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A hemipelagic succession 29m thick, situated in South Tibet within the Tethyan Himalaya tectonic unit, has been investigated for its calcareous nannofossil content. A total of 17 samples were subject to qualitative and semi-quantitative analysis. The studied interval belongs to the upper Albian-lowermost Cenomanian and extends into the UC0 nannofossil zone; based on the last occurrence of Hayesites albiensis , the UC0a and UC0b-c subzones were recognized. The most abundant nannofossil of the Youxia section is Watznaueria barnesiae. Other common taxa are Eiffellithus turriseiffelii , Eprolithus floralis, Rhagodiscus spp., and Zeugrhabdotus spp. In the lowermost part of the studied section, below the beginning of the Albian-Cenomanian Boundary Event (ACBE), i.e., prior to the δ13C positive excursion related to OAE1d, the nannofossils confined to high paleolatitudes, namely Repagulum parvidentatum , Seribiscutum primitivum , and Sollasites horticus , are present with a low abundance. This occurrence is believed to be evidence of a short episode of cooler surface waters linked to a transgressive event. The nannofossil abundance and diversity, along with the fluctuation patterns of the nutrient and temperature indices throughout the section, reflects a primary signal of mesotrophic to eutrophic conditions from the base of the succession up to the two oldest δ13C peaks of ACBE, both late Albian in age and within the OAE1d. By contrast, the dominance of Watznaueria barnesiae , representing more than 80% of the total assemblages, along with the significant drop in abundance and diversity shown by nannofossils within late phases of ACBE, are interpreted as a diagenetic signal. Mesotrophic to eutrophic conditions returned towards the top of the studied succession, where Biscutum constans and Zeugrhabdotus erectus again show a higher abundance. [ABSTRACT FROM AUTHOR]

Following sustained development, numerous palaeontology databases and datasets of various types have been created. However, the lack of a unified standard language to describe knowledge and unclear sharing mechanisms between different databases and datasets has limited the large‐scale integration and application of paleontological data. The knowledge graph, as a key technology for semantic translation and data fusion, offers a possible solution to these challenges. Given the potential of knowledge graphs to overcome these obstacles, this paper presents a practical approach to express paleontological knowledge in a knowledge graph via the resource description framework language. By delving into the structured data associated with calcareous nannofossil biozones (the UC zone, CC zone and NC zone), we propose an ontology to describe the semantic units and logical relationships of paleontological biozones and species and then integrate relevant species records from unstructured research reports to construct a knowledge graph for calcareous nannofossils, that integrates multisource paleobiological data and knowledge reconstruction. Our focus lies in detailing the technical aspects of constructing a paleontological knowledge graph. The results demonstrate that knowledge graphs can integrate semistructured and unstructured paleontological data from various sources. This work aims to assist palaeontologists in building and utilizing knowledge graphs, serving as an initial effort for future paleontological knowledge reasoning. [ABSTRACT FROM AUTHOR]

Two sediment sections are investigated at Cape Arkhangelos, island of Rhodes, where Pleistocene marine sediments crop out in horsts and grabens of a Mesozoic basement. There, hemipelagic sediments characterized by upper bathyal communities are atypically mixed with much shallower faunal components because they were deposited close to rugged coastal landforms. Biostratigraphic analyses show that the sections were deposited between 1.8 and 0.9 Ma, and between 1.8 and 1.6 Ma, respectively. By combining the planktonic/benthic foraminiferal ratio with 31 bathymetric indicators chosen among extant species of benthic foraminifera, mollusks, and bryozoans, we show that relative sea-level fluctuations can be reconstructed in these atypical settings despite the proximity of steep slopes that favored transportation of allochthonous fauna. The shallow-water components (including gravels and calcareous algae) were transported downslope by the combined action of gravity, currents, and tectonic disturbance that promoted drowning (with a maximum flooding recorded at ca. 1.7 Ma) and then uplift of fault-bounded paleovalleys that formed during the Early Pleistocene. Abrupt facies changes and age differences between sections have been triggered by the irregular paleotopography of the Mesozoic basement, which fostered differential depositional settings, with outer to middle neritic deposits above the horsts and upper bathyal deposits in paleovalleys. [ABSTRACT FROM AUTHOR]

The analysis of water samples collected during the MD218 CROTALE expedition (February-March, 2019), and the 4th Indian Southern Ocean Expedition (SOE) (January-February, 2010) (re-visited samples) resulted in the occurrence of a new coccolithophore species belonging to the genus Alisphaera, and is named Alisphaera crostae sp. nov. This new species appears monomorphic and shows distinctive morphological differences in terms of its coccolith size, flange structure, and nodules, compared to other known Alisphaera species. In this study, morphological differences between A. crostae and other Alisphaera species are illustrated and compared. We suggest that the genus Alisphaera may have a higher diversity and may possess a wider distribution than previously evidenced, which requires more careful observation [ABSTRACT FROM AUTHOR]

Nannofossils and planktonic foraminifers from the Lower Miocene Alkun Formation of central and western Ciscaucasia were studied in the following sections: the stratotype section on the Alkunka River, the Republic of Ingushetia; stratotype of the Caucasian Regional Stage on the Kuban River, Karachay-Cherkessia; Lower Miocene reference section on the Belaya River, Adygea; and in the sections of the Alkun Formation stratotype area on the Fiagdon and Mairamadag rivers, North Ossetia. Planktonic foraminifers in the Alkun Formation were studied for the first time. The available results made it possible to reveal the composition and structure of nannofossil and planktonic foraminiferal assemblages from the Alkun sediments in Ciscaucasia, to refine their stratigraphic and correlation potential and to recognize bionomic conditions of the Alkun basin in the studied area. As a result of the nannoplankton study the Cyclicargolithus floridanus Beds were recognized in the Alkun Formation and, taking into account the occurrence of the zonal species Triquetrorhabdulus carinatus along with Tr. milowii, they are correlated with the upper (Miocene) part of the Aquitanian Zone NN1. Planktonic foraminiferal data permitted to recognize the Streptochilus pristinum Beds. [ABSTRACT FROM AUTHOR]

This study investigated the calcareous nannofossil assemblages in detail from the early Miocene aged Lice Formation outcropping in the Kahramanmaraş basin. The biostratigraphy of calcareous nannofossils was outlined and paleoenvironmental features determined. In 81 samples taken from three measured sections in the region, 17 calcareous nannofossil genus and 48 nannofossil species were identified. These calcareous nannofossil genus and species identified the Lice Formation as being in the CNM4 nannofossil biozone. The abundance and diversity of early Miocene calcareous nannofossil species varied in the measured sections, with the samples generally moderate‐poor, apart from a few samples. The relative abundance of individuals of Cyclicargolithus floridanus, Coccolithus pelagicus, Reticulofenestra hagii and Sphenolithus moriformis species, with paleoecological importance identified in the study region, indicate that in early Miocene times, the basin in which the Lice Formation deposited was meso‐eutrophic with excess nutrient input, temperate and generally stable shallow marine conditions. [ABSTRACT FROM AUTHOR]

Background: Calcareous nannofossils are minute microfossils widely present in marine strata. Their identification holds significant value in studies related to stratigraphic dating, paleo-environmental evolution, and paleoclimate reconstruction. However, the process of identifying these fossils is time consuming, and the discrepancies between the results obtained from different manual identification methods are substantial, hindering quantification efforts. Therefore, it is necessary to explore automated assisted identification of fossil species. This study mainly focused on 18 key fossil species from the Miocene era. Five convolutional neural network (CNN) models and 10 data augmentation techniques were compared. These models and techniques were employed to analyze and collectively train two- and three-dimensional fossil morphologies and structures obtained from three different fossils observed under single-polarized light microscopy, orthogonal polarized light microscopy, and scanning electron microscopy. Finally, the model performance was evaluated based on the predictive outcomes on the test set, using metrics such as confusion matrix and top-k accuracy. Result: The results indicate that, for the calcareous nannofossil images, the most effective data augmentation approach is a combination of four methods: random rotation, random mirroring, random brightness, and gamma correction. Among the CNN models, DenseNet121 exhibits the optimal performance, achieving an identification accuracy of 94.56%. Moreover, this model can distinguish other fossils beyond the 18 key fossil species and non-fossil debris. Based on the confusion matrix, the evaluation results reveal that the model has strong generalization capability and outputs highly credible identification results. Conclusion: Drawing on the identification results from CNN, this study asserts a robust correlation among extinction photographs, planar images, and stereoscopic morphological images of fossil species. Collective training facilitates the joint extraction and analysis of fossil features under different imaging methods. CNN demonstrates many advantages in the identification of calcareous nannofossils, offering convenience to researchers in various fields, such as stratigraphy, paleo-ecology, paleoclimate, and paleo-environments of ancient oceans. It has great potential for advancing the development of marine surveys and stratigraphic recognition processes in the future. [ABSTRACT FROM AUTHOR]

