titre1
titre2
fr_2  Current Issue  Books  Registration  DVD      
GeoSciences e-Journals are back!

up2  

2024 (vol. 24)

Extraordinary trilobite collected by František Pošepný discovered after 140 years
Oldřich FATKA

 | HTML  | PDF [390 KB]  | DOI: 10.2110/carnets.2024.2411

 Abstract:  This extraordinary specimen, a well-preserved articulated thorax of a large specimen of the middle Cambrian paradoxidid trilobite Paradoxides (Hydrocephalus) minor (Boeck, 1827), was collected by the notable geologist František Pošepný during an excursion to the Hřebeny mountain range, Czech Republic, in the 1890s, and was thought to have been lost for nearly 140 years. The trilobite originates from the Brdlavka locality, one of the easternmost outcrops of the Jince Formation. There is no fossil collected at this locality housed in institutional and private collections. The recent discovery of this fossil in the Geological Pavilion of the Technical University of Ostrava, Czech Republic, enabled its assignment to the common species Paradoxides (Hydrocephalus) minor (Boeck, 1827). This species confirms the occurrence of the middle levels of the middle Cambrian Jince Formation at the Brdlavka locality.

Carnets Geol., vol. 24, no. 11, p. 173-178

Online since October 31, 2024


A larger benthic foraminiferal zonation for the Cenozoic of the Americas
Simon F. MITCHELL, Edward ROBINSON, Ercan ÖZCAN, Mark M. JIANG & Natalie ROBINSON

 | HTML  | PDF [762 KB]  | DOI: 10.2110/carnets.2024.2410

 Abstract:  The Cenozoic of the Americas does not have a zonation based on Larger Benthic Foraminifera (LBF) unlike the Tethys where there is a shallow-water benthic zonation. Although there were faunal exchanges, the different evolutionary patterns between the Americas and the Tethys require separate zonations. We have calibrated LBF, stratigraphic distributions and events in the Americas using calcareous nannoflora (Paleocene-Eocene), planktic foraminifers (Oligocene-Miocene) and published strontium (Sr) isotope values. We define 29 zones spanning the Paleocene to Recent based on changing LBF assemblages and evolving lineages, with some zonal boundaries related to global or local palaeoenvironmental events. This will allow correlation across carbonate platforms in the tropical Americas at a higher resolution than previously possible.

Carnets Geol., vol. 24, no. 10, p. 163-172

Online since October 31, 2024


Shell injuries in Densepustula Lazarev, 1982, Pennsylvanian productidine brachiopod from the Donets Basin, Ukraine
Vitaly DERNOV

 | HTML  | PDF [1,669 KB]  | DOI: 10.2110/carnets.2024.2409

 Abstract:  Nine injured ventral valves of productidine brachiopods belonging to the genus Densepustula Lazarev, 1982, from the Mospyne, Smolyanynivka, Belaya Kalitva, and Kamensk formations (Upper Bashkirian-lower Moscovian, Lower and Middle Pennsylvanian) of the Donets Basin (eastern Ukraine) were studied. Three morphological types of damage traces have been recognized: Type A) longitudinal, sublongitudinal, and transversal thin straight or sinuous furrows, about 5-7 mm long and 0.5-1.5 mm thick; Type B) rounded and ellipsoidal pits, about 3-4 mm in diameter, located on the umbo, the anterior margin of the ventral valve, and the lateral slopes of the ventral valve; and Type C) irregularly-shaped dimples on the anterior margin and in the sulcus, 2-3 mm in size. These injuries are present on 9 out of 61 (15%) of ventral valves studied, but entirely absent from dorsal valves (0 out of 25). The most likely producers of these damage traces are cartilaginous fishes and parasites of unclear affinity.

Carnets Geol., vol. 24, no. 9, p. 143-162

Online since September 20, 2024


Tooth marks of the Great White Shark from a Pliocene outcrop of the Northern Apennines (Castell'Arquato, Italy)
Alessandro FRESCHI & Simone CAU

 | HTML  | PDF [596 KB]  | DOI: 10.2110/carnets.2024.2408

 Abstract:  We describe and analyze a rib fragment of a small cetacean from the Castell'Arquato Plio-Pleistocene Basin (Northern Apennines, Italy) that displays various tooth marks featuring parallel striations similar to those left by the serrated tooth of the extant white shark, Carcharodon carcharias. The discovery locality, known as "Buca della Balena", was an inner-shelf marine setting where sharks may have scavenged on drifting cetacean carcasses in Piacenzian times. The high number of marks found on the small bone fragment suggests multiple bites by one or more shark individuals. The rib fragment studied is one of the few osteological specimens from the Pliocene of the Mediterranean Basin to preserve white shark tooth marks.

