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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]

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]

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]

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 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]

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]

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]

The Albanian-Thessalian Basin, which is located in the vicinity of Mount Morava, includes Eocene to Middle Miocene sediments with a poorly-known, calcareous nannofossil content. This study is focused on the investigation of calcareous nannofossil assemblages from the Lower Miocene sediments outcropping in the area, resulting in the correlation to the global nannofossils zones/subzones NN2-NN3/CN1c-CN2, as well as to the zonation from the Mediterranean area, where the MNN2b and MNN3a biozones have been identified. An early-middle Burdigalian age for the studied outcrops is supported by primary and secondary index species (Helicosphaera ampliaperta, Helicosphaera mediterranea, Sphenolithus belemnos, Sphenolithus disbelemnos, Sphenolithus pseudoheteromorphus). Quantitative analyses were performed on calcareous nannofossils and statistics were applied to all of the counted samples. Based on the statistical analysis, short-time fluctuations in palaeoenvironmental parameters, such as temperature, salinity and eutrophic regime, are documented through the changes in the calcareous nannofossil assemblages and their abundance patterns. The depositional palaeoenvironment indicates changes in basin water depth, with influence of cold upwelling currents, terrigenous nutrient influx, and increased palaeoenvironmental perturbations over short time intervals. [ABSTRACT FROM AUTHOR]

The results of a study of calcareous nannofossils found for the first time in the lower part of the Stolbovaya Group of the Kamchatsky Mys Peninsula in Eastern Kamchatka are presented. Two assemblages of different age are identified, with one assigned to the Upper Cretaceous and the other to the Paleogene (not older than the Lutetian Stage of the Middle Eocene). These data make it possible to refine the age of terrigenous–tuffaceous sequences in the lower part of the Stolbovaya Group, which are poor in organic remains. [ABSTRACT FROM AUTHOR]

Calcareous nannofossil assemblages have been investigated in the uppermost Eocene to the lowest Oligocene in the Marun oil field in the Dezful Embayment (south‐west Iran). The studied interval includes shales, marlstones and limestones. Seventeen genera and 35 species of calcareous nannofossils have been determined. Regarding the succession of nannofossil bioevents, the studied interval ranges from the late Eocene (Priabonian, CNE18 Zone or NP18 Zone) to the early Oligocene (Rupelian, CNO2 Zone, or NP22 Zone). A high relative abundance of warm water taxa (such as Sphenolithus spp., Discoaster spp. and Helicosphaera spp.) is recorded in the late Eocene, while towards the Eocene–Oligocene boundary (EOB), an increase in the relative abundance of cool and temperate taxa (such as Reticulofenestra spp., Cyclicargolithus floridanus, Dictyococcites bisecta and Markalius inversus) is identified. A marked decrease in the abundance of warm water taxa along with a decrease in species diversity indicates that the cooling event at the EOB in the Marun oil field in Iran is similar to other parts of the world (Tethys realm). [ABSTRACT FROM AUTHOR]

New field observations and discovery of calcareous nannofossils and planktonic foraminifera from the 'shallow-marine' Çayraz Formation (Haymana Basin, Central Anatolia), a contributing Eocene section to the shallow benthic zonation (SBZ) in the Tethys, allow us to revise its stratigraphy and establish an integrated biostratigraphic scheme for the first time. The hemipelagic marls in the uppermost part of the Eskipolatlı Formation that underlies the Çayraz Formation yielded nannofossil assemblages of Zone CNE3, pinning down the initiation of the Çayraz shelf system into the 'middle' Ypresian. The prominent marly part (Member B) between the carbonate-clastic packages of the Çayraz Formation with prolific occurrences of larger benthic foraminifers (LBFs) (Members A below and C above) yielded calcareous nannofossils suggesting Zone CNE6 (late Ypresian). We show that the mixed carbonate-siliciclastic sequence with abundant LBFs in the upper part of the formation (Member C) is overlain by newly discovered hemipelagic marls (here named as Member D). These marls yielded calcareous nannofossils indicating Zone CNE9 and CNE10 for the lower and Zone CNE12(?Lutetian) for the upper samples. The same beds yielded planktonic foraminifers indicating Zone E8 for the lower and Zone E9 for the upper samples. We conclude that shallow-marine sedimentation in the Çayraz section ended in the 'middle' Lutetian, challenging the previous Bartonian records by LBFs. A new lithostratigraphic scheme consisting of four members with distinctive lithological and biotic characteristics is proposed for the Çayraz Formation: two main shelf systems (Members A and C), each followed by deep-marine sedimentation (Members B and D). [ABSTRACT FROM AUTHOR]