The first calcareous nannoplankton extinction and recovery close to the Triassic/Jurassic boundary (TJB) were studied in two Tatra Mountains sections of Kardolína and Furkaska. The studied sediments were deposited in an intra-shelf depression of the Tethyan shelf (the Zliechov Basin). Rare nannofossil assemblages were discovered in both sections. Rhaetian nannofossils are characterized by the dominance of Prinsiosphaera triassica and by episodic increases in the abundance of small-sized coccoliths. Coccoliths belonging to Calyculus? kardolinae sp. nov. were found on tops of the bedding planes. Triassic index species Eoconusphaera aff. hallstattensis was also recovered, it is rare though, probably due to the marginal or relatively high-latitudinal position of the area. The uppermost Triassic is characterized by a significant reduction in nannofossil abundance accompanied by the presence of organic matter in the rock, which was significant especially in the Kardolína section. The signal of the last occurrence of Prinsiosphaera triassica is overwritten by the reworking of Upper Triassic material into Jurassic strata within the boundary clay interval. The presence of representatives of Watznaueriaceae in the Jurassic Kopieniec Formation is surprising and might indicate hiatus in the TJB in the studied sections. We are also presenting the results of a newly developed method for the extraction of calcareous nannofossils from indurated rocks. [ABSTRACT FROM AUTHOR]

We provide new insights into the Badenian transgression (Langhian to early Serravallian) in western Serbia, focusing on the marginal part of the Central Paratethys. Nano- and microfossils (calcareous nannofossils, foraminifers, and ostracods) are used along with U–Pb radioisotope dating of a tuff layer near the Badenian lower boundary to reconstruct the timing of the middle Badenian marine flooding. Our findings reveal the occurrence of a second (main) Badenian transgression (TB2.4 third-order cycle) around 14.2–13.8 million years ago. The Badenian marine waters flooded the continental formation of the poorly defined early-middle Miocene sequences. The sedimentary succession (KC-4 core, 490–205 m) is grouped into five units (I–V). The lower two units (I–II) are non-marine alluvials that are characterized by coarse-grained siliciclastics. Unit III represents the basal coarse-grained clastites and sandy limestones of the initial shallow-marine environment and unit IV consists of marls and high-calcitic fine-grained clastites of neritic facies. Unit V contains carbonaceous marlstone and limestone deposited in a restricted marine shallow-water environment. Biostratigraphically, over 154 m of dominantly fine-grained clastites (units III–IV) confirm the presence of the marine middle and upper Badenian. Its lower part (366–325 m) corresponds to the nannofossil NN5 Zone and the youngest Upper Lagenidae Zone (local Zone Ammonia viennensis–Trilobatus trilobus), as well as a part of the Spirorutilus carinatus Zone. The upper part (325–212 m) corresponds to the nannofossil NN6 Zone as well as the foraminifer Bulimina-Bolivina Zone. The U–Pb age for zircon grains is 14.58 ± 0.08 Ma. Petrographic data from the tuff sample show a strong correlation with volcanic records along the S-SW margin of Central Paratethys (N Croatia, NE Bosnia, and central Serbia). The U–Pb age as well as tuff glass composition and mineralogy suggest the possible source of the tuff as from the Subotica area (N Serbia) or the Bükkalja Volcanic Field in NE Hungary. [ABSTRACT FROM AUTHOR]

The Eocene-Oligocene Transition is one of the major stages of the Cenozoic reshaping of the world oceans with associated changes in climate, of ocean coastlines and circulation patterns. This altogether created challenging environments for fossilization and preservation of native biota. Consequently, well preserved Oligocene fossils are infrequent worldwide and just as rare in the Central Paratethys. The well-preserved Rupelian (Early Oligocene) diatomites from the Skole Nappe, the external unit of the Outer Carpathians in southeastern Poland were deposited in the Central Paratethys. In some samples, in addition to diatoms, sediments also contain a great diversity of other silicified micro- and nannofossils. Here we report our findings of silicoflagellates (fifteen taxa from five genera), two rotosphaeridians, and several morphotypes of fossil scales, some of uncertain taxonomic affinity. Among silicoflagellates, the most common are species from genera Corbisema (C. triacantha, C. hastata, and C. apiculata) and Dictyocha (D. clinata and D. fibula). We also recovered scales of rotosphaeridians (Pinaciophora and possibly Rabdiophrys) and remains of organisms of uncertain affinity (Clathropyxidella and Macrora) often reported together with silicoflagellates. All of these taxa are the first reports for the Central Paratethys. Silicoflagellate species composition is consistent with the datums derived from other fossils. Silicoflagellates, marine diatoms and archaeomonads suggest a neritic depositional environment. [ABSTRACT FROM AUTHOR]

We investigate a new event of accelerated environmental change that was recorded during the late Barremian in the pelagic Subbetic Basin (Western Tethys). Two pelagic sections have been studied using a multi-proxy approach based on C-isotope stratigraphy and a high-resolution quantitative study of nannofossil assemblages, along with major and trace elements and biomarkers. Our results provide a detailed biostratigraphy and C-isotope stratigraphy, and outline the paleoenvironmental conditions recorded during the early stages of the Taxy Episode. A disturbance has been identified in the C-isotope record, called the IFeNE (Intra-Feradianus negative C-excursion), which is coeval with environmental and biotic changes that predate the well-known ISNE (Intra-Sarasini negative C-excursion). The combined analysis of nannofossil associations, C-isotopes, major and trace elements, and biomarker distributions indicates a separate episode of warming heralding the ISNE, resulting in the acceleration of the hydrological cycle and a consequent increase in continental inputs and the fertilization of surface waters. The origin of the Taxy Episode (the IFeNE and ISNE) has been related to orbital factors (high-eccentricity cycles), and to a global increase in volcanism, probably related to the early phases of the Ontong Java Plateau. [ABSTRACT FROM AUTHOR]

In this study, biostratigraphy of the the Ziyarat Formation was investigated based on calcareous nanoplankton in the Tochal section (southeast of Tehran). In this section the Ziyarat Formation conformably overlies the Fajan conglomerate and is overlain the Karaj Formation. The thickness of the formation in Tochal section with four rock units is 212 meters and it mainly consists of limestone, and marl. In this study, investigation of 105 prepared samples and calcareous nannoplanktons has led to the identification of 37 species belonging to 16 genera. Based on the first and last occurences of nannofossil species and assemblage species such as Discoaster sublodoensis, Nannotetrina fulgens, Tribrachiatus orthostylus, Discoaster lodoensis and Tribrachiatus contortus the NP9-NP15 and CNP11-CNE9 biozones in the Ziyarat Fsormation were determined. The nannofossil biozones and their stratigraphic location indicate the age of the late Paleocene - middle Eocene (Thanetian- Lutetian) for the Ziyarat Formation in the Tochal section. [ABSTRACT FROM AUTHOR]

A biostratigraphic integration study based on the planktonic foraminifera and calcareous nannofossils from the Mango-2 well, North El Fayrouz Offshore Field, Mediterranean Sea, Egypt, provides a well-defined zonal scheme for the Oligocene-middle Miocene interval. The lithologic succession was subdivided into three formations, from oldest to youngest; Sidi Salem, Qantra and Tineh. Six planktic foraminiferal zones and four calcareous nannofossils zones, in addition to two unconformities are identified. The planktic foraminiferal zones include Ciperoella angulisuturalis, Paragloborotalia opima opima (Oligocene), Globigerinoides primordius, Praeorbulina curva (early Miocene), Praeorbulina glomerosa and Fohsella peripheroronda (middle Miocene). The calcareous nannofossil zones include Furcatolithus distentus, (Oligocene), Discoaster druggii, Helicosphaera ampliaperta (early Miocene) and Sphenolithus heteromorphus (middle Miocene). The absence of the Paragloborotalia kugleri, Paragloborotalia pseudokugleri and Furcatolithus ciperoensis zones suggests an unconformity across the Oligocene-Miocene boundary. Another unconformity was identified across the Aquitanian-Burdigalian boundary based on the absence of the Globoquadrina dehiscens, Globigerinita dissimilis, Globigerinatella insueta and Sphenolithus belemnos zones. These unconformities are most likely related to regional tectonics. [ABSTRACT FROM AUTHOR]

