Planktonic Foraminifera Research Articles

North Atlantic Temperature Change Across the Eocene‐Oligocene Transition From Clumped Isotopes

AbstractThe Eocene‐Oligocene transition (EOT) (∼34 Ma) is marked by the rapid development of a semi‐permanent Antarctic ice‐sheet, as indicated by ice‐rafted debris and a 1–1.5‰ increase in deep sea δ18O. Proxy reconstructions indicate a drop in atmospheric CO2 and global cooling. How these changes affected surface ocean temperatures in the North Atlantic and ocean water stratification remains poorly constrained. In this study, we apply clumped‐isotope thermometry to well‐preserved planktonic foraminifera, that are associated with lower mixed‐layer to subthermocline dwelling depths from the drift sediments at international ocean discovery program Site 1411, Newfoundland, across four intervals bracketing the EOT. The thermocline/lower mixed‐layer dwelling foraminifera record a cooling of 1.9 ± 3.5 K (mean ± 95% CI) across the EOT. While the cooling amplitude is similar to previous sea surface temperature (SST) reconstructions, absolute temperatures (Eocene 20.0 ± 2.9°C, Oligocene 18.0 ± 2.2°C) appear colder than previous organic proxy reconstructions for the northernmost Atlantic extrapolated to this location. We discuss seasonal bias, recording depth, and appropriate consideration of paleolatitudes, all of which complicate the comparison between SST reconstructions and model output. Our subthermocline dwelling foraminifera record a larger cooling across the EOT (Eocene 19.0 ± 3.5°C, Oligocene 13.0 ± 3.2°C, cooling of 5.5 ± 4.6 K) than foraminifera from the thermocline/lower mixed‐layer, consistent with global cooling and an increase in ocean stratification which may be related to the onset or intensification of the Atlantic meridional overturning circulation.

Biostratigraphy and determination of the base of the Santonian stage in the east of the Kopeh-Dagh Basin based on planktonic foraminifera, NE Iran

The Abderaz Formation has been studied in five stratigraphical sections (Qarehso, Abderaz village, Muzduran pass (type section of the formation), Padeha village, and Shorab) in the east of the Kopeh-Dagh Basin. Twenty-four species of planktonic foraminifera belonging to eleven genera were identified. The vertical distribution of these species helped to recognize five biozones within the Abderaz Formation as follows: 1) Whiteinella archaeocretacea Partial Range Zone, 2) Helvetoglobotruncana helvetica Total Range Zone, 3) Marginotruncana schneegansi Partial Range Zone, 4) Dicarinella concavata Interval Zone, 5) Dicarinella asymetrica Total Range Zone. Based on these data, the Abderaz Formation ranges from the latest Cenomanian to late Santonian. The base of the Santonian stage was placed close to the onset of the Dicarinella asymetrica Total Range Zone at the studied sections. It was precisely traced at the FO of Globotruncana linneiana (pillbox-like).

The Badenian/Sarmatian (Middle Miocene) boundary in the Central Paratethys (Kreminna, western Ukraine): Foraminiferal and palynological evidence

The Badenian/Sarmatian boundary in the Paratethys basin, that marks the transition from normal marine to restricted semi-marine conditions due to isolation of the basin from the world ocean at the onset of Sarmatian time, is still far from being fully understood. The Kreminna section is located at the northeastern margin of the Carpathian Foreland Basin (Central Paratethys) in the Medobory Hills region. The Miocene deposits that overlie here the Upper Cretaceous substratum comprise the >1 m thick upper Badenian marls and clays passing upwards into ~4 m thick Sarmatian marly limestones with intercalations of marls, clays and limestones, and >2 m thick limestones in the uppermost part of the exposure. Fifty-three species of benthic foraminifera and four species of planktonic foraminifera have been recorded. Six benthic foraminiferal assemblages are composed almost exclusively of calcareous forms; agglutinated taxa are practically lacking. Elphidium spp., miliolids, Lobatula lobatula and Ammonia spp. are the most common calcareous benthic foraminifera in the material studied. Planktonic foraminifera are represented only by species of Globigerina and occur rarely in the lowermost part of the section. A characteristic feature of palynofacies is the very low proportion of land-derived elements – sporomorphs and cuticles, which suggests a sedimentary setting without terrestrial influx, and taxonomical impoverishment of dinoflagellate cyst assemblages, which are either monospecific or consist mainly of two to three species: in a majority of samples, assemblages with Polysphaeridium zoharyi and P. subtile occur. Most δ18O values range from –1.5 to ~+0.5‰ VPDB and most δ13C values are between 0 and +2‰ VPDB. In general, the δ13C curve mirrors the δ18O changes in the section. The Badenian/Sarmatian boundary is placed at the level where the Cibicidoides ungerianus Assemblage is replaced by the Elphidium fichtelianum Assemblage. At the boundary, planktonic foraminifers and most abundant stenohaline benthic foraminifera disappeared. Bottom waters were well-oxygenated both in the latest Badenian and earliest Sarmatian in the Kreminna location.