We combine extensive field data with calcareous nannofossils and dinocysts analysis and detrital zircon U-Pb ages to identify six Paleocene-Oligocene stratigraphic units in a previously poorly studied area in the external fold and thrust belt of the Fuegian Andes. Detailed petrographic analysis coupled with detrital zircon ages indicate three main provenance peaks, which reflect that 1) the lowermost upper Cretaceous was already exhumed during the Paleocene-early Eocene, 2) the upper Cretaceous rocks were a continuous source at least until the late Eocene, 3) volcanism was coetaneous with the deposition of middle Eocene successions. Three contractional stages known elsewhere in the thrust-belt are identified in the study area in the Danian, the early Eocene-early middle Eocene, and the latest Eocene-early Oligocene. This suggests synchronicity along strike during the evolution of the Fuegian fold and thrust belt. • Identification and characterization of six Cenozoic poorly known or unknown units in the area. • Petrology and detrital U-Pb ages indicates three provenance peaks, two from the Cretaceous and one from the Eocene. • Identification of three contractional stages: a Danian stage, an early Eocene stage and an Oligocene stage. • Synchrony along strike in the development of the Fuegian Andes. [ABSTRACT FROM AUTHOR]

An integrated study including magnetostratigraphy, larger benthic foraminifera and calcareous nannofossil biostratigraphy is presented herein. This work was performed in shallow marine siliciclastics rich in larger foraminifera, around the Ypresian/Lutetian boundary in the Ésera valley (South-Central Pyrenees). Although the calcareous nannofossil content in the studied interval is low, not allowing a precise Y/L boundary to be recognised, the taxa found are enough to support the chronostratigraphic attribution. Data obtained in the Ésera valley section has improved the knowledge of larger benthic foraminifera (Nummulites and Assilina) distribution through chron C21. SBZ 11 to SBZ 12 transition took place at the lowermost C21r, as shown in previous works. SBZ 12 assemblages extend into C21n, where the SBZ 12 to SBZ 13 boundary occurs. These data, obtained in shallow marine siliciclastic facies, with in situ fauna, results in a shift of the SBZ 12/SBZ 13 boundary to the Lower Lutetian, younger than previously believed. Accordingly, the Ypresian/Lutetian boundary occurs in SBZ 12. [ABSTRACT FROM AUTHOR]

This work documents the biostratigraphy of dinoflagellate cysts from the La Barca Formation at the Punta Ainol Locality, Tierra del Fuego Province, Argentina. The succession at Punta Ainol represents a new record for the Paleogene (late Paleocene–middle Eocene) from southern South America, based on current data on nannofossils and dinoflagellate cysts. Some significant events are in agreement with nannofossil data. In ascending stratigraphic order, they include the first occurrences (FOs) of Impagidinium crassimuratum, Apectodinium homomorphum, Pyxidiniopsis waipawaensis, Samlandia septata, Cleistosphaeridium diversispinosum, and Enneadocysta dictyostila, and the latest occurrence (LO) of Palaeocystodinium golzowense. Three Paleocene/Eocene dinoflagellate cyst zones (Palaeocystodinium golzowense, NZDP7 and Apectodinium homomorphum) are recognized here. [ABSTRACT FROM AUTHOR]