This research offers a comprehensive examination of calcareous nannofossils, isotopic ratios (δ18O and δ13C), and carbonate content spanning the critical Paleocene-Eocene transition at Gebel Nukhul. The study covers three lithostratigraphic formations: Tarawan, Esna, and Thebes. By meticulous analysis, we've identified five distinct calcareous nannofossil zones, including NP7/8 and NP9-12. Zone NP9 is further divided based on the lowest occurrences of specific nannofossils (Discoaster anartios, D. araneus, and/or Rhomboaster spp.), while Zone NP10 is subdivided using Tribrachiatus contortus as a marker. We discussed the significance of various calcareous nannofossil taxa in biostratigraphy, highlighting their role as valuable stratigraphic markers. Our research precisely locates the base of the Eocene at the onset of Subzone NP9b within the Esna Formation, revealing no discernible lithological changes coinciding with this boundary. Additionally, our findings align with the global record, indicating significant decreases in δ13C, δ18O, and calcium carbonate (CaCO3) content during the Paleocene–Eocene transition. These changes underscore the climatic and environmental perturbations during this pivotal geological phase. This study provides valuable insights into the stratigraphy and paleoclimatology of the Paleocene–Eocene transition, contributing to our understanding of past climatic variations on Earth. [ABSTRACT FROM AUTHOR]

Pronounced warming negatively impacts ecosystem resilience in modern oceans. To offer a long‐term geological perspective of the calcareous plankton response to global warming, we present an integrated record, from two Tethyan sections (northeastern Italy), of the planktic foraminiferal and calcareous nannofossil response to the Eocene Thermal Maximum 2 hyperthermal (ETM2, ∼54 Ma). Our study reveals pronounced changes in assemblage composition and a striking dwarfing of planktic foraminiferal tests of up to 40% during the event, impacting both surface and deeper dwellers. The increased abundance of small placoliths among calcareous nannofossils is interpreted as community size reduction. Literature and our foraminiferal size data from Sites 1263 and 1209 (Atlantic and Pacific Oceans) highlights that the pronounced dwarfism is restricted to the Tethyan area. The ETM2 is characterized by warm sea surface temperatures as indicated by our δ18O data, but this warming is of global extent and cannot explain the unique dwarfism. Excluding evolutionary modifications, other potential drivers of dwarfism (eutrophication, deoxygenation, metabolic adaptation) cannot explain the exceptional dwarfism by themselves. The smallest sizes are in close temporal association with peaks in volcanic derived Hg/Th‐Hg/Rb recorded just before and at the ETM2 which could not have been brought into our sections through weathering. In contrast, size reductions are absent below and above the ETM2 at Hg peaks where δ18O data do not show warm conditions. We speculate that the local input of toxic metals from submarine volcanic emissions could have acted synergistically to warming, causing the unique dwarfism. Key Points: Calcareous plankton size in the Tethys during the Eocene Thermal Maximum 2 (ETM2) reveals marked dwarfismPronounced dwarfism was restricted to the Tethyan area, highlighting the importance of local signals in interpreting hyperthermalsCalcareous plankton were highly unstable across the ETM2 but ultimately resilient [ABSTRACT FROM AUTHOR]

A hemipelagic succession 29m thick, situated in South Tibet within the Tethyan Himalaya tectonic unit, has been investigated for its calcareous nannofossil content. A total of 17 samples were subject to qualitative and semi-quantitative analysis. The studied interval belongs to the upper Albian-lowermost Cenomanian and extends into the UC0 nannofossil zone; based on the last occurrence of Hayesites albiensis, the UC0a and UC0b-c subzones were recognized. The most abundant nannofossil of the Youxia section is Watznaueria barnesiae. Other common taxa are Eiffellithus turriseiffelii, Eprolithus floralis, Rhagodiscus spp., and Zeugrhabdotus spp. In the lowermost part of the studied section, below the beginning of the Albian-Cenomanian Boundary Event (ACBE), i.e., prior to the δ13C positive excursion related to OAE1d, the nannofossils confined to high paleolatitudes, namely Repagulum parvidentatum, Seribiscutum primitivum, and Sollasites horticus, are present with a low abundance. This occurrence is believed to be evidence of a short episode of cooler surface waters linked to a transgressive event. The nannofossil abundance and diversity, along with the fluctuation patterns of the nutrient and temperature indices throughout the section, reflects a primary signal of mesotrophic to eutrophic conditions from the base of the succession up to the two oldest δ13C peaks of ACBE, both late Albian in age and within the OAE1d. By contrast, the dominance of Watznaueria barnesiae, representing more than 80% of the total assemblages, along with the significant drop in abundance and diversity shown by nannofossils within late phases of ACBE, are interpreted as a diagenetic signal. Mesotrophic to eutrophic conditions returned towards the top of the studied succession, where Biscutum constans and Zeugrhabdotus erectus again show a higher abundance.

The Keresta Formation, located in the Volgograd–Volga region (the Volga–Caspian subregion of south-west Russia) has been dated as Middle Eocene, Lutetian, based on dinoflagellate cysts of the Enneadocysta arcuata Zone and nannofossils from the Lutetian subzones CP13c–CP14a. Within this interval, four new species of dinoflagellate cysts are described: Spiniferella grigorovichiae sp. nov., Impagidinium tuberculatum sp. nov., Hystrichostrogylon crassitunicatum sp. nov. and Hystrichosphaeropsis tenerum sp. nov. The new species present a high correlation potential for Middle Eocene stratigraphy over the southern part of the Russian Platform. Also, the assemblage of organic-walled microphytoplankton from the Keresta Formation indicates warm-water marine environments within the marginal part of the Paratethys Basin. [ABSTRACT FROM AUTHOR]

Investigations of calcareous nannofossils were done on the Serikagni Formation in the southern limb of the Sinjar anticline northwest of Iraq, specifics of the identification process's investigation (18 species of calcareous nannofossils belonging to 10 genera). Two biozones were proposed in this study based on their stratigraphic distribution, and they are as follows: Triquetrorhabdulus carinatus partial range Biozone CN1 and Sphenolithus belemnos Interval Biozone CN2. Correlation with other calcareous nannofossil biozones from regional schemes led to the conclusion that the Serikagni Formation's age is Early Miocene (Aquitanian)in the studied sections. It can conclude from higher speciation for calcareous nannofossils that the bloom at the Miocene because of increased temperature impacts climate change on the warm ocean's ecosystem. [ABSTRACT FROM AUTHOR]

The Eocene Kuldana Formation (KF) in the Yadgar area of Pakistan, comprises a diverse range of sedimentary facies, including variegated red beds of shales, mudstones, and sandstones, as well as interbedded limestone and marl. In this study, we conducted an integrated micropaleontological, sedimentological, mineralogical, and geochemical investigation to determine the depositional setting, biochronology, provenance, and paleoclimate of the KF. The study identified six lithofacies and six microfacies, which indicate a variety of environments ranging from floodplains and channels to the margins and shallow marine settings. The nannofossil biostratigraphy places the KF in the Early Eocene, more precisely the NP10 zone (Ypresian), and the fossil zone of benthic foraminifera classifies the study section as the Shallow Benthic Zone SBZ-8 (Middle Ilerdian 2). In terms of petrography, the KF sandstone was classified as litharenite and feldspathic litharenite, while the QtFL diagram suggests a recycled orogen. Geochemical proxies indicate an oxidizing environment, a high-to-low regular sedimentation rate, moderate-to-intense chemical weathering in the source region, and a warm-humid to dry climate during the deposition of KF. Overall, the findings suggest that the deposition of KF marks the end of Neo-Tethys due to the Early Eocene Indian–Kohistan collision and that the uplifting of the Himalayas provided the source for the deposition of KF in the foreland basin. The study provides new insights into the depositional environment, biochronology, provenance, and paleoclimate of KF, and highlights the potential for red beds as reliable indicators of oxygenation levels in proximity to mineral deposits. [ABSTRACT FROM AUTHOR]

