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2017 (vol. 17)

Revision of the Barrande's specimen "Tige d'une Cystidée indéterminée" (Cambrian, Echinodermata, Eocrinoidea)
Martina NOHEJLOVÁ & Oldřich FATKA

 | HTML  | PDF [548 KB]  | DOI : 10.4267/2042/62768

 Abstract:  Reexamination of the type specimen described by Barrande in 1887 as "Tige d'une Cystidée indéterminée" shows that this unique specimen represents an articulated but incomplete remnant of the gogiid eocrinoid Akadocrinus jani Prokop. The specimen is preserved as an external mould in shale from the mid-Cambrian Jince Formation, and comprises a proximal part of a stem associated with a slightly disarticulated distal portion of a theca, composed of over twenty polygonal plates. With the exception of the basal-most plates, all other preserved thecal plates bear ellipsoidal marginal epispires, and substantiate assignment of this specimen to the epispire-bearing phase in ontogenetic development of Akadocrinus.

Carnets Geol., vol. 17, no. 8, p. 153-160

Online since October 16, 2017

Rare rugosan-bryozoan intergrowth from the Upper Ordovician of Estonia
Olev VINN, Andrej ERNST & Ursula TOOM

 | HTML  | PDF [1,517 KB]  | DOI : 10.4267/2042/62664

 Abstract:  Two relatively large specimens of the rugosan Lambelasma sp. are fully intergrown with the bryozoan Stigmatella massalis colony. The intergrown specimen occurs in the Oandu Regional Stage (lower Katian) of Estonia and constitutes the earliest record of bryozoan-rugosan intergrowth from Baltica. Most likely this symbiotic association was accidental. Rugosans presumably benefitted from the bryozoan, which served as an anchor to stabilize them in hydrodynamically active waters. The lack of malformations and no decrease in the size of bryozoan zooids near the rugosans indicate a lack of negative effect of the rugosans on the bryozoan. Bryozoan-rugosan symbiosis is only known from the Ordovician of Baltica and Laurentia.

Carnets Geol., vol. 17, no. 7, p. 145-151

Online since October 16, 2017

The most distal moldavite findings from Lower Silesia, Poland

 | HTML  | PDF [1,366 KB]  | DOI : 10.4267/2042/62663

 Abstract:  The present note reports new findings of moldavites from southwestern Poland. The material was found in the Nowa Wieś Kącka sandpit. To date, it represents the most distal locality where moldavites have been found. These moldavites, like other moldavites previously described from Lower Silesia, are recovered from fluvial sands and gravels of the Gozdnica Formation. Like other Polish moldavites, the moldavites in this study display high SiO2 contents (~77 wt.%). Their dimensions range from 9 to 11 mm in maximum diameter. Their relatively large sizes suggest that the distribution of Polish tektites defines a sub-strewnfield larger than previously expected.

Carnets Geol., vol. 17, no. 6, p. 139-144

Online since October 16, 2017

Importance of the Quatrehomme collection (Monnaye Museum, Meung-sur-Loire) in the French palaeontological landscape
Morgane DUBIED, Charlène GILBERT, Maxime DELÉGLISE, Flavie LAURENS & Bastien MENNECART

 | HTML  | PDF [528 KB]  | DOI : 10.4267/2042/62541

 Abstract:  The Quatrehomme collection is described by Ginsburg as "modest to very modest" and there is no accurate inventory. In order to highlight this collection and better understand its importance, an inventory of the terrestrial mammal remains is in progress. In the current state of the inventory 35 different locations were identified, mostly in the Savigné-sur-Lathan Basin. 3,266 specimens, covering 8 of the 9 orders of terrestrial mammals found in the Faluns, are currently registered in the data set. To date, the most impressive published Faluns mammal collections are from Hartmann, hosted at the volunteer "Musée du Savignéen" (Savigné-sur-Lathan) and Bourgeois (today splitted in different museums). While this Hartmann's collection contains 1,475 mammal remains (marine and terrestrial) and Bourgeois' one 1850 (only terrestrial), we estimate that the Quatrehomme collection encompasses more than 7,500 terrestrial specimens. It is the largest known Faluns collection of Pliopithecus (25 specimens) and of Lagomorpha (1,355 specimens). Also, eight Tapiroidea specimens (including a jaw with teeth) and three Chalicotherium remains are inventoried. This collection is now being studied in detail. In the next few years it will take a more prominent place in the French paleontological landscape.