Hydrocarbon source potential of the Paleogene Pabdeh Formation was studied by means of organic geochemistry and distribution of calcareous nannofossils. Based on the results, an Eocene-aged organic matter (OM)-rich interval was identified and traced across different parts of the North Dezful zone and partly Abadan Plain. In order to characterize the OM quality and richness of the studied intervals, Rock-Eval pyrolysis and nannofossils evaluation were performed, and the geochemical data collected along selected wells were correlated to capture the variations of thickness and source potential of the OM-rich interval. Accordingly, remarkable variations were identified within the depth ranges of 2 480–2 552 m and also 2 200–2 210 m, which were attributed to the maximum increase in the rate of growth R-selected species. This increase in the productivity rate was found to be well correlated to high Rock-Eval total organic carbon (TOC) and hydrogen index (HI) values. Given that the maturity of Pabdeh Formation in the studied area was found to have reached the oil window, we expect significant hydrocarbon generation (Type II kerogen), making the play economically highly promising. [ABSTRACT FROM AUTHOR]

Environmental and biotic responses to early Eocene hyperthermal events in the southwest Pacific are critical for global paleoclimate reconstructions during Cenozoic greenhouse intervals, but detailed multidisciplinary studies are generally missing from this time and location. Eocene carbonate sediments were recovered during International Ocean Discovery Program Expedition 371 at Site U1510 on southern Lord Howe Rise in the Tasman Sea. Part of the Early Eocene Climatic Optimum (EECO; 53.26–49.14 Ma) and superimposed hyperthermal events have been identified based on refined calcareous nannofossil biostratigraphic data and carbon stable isotope records on bulk sediment and benthic foraminifera. Four negative carbon isotope excursions (CIEs) associated with negative oxygen isotope excursions are recognized within the EECO. Comparison with a global compilation of sites indicates these CIEs correlate to the K event (Eocene Thermal Maximum 3), and tentatively to the S, T, and U events. Sediments with a high carbonate content throughout the EECO provide an excellent opportunity to examine these CIEs, as carbonate dissolution often impacts correlative records elsewhere. Benthic foraminifera and calcareous nannoplankton taxa indicative of warm waters are most abundant during the K event, the most prominent hyperthermal of the EECO. Eutrophication of surface waters during the K event did not lead to increased trophic conditions at the seafloor, whereas a coupled response is observed during smaller hyperthermals. The biotic turnover sheds new light on the paleoenvironmental consequences of hyperthermal events. Key Points: A succession of carbon isotope excursions occurs in the early Eocene at IODP Site U1510Individual hyperthermal events of the Early Eocene Climatic Optimum have been identified for the first time in the Tasman SeaA decoupled response of benthic foraminifera and calcareous nannofossils is only observed during the largest hyperthermal [ABSTRACT FROM AUTHOR]

Copyright of Iraqi Bulletin of Geology & Mining 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.)

The Cretaceous/Paleogene boundary in the Kurdistan region of Iraq in general is still debatable; however, examination of the boundary at the Qalbaza and Dartw localities in the Sulaimani area of the Kurdistan Region shows different results regarding the biostratigraphy of the boundary zone. In the current study, the calcareous nannofossil assemblages and biostratigraphy across the K/Pg boundary in the Sulaimani area of Kurdistan were focused on. The rock strata in the study sections are characterized by alternations of organic shale, siltstone, fine-grained sandstone, gravel and organic limestone interlayers within the Tanjero Formation (Late Maastrichtian) and the overlying Kolosh Formation (Paleocene-early Eocene). The boundary is biostratigraphically delineated by the first occurrences of Biantholithus sparsus, Cruciplacolithus spp. and Coccolithus pelagicus. An additional important biostratigraphic marker is plus an acme of Thoracosphaera operculata of biozone NP1 above biozone CC26 which generally consisted of Micula murus, Micula Prinsii and Lithraphidites quadratus. This biostratigraphic analysis indicates no hiatus, although it shows that reworked Cretaceous taxa are recorded above the K/Pg boundary within zones NP1 and NP2. [ABSTRACT FROM AUTHOR]