MERIDIONAL MIGRATIONS OF THE INTERTROPICAL CONVERGENCE ZONE DURING THE LAST DEGLACIATION IN THE TIMOR SEA DETECTED BY EXTENSIVE RADIOCARBON DATING

ABSTRACT At the Intertropical Convergence Zone (ITCZ), the northern and southern Tradewinds converge, and this region is characterized by low atmospheric pressure and high precipitation. The climate in the Timor Sea is characterized by seasonal precipitation changes driven by meridional migrations of the ITCZ and the monsoonal front. The ITCZ shifts in response to changes in the thermal balance between the northern and southern hemispheres. Thus, reconstruction of paleo-precipitation in the Timor Sea is expected to reveal past changes in both regional and global climate, the latter through inference of the ITCZ position. To reconstruct paleo-precipitation in the Timor Sea, we performed extensive radiocarbon analysis on both planktonic foraminifera and total organic carbon (TOC), which is derived from terrestrial and marine sources. Increased precipitation enhances the fraction of relatively old, terrestrial carbon to the core site, which in turn increases the difference between the ages of TOC and planktonic foraminifera. Variations in radiocarbon ages reveal that during northern hemisphere cooling intervals such as Heinrich Stadial 1 and the Younger Dryas, the ITCZ was in a southern position, thus increasing precipitation in the Timor Sea. However, the Timor Sea was dryer during the Bølling–Allerød warming as the ITCZ shifted northward.

Continuous reproduction of planktonic foraminifera in laboratory culture.

Planktonic foraminifera were long considered obligate sexual outbreeders but recent observations have shown that nonspinose species can reproduce by multiple fission. The frequency of multiple fission appears low but the survival rate of the offspring is high and specimens approaching fission can be distinguished. We made use of this observation and established a culturing protocol aimed at enhancing the detection and frequency of fission. Using this protocol, we selectively cultured specimens of Neogloboquadrina pachyderma and raised the frequency of reproduction by fission in culture from 3% in randomly selected specimens to almost 60%. By feeding the resulting offspring different strains of live diatoms, we obtained a thriving offspring population and during the subsequent 6 months of culturing, we observed two more successive generations produced by fission. This provides evidence that in nonspinose species of planktonic foraminifera, reproduction by multiple fission is likely clonal and corresponds to the schizont phase known from benthic foraminifera. We subsequently tested if a similar culturing strategy could be applied to Globigerinita glutinata, representing a different clade of planktonic foraminifera, and we were indeed able to obtain offspring via multiple fission in this species. This work opens new avenues for laboratory-based experimental work with planktonic foraminifera.

REFERENCE SECTION OF THE UPPER MAASTRICHT OF MOUNT KLEMENTYEVA (SOUTH-EASTERN CRIMEA)

The results of a comprehensive study of the reference section of the Upper Maastrichtian of Mount Klementyev (South-Eastern Crimea), composed of a terrigeneous-carbonate strata. It was found that sedimentation occurred in relatively deep-water conditions. Biostratigraphic analysis of benthic and planktonic foraminifera assemblages made it possible to identify foraminiferal zones in the section and confirm the deep-water type of sedimentation in the basin at this interval.

The global genetic diversity of planktonic foraminifera reveals the structure of cryptic speciation in plankton.