Carnets Geol., vol. 24, no. 8, p. 135-141

Online since July 24, 2024


Octahedronoides tethysianus n.gen., n.sp., enigmatic clusters of microspheres at the Jurassic-Cretaceous transition
Bruno R.C. GRANIER

 | HTML  | PDF [1,821 KB]  | DOI: 10.2110/carnets.2024.2407

 Abstract:  In the literature, numerous accounts exist of microspheres scattered in the pelagic environments of the Tethys realm at the Jurassic-Cretaceous transition. These microspheres are commonly associated with genera such as Cadosina, Colomisphaera, or Stomiosphaera, and attributed to calcareous dinocysts. On the other hand, there are few records of the microsphere, initially described as Cadosina minuta Borza, 1980, which are arranged in small clusters, likely comprising six cells. This distinctive grouping and its architecture preclude attribution to the calcareous dinocysts. A new genus and a new species (as Octahedronoides tethysianus n.gen., n.sp.) are introduced to define these clusters of leiospheres, which are here reascribed to the acritarchs.

Carnets Geol., vol. 24, no. 7, p. 127-133

Online since May 8, 2024


A new fossil psychodomorphan fly from Lower Barremian Lebanese amber elucidates the relationship of the Tanyderinae stat. nov. within the Psychodidae
Dany AZAR, Sibelle MAKSOUD, Di-Ying HUANG, Mounir MAALOUF & Chen-Yang CAI

 | HTML  | PDF [949 KB]  | DOI: 10.2110/carnets.2024.2406

 Abstract:  A new species, Nannotanyderus granieri sp. nov., belonging to the Tanyderidae (Diptera, Nematocera), from Lower Barremian amber of Bqaatouta (Lebanon), is characterized, described, figured, and its taxononomic position discussed. The possible confusion regarding the attribution of new fossils to either the Tanyderidae or the Psychodidae, in addition to the results of recent molecular phylogenies, have led us to re-evaluate the taxonomic position of the Tanyderidae and to consider it as a subfamily within the Psychodidae. The fossil described herein is a tiny tanyderine sensu nov. species, and the second one belonging to the genus Nannotanyderus from Lebanese amber. A tentative molecular phylogeny of recent Psychodidae and an exhaustive catalogue of fossil Tanyderinae stat. nov. are provided.

Carnets Geol., vol. 24, no. 6, p. 113-125

Online since April 1, 2024


Nomenclatural Note, p. 126


The Kalkowsky Project - Chapter VI. A panorama of synsedimentary broken ooids
Bruno R.C. GRANIER & Philippe LAPOINTE

 | HTML  | PDF [3,988 KB]  | DOI: 10.2110/carnets.2024.2405

 Abstract:  Broken ooids are known to occur in both aragonitic and calcitic ooids with radial fabrics. In the literature, it has been suggested that synsedimentary breakage could be related to attrition/mechanical impacts, hypersalinity, or desiccation. However, this paper demonstrates that none of the aforementioned phenomena provides a valid explanation. Although the exact process remains unknown (potentially involving some synsedimentary recrystallization), it is shown that: 1) the breakage is genetically linked to the radial fabrics; 2) the ratio of ooid breakages increases with the relative thickness of the radial cortical layers; 3) fracture growth in broken ooids proceeds centripetally.

Carnets Geol., vol. 24, no. 5, p. 91-112

Online since February 29, 2024


A new record of ground sloth in the Ribeira de Iguape valley, southeastern Brazil
Artur CHAHUD, Gabriella da C. PEREIRA, Paulo R. de O. COSTA & Mercedes OKUMURA

 | HTML  | PDF [377 KB]  | DOI: 10.2110/carnets.2024.2404

 Abstract:  In the early 1980s, an assemblage of extinct and extant vertebrates was collected from the Abismo Ponta de Flecha, a vertical cave in southern S o Paulo, Brazil, for archaeological, geological, and paleontological analyses. While materials identified as ground sloths have been referenced in earlier publications, they have never been thoroughly described. In this study, we provide the first detailed description of a large, previously unidentified taxon found in Brazil, interpreted herein as belonging to the family Nothrotheriidae. Although direct dating of the specimen was not possible, other dated occurrences from the Ribeira de Iguape Valley suggest that it may have inhabited the region during the Late Pleistocene, coinciding with the local presence of a dense forest cover.

Carnets Geol., vol. 24, no. 4, p. 83-89

Online since January 31, 2024


The Kalkowsky Project - Chapter V. Asymmetric ooids from the Yacoraite Formation (Argentina)
Bruno R.C. GRANIER & Philippe LAPOINTE

 | HTML  | PDF [2,420 KB]  | DOI: 10.2110/carnets.2024.2403

 Abstract:  Asymmetric ooids are documented in a brackish Maastrichtian to Danian paleolake in NW Argentina. Their distinctive asymmetric growth pattern is likely related to an uneven distribution of the Extracellular Polymeric Substances (EPS) around the coated allochem, within which calcite fibers (i.e., the 'fibrite') have grown. This pattern is unlikely to be mistaken for that of other 'eccentric' ooids, such as wobbly ooids, spiny ooids, hiatus ooids, half-moon ooids, 'broken' ooids sensu lato, or collapsed oomolds (referred to as 'distorted' ooids).