The Cretaceous Period is a vital time interval in deciphering the evolutionary history of the Neo-Tethys Ocean and the convergence of different plates and blocks across the Qinghai-Tibetan Plateau. A detailed stratigraphic framework and paleogeographic patterns are the basis for understanding the evolution of the Neo-Tethys Ocean and the formation of the Qinghai-Tibetan Plateau. Here, the Cretaceous stratigraphy, biota, paleogeography, and major geological events in the Qinghai-Tibetan Plateau are analyzed to establish an integrative stratigraphic framework, reconstruct the paleogeography during the Cretaceous Period, and decode the history of the major geological events. The Cretaceous rocks of the Qinghai-Tibetan Plateau and its surrounding area are predominantly marine deposits, with a small amount of interbedded marine-terrestrial and terrestrial conponents. The Indus-Yarlung Tsangpo Suture Zone was responsible for the deposition of deep marine sediments dominated by ophiolite suites and radiolarian silicalite. To the south, the Tethys Himalayas and Indus Basin received marine sediments of varying depths and lithology; to the north, the Xigaze and Ladakh forearc basins are also filled with marine sediments. The Lhasa Block, Karakorum Block, western Tarim Basin, and West Burma block consist of shallow marine, interbedded marine-terrestrial, and terrestrial sediments. The Qiangtang Basin and other areas are dominated by terrestrial sedimentation. The Cretaceous strata of the Qinghai-Tibetan Plateau and its surrounding areas are widely distributed and diversified, with abundant foraminifera, calcareous nannofossils, radiolarians, ammonites, bivalves, and palynomorphs. On the basis of integrated lithostratigraphic, biostratigraphic, geochronologic, and chemostratigraphic analyses, we proposed herein a comprehensive stratigraphic framework for the Cretaceous Period of the eastern Neo-Tethys. By analyzing the Cretaceous biota of different biogeographic zones from eastern Neo-Tethys and its surrounding areas, we reconstructed the paleobiogeography of different periods of eastern Neo-Tethys. The Cretaceous paleogeographic evolution of the Qinghai-Tibetan Plateau and its surrounding areas can be divided into three phases: (1) gradual breakup of the Indian Plate from the Australia-Antarctica continent and the early collision phase of the Lhasa-Qiangtang blocks (145–125 Ma); (2) northward drift of the Indian Plate and the collision phase of the Lhasa-Qiangtang blocks (125–100 Ma); (3) rapid northward drift of the Indian Plate, formation of the Tarim-Tajik-Karakorum Bay, and early uplift of the Gangdise Mountains (100–66 Ma). The Indus-Tethys Himalayan biota underwent a transition from the cold-water type in the high latitudes of the southern hemisphere to the warm-water type near the equator from the Early Cretaceous to the Mid-Cretaceous. The biodiversity and abundance of the eastern Neo-Tethys Ocean increased gradually in the Early Cretaceous, peaking in the Mid-Cretaceous, and decreased sharply during the late Late Cretaceous (late Maastrichtian). Along with the northward drift of the Indian Plate and subduction of the Neo-Tethys, the eastern Neo-Tethys and its surrounding areas experienced a series of major geological events, including the formation of the large igneous province, oceanic anoxia events, and mass extinction, etc. [ABSTRACT FROM AUTHOR]

A rich larger foraminifera assemblage from the Eocene carbonates of the south Sabzevar region (Now-Deh section) in central Iran indicates a late Ypresian to early Lutetian age. Nine species of Alveolina d’Orbigny are studied for systematics and biostratigraphy. The assemblage includes A. minuta, A. decastroi, A. cremae, A. cremae elongata, A. decipiens ayrancensis, A. celali, A. rugosa, A. cuspidata, A. frumentiformis. We have also found nummulitids (genus Nummulites and Assilina) and orthophragmines identified as N. campesinus, N. praediscorbinus, A. placentula, A. praespira, A. reicheli, A. ex. intrec. laxispira-maior and Discocyclina archiaci bartholomei. The recovery of Alveolina cremae elongata, A. decipiens ayrancensis, A. celali, A. rugosa, A. cuspidata and Assilina praespira has permitted for the first time to extend their geographical distribution outside of the classical peri-Mediterranean area to the central Tethys regions. The obtained biostratigraphy points to the Shallow Benthic Zones SBZ11 to SBZ13, indicating the occurrence of a Lower-–Middle Eocene carbonate system. Part of the age model is supported by the calcareous nannofossil biostratigraphy that belong to the NP14b and CNE8 biozones, recorded from the central portion of the studied section. Issues regarding the application of the SBZ into the Middle East domains are discussed in terms of relative stratigraphic position and biogeographic dispersal of some significant Alveolina species. [ABSTRACT FROM AUTHOR]

The Eocene‐Oligocene transition (EOT; ∼34 Ma) was one of the most prominent global cooling events of the Cenozoic, coincident with the emergence of continental‐scale ice‐sheets on Antarctica. Calcareous nannoplankton experienced significant assemblage turnover at a time of long‐term surface ocean cooling and trophic conditions, suggesting cause‐effect relationships between Antarctic glaciation, broader climate changes, and the response of phytoplankton communities. To better evaluate the timing and nature of these relationships, we generated calcareous nannofossil and geochemical data sets (δ18O, δ13C and %CaCO3) over a ∼5 Myr stratigraphic interval recovered across the EOT from IODP Site U1509 in the Tasman Sea, South Pacific Ocean. Based on trends observed in the calcareous nannofossil assemblages, there was an overall decline of warm‐oligotrophic communities, with a shift toward taxa better adapted to cooler more eutrophic conditions. Assemblage changes indicate four distinct phases caused by temperature decrease and variations in paleocurrents: late Eocene warm‐oligotrophic phase, precursor diversity‐decrease phase, early Oligocene cold‐eutrophic phase, and a steady‐state cosmopolitan phase. The most prominent shift in the assemblages occurred during the ∼550 kyr‐long precursor diversity‐decrease phase, which has relatively high bulk δ18O and %CaCO3 values, and predates the phase of maximum glacial expansion (Earliest Oligocene Glacial Maximum–EOGM). Plain Language Summary: Around 34 Ma, Earth experienced a major glaciation in the southern hemisphere, leading to the formation of permanent continental‐scale ice‐sheets on Antarctica. The Antarctic glaciation is supposed to have been triggered by a gradual decline of carbon dioxide with tectonic changes playing a secondary role. The separation of Antarctica from Australia and South America, and thus the development of the cold Antarctic Circumpolar Current, may have further intensified the conditions necessary for glacial expansion. This new scenario had profound consequences on climate, with direct effects on the global oceans and marine biota. In the past decades, geoscientists have tried to understand the glacial, tectonic and climatic history of Antarctica, but many questions remain unresolved. In particular, what were the impacts on the oceans in key areas between the Southern Ocean (high‐latitudes) and the Equator (low‐latitudes), such as the Tasman Sea? We use changes observed in the fossil record of calcifying unicellular algae (calcareous nannofossils) and stable oxygen and carbon isotopes to reconstruct the past surface‐ocean evolution of this area. Our results suggest that biological productivity increased as cooler surface‐water conditions developed in the Tasman Sea. This was likely driven by invigorated northward‐moving nutrient‐rich bottom‐waters formed in the colder circum‐Antarctic area. Key Points: Significant changes in calcareous nannofossil assemblages occurred at the onset of the Eocene‐Oligocene transition (EOT; ∼34 Ma)Calcareous nannofossil diversity decreased during the EOT and warm‐oligotrophic taxa were replaced by cold‐eutrophic taxaIncreased paleoproductivity and surface ocean cooling are inferred from the calcareous nannofossil assemblage [ABSTRACT FROM AUTHOR]

The biostratigraphy of the Tonasa Formation in the Jeneponto Regency of South Sulawesi, Indonesia, is still poorly known, and there are barren ages, such as much of the Oligocene to Early Miocene. The Tonasa Formation is well exposed along the coast of the Jeneponto Regency, in which the Karama area consists of the most important outcrops of this formation which in this area consists of interbedded marl and limestone. Our study focuses on the biostratigraphy of the Karama area section A based on nannofossil. Samples were collected by measured stratigraphy methods and then subjected to investigation using smear slides. The assemblages of species were determined by semiquantitative analysis. Data analysis obtained three nannofossil datums (boundaries): The First Occurrence (FO) of Sphenolithus pseudoradians NP19/NP20), the First Occurrence of Sphenolithus distentus (CP.16/CP.17), and the Last Occurrence (LO) Sphenolithus predistentus (NP.23/NP.24. The zonal boundary was determined based on calcareous nannoplankton; the Late Eocene to Middle Oligocene boundary of the Tonasa Formation was found in this section. Interestingly, throughout this period, the marker species in this section is Sphenolithus. In addition, the presence of Sphenolithus, Discoaster, and Zygrhablithus bijugatus indicated that the basin was in warm water condition. [ABSTRACT FROM AUTHOR]