The nature and extent of diversity in the plankton has fascinated scientists for over a century. Initially, the discovery of many new species in the remarkably uniform and unstructured pelagic environment appeared to challenge the concept of ecological niches. Later, it became obvious that only a fraction of plankton diversity had been formally described, because plankton assemblages are dominated by understudied eukaryotic lineages with small size that lack clearly distinguishable morphological features. The high diversity of the plankton has been confirmed by comprehensive metabarcoding surveys, but interpretation of the underlying molecular taxonomies is hindered by insufficient integration of genetic diversity with morphological taxonomy and ecological observations. Here we use planktonic foraminifera as a study model and reveal the full extent of their genetic diversity and investigate geographical and ecological patterns in their distribution. To this end, we assembled a global data set of ~7600 ribosomal DNA sequences obtained from morphologically characterised individual foraminifera, established a robust molecular taxonomic framework for the observed diversity, and used it to query a global metabarcoding data set covering ~1700 samples with ~2.48 billion reads. This allowed us to extract and assign 1 million reads, enabling characterisation of the structure of the genetic diversity of the group across ~1100 oceanic stations worldwide. Our sampling revealed the existence of, at most, 94 distinct molecular operational taxonomic units (MOTUs) at a level of divergence indicative of biological species. The genetic diversity only doubles the number of formally described species identified by morphological features. Furthermore, we observed that the allocation of genetic diversity to morphospecies is uneven. Only 16 morphospecies disguise evolutionarily significant genetic diversity, and the proportion of morphospecies that show genetic diversity increases poleward. Finally, we observe that MOTUs have a narrower geographic distribution than morphospecies and that in some cases the MOTUs belonging to the same morphospecies (cryptic species) have different environmental preferences. Overall, our analysis reveals that even in the light of global genetic sampling, planktonic foraminifera diversity is modest and finite. However, the extent and structure of the cryptic diversity reveals that genetic diversification is decoupled from morphological diversification, hinting at different mechanisms acting at different levels of divergence.

Assessment of Chalk as an Archive for the Lithium Isotope Composition of Seawater

AbstractThe understanding of silicate weathering and its role as a sink for atmospheric CO2 is important to get a better insight into how the Earth shifts from warm to cool climates. The lithium isotope composition (δ7Li) of marine carbonates can be used as a proxy to track the past chemical weathering of silicates. A high‐resolution δ7Li record would be helpful to evaluate the role of silicate weathering during the late Cretaceous climate cooling. Here, we assess chalk as a potential archive for reconstructing Late Cretaceous seawater Li isotope composition by comparing Maastrichtian chalk from Northern Germany (Hemmoor, Kronsmoor) to a Quaternary coccolith ooze from the Manihiki Plateau (Pacific Ocean) as a lithological analog to modern conditions. We observe a negative offset of 3.9 ± 0.6‰ for the coccolith ooze relative to the modern seawater Li isotope composition (+31.1 ± 0.3‰; 2SE; n = 54), a value that falls in the range of published offsets for modern core‐top samples and for brachiopod calcite. Further, the negative offset between the Li isotope compositions of Manihiki coccolith ooze and modern planktonic foraminifera is 2.3 ± 0.6‰. Although chalk represents a diagenetically altered modification of pelagic nannofossil ooze, manifested by changes in the composition of trace elements, we observe a consistent offset of Li isotope data between Maastrichtian chalk and Maastrichtian planktonic foraminiferal data (−1.4 ± 0. 5‰) that lies within the uncertainty of modern values. We therefore suggest that chalk can be used as a reliable archive for δ7Li reconstructions.

