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2017 (vol. 17)

Revision of the Juliette Pfender Collection. 3rd part. About some fossil green algae

 | HTML  | PDF [6,036 KB]  | DOI : 10.4267/2042/64293

 Abstract:  This work is a new but minor contribution to the récolement of Juliette Pfender's collection of fossil green algae. It aims to establish a partial inventory of the green algae studied by this female researcher mostly renowned for her studies on red algae. The poor preservation of some thin sections and the scarcity of whole specimens only rarely allow the identification of the taxa at the level below the genus.

Carnets Geol., vol. 17, no. 14, p. 251-269

Online since December 24, 2017

Additional contributions to the knowledge of the Taquaral Member, Irati Formation (Lower Permian, Paraná Basin): Taphonomy and paleoenvironmental implications

 | HTML  | PDF [2,725 KB]  | DOI : 10.4267/2042/64291

 Abstract:  The silty shale facies of the Taquaral Member (Irati Formation), which is one of the Permian units in the Brazilian Paraná Basin, is discussed here based on the taphonomy relevant to the paleoenvironmental interpretation. The fossils are crustaceans (Clarkecaris and other indeterminate forms), isolated teeth, scales and bones of Actinopterygii, "Palaeonisciformes", which are the most common vertebrate remains, and also frequent scales of Coelacanthiformes. The scales, teeth and disarticulated bones are found together in accumulations, which may be interpreted as coprolites. Many of the fossil crustaceans display characteristics of ecdysis.

Carnets Geol., vol. 17, no. 13, p. 243-250

Online since December 24, 2017

Cornulitids from the Upper Ordovician of northwestern Russia

 | HTML  | PDF [958 KB]  | DOI : 10.4267/2042/64289

 Abstract:  Four cornulitid species occur in the Rakvere Regional Stage in NW Russia. The new species Conchicolites rossicus is here described; it is the earliest known Conchicolites from the Ordovician of Baltica. The new species has very small tubes with sharp, strong and regular annulations. The diversity of cornulitids in the Rakvere Regional Stage at the Pechurki quarry is usual for the Upper Ordovician of Baltica. The cornulitids of Pechurki quarry encrusted hard organic substrates in a mud bottom (clay and carbonate clay) environment. Cornulites sterlingensis occurs both in the Upper Ordovician of North America and Baltica, which suggest a short distance between these two paleocontinents and/or similar environmental conditions

Carnets Geol., vol. 17, no. 12, p. 235-241

Online since December 24, 2017

Mecaster texanus (Echinoidea) from Turonian-Coniacian strata in the Sergipe-Alagoas Basin, Brazil
Cynthia L. de C. MANSO & Wagner SOUZA-LIMA

 | HTML  | PDF [1,325 KB]  | DOI : 10.4267/2042/64287

 Abstract:  The spatangoid echinoid Mecaster texanus (Roemer) was first described from the Austin Chalk in Texas (USA). In northeast Brazil, this species was recorded from the Upper Cretaceous (Turonian-Coniacian) Jandaíra Formation in the Potiguar Basin. Here we extend the palaeogeographical distribution of M. texanus southwards to the Sergipe-Alagoas Basin, where this species occurs in the Turonian-Coniacian Cotinguiba Formation. A key to identification of spatangoids from the Cretaceous-Cenozoic sequence at Sergipe-Alagoas is added and considerations about other spatangoid species from that basin are presented.

Carnets Geol., vol. 17, no. 11, p. 221-234

Online since December 24, 2017

Palynology and sedimentary environments of the Devonian from the Saida area (northwestern Algeria)
Mohammed BOUGARA, Philippe STEEMANS, Alain LE HÉRISSÉ & Frédéric BOULVAIN

 | HTML  | PDF [1,679 KB]  | DOI : 10.4267/2042/64285

 Abstract:  Palynological interpretations of both spores and acritarchs from the Devonian Tiffrit Formation located in Saïda (North-Western Algeria) support identical conclusions. Species of spores and acritarches that appear in the upper layers of the younger reference unit, named Boukourdène (BK1), are compatible with a Pragian-Emsian age, based especially on the presence of the miospores Dibolisporites wetteldorfensis, Dictyotriletes emsiensis, D. subgranifer, Verrucosisporites polygonalis, and the acritarchs Evittia crucistellata, E. spicifera, Fimbriaglomerella aulerca, Florisphaeridium toyetae, and Veryhachium aff. V. vandenbergheni.

On the basis of occurrences of microconglomeratic levels with elements of Silurian phtanites found along the sedimentary units of Tiffrit, we consider that Silurian sediments as well as Lower Devonian sediments have been reworked. We thus propose a Praguian-Emsian age for the Boukourdène units.

From a sedimentological point of view, the Devonian sedimentary units of the Tiffrit Massif are linked to a gravitational deposition controlled by sea level rise and significant subsidence. Facies seems to change along an East-West axis. The particle size, the nature of the facies, and their extreme variability over short distances indicate a slope apron environment of deposition. The lithological, sedimentological and environmental characteristics of the studied system are consistent with deposition in an active tectonic margin setting.

Carnets Geol., vol. 17, no. 10, p. 191-219

Online since December 24, 2017

GSSP proposal for the upper Aptian substage in the Apt Basin (Vaucluse, SE France): Synthesis of the stratigraphic data

 | HTML  | PDF [2,338 KB]  | DOI : 10.4267/2042/62954

 Abstract:  The synthesis of the stratigraphic data collected over more than a decade in the stratotypic area has made it possible to establish a composite section of the "Aptian marls" from the Grandis ammonite Subzone to the base of the Melchioris Zone, i.e., from the Schackoina (Leupoldina) gr. cabri foraminiferal Zone to the Globigerinelloides algerianus Zone. This composite section includes the partial sections from Clavaillan, South and East Pichouraz, La Tuilière, Les Gays and Gargas (Vaucluse, SE France). In particular, our revision has shown that the marly calcareous bed, which divides the marly series of Clavaillan and Pichouraz, compared with  the Vocontian "Niveau blanc" and thought to be unique and isochronous, corresponds in fact to two stratigraphically distinct levels.
The present study confirms that the visible series of marls in the stratotypic area, not taking into account the "A1" supra-Urgonian formation of Leenhardt (1883), includes only the uppermost terms of the Bedoulian and the lower terms (= Lower and Middle Gargasian) of the Aptian s.s. (i.e., sensu Orbigny, 1840).
Based on the methods of integrated stratigraphy, a comparison of the series of the Apt Basin with the contemporary terms of the Cassis-La Bédoule Basin has also made it possible to detect and quantify important variations in the rhythms of sedimentary accumulation between the two sectors. In the end, the Clavaillan section, located 8 km WSW from the Gargas section, is the only outcrop where the boundary between the Grandis Subzone and the Furcata Zone is visible in a context which supports a proposal that this exposure be a candidate for the GSSP of the Gargasian substage (or of the Aptian s.s. in the initial concept of the creator of the stage).

Carnets Geol., vol. 17, no. 9, p. 161-189

Online since October 20, 2017

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

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 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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