The distribution of calcareous nannofossil species in the upper part of Gurpi Formation and lower part of Pabdeh Formation has been investigated in the Karta section (northwest of Izeh in Zagros Basin, Iran, Eastern Tethys) to provide a biostratigraphic framework from Maastrichtian to Thanetian interval. In this study, 31 genera and 52 species of calcareous nannofossils have been identified and based on the recognized bioevents and the resulting biozones, the studied interval spans from the top of the nannofossil zone UC19TP to the base of the NP7 zone and covers ~10.8 Myr. In this study, the Gurpi Formation spans from the upperUC19TP to NP4 zones, while the lowest part of Pabdeh Formation covers NP5, NP6 and NP7 zones. The studied sequence is continuous and encompasses Cretaceous-Paleogene (K/Pg), Danian/Selandian and Selandian/Thanetian boundaries. The K/Pg boundary is characterized by nannofossil assemblage recognized worldwide, such as the occurrence of Biantholithus, Cruciplacolithus, Braarudosphaera, Praeprinsius, and calcareous blooms of Thoracosphaera spp. A decrease in the abundance of nannofossils is observed in the upper part of the Maastrichtian to the lower part of the Danian; poor to moderate preservation of nannofossils and low diversified nannofossil assemblages cover most of the studied samples. Here, as a result of species poor to moderate preservation, we observe patterns of stepwise extinctions upward in the top of CC25 zone, that culminate with the last occurrence of eight species, just prior to the base of the UC20bTP. We interpret these patterns to be mainly the result of diagenetic alteration. Our dataset provides a record over a long-lasting interval of stepwise extinctions toward the K/Pg boundary that was likely caused by the diagenetically-enhanced Signor-Lipps effect. [ABSTRACT FROM AUTHOR]

This study presents the first detailed data on calcareous nannofossil assemblages from the Sabiñánigo Sandstone Formation in the Jaca Basin (central south Pyrenees). This formation is mainly composed of deltaic and outer-shelf sediments. These siliciclastic deposits contain nannofossil assemblages that are moderately to well-preserved, particularly in fine-grained levels. They contain a calcareous nannofossil assemblage dominated by the species Cyclicargolithus floridanus, Coccolithus pelagicus, Coccolithus formosus, Clausicoccus fenestratus, Zygrhablithus bijugatus, and several species of Sphenolithus and Chiasmolithus. The biostratigraphic results enabled the characterization of the Middle Eocene biohorizons, based on global stratigraphic scales and the improvement of the temporal correlation and lateral evolution of this basin's deposits. The sedimentary sequence of the Sabiñánigo Sandstone was deposited during the Middle Eocene, between the upper part of biozone NP16 and the base of NP17, in the Bartonian. The calcareous nannoplankton assemblage suggests warm and oligotrophic surface waters for the Bartonian interval in the Jaca Basin. [ABSTRACT FROM AUTHOR]

The Mid-Cretaceous interval has been recognized as a crucial period in Earth's history, and a number of studies on Neo-Tethyan successions illustrate intense evolutions in the nature of Mid-Cretaceous ocean chemistry, sea level, and marine faunal communities. However, much less investigations have been conducted in the Sistan Ocean, in the eastern Neo-Tethys. Here, the Nimbolook Section (Lut Block, central Iran) has provided an opportunity to address these shortcomings and provide a better understanding of the paleoenvironmental changes in this region. The biostratigraphic analysis and age interpretation of the Nimbolook Section have been performed in earlier investigations by means of planktonic foraminifera, ammonites and calcareous nannofossils. This provides a reliable age framework for the chemostratigraphic interpretations. In the Nimbolook Section, the δ13C stratigraphy was carried out on a total of 41 samples, which ranged between −3.26‰ and 2.86‰ with an average of 1.09‰ (standard deviation = 1.15‰), and expanded within the upper Aptian to lower Cenomanian stages. However, there is a prominent negative shift at the base of the section, accompanied by episodes of sea-level fluctuations. Notably, according to the age-diagnostic calcareous nannofossils records, this carbon isotope negative shift (0.88‰ to −3.26‰) straddle between late Aptian and early Albian ages. Furthermore, these new chemostratigraphic observations could be interpreted as being the coeval data from the reference well-studied successions in the other parts of the world, tentatively reflecting the oceanic anoxic event (OAE) 1b. [ABSTRACT FROM AUTHOR]

The middle Miocene Fatha Formation is a prominent cap rock for hydrocarbon accumulations in Iraq's oil fields. It is widely distributed in the Low Folded Zone but less common in the High Folded Zone of Iraq. For the first time, a nannostratigraphic study has been conducted on the formation at the Miryas locality in the High Folded Zone of the Qaradagh Mountain Series, southwest of Sulaimaniyah, Kurdistan Region, Iraq. The Fatha Formation consists of claystone, siltstone, marlstone, gypsum and few limestone beds. Ten samples were taken from marl-rich strata in the upper part of the formation between the red claystones of the Miryas. On the basis of the identified calcareous nannofossils, three biozones are recorded from the upper part of the Fatha Formation: the NN1, NN2 and NN3 zones. The combined stratigraphic ranges of the calcareous nannofossils identified here support the early Miocene-Aquitanian age; Discoaster druggii, Sphenolithus belemnos, S. cometa, S. procerus, S. tintinnabulum, S. delphix and S. capricornutus are marker species of the Aquitanian that have been identified inside the Miryas's smear slides. These genera/species are also accompanied by the occurrences of Sphenolithus moriformis, Cyclicargolithus floridanus, Reticulofenestra minuta, R. bisecta, S. minuta, S. dictyoda, Coccolithus pelagicus, Helicosphaera carteri and Coronocyclus nitescens. The appearance of Discoaster saundersi at the top of the formation indicates the last occurrence of the NN2 zone of the Aquitanian and first occurrence of the NN3 zone of the Burdigalian. Through this study, for the first time, the early Miocene biozones determined within the Fatha Formation indicate that lower Miocene sediments (facies) were not deposited at some locations in the Qaradagh Mountain Series. Instead, the equivalent cap rock sediments of the Fatha Formation were deposited in the High Folded Zone; this clarifies why accumulation of hydrocarbons is rare within the late Oligocene-earliest Miocene succession in the High Folded Zone rather than the reservoir rocks of the same age in the Low Folded Zone (such as Kirkuk Oil Fields). [ABSTRACT FROM AUTHOR]

Copyright of Iraqi National Journal of Earth Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Iraqi National Journal of Earth Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Chalk has been used since Antiquity for various purposes, and since Gothic for preparatory layers of painted cultural heritage objects. Several materials are called chalk in Cultural Heritage, but this work especially focuses on chalk composed of calcareous nannofossils (up to 98%). These are fossil remains of photoautotrophic algae generally smaller than 30 μm. They are mainly visible as platelets of various shapes under a cross-polarised or scanning electron microscope. The provenance of chalk can be determined using calcareous nannofossils due to their well-known paleobiogeographic localities. They are already used as proxies since the 90s in Cultural Heritage, but rarely for paintings. In this work, 6 chalk historical mining areas were chosen: Germany (Ruegen), France (Champagne, Meudon), Belgium (Mons), England (Norfolk) and Italy (Bologna). Natural and processed chalk were used as reference materials and compared to 3 original paintings. The difference between the chalks calcareous nannofossil assemblages was shown using multivariate statistical analysis based on species relative abundance. Marker nannofossil species were defined for each chalk locality. One painting material could not be originated due to the preservation of its nannofossils assemblage, but the origins of the rock chalk material from the two other paintings could be geographically located in France.