Sedimentology Study Of Exposed Formations In Al-Assad Valley, Al-Baghdadi Area, Western Iraq

The presence of the Sheikh Alas Formation, the Shurau Formation, and the Euphrates Formation in the area of the current study. The inference of the Sheikh Alas Formation was from Nummlite fossils and planktonic Foraminifera fossils. The Euphrates Formation was deposited in a shallow marine environment, the Sheikh Alas Formation was deposited in an environment in for reef, and the Shurau Formation was deposited in an environment Back reef. The environment of the Euphrates Formation is a shallow lagoon environment for the presence of milliolied fossils, which represent the Miocene age as evidenced by the presence of the Borlis melo melo fossil. As for the environment of the Sheikh Alas Formation, it was deposited in a marine environment in for reef due to the presence of Planktonic foraminifera fossils and the Nummlite fossil, which represents the Oligocene age, and the environment of the Shurau Formation In a shallow, lagoon marine environment Back reef, there are abundant milliolid fossils. The boundary between the Miocene formations and the Oligocene formations is characterized by an unconformable boundary composed of a layer of basal conglomerate with a thickness of 6.5 m, which is affiliated with the Euphrates Formation in terms of age.

Roles of changes in land weathering intensity in the Nd cycle of the South China Sea during the past 30 kyr as inferred from neodymium isotopic composition in foraminifera

Neodymium isotopic compositions (εNd) in the marginal sea is influenced by the ocean circulations as well as the lithogenic input from continents, but their relative contributions and the impact of detrital sediments are not well constrained. In this study, Nd isotopic compositions of mixed planktonic foraminifera species and carbonate-free fraction of sediment from two cores collected at 1250–1350 m water depth in the southwestern (core MD01–2393) and northeastern (core MD18–3569) South China Sea (SCS) have been investigated in order to constrain the relative contributions of lithogenic Nd inputs from large Asian rivers and hydrological variations at intermediate depth in the SCS. The foraminiferal εNd values of both cores (−7.3 ± 0.2 to −5.8 ± 0.2 for core MD18–3569 and − 8.1 ± 0.2 to −7.2 ± 0.2 for core MD01–2393) indicate strong modifications of the initial εNd of the North Pacific Intermediate Water (NPIW) (εNd of −4) flowing into the SCS by unradiogenic sediments (−13 to −11) from large Asian rivers. The foraminiferal εNd record of core MD01–2393 displays significantly unradiogenic values from 18 to 8 cal kyr BP which are associated with intensification of monsoon rainfall and river input of detrital material characterized by strongly altered minerals (high illite chemical index and kaolinite/illite ratio) deriving from tropical plain soils of the Mekong River basin. We suggest here that pedogenetic minerals from tropical plain soils are more efficient in terms of Nd exchange with the seawater than primary minerals produced by intense physical erosion during the glacial period. In contrast, the foraminiferal εNd record for the northern core MD18–3569 is characterized by radiogenic εNd values from 18 to 12 cal kyr BP; these values have been linked to an increased intrusion of radiogenic glacial NPIW to the northern SCS and greater ventilation of water masses (deduced from Δ14C) in the northern deep basin of the SCS compared to the southern one. This time interval is associated with newly formed NPIW in the subarctic Pacific Ocean beginning at about 18 cal kyr BP. Overall, our results indicate that the state of chemical weathering of sediment delivered by rivers is the main factor controlling the detrital modification of past seawater εNd distributions in the marginal sea of the SCS.

The Central South Atlantic: The origin of its waters, its evolution and effects beyond

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.

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)

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).

Short-term middle Eocene (Bartonian) paleoenvironmental changes in the sedimentary succession of Olivetta San Michele (NW Italy): the response of shallow-water biota to climate in NW Tethys

This study focuses on the paleontological content of the middle Eocene (Bartonian) carbonate–siliciclastic sediments of the Capo Mortola Calcarenite Formation from Olivetta San Michele (Liguria, Italy). Along the succession, there are significant paleoecological changes triggered by the variation in neritic input as a consequence of tectonic and climatic instability. Among microfossils, nummulitids prevail, followed by orthophragmines, smaller benthic, and planktonic foraminifera, whereas mollusks and ichnofossils are the most abundant macrofossils. The sudden changes in the benthic communities due to the progressive increase in fluvial input are recorded throughout the sedimentary succession. An increase in water turbidity caused stressful conditions for autotrophic taxa, reducing their size and abundance. In contrast, filter feeders became dominant, suggesting an increase in dissolved and suspended nutrients. Ichnological analysis shows environmental fluctuations controlled by the transport of neritic material offshore, thus confirming the general deepening trend of the studied succession. In the upper part of the succession, we recorded an alternation between gravity flows and marly sediments that are interpreted as short-term alternations between low and intense precipitations. The gravity flows yield taxa such as larger benthic foraminifera (LBF), smaller benthic and planktonic foraminifera, mollusks, and corals. In turn, marls display only a few LBF and abundant smaller benthic and planktonic foraminifera. In these intervals, the increase in planktonic foraminifera also suggests a deepening of the carbonate ramp coinciding with a reduction of light that did not favor the development of LBF. These changes are probably related to the climatic dynamics that occurred in the Bartonian in the western Tethys.