Carnets Geol., vol. 17, no. 5, p. 128-138

Online since September 12, 2017

New stratigraphic and genetic model for the dolomitic Cretaceous Pinda reservoirs in Angola. Part I - The Pinda of Angola, an integrated lithostratigraphic approach

 | HTML  | PDF [6,754 KB]  | DOI : 10.4267/2042/62283

 Abstract:  The Pinda Group of the Congo basin in the northern Angolan offshore is an overall transgressive supersequence of late Aptian - ? early Cenomanian age. Due to synsedimentary salt tectonics of the underlying Loeme Salt, the original ramp arrangement is split into discrete structures corresponding to many proven, probable and possible oil and gas plays. Where the biostratigraphic information was not destroyed by pervasive dolomitization, the little that remains is not available to the general public because it is treated as proprietary data by the Sociedade Nacional de Combustíveis de Angola Empresa Pública – Sonangol E.P. Only a limited set of data containing lithostratigraphic information (e.g., some published well logs and photomicrographs of facies) is available. The aim of this paper is to give a little more information about the Pinda stratigraphy. For instance, to be formally defined, this poorly known unit required a type section, a shortcoming that is addressed here. The wireline log signatures of some regional seismic markers are documented because they are used to correlate wells and subdivide the Group into formations. The microfacies corresponding to some key electrofacies as well as the porosity types are also condensed in a microphotograph catalog. Finally, few examples of typical LoC (i.e., Line of Correlation) diagrams are displayed and interpreted.

Carnets Geol., vol. 17, no. 4, p. 105-127

Online since June 25, 2017

Sedimentological investigation on Holocene deposits in the Mussafah channel (Abu Dhabi, United Arab Emirates)

 | HTML  | PDF [21,535 KB]  | DOI : 10.4267/2042/62267

 Abstract:  Eight macrofacies types (5) plus subtypes (3) were identified while measuring sections along the Mussafah channel profile. These include:
• aeolian sands,
• microbial mat and microbial-laminated sediments,
• gypsum and enterolithic anhydrite, i.e., a diagenetic variation of the previous facies,
• muds with small pelecypods, and • its seagrass meadow version,
• Potamid sands, and • its cemented version, i.e., the Potamid beach-rock,
• washover fan coquina.

A complete set of analyses, including granulometry, mineral composition, clay composition, TOC, and identification of the allochems and the microfossils, was performed on this material. The facies and their genetic setting, i.e., the sequence of facies, provide a perspective on both the environmental and stratigraphical significance of their distribution, both lateral and vertical, and an example of the application of the Walther's law. The lower microbial mat is the mark of a transgression whereas the upper microbial mat is the mark of a forced regression. In conclusion, the sequence of facies allows identification of the last Holocene transgressive-regressive cycle that includes a forced regression, which probably dates back to 6,000 years BP.

Carnets Geol., vol. 17, no. 3, p. 39-104

Online since June 25, 2017

Biostratigraphy and paleoenvironmental reconstruction of the marine lower Miocene Chechiș Formation in the Transylvanian Basin based on foraminiferal assemblages

 | HTML  | PDF [3,045 KB]  | DOI : 10.4267/2042/62041

 Abstract:  Planktonic and benthic foraminiferal assemblages were used for biostratigraphy and paleoenvironmental reconstruction of the marine lower Miocene Chechiș Formation from the Gălpâia section (Sălaj county, Romania) in the northwestern Transylvanian Basin. Planktonic foraminifera suggest an Eggenburgian (Burdigalian) age for the deposits studied and reveal episodes of high primary productivity and mostly cool surface waters. Benthic foraminiferal assemblages indicate paleoenvironmental deepening from outer shelf to upper bathyal settings. Deltaic influences may be observed at the base of the studied section in outer shelf (possibly upper bathyal) environments with oxygenated bottom water and episodic high primary productivity, as a consequence of nutrient input from the land. Changes in paleobathymetry resulted in reduction of primary productivity. The benthic assemblages from the uppermost part of the section are dominated by tubular agglutinated foraminifera and indicate an upper bathyal setting with low organic flux to the sea floor. The sediments of the studied section were deposited during the late stage of the first early Miocene relative sea-level rise in the Transylvanian Basin.

Carnets Geol., vol. 17, no. 2, p. 11-37

Online since March 24, 2017

Review of the early Albian ammonites of the Montmell Formation near Marmellar (Salou-Garraf Basin, Tarragona, Catalonia, Spain)

 | HTML  | PDF [1,482 KB]  | DOI : 10.4267/2042/62038

 Abstract:  In this work, we review the ammonites of the Montmell Formation in the Marmellar area housed in the collections of the Museo Geológico del Seminario de Barcelona and the Museu de Geologia de Barcelona. This taxonomic update allows the proper biostratigraphic analysis of the ammonite assemblage and assigns it to the early Albian, Leymeriella tardefurcata Zone. The taxonomic analysis of all the studied material allows us to recognize the presence of the following taxa: Uhligella sp., Parengonoceras bassei, Hypacanthoplites plesiotypicus, Hypacanthoplites milletianus, Hypacanthoplites subelegans, and Hypacanthoplites sp. The current work is a step forward in the chronostratigraphic knowledge of the Salou-Garraf Basin in the Catalan Coastal Ranges.

Carnets Geol., vol. 17, no. 1, p. 1-10

Online since March 24, 2017

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