Local geological and tectonic processes have been pivotal in shaping the diverse sedimentation patterns observed in Jordan, forming sub-basins characterized by elevated organic matter content (TOC). This study aims to characterize the Maastrichtian basin, focusing on sedimentation rates using calcareous nannofossils and understanding paleoecological and paleo-oceanic conditions. It offers insights into the paleoenvironmental factors impacting oil shale deposition in the late Maastrichtian–Paleocene period. It employs classical biostratigraphical, semi-quantitative, and statistical methodologies to achieve its objectives of age determination and paleoecological insights. A total of 116 smear slides from two sites were obtained: the first, consisting of WA-1 (23 samples), WA-2 (18 samples), and WA-3 (11 samples), and the second, with 60 samples. Notably, the sites exhibit varying topography. WA-1 and WA-2, situated at lower elevations, have the highest Total Organic Carbon (TOC) levels, while areas with higher elevations in section four are visually identified by a light color. The study revealed varying patterns of calcareous nannofossil richness in the two investigated sites. These patterns were instrumental in defining biozones, with the utilization of marker species such as Lithraphidites quadratus, Micula murus, Micula prinsii, and Cruciplacolithus tenuis. Chronologically, these sections were classified as Maastrichtian–Paleogene, encompassing the following biozones in sequential order: UC-20a, UC-20b, UC-20c, UC-20d, and NP-2. Furthermore, the study identified two hiatus intervals, observed in sections WA-1 and KAS-1. The absence of certain biozones in the analyzed sections suggests that these sections correspond to distinct geological blocks within the basin, underscoring the role of tectonic forces during the deposition period. The sedimentation rate initially commenced at low levels but gradually increased due to topographic alterations. Notably, the biozone UC-20c demonstrated a clear trend toward warming and enhanced nutrient availability. In this context, the abundance and diversity of species were associated with increased continental influx into the sub-basin, resulting in rising nutrient levels and the number of calcareous nannofossils. This study enhances the understanding of the local and global effects such as tectonic and climates of the continuity of basins by deciphering calcareous nannofossil patterns and their correlation with sedimentation factors. [ABSTRACT FROM AUTHOR]

Despite their extremely rare and fragmentary record, aquatic crocodylomorphs from the Middle to Upper Jurassic (Bajocian-Tithonian) Rosso Ammonitico Veronese (RAV) of northeastern Italy have sparked interest since the late 18th century. Among marine reptiles, Thalattosuchia is by far one of the best represented groups from the RAV units, especially in the Middle Jurassic. Although some specimens have been the subject of multiple studies in recent times, most of them still lack precise stratigraphic assignment and taphonomic assessment, while others remain undescribed. Here we provide a comprehensive revision of the thalattosuchian record from the RAV, alongside the most up-to-date age determination, by means of calcareous nannofossils, when available. Three new metriorhynchoid specimens are described for the first time from the Middle Jurassic of Asiago Plateau (Vicenza province). While the taphonomy of the newly described specimens hampers any taxonomic attribution below superfamily/family level, all three were confidently assigned to a precise interval between the upper Bajocian and the upper Bathonian. This revised record has major paleobiogeographical implications: the new specimens confirm an early origin and distribution of Metriorhynchoidea in the Tethys area and suggest a fast colonization of the open-ocean environment since the upper Bajocian. [ABSTRACT FROM AUTHOR]

The fossil record of Quaternary reef systems, as expressed in uplifted regions by sequences of stacked terraces, has been extensively used either to understand their morphodynamics or to unravel sea level variations. Yet, because these two aspects are intimately linked, Quaternary reef analysis is often underdetermined because the analysis often focuses on single sequences, along one‐dimensional profiles. Here, we take advantage of the lateral variations of coral reef sequences by documenting the morphological variations of the reef sequence on Sumba Island. Near Tambolaka, northwest Sumba, we analysed a reef transect, topography, and associated sedimentological record to obtain a precise coral reef stratigraphy and geomorphic patterns that can be compared with the well‐documented eastern counterpart. In Tambolaka, the reef sequence displays four lower layers of bedded chalky limestone units with a weakly cemented sandy matrix, which we attribute to the Middle Miocene to Pliocene Wakabukak formation based on calcareous nannofossils and planktonic foraminifers. The uppermost layer is a calcretized reefal limestone unit with a well‐lithified sandy matrix, which we attribute to the Plio–Pleistocene reef sequence of the Kalianga formation. Seven marine terraces imprint the regional morphology, four of which we correlate with Marine Isotope Stage (MIS) 5e, MIS 7e, MIS 9e, and MIS 11c terraces of Cape Laundi, northeast Sumba. When scrutinized at the light of numerical models of reef development, these results indicate that the morphodynamics of reefal sequences is strongly impacted by the tectonic evolution. The geodynamic context sets both the extrinsic conditions of reef development, such as the morphology of the basement and hydrodynamics, and the intrinsic properties, in particular reef growth rate. While the morphodynamic evolution of the sequence is at first‐order representative of the interplay between uplift rates and sea level oscillations, the detailed assemblage of the reef units drastically varies along the coastline. [ABSTRACT FROM AUTHOR]

This paper summarizes sedimentological and biostratigraphic data for the Minjur and Marrat Formations in Kuwait and places them within an expanded sequence stratigraphic framework based on the letter and number scheme initiated by Sharland and others (2001). Only two sequences (Tr80 and J10) were identified in this interval in the original scheme, whereas, between Tr80 and the top of the Upper Marrat, 18 sequences are now recognized and their sequence boundaries and maximum flooding surfaces identified and illustrated herein. One new sequence (Tr90) was proposed in the underlying Jilh A Member. Three new sequences (Tr100, Tr105 and Tr110) are recognized in the Minjur Formation (= Lower Minjur in Saudi Arabia). Four sequences (J02, J04, J06 and J08) and part of a fifth (J10) are recognized in the Lower Marrat. Seven sequences (part of J10 and J11-J16) are recognized in the Middle Marrat. Three sequences (J17, J18 and J19) are recognized in the Upper Marrat. Biostratigraphic data are sparse for the Minjur and Marrat Formations. In the Marrat Formation, calcareous nannofossils are extremely rare, benthic foraminifers are relatively common but long-ranging and palynomorphs are sparse and most commonly non-age diagnostic. Published and unpublished proprietary data from 33 wells have been combined to determine the ages of the succession. Using palynology, the Minjur Lower Member was dated as Norian. An undifferentiated Norian-Rhaetian age range is assigned to the Middle and upper Members of the Minjur Formation. The Triassic/Jurassic boundary is placed just below the base of the Lower Member of the Marrat Formation, where cuttings samples from a thin interval of strata yielded long age-ranging palynomorphs. The Sinemurian/Pliensbachian boundary occurs in the Lower Marrat at the base of the S J06 transgressive systems tract. The Pliensbachian/Toarcian boundary, dated on the basis of Nannoceratopsis triceras and Lotharingius crucicentralis, is also in the Lower Marrat at the base of the S J10 transgressive systems tract. The contact of the Middle and Upper Marrat is unconformable and locally karsted but appears to correlate to the Toarcian/Aalenian boundary. The upper section of the Upper Marrat and the base of the overlying Dhruma Formation have not been cored but the Aalenian/Bajocian boundary is placed in the upper portion of Sequence J19. SB J20 is placed at the top of the Upper Marrat Member. Change in the age of the Late Triassic Baluti Formation in Iraq has resulted in changes in correlations of the Minjur and Marrat Formations to each other and to other formations in the region. The Lower Marrat is shown to be the shallow marine equivalent of the Upper Minjur siliciclastics in the subsurface Rub al Khali Basin and in the shallow subsurface Arabian Basin near the outcrop belt in Saudi Arabia. The Lower Marrat correlates to the Adaiyah Formation and the Upper Sarki Formation in Iraq. The Middle Marrat correlates to the Mus and Alan Formations in Iraq and to all of the Marrat Formation as defined in outcrop in Saudi Arabia. The Upper Marrat is largely represented by an Aalenian-age hiatus in the Saudi Arabian outcrop belt but a thin, condensed Aalenian section is present in the subsurface, basinward of the outcrop belt, and correlated with the Lower Dhruma (D1-D2). The Upper Marrat is correlated to the lower Sargelu Formation in Iraq. These new and revised correlations clarify the timing of the Late Triassic (Norian) uplift of the Qatar Arch. [ABSTRACT FROM AUTHOR]

Three sedimentary sections (Dalgi Rid, Milkova Cheshma and Toplika), containing Mn-bearing nodules, of the Mirkovo Formation in the Central Srednogorie tectonic unit have been investigated for their calcareous nannofossil content. The assemblages are very poorly preserved, depleted and relatively low in taxonomic diversity. The most abundant taxa are Watznaueria barnesiae, Eiffellithus eximius, Helicolithus anceps, Micula staurophora and Lucianorhabdus cayeuxii. Additionally, Lithastrinus grillii was detected in the section Toplika. Based on the nannofossil data, the sediments at Dalgi Rid and Milkova Cheshma have been referred to the middle--late Coniacian, whereas those at Toplika have been dated as late Coniacian--early(?) Santonian. These data indicate that the formation of the Mn-bearing nodules in the studied successions is time-transgressive. [ABSTRACT FROM AUTHOR]