First record of Reticulinella? kaeveri in the Laffan and Ilam formations (Zagros fold and thrust belt, SW Iran): new constraints on the chronostratigraphic calibration of the Arabian Plate sequence stratigraphy

Over the past two decades, sequence stratigraphy has proven to be a valuable tool in addressing challenges arising from the inconsistent application of lithostratigraphic nomenclature across diverse geological provinces. It has been particularly successful in achieving regional correlations within the Cretaceous deposits of the Arabian Plate. The key sequence stratigraphic surface in the currently adopted standard sequence stratigraphic scheme is the K150 SB, marking the transition from a passive to an active margin along the eastern edge of the Arabian plate. Despite its importance, the chronostratigraphic age of this surface is poorly constrained. In the Zagros FTB, the uppermost part of the Sarvak Formation, just below the K150 SB, was recently assigned to the upper part of middle Turonian to upper Turonian, based on the presence of Reticulinella? kaeveri. Our research reveals that the range of R.? kaeveri extends above the K150 SB as this species is also present in the Laffan and base of Ilam formations. The Last Occurrence of this taxon provides a new chronostratigraphic marker of the upper Turonian within the Ilam Formation. This finding proves that more Turonian deposit are present in the study area than was previously recognized. We have studied the deposits enclosing the K150 SB in outcrop sections and wells along a transect from basin to platform margin to inner platform setting. Based on planktonic foraminifera and calcareous nannofossils biostratigraphy of basinal sections and sequence stratigraphic correlation to carbonate platform sections, the age of the uppermost part of the Sarvak Formation, immediately below the K150 SB, is firmly constrained within the interval lower Turonian–lower part of middle Turonian. Sequence stratigraphic correlation from basin to platform interior reveals also that the oldest deposits above the K150 SB are not younger than late Turonian. Our new data represents a significant improvement in the chronostratigraphic calibration of sequence stratigraphy in the Cretaceous of the Zagros fold-and-thrust belt.

Middle Eocene Climatic Optimum (MECO): The first record based on planktonic foraminifera and stable isotopes from SW Anatolia/Turkiye

The Kayikoy Formation (Isparta, SW Turkiye) consisting of sandstone, claystone, and marl units contains abundant, low-moderate preserved, and diverse planktonic foraminifera assemblages. Eight planktonic foraminiferal biozones (E9-E16) were determined encompassing the Lutetian-Priabonian stages (middle-upper Eocene) by using the biostratigraphic distributions of 17 genera and 62 species of planktonic foraminifera. Stable delta 18O and delta 13C isotope values were measured for 53 individuals belonging to Morozovelloides crassatus, Acarinina bullbrooki, A. topilensis, A. echinata, Globigerinatheka curryi, G. index, G. subconglobata, G. mexicana, G. barri, G. euganea, Orbulinoides beckmanni, Turborotalia frontosa, T. pomeroli, Hantkeninamexicana, H. liebusi, H. dumblei, H. alabamensis, and Dentoglobigerina eotripartita. By integrating planktonic foraminiferal biostratigraphy, stable delta 18O and delta 13C isotopes, and paleotemperature analyses, the first detailed study of the Middle Eocene Climatic Optimum (MECO) record was performed in SW Anatolia/Turkiye. The overall signature of the MECO is similar to global observations but also involves some regional differences. The MECO paleotemperatures, determined to vary between approximately 2 degrees C and 5 degrees C, were similar to the global records, but the slight differences in values in the three sections are most likely due to the paleogeographic position of the studied section in Turkiye.

