upper Oxfordian microbial-sponge agglutinated to open-frame reef complex of the Zegarowe Crags in the Kraków-Częstochowa Upland originated upon an elevation of the Late Jurassic stable northern shelf of the Tethys. This elevation was formed, owing to a local decrease in subsidence rate during Jurassic time, induced by the presence of a Palaeozoic granitoid intrusion in the shelf substratum, and Late Jurassic, synsedimentary tectonics, which controlled the topography of the sea bottom. The Zegarowe Crags (Skały Zegarowe) complex at the top contains microbial laminites, composed of peloidal and agglutinated stromatolites, and intercalations of grainstones with indeterminable, favrenoid coprolites, occurring in large numbers. The development of stromatolites was associated with low nutrient availability. In contrast, the periodic activity of crabs, the main producers of the coprolites, forming the coprolitic grainstone intercalations, indicates periods, when nutrients were abundant in the sea water. The nutrinets most likely were associated with the occurrence of clouds of suspended matter, induced by gravity flows, generated by active, synsedimentary tectonics. The results of isotopic studies do not support the presence of warm, mineralizing solutions, connected with synsedimentary tectonics during development of the Zegarowe Crags complex in the Late Jurassic.

13

The succession of ammonites of the genus Amoeboceras in the Upper Oxfordian – Kimmeridgian of the Nordvik section in northern Siberia

Rogov M., Wierzbowski A.

Volumina Jurassica

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2009

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Vol. 7, no. 1

147-156

EN

A collection of ammonites of the genus Amoeboceras located carefully in the section of Nordvik Peninsula in northern Siberia has enabled recognition of the standard Boreal ammonite zones of the Upper Oxfordian and Kimmeridgian. The recognition of the standard Amoeboceras zones, well known in NW Europe and the Barents Sea area, in northern Siberia indicates the uniform character of the Late Oxfordian and Kimmeridgian ammonite faunas across the whole Boreal Province. Some comments on the occurrence of Boreal oppeliids of the genus Suboxydiscites in the studied section are also given.

14

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

Page K., Melendez G., Wright J.

Volumina Jurassica

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2009

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Vol. 7, no. 1

89-99

EN

At Moenkopi Wash along the Ward Terrace escarpment of northern Arizona strata of the upper Dinosaur Canyon Member of the Moenave Formation contain sedimentary structures we interpret as casts of tetrapod burrows. Sandstone casts and in situ burrows occur concentrated in two horizons that extend several hundred meters along the Ward Terrace escarpment. The structures, hosted in beds of eolian sandstone, form interconnecting networks of burrows that branch at right angles. Individual burrow casts have sub-circular cross sections and consist of nearvertical tunnels and horizontal to low-angle galleries that connect to larger chambers. Most burrow casts measure 5 to 15 cm in diameter, are filled by sandstone of similar grain size as the host rock, and have walls that are unlined and lack external ornamentation. Bedding plane exposure of the lower horizon reveals that the density of burrows exceeds 30 vertical tunnels per square meter. One exposure in the upper horizon reveals burrows concentrated in a mound-like structure with 1 m of relief. Rhizoliths, distinguished from burrows by their typical smaller diameters, calcareous infilling, and downward branching, co-occur with these burrows in the upper horizon. The fossil burrows in the Moenave Formation appear to have been constructed by a fossorial tetrapod with social behavior similar to the modern Mediterranean blind mole-rat. Although no skeletal remains are associated with the burrows, the fossil record suggests that the most likely producers of the Moenave burrows were tritylodontid cynodonts.

15

Oxfordian biofacies and palaeoenvironments of Saudi Arabia

Hughes G., Al-Khaled M., Varol O.