1. Introduction Aida Sergeevna Andreeva-Grigorovich, an eminent Soviet and Ukrainian palynologist and micropalaeontologist, passed away on the 13 SP th sp of April 2022 at the age of 86. Later, an updated Palaeogene dinoflagellate cyst zonation was proposed by Aida Sergeevna and her colleagues for the southern regions of the former USSR (Andreeva-Grigorovich [6]) and Ukraine (Andrejeva-Grigorovich and Shevchenko [26]; Andreeva-Grigorovich et al. [23]). For example, she established a new genus ( I Carpatella i ), and described 18 new species (Grigorovich [33], [34]; Andreeva-Grigorovich and Savitskaya [18], [19]; Andreeva-Grigorovich et al. [23]). Aida Sergeevna paid special attention to the study of boundary strata such as the Eocene/Oligocene transition (Andreeva-Grigorovich and Portnyagina [17]; Andreeva-Grigorovich [5]; Andreeva-Grigorovich et al. [22], [13]) and the Palaeogene/Neogene boundary (Grigorovich [36]; Andreeva-Grigorovich and Gruzman [10], [11]; Andreeva-Grigorovich [7]). [Extracted from the article]

To understand the important significant climatic and paleoceanographic changes occurred in the Southern Hemisphere during the Paleogene, and especially those related to the opening of the Drake Passage, is essential to correlate the Eocene lithostratigraphic units in areas adjacent to this passage, such as those from the Austral-Magallanes and James Ross basins, to the north and to the south, respectively. For many years, there was no correlation between these units due to the absence of reliable chronostratigraphic and biostratigraphic information. Recently, other authors published U/Pb data for the Austral-Magallanes Basin and introduced important modifications to the previous stratigraphic scheme. Subsequently, due to reinterpretating the available isotope data together with U/Pb ages, the chronostratigraphic model has modified again, also including the James Ross Basin. In light of an updated quantitative dinoflagellate cyst dataset from the units adjacent to the Drake Passage, we performed a Principal Component Analysis (PCA) to discuss the correlation between the studied sections. The PCA groups assemblages with a high contribution of Antarctic taxa (e.g., Enneadocysta dictyostila, Deflandrea antarctica) containing in the Upper Member of the Río Turbio Formation (lower part), Man Aike, Leticia, and La Meseta formations, being Bartonian in age. The other group joined assemblages with younger ages, Priabonian, dominated by Antarctic species (Vozzhennikovia-Spinidinium) and cosmopolitan taxa, corresponding to the Upper Member of the Río Turbio Formation (upper part). This study reinforces the most recent chronostratigraphic proposal and proves the biostratigraphic useful of some taxa for sites near the Drake Passage. [ABSTRACT FROM AUTHOR]

On the Fueguian Atlantic coast and in the southern Andean fold and thrust belt, the Paleogene is partially represented by numerous turbiditic deposits. Between Río Bueno and Cabo Leticia in Península Mitre, the Paleocene-Eocene is represented by the Río Claro Group (Cabo Leticia, La Barca, Punta Noguera, and Cerro Ruperto formations) and the Río Bueno Formation; which together constitute a ~1050-m-thick succession. Calcareous nannofossil assemblages recovered from 95 samples were analyzed to determine their relative ages. The Cabo Leticia Formation was barren in nannofossils. The upper LB2 Member of La Barca Formation contained Rhomboaster cuspis and Fasciculithus richardii, frequent in the Paleocene/Eocene boundary (subzones NP9a/NP9b). Nannofossils recovered from Punta Noguera Formation indicate an early Eocene age (biozones NP9b-NP10), with Fasciculithus tympaniformis, Rhomboaster cuspis, and abundant Toweius spp. The Cerro Ruperto Formation provided one productive sample, with specimens of Reticulofenestra spp. and Toweius spp., which indicates an early Eocene age for the formation (biozones NP12-NP13). The Río Bueno Formation yields calcareous nannofossil assemblages characterized by Chiasmolithus eograndis, Chiasmolithus expansus, Toweius spp., and Reticulofenestra spp., which indicate a late early Eocene to middle Eocene age (biozones NP14-NP15). Although the calcareous nannofossil record is discontinuous due to preservational biases in the Río Claro Group, our data allow a better age constraint for the investigated formations and to correlate these units with other surface and subsurface units in the Austral Basin. [ABSTRACT FROM AUTHOR]

During the Late Cretaceous, northern South America was characterized by broad epicontinental seas, with variable surface productivity and changing bottom-water oxygenation. Global sea-level fluctuations and local tectonic shifts caused their disappearance in the latest Cretaceous. We present an integrated micropaleontological and geochemical study of a section comprising the Umir Formation and its lower stratigraphic contact with the La Luna Formation, in the Middle Magdalena Valley, northeastern Colombia. Foraminiferal assemblages were moderately diverse and mainly dominated by benthic taxa, characterizing the biozones Siphogenerinoides bramlettei and Ammobaculites colombiana (Maastrichtian). Planktonic foraminiferal assemblages were less diversified, being species assigned to Heterohelicidae and scarce keeled forms (Globotruncana spp.) the most recurrent taxa. Ostracod recovery was very scarce, and we could only identify the genus Actinocythereis. In contrast, calcareous nannofossil assemblages were moderately diversified along the section, and composed of typical Late Cretaceous low-latitude taxa such as Micula staurophora, Cribrosphaerella ehrenbergii, Gartnerago segmentatum. The identified microfossils indicate a transition from middle-inner shelf conditions, with moderately oxygenated bottom waters within the La Luna Formation, to a shallower marine setting within the Umir Formation. This interpretation is supported by Sr/Ba and log(Fe/Ca) ratios measured in bulk sediment, which indicate increased continental runoff and terrigenous input in the upper part of the section. Moreover, a significant biotic turnover was identified at the base of the section, suggesting the presence of a xenoconformity at the La Luna-Umir contact, which has been previously described and proposed as a regional stratigraphic feature. [ABSTRACT FROM AUTHOR]

Micropaleontological investigations performed at four sections in the Pucará Group, northwestern Peru, revealed the presence of late Triassic calcareous nannofossils. Recovered assemblages are poorly preserved and show low abundance and species richness. However, these findings represent one of the three records outside the Tethyan Realm and allow independent biostratigraphic constraints for the Pucará Group. In the Cantera Tello section, Chambará Formation, only the genus Prinsiosphaera was observed, suggesting a late Norian age for the lower part, and the occurrence of Eoconusphaera zlambachensis indicates a Rhaetian age for the upper part. In the Río Cocahuayco section, Chambará, and Aramachay formations, only the genus Prinsiosphaera was recovered, indicating the late Triassic. In Ricardo Palma section, Aramachay Formation, the presence of E. zlambachensis indicates a Rhaetian age. The Aguas Verdes section, Condorsinga Formation, yields an assemblage with P. triassica and E. zlambachensis, indicating that, at least in this part of the basin, the lower section of this Formation is Rhaetian. [ABSTRACT FROM AUTHOR]

To reconstruct the paleoclimate in North Africa during the Paleocene, the calcareous nannofossils were quantitatively analyzed at higher resolution from the stratigraphic succession of Gebel Nezzazat (west central Sinai, Egypt). The studied interval extends from NP4 to NP8. Zone NP4 can be subdivided into four subzones from base to top: NTp7B, NTp8A, NTp8B, and NTp8C. The base of the Selandian age is located at the base of NTp8B (Second Radiation of Fasciculithus). The Selandian/Thanetian boundary (S/T) is tentatively placed at the base of Zone NP7/8. The identified nannofossil zones were compared with that of the Tethyan region for the Danian/Selandian boundary. The calcareous nannofossil assemblages were used as indicators for medium-term climatic fluctuations. The pre-Danian (LDE) is dominated by the cool-water Zeugrhabdotus sigmoides and Neochiastozygus modestus, while the post-Danian interval is dominated by Coccolithus pelagicus and Ericsonia subpertusa. Before the onset of the Selandian-Thanetian boundary, a marked shift in the nannofossil species was observed, where Fasciculithus increased significantly, while marker Danian-Selandian genera (e.g., Lithoptychius Neochiastozygus, Chiasmolithus, and Cruciplacolithus) decreased dramatically. Non-Metric Multidimensional Scaling (nMDS) and permutational analysis of variance (PERMANOVA) in addition to the Temperature and Nutrient indices (TI and NI) indicated a marked difference between the warm eutrophic nannofossil assemblages at the Danian/Selandian (D/S) and the Selandian/Thanetian (S/T) transitions and the eutrophic cold-water assemblages during the background sedimentation. A sharp increase in sea surface temperature and decrease in nutrients was observed at D/S and represents the Latest Danian Event (LDE), while the second warming event was started prior to the Selandian and may represent the Early Late Paleocene Event "ELPE." The sea-level lowstand may have limited water circulation, where surface water fertility decreased significantly. Consequently, nannofossil diversity decreased. The rapid recovery after the LDE was attributed to the radiation of warm-water taxa. [ABSTRACT FROM AUTHOR]