Особенности экологического состава планктонных и бентосных фораминифер в поверхностных осадках Татарского пролива (Японское море)

he fauna of planktonic and benthic foraminifera of the Tatar Strait in the surface layer of sediments from cores sampled during the cruise LV85 on the R/V «Akademik Lavrentiev» in May 2019 has been studied. The benthic foraminifera assemblages, consisting of living and dead shells, correspond in their ecological appearance to the modern cold-water oceanographic conditions of the studied area. Among planktonic foraminifera, along with the dominant subarctic form Neogloboquadrina pachyderma dex., there are single tropical and subtropical species (Globorotalia inflatа, Globigerinoides ruber and Neogloboquadrina dutertrei). The authors believe that the above warm-water forms entered the Tatar Strait from the southwestern part of the Sea of Japan with the warm waters of the Tsushima Current. Fossil finds of warm-water fauna in Pleistocene and Holocene sediments play an important role in deciphering the geological record in the northern part of the Sea of Japan. Their presence in sedimentary sections makes it possible to trace the northward migration of the warm current and assess the extent of its influence on coastal ecosystems in the past.

Strontium Isotopic, Ostracod fauna, and Paleoenvironmental Features of the Late Miocene Sequence in Mut/Dağpazarı Region (Southern Turkey)

The primary focus of this study was the Dağpazarı village in the Mut region of Mersin, southern Turkey. In this research area, two stratigraphic sections were meticulously measured. The study conducted a comprehensive examination of the Middle-Late Miocene period in the Dağpazarı, Ballı, and Mut Formations by analyzing the ostracod fauna and utilizing strontium isotope chemostratigraphic dating. This research determined that the upper levels of the Mut/Köselerli formations, specifically from the Burdigalian to Serravallian, signify the commencement of the Miocene succession in the study area.The Dağpazarı Formation, characterized by abundant silty-clay, Ostrea fossils, and lignite layers, is deposited unconformably just above these levels.This formation contains the following ostracod taxa; Bairdia subdeltoidea, C. glypta, Cytheridea acuminata acuminata, Acanthocythereis hystrix, Krithe monosteracensis, Neomonoceratina mouliana, Hemicyprideis sp., Cistacythereis caelatura, Cyherella terguemi, T. prava, K. langhiana, A. ulicznyi, Pokornyella deformis minor, Loxoconcha alata, Tenedocythere salebrosa. Furthermore, the planktonic foraminifera species are; O. universa, Globigerinoides trilobus, Glb. ruber, Orbulina bilobata, Glb. sacculifer, O. suturalis, and the formation includes abundant bryozoa, echinoid spines, gastropods such as Terebralia at distinct levels, and fish otolith. The formation, dating from the late Serravallian to the early Tortonian, exhibits the shallow reef characteristics that continued to develop in the late Miocene.The formation consists of dark green, bulbous weathered claystone, Bairdia subdeltoidea and Ostrea which are reduced in size at the levels that pass into hard clayey sandstone, abundant benthic foraminifera with abundant echinoid spines. The formation consists of benthic foraminifera, hard clayey sandstone, and weathered dark green claystone, which contains numerous echinoid spines.Ostrea and Bairdia subdeltoidea are also present. The upper section of the analyzed succession concludes with silty, compact, clayey limestone layers and light-colored limestone bands. The Tırtar Ballı Formation, which conformably overlays the Dağpazarı Formation, signifies the culmination of a relatively recent reef formation during the Tortonian period.Ostracod species such as Aurila pigadiana, Thalmannia hodgii, Buntonia sublatissima dertonensis, Bairdia subdeltoidea, Aurila sp. Bassiouni have been defined. The limestones also contain abundant benthic foraminifera and echinoid spines. The 87Sr/86Sr ratio analyzed from the carbonate sample obtained from the Dağpazarı formation is 0.708920. Based on these isotope data, the age of the Dağpazarı formation was calculated to be 8.7 million years (Ma).