Volumina Jurassica

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2008

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Vol. 6, no. 1

47-60

EN

The Hanifa Formation in Saudi Arabia consists of a succession of carbonates, over 100 m thick, that were deposited during the Late Jurassic. It consists of two depositional sequences represented by the lower Hawtah Member and an upper Ulayyah Member, respectively. The Hawtah Member is assigned an Early (?) to Middle Oxfordian age, based on brachiopod, nautiloid and coccolith evidence. The Ulayyah Member is assigned a Late Oxfordian age based on ammonite, nautiloid, coccolith and foraminiferal evidence. Detailed study of the microbiofacies and lithology of the late highstand succession of the Ulayyah sequence in 41 cored wells distributed across the Kingdom was aimed at determining the most suitable locations for porous and permeable grainstone accumulation as lithofacies hosts the Hanifa Reservoir elsewhere in the region. A range of palaeoenvironments has been determined, based on integrated biofacies and lithofacies, that include shallow lagoon packstones and foraminiferal dominated grainstones and deep lagoon wackestones and packstones with Clypeina/Pseudoclypeina dasyclad algae. In addition, a series of basin-margin, shoal-associated biofacies are present that include stromatoporoid back-bank packstones and grainstones with the branched stromatoporoid Cladocoropsis mirabilis, bank-crest grainstones with encrusting and domed stromatoporoids. A few wells also proved the presence of intrashelf basin-flank mudstones and wackestones containing sponge spicules, deep marine foraminifera and coccoliths. This study provided control to delimit an intrashelf basin with an irregular margin situated in the east-central part of the Saudi Arabian portion of the Arabian Plate carbonate platform during Late Oxfordian. The basin is flanked by a belt of stromatoporoid banks that pass laterally into a back-bank facies before developing into a lagoon facies. There is no evidence for the shoreline of this basin, although the presence of rare charophytes in the northwest testifies to possible proximity of fluviatile input. The grainstone dominated basin margin facies presents good hydrocarbon reservoir facies and its juxtaposition to intrashelf basinal sediments with potential source rock character provides exciting new prospects in areas hitherto uninvestigated for hydrocarbon reservoirs.

16

A rare comatulid crinoid, Semiometra petitclerci (CAILLET, 1923), from the Upper Oxfordian of Poland

Radwańska U.

Acta Geologica Polonica

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2007

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Vol. 57, no. 2

161-167

EN

A small faunule of feather stars or comatulids (free-living crinoids of the order Comatulida A.H. CLARK, 1908) is recorded from Upper Oxfordian strata (Bielawy/Wapienno sequence) in the Couiavia region, north-western Central Poland. It represents a single, very small-sized species, Semiometra petitclerci (CAILLET, 1923), hitherto an extreme rarity in the Jurassic sequences of France and Germany. The present record extends the geographic distribution of the species in Europe, to evidence a wider range of the genus Semiometra GISLEN, 1924, prior to its fairly common occurrence and higher diversity during the Late Cretaceous.

17

Upper Oxfordian – Lower Kimmeridgian ammonite succession (Amoeboceras, Suboxydiscites) in the Nordvik section (northern Siberia)

Rogov M., Wierzbowski A.

Volumina Jurassica

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2006

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Vol. 4, no. 1

211-212

EN

Nordvik Peninsula situated at the Laptiev Sea, east of Taimyr Peninsula provides one of the most fossiliferous Jurassic - Lower Cretaceous successions of northern Siberia. The succession consists of clays and mudstones with numerous levels of phosphatic and calcareous concretions. The Mesozoic deposits of the area were discovered at the beginning of XX century, but more detailed studies were undertaken by Russian geologists from sixties to eighties of the century: see Zakharov et al. (1983) and earlier papers cited therein. The present study is based on the collection of ammonites gathered during joint field-trip of the Russian (Zakharov V., Rogov M.) and Czech geologists (Kostak M., Chadima M., Slechta S., Mazuch M.) in August 2003. The collection of Upper Oxfordian - Kimmeridgian ammonites consists of about 60 specimens carefully located in the 20 meters thick section. The most abundantly represented and zonally diagnostic are representatives of the genus Amoeboceras, whereas rarely encountered but palaeogeographically important are representatives of the genus Suboxydiscites. The Amoeboceras ammonites enable recognition of the standard Boreal ammonite zones of the Upper Oxfordian and Kimmeridgian. These of the Upper Oxfordian (cf. Sykes & Callomon 1979) include: the Glosense Zone with ammonites Amoeboceras transitorium Spath, A. glosense (Bigot et Brasil); the Serratum Zone with A. serratum (Sowerby), A. koldeweyense Sykes et Callomon, A. nunningtonense Wright; the Regulare Zone with A. freboldi Spath, A. regulare Spath; the Rosenkrantzi Zone with A. rosenkrantzi Spath. The Kimmeridgian ammonite zones (cf. Wierzbowski & Smelror 1993) include: the Bauhini Zone with A. lineatum (Quenstedt); the Kitchini Zone with A. subkitchini Spath below (Subkitchini Subzone), and A. kitchini Salfeld and A. modestum Mesezhnikov et Romm above (Modestum Subzone); the Elegans Zone with A. elegans Spath and A. decipiens Spath. The Kochi Zone is the only standard zone not recognized in the succession, but the interval possibly corresponding to this zone in the Kimmeridgian unfortunately has not yielded recognizable ammonites. The recognition of the standard Amoeboceras zones in the northern Siberia well known in NW Europe and the Barents Sea area indicates the uniform character of the Late Oxfordian to Kimmeridgian ammonite faunas in the Boreal Province. The ammonites of the genus Suboxydiscites appear for the first time in the studied succession in the upper part of the Kitchini Zone of the Kimmeridgian, and do occur in the younger interval of the Kimmeridgian. The ammonites represent the group of oppeliids of the Submediterranean roots (Ochetoceras(?), see Rogov 2001) that colonized the Boreal Province during Late Kimmeridgian. In the studied section Suboxydiscites are represented by both microconchs and macroconchs, belonging to the new species.