Chalk has been used since Antiquity for various purposes, and since Gothic for preparatory layers of painted cultural heritage objects. Several materials are called chalk in Cultural Heritage, but this work especially focuses on chalk composed of calcareous nannofossils (up to 98%). These are fossil remains of photoautotrophic algae generally smaller than 30 μm. They are mainly visible as platelets of various shapes under a cross-polarised or scanning electron microscope. The provenance of chalk can be determined using calcareous nannofossils due to their well-known paleobiogeographic localities. They are already used as proxies since the 90s in Cultural Heritage, but rarely for paintings. In this work, 6 chalk historical mining areas were chosen: Germany (Ruegen), France (Champagne, Meudon), Belgium (Mons), England (Norfolk) and Italy (Bologna). Natural and processed chalk were used as reference materials and compared to 3 original paintings. The difference between the chalks calcareous nannofossil assemblages was shown using multivariate statistical analysis based on species relative abundance. Marker nannofossil species were defined for each chalk locality. One painting material could not be originated due to the preservation of its nannofossils assemblage, but the origins of the rock chalk material from the two other paintings could be geographically located in France. [ABSTRACT FROM AUTHOR]

Well-preserved fossil assemblages provide valuable insights into the evolutionary history of biota and their environments. Here, we report on Rupelian (early Oligocene) siliceous nanoeukaryotes from diatomites in the Carpathian Mountains, southeastern Poland. These sediments yielded novel forms of parmaleans and parmalean-like fossils. Their cell wall structure differs from that of described genera. Instead of the generically specific separate dorsal plate and set of girdle plates, some of our taxa contain one upended, hollow, subspherical, perforated cup. To accommodate these differences, we propose a new division Parmaphyta, a new family Parmoligocenaceae, a new genus Parmoligocena and a new species Parmoligocena janusii. Other remains are reminiscent of the extant genus Pentalamina and for this we propose a new genus and species, Pentalaminamorpha radiata. The taxonomic affinity is less certain for other nannofossils found, as they are only somewhat similar to parmaleans, and so we only tentatively associate them with this group. All these fossils occur together with a diverse assemblage of diatoms (mostly from Leptocylindrales, Rhizosoleniales, Coscinodiscales, Cymatosirales, and Hemiaulales), silicoflagellates (mostly species from the genus Corbisema) and archaeomonads. Together they suggest the palaeoenvironmental context for the parmaleans, a neritic marine environment, thus similar to where silicified parmaleans can be found today. [ABSTRACT FROM AUTHOR]

Due to modern hydrocarbon development and exploration activities throughout the onshore Nile Delta of Egypt, a high-resolution biochronologic sequence stratigraphy of the Neogene sequence was conducted to illustrate the gas-bearing reservoirs' depositional sequences. Our study used a multidisciplinary approach comprising biostratigraphy, facies analysis, geophysical logs, and seismic data to shed light on the Neogene stratigraphic framework. The biostratigraphic analysis of planktonic foraminifera and calcareous nannofossils allowed the recognition of six zones and/or subzones and nine zones, respectively. An open-shelf environment was suggested for the Middle–Upper Miocene Sidi Salem Formation, while the Upper Miocene Qawasim and Abu Madi formations were deposited under stressed environmental conditions interpreted as estuary facies. The Lower Pliocene (Zanclean) succession deposited in the middle to outer shelf domains, including the upper-bathyal environments. Seven depositional sequences bounded by six major sequence boundaries were recognized from Serravallian to Zanclean times. These boundaries significantly influenced changes in reservoir properties and architecture of the incised valley fills. The sea-level oscillations are interpreted by correlating the sequence boundaries and flooding surfaces with global eustatic charts. [ABSTRACT FROM AUTHOR]

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The Mochras core, UK, an historic reference site for the study of Early Jurassic calcareous nannofossils, has been reinvestigated here across the Hettangian to Lower Pliensbachian. Both relative and absolute abundances of 24 calcareous nannofossil species reveal patterns and occurrences that define not less than 37 defined biohorizons. However, due to the low abundance of many of those species towards the base and top of their stratigraphical range, we observe large inconsistencies in first and last occurrences of these species. Instead, we consider records of first consistent and last consistent occurrences (FCOs and LCOs), as well as base and top of acme events, as more reliable biohorizons. Accordingly, we assess the reliability of our biohorizons and show that, in addition to previously established zonal and sub-zonal biomarkers, nine non-zonal biohorizons prove to be robust. Based on that, an updated biozonations scheme with additional subzones for NJB has been proposed and tested against other localities. [ABSTRACT FROM AUTHOR]

Three key Paleocene deep-sea sections cropping out in northern Italy contain intercalations of calciturbiditic, larger foraminifera-bearing beds derived from shallow water environments. The reconstructed Southern Alps record obtained by splicing the three sections allowed a direct correlation of the shallow benthic SB and calcareous nannofossils CN Zones, leading new data about the Shallow Benthic biozonation for the Danian-Thanetian interval and proposing four new SBP (Shallow Benthic Paleocene) Zones (SBP1-4). Such revision relies on an innovative biostratigraphic approach based on larger foraminiferal biohorizons instead of marker species according to the traditional approach used since the introduction of the SB Zones. Based on our study, the SBP1/SBP2 boundary turns out to be about 2 Ma after the K/Pg crisis, highlighting a quite fast recovery of the complexity among foraminifera. [ABSTRACT FROM AUTHOR]

Abiometrical study on four reticulate Nummulites populations from the lower part of Asmari Formation of the Vazag section (Zagros zone) is carried out. The biostratigraphy obtained by studing the succession points to the Early Oligocene (Rupelian), indicating shallow benthic zones SBZ21 and SBZ22A by the occurrence of Operculina cf. complanata, Eulepidina formosoides, Nephrolepidina sp. The age assignment is calibrated with calcareous nannofossils biostratigraphy indicating the NP22–NP23 (=CNO2–CNO3) Zones. We have observed a stratigraphic trend related to Nummulites bormidiensis Tellini 1888 that results to be characterized by two populations composed of transitional Nummulites fichteli/bormidiensis with values of mean inner proloculus that exceeds by very little the boundary commonly established at 300 µm. Such a populations, indicated as Nummulites ex interc. bormidiensis et fichteli, span through the lower Rupelian where classically just N. fichteli is reported so far. The stratigraphic distribution ofNummulites bormidiensisis and related transitional forms is here stretched to the Rupelian (SBZ21 and SBZ22A), encompassing older ages than previously recorded throughout the Neo-Tethys Ocean. [ABSTRACT FROM AUTHOR]

Molecular clocks estimate that diatom microalgae, one of Earth's foremost primary producers, originated near the Triassic–Jurassic boundary (200 Ma), which is close in age to the earliest, generally accepted diatom fossils of the genus Pyxidicula. During an extensive search for Jurassic diatoms from twenty-five sites worldwide, three sites yielded microfossils initially recognized as diatoms. After applying stringent safeguards and evaluation criteria, however, the fossils found at each of the three sites were rejected as new diatom records. This led us to systematically reexamine published evidence in support of Lower- and Middle-Jurassic Pyxidicula fossils. Although Pyxidicula resembles some extant radial centric diatoms and has character states that may have been similar to those of ancestral diatoms, we describe numerous sources of uncertainty regarding the reliability of these records. We conclude that the Lower Jurassic Pyxidicula fossils were most likely calcareous nannofossils, whereas the Middle Jurassic Pyxidicula species has been reassigned to the Lower Cretaceous and is likely a testate amoeba, not a diatom. Excluding the Pyxidicula fossils widens the gap between the estimated time of origin and the oldest abundant fossil diatom record to 75 million years. This study underscores the difficulties in discovering and validating ancient microfossils. [ABSTRACT FROM AUTHOR]