Biostratigraphy of Shiranish Formation from Selected Wells, Central of Iraq

The Quantitative high-resolution planktonic foraminiferal analysis of the subsurface section in three selected wells in the Ajeel Oil Field (Aj-8, Aj-12, and Aj-15) in Tikrit Governorate, Central Iraq has revealed that Shiranish Formation deposited in Late Campanian- Latest Maastrichtian age. This formation consists mainly of marly and marly limestone yielding diverse planktonic foraminiferal assemblages and calcareous benthic foraminifera, with a total of 46 species that belong to 23 genera, Three zones and four subzones, which cover the Late Campanian to the Latest Maastrichtian, were identified based on the recorded planktonic foraminifera and their ranges. They are as follows:1. Globotruncana aegyptiaca Zone that dated to be Late Campanian 2. Gansserina gansseri Zone that refers to Early Maastrichtian 3. Abathomphalus mayaroensis Zone that indicates Late Maastrichtian, in this section, the Abathomphalus mayaroensis Zone is divided into four subzones, namely in that order from bottom to top: Racemiguembelina fructicosa (Early Late Maastrichtian), Pseudoguembelina hariaensis (Middle-Late Maastrichtian), P. palpebra ( Late Late Maastrichtian), and Plummerita hantkeninoides (latest Maastrichtian).

Facies Analysis, Diagenetic Features and Depositional Environment of the Kometan Formation from Northeastern Iraq

This study involves microfacies analysis of the Kometan Formation from northeastern Iraq supported by detailed petrographic investigation for the main components and diagenetic processes using a petrographic microscope, scanning electron microscope (SEM), and X-Ray diffraction (XRD). The techniques have revealed that the formation includes two microfacies; lime wackestone and lime packstone microfacies which in turn are subdivided into seven sub-microfacies, that were deposited in the quiet and deep marine environment. Planktonic foraminifera (keeled and globular chamber types) are dominant, along with oligostegina in addition to subordinate benthonic foraminifera and fine-grained bioclasts. Calcite forms the main mineralogical composition in euhedral (rhombohedral), microcrystals, star-shaped, and columnar crystals in addition to pyrite and glauconite. All components are embedded in the micritic groundmass. The main diagenetic processes affecting the studied rocks include; chemical compaction (stylolite formation), dissolution, recrystallization, and cementation.

ON THE AGE AND CONDITIONS OF THE FORMATION OF THE POLYANYTSKA SUITE ACCORDING TO THE FORAMINIFERA STUDY RESULTS (LOWER MIOCENE, BORYSLAV-POKUTTYA NAPPE, UKRAINIAN CARPATHIANS)

Neogene deposits of the Polyanytska Suite were exposed by the South Boryslav-1 well within the eastern block of the South Boryslav structure of the Boryslav oil and gas condensate field of the Outer Carpathians. The studied sediments of the Polyanytska Suite belong to the complex zone of planktonic foraminifers Globigerina pseudoedita with a characteristic association: Globigerina pseudoedita, Globoquadrina dehiscens, Dentoglobigerina langhiana, Trilobatus trilobus, Tenuitella brevispira, Tenuitella denseconnexa, Globorotalia tetracamerata, Globigerinella evoluta, Globigerinella obesa, Chiloguembelina gracillima. The Globigerina pseudoedita zone of planktonic foraminifera correlates with the zonal interval of nannoplankton NN2-NN3 of the Central Paratethys, which covers the upper part Eggerian, Eggenburgian, and the lowest part Ottnangian of the Central Paratethys and is compared with the upper Aquitan – the lower part of the Burdigal of the lower Miocene of the Neogene of the International Chronostratigraphic Scale. The sediments of the Polyanytska Suite were formed in a normally saline sea basin, with depths from the middle to the inner shelf. The medium shelf conditions (intervals 1812–1805 m; 1684–1645 m and 1546–1485 m in the the South Boryslav-1 well) are indicated by a relatively high percentage content and morphology of the shells of planktonic foraminifera, the taxonomic composition of calcareous benthic foraminifera. The presence of plankton indicates normal water salinity. Analysis of foraminifera in the interval 1395–1365 m indicates the depths of the inner shelf. The identified redeposited foraminifera of the Paleocene-Lower Oligocene testify to the erosion and demolition of clastic material from the uplifted part of the Carpathians.