18

Upper Jurassic dinoflagellate cyst biostratigraphy of the Shaim petroleum-bearing region (Western Siberia)

Trubicyna A., Ilyina V.

Volumina Jurassica

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2006

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Vol. 4, no. 1

216-217

EN

The results of palynological analysis of the sediments of the Abalak Formation from five boreholes in the Shaim petroleum-bearing region (northwestern part of Western Siberia) allow determining the Late Jurassic (Oxfordian to Volgian) age of the deposites in question. The study of taxonomic composition and stratigraphic distribution of dinoflagellate cyst as well as spores and pollen grains, acritarchs and prasinophyts have provided the basis for a local biostratigraphic subdivision of these deposits. The geosequence of five dinozones has been defined.

19

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.

20

Strontium isotope variations in Oxfordian seawater

Wierzbowski H., Zieliński G.

Volumina Jurassica

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2006

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Vol. 4, no. 1

222-223

EN

The Jurassic strontium isotope curve is characterized by a broad and deep minimum at the Callovian/Oxfordian boundary. However, there are some discrepancies among its datings and the 87Sr/86Sr values represented in various papers (cf. Jones et al. 1994; Podlaha et al. 1999). We analysed well-stratigraphically dated and well-preserved (Fe <150 ppm, Mn <50 ppm) belemnite rostra derived from the Submediterranean and Boreal Provinces (Polish Jura Chain, Swabian Alb, Isle of Skye). Rostra were carefully separated from surrounding sediment with microdrill, ground and dissolved in 2M acetic acid. After removal of insoluble residue, the leachates were evaporated with an admixture of concentrated nitric acid. Strontium separation was performed at two steps: with 100% nitric acid and cation exchange resin (Bio-Rad 50W-X8 with 2.5 M HCl as eluent). Total blank of chemical procedures has been determined to be less than 1 ng of total Sr. The blank value was not enough to affect the Sr isotope ratio at the average sample weight (50 mg). Analyses of strontium isotopic ratio (87Sr/86Sr value) were performed by a VG Sector 54 mass spectrometer (equipped with 7 faraday collectors) at the Institute of Geological Sciences PAS in Warsaw. All isotope ratios were instrumentally corrected for fractionation effect by using the 87Sr/86Sr value of 0.1194 and normalized with NIST 987 isotopic standard (87Sr/86Sr ratio = 0.710248). The scarcity of the data and the spread of results do not allow the exact recognition of the 87Sr/86Sr values in the lowermost Oxfordian (Fig. 1). However, the strontium isotope curve is characterized by a discernible minimum (87Sr/86Sr ratios between 0.70679 and 0.70681) in the uppermost Lower and the Middle Oxfordian. The 87Sr/86Sr ratio rapidly increases starting from the Middle/Upper Oxfordian boundary and reaches about 0.70685 in the uppermost Oxfordian (Bimmamatum and Planula zones). The 87Sr/86Sr ratio of Callovian-Oxfordian seawater, which was the lowest in the Mesozoic, might have been linked to enhanced hydrothermal activity of the seafloor. Nevertheless, the long time-span of this minimum is unusual. The Callovian-Oxfordian 87Sr/86Sr ratio minimum may also be correlated with a crisis in carbonate sedimentation. In addition, the increase of seawater 87Sr/86Sr ratio coincides with a new period of acceleration of carbonate sedimentation in the oceans. The present data may be used to obtain a best fit of the strontium isotope curve in the Oxfordian.