Carnets Geol., vol. 24, no. 3, p. 75-82

Online since January 20, 2024


The Central South Atlantic: The origin of its waters, its evolution and effects beyond
Ricardo L.M. AZEVEDO, Rogério L. ANTUNES, Mauro D.R. BRUNO, Thomas R. FAIRCHILD & Dimas DIAS-BRITO

 | HTML  | PDF [3,554 KB]  | DOI: 10.2110/carnets.2024.2402

 Abstract:  The primitive sea that occupied the Central South Atlantic (CSA), part of the intra-Gondwana rift during the Early Cretaceous, allowed precipitation of an extensive and thick layer of evaporites, the Ibura Salt, followed by the deposition of a prominent Albian carbonate package. Although the shallow platform facies do not contain classical benthic Tethys markers, the pelagic open sea carbonates are essentially dominated by planktonic elements coming from the Tethys Realm. This condition led some researchers to think that Tethys waters also contributed to salt formation, an idea that clashes with the geotectonic model of northward separation of Africa and South America and ingression of predominantly Austral marine waters. Now, a new controversy arises as to the age of this salt layer when trying to position bio-events and lithological and chemostratigraphic markers from these rocks with respect to established data for the Global Boundary Stratotype Section and Point for the Aptian/Albian boundary (GSSP-Alb). Biochronostratigraphic information on planktonic foraminifera points to an Aptian age as opposed to the earliest Albian traditionally accepted for the carbonate section that overlies the giant salt layer. On the other hand, stratigraphic and geochronological data suggest an age of 113 Ma for the base of the salt, very near to the 113.2 0.1 Ma arbitrated for the GSSP-Alb. In this study, we adopt the base of the evaporite bed as the Aptian/Albian boundary in the CSA, Equatorial South Atlantic (ESA), and northeastern Brazilian interior basins (BNE) as well. Based on these criteria, a broad review and the integration of available information have led to new interpretations regarding the earliest phase of these segments of the South Atlantic and adjacent areas. Initially, during the Aptian-Albian transition, an ephemeral interior sea within Brazil, drawing its waters from the north, would have contributed to salt deposition in the intra-Gondwana rift (evaporitic stage of the CSA). Afterward, but still within the earliest Albian, the evaporitic system evolved into a carbonate gulf when the northern barrier, the Exception Zone (EZ), disappeared. The lagoonal circulation pattern that then formed in the CSA created a hypersaline and warm outflow plume that swept across the marine bottom of the ESA and part of the Tethys Sea. Paleoceanographic events registered at Site 545, Mazagan Plateau, support this new hypothesis and illustrate the potential complexity of correlation of organic-rich deposits in which local influences have been greater than global ones. This long, narrow, and continuous carbonate gulf disappeared at the end of the Albian with the arrival of southern waters from the Meridional South Atlantic (MSA), and the South Atlantic became consolidated as a proto-ocean.

Carnets Geol., vol. 24, no. 2, p. 29-74

Online since January 20, 2024


Paleoenvironmental changes preceding the onset of the Messinian salinity crisis in the western Mediterranean Sea (pre-evaporitic Messinian of the Melilla-Nador Basin, NE Morocco)
Hanane BAHAJ, Nadia BARHOUN, Naima BACHIRI TAOUFIQ, Jihad RAHMOUNA, Soukaina TARGHI, Naima BERRY, Jean-Pierre SUC & Speranta-Maria POPESCU

 | HTML  | PDF [1,534 KB]  | DOI: 10.2110/carnets.2024.2401

 Abstract:  In order to contribute to the understanding of the evolution of marine and continental environments, preceding the onset of the Messinian salinity crisis in the western Mediterranean, we conducted an integrated study of the pre-evaporitic Messinian sedimentary series in the Melilla-Nador basin. Three sections have been carried out in the marl-diatomite series and were the subject of a detailed biostratigraphic and palynological study. The study of planktonic foraminifera, pollen, dinocysts, and palynofacies allowed us to characterize the evolution of these environments. From 6.83 to 6.52 Ma, the marine environment was relatively open, calm, probably subject to the action of upwellings and received periodic continental inputs. Starting 6.52 Ma, the abundance and diversity of planktonic foraminifera decreased. Continental inputs gradually dominate, alternating with marine ones, and reflecting a succession between proximal and distal neritic environments. The surface water conditions were warm. After 6.35 Ma, began the degradation of marine conditions. The continental environment shows an open vegetal landscape dominated by herbaceous plants, reflecting a tropical to arid subtropical climate, slightly less dry than that of the South Rifian Corridor.
This study confirms the existence of several parameters that contributed to the deposition of the cyclical marl-diatomite series: on the one hand, the hot and dry climate favored the reduction of the plant landscape and therefore erosion (continental inputs); on the other, the tectonics (volcanism and uplift).

Carnets Geol., vol. 24, no. 1, p. 1-27

Online since January 17, 2024


Except where otherwise noted,
content on this site is licensed
under a Creative Commons BY-NC-SA 4.0 License
Creative Commons