GeoSciences

Carnets Geol., Article, vol. 26, no. 19

Cemile Solak.- Some stratigraphically important Larger Benthic Foraminifera from the Lower Jurassic and Sievoides blumenthali sp. nov., Beyaz Aladag Unit, Eastern Taurides, S Türkiye.- The Lower Jurassic succession in the Beyaz Aladağ Unit (Eastern Taurides) includes Hettangian-Pliensbachian shallow-marine carbonates. The studied Sinemurian-Pliensbachian strata, characterized by abundant oncoids and megalodontid bivalve shells, contain a diversified benthic foraminiferal assemblage including orbitopsellids, hauraniids, biokovinids, cyclamminids, and siphovalvulinids taxa. This paper focuses on the morphological analysis of the key biostratigraphic marker species Lituosepta recoarensis Cati, 1959, Lituolipora termieri (Hottinger, 1967), Bosniella oenensis Gušić, 1977, and introduces a new Larger Benthic Foraminifera, Sievoides blumenthali sp. nov. Some poorly known morphological characteristics of these index species have been illustrated, and some potential discrepancies have been improved. The selected taxa have been documented here for the first time from the Beyaz Aladağ Unit, Eastern Taurides. The new species, probably restricted to the Pliensbachian Orbitopsella Zone, is characterized by a coarse agglutinated wall with an irregular, subepidermal polygonal network, a developed spiral stage followed by a long uniserial cylindrical stage, and a simple aperture. It differs from the type species Sievoides kocyigiti Farinacci & Ekmekçi (2004) by a developed spiral stage and stratigraphic position (Pliensbachian). This new species is distributed in the peri-Mediterranean platforms (Taurides, Apennines, Dinarides). The discovery of Sievoides blumenthali in the Lower Jurassic confirms the earlier appearance of the larger Foraminifera having a wall with a subepidermal network, which is known to be common in the Mid-Late Jurassic.- DOI: https://doi.org/10.2110/carnets.2026.2619
https://carnetsgeol.net/cg/26/19/index.html
Wed, 14 Oct 2026 18:37:25 GMT

Carnets Geol., Article, vol. 26, no. 18

Vitaly Dernov.- The taxonomic status of Eurypterus podolicus Chernyshev, 1947 (Arthropoda: Eurypterida), from the Silurian of Podillia, Ukraine.- This article presents the results of an investigation into the complex history of the eurypterid species "Eurypterus podolicus Chernyshev, 1947", for which neither an original description nor a type series is known. The study confirms that this species is a nomen nudum, as it was never formally described. Moreover, the specimens of "Eurypterus podolicus" from the Borys Chernyshev's collection lack distinct morphological features that would justify recognizing it as a separate species.- DOI: https://doi.org/10.2110/carnets.2026.2618
https://carnetsgeol.net/cg/26/18/index.html
Sat, 10 Oct 2026 18:34:37 GMT

Carnets Geol., Article, vol. 26, no. 17

Bruno R.C. Granier, José Enrique E. Tent-Manclús, Jingyi Yang, Emmanuel Robert, Antonio Estévez Rubio & Davide Bonomo.- Serra Gelada (Alicante, Spain): Evidence and implications of a paleo-island setting during the Jurassic-Cretaceous transition.- This study revisits the uppermost Jurassic-lowermost Cretaceous succession of Serra Gelada (Alicante, SE Spain) based on new field observations and petrographic analyses. It is the second publication presenting and discussing results and interpretations of the PhD thesis of the first author, defended forty years ago. Several previous interpretations, including the identification of mud-mound facies, tectonic breccias, and hardgrounds, are reassessed. The Tithonian-lower Berriasian limestones are reinterpreted as deposits formed in very shallow-marine environments, ranging from subtidal to intertidal settings and strongly influenced by microbial activity. A major outcome of this study is the recognition of a genuine paleokarst system comprising dolines, caves, chimneys, and chaotic collapse breccias. These features record a significant phase of subaerial exposure during the late Berriasian-early Valanginian and indicate that Serra Gelada formed a small paleo-island, most likely uplifted through salt tectonics involving Triassic evaporites. During the Valanginian transgression, wave erosion produced an abrasion surface across the karstified rocky substrate, while marine sediments progressively infilled the cavities and fractures, ranging from microscopic to decimetric scale. In addition to collapse breccias, coloured micritic infills help visualize repeated episodes of fracturing, cementation, and sediment percolation from the Valanginian to the earliest Aptian. These processes are interpreted in relation to the extensional tectonic phase that affected the External Zones of the Betic Range. Petrographic and cathodoluminescence analyses reveal a complex cement stratigraphy recording successive stages of early marine cementation, meteoric-phreatic diagenesis with limited marine mixing, and later burial diagenesis. This revised interpretation provides a more robust reconstruction of the geological evolution of Serra Gelada and contributes to a better understanding of the paleogeographic evolution of the Prebetic domain during the Jurassic-Cretaceous transition.- DOI: https://doi.org/10.2110/carnets.2026.2617
https://carnetsgeol.net/cg/26/17/index.html
Mon, 14 Sep 2026 18:30:36 GMT

Carnets Geol., Article, vol. 26, no. 16

Robert W. Scott.- Late Jurassic-Early Cretaceous phytoplankton ecosystem evolution interrupted by the late Valanginian Weissert carbon isotope event.- The Late Jurassic-Early Cretaceous Phytoplankton Ecosystem Evolution and its associated Calcification Event were major evolutionary innovations of calcareous marine pelagic micro-organisms. Beginning about 160 Ma in the Oxfordian Stage calcareous nannofossils and calcareous dinoflagellates began calcifying their tests that subsequently accumulated as calcareous ooze. By the Tithonian Stage and continuing into the early Valanginian, calpionellids added to the diversification and expansion of this new pelagic ecosystem. This gradual, progressive ecosystem change in the oceanic photic realm was associated with increased burial of light carbon isotope. This calcareous plankton ecosystem suffered a crisis about 135 Ma by the late Valanginian Carbon Isotope Excursion. This isotope excursion was temporally related to emplacement of the Paraná-Etendeka LIP in the Paraná Basin in South America.- DOI: https://doi.org/10.2110/carnets.2026.2616
https://carnetsgeol.net/cg/26/16/index.html
Sat, 12 Sep 2026 18:26:23 GMT