New data from a continuously cored succession, the Mossy Grove core, near Jackson, central Mississippi, recovered ∼137 m of marine clays (Yazoo Formation), spanning ∼5 Ma and including the critical Eocene–Oligocene transition (EOT) event. These clay-rich sediments yield well-preserved calcareous microfossil and palynomorph assemblages. Here, we present a new organic-walled dinoflagellate cyst (dinocyst) biostratigraphic framework, including the recognition of 23 dinocyst bioevents. These are integrated with new age constraints based on calcareous nannofossil biostratigraphy and a reassessment of the existing radiometric dates and planktonic foraminiferal biostratigraphy, permitting the establishment of a robust and significantly refined age model for the core. According to this new age model, a major increase in sedimentation rate – from ∼2.1 to ∼4.7 cm kyr -1 – is observed at a core depth of ∼89.1 m (∼34.4 Ma). In the new age model the section is significantly older than previously thought, by up to 1 Ma, with the Eocene-Oligocene boundary (∼33.89 Ma) placed ∼34 m below the level previously identified. With these more accurate age estimates, future isotopic and palaeoecological work on this core can be more precisely integrated with other, globally distributed records of the EOT. [ABSTRACT FROM AUTHOR]

The study represents new data about chronostratigraphic range of the Emine flysch Formation in its type section at the Black Sea coast near the "Irakli" touristic resort. In the highest stratigraphic levels, calcareous nannofossils of NP 10 Rhomboaster bramlettei zone have been documented, supporting early Eocene age for the formation. These new finds will shed light on the timing of cessation of the turbiditic sedimentation in East Balkan, as well as on the specific expression of the global event - the Paleocene-Eocene Thermal Maximum (PETM) in deep-water environment. [ABSTRACT FROM AUTHOR]

Calcareous nannofossil assemblages from the interval covering the middle Paleocene to early Eocene (P/E), studied in sediments from two sections located in the western Tarim Basin (Kuzigongsu and Bashibulake), indicate that the record of the PETM (Paleocene-Eocene Thermal Maximum) is inscribed in a transgression-regression cycle. A large sea transgression occurred concomitant to the Qimugen Formation, according to earlier studies. Here we present detailed evidence of richness and abundance of calcareous nannofossils to study the PETM and sea-level change in the western Tarim Basin. The gradually increasing sea level from the base of the Qimugen Formation is dated to the nannofossil zones NP7 to 9a (Thanetian), in which the first occurrences of H. riedelii and of D. multiradiatus have been recorded. The highstand of the sea level cycle coincides with increasing Discoaster spp. amounts near the Paleocene/Eocene boundary (NP9a-10), which is dated by the occurrence of RD assemblages (namely, Rhomboaster spp. and Discoaster araneus group). Evidence of regression, observed in the top of Qimugen Formation (NP10–11) corresponds to low abundance and diversity of nannofossils, and is characterized by a rapid increase of Micrantholithus spp. in the assemblage. Inter-regional correlations between the two sections show that in the Tianshan Mountain area the highest relative sea level occurred near the middle part of NP9a. • Age of Qimugen formation confirmed. • Nannofossil paleoecology confirmed and contrasted. • PETM event in shallow epicontinental sea in western Tarim Basin. • Three stages of Tethys sea regression confirmes by inter-regional correlations. [ABSTRACT FROM AUTHOR]

We combine stable isotope, calcareous nannoplankton, and benthic foraminiferal records for Ocean Drilling Program Sites 1262 (paleodepth ~3,500 m) and 1263 (paleodepth ~1,500 m) on Walvis Ridge (SE Atlantic), to document the marine biotic response to Eocene Thermal Maximum 3, in the early part of the Early Eocene Climate Optimum, ~3.1 Myr after the Paleocene/Eocene Thermal Maximum. Bottom water warming may have decreased the vertical thermal gradient at both sites, but more at Site 1263 than at Site 1262. Floral and faunal changes were more muted at Site 1262 than at shallower Site 1263, indicating that carbonate dissolution was not the most important cause of biotic effects. Assemblage changes were more pronounced in benthos than in plankton. Calcareous nannofossils underwent minor ecological changes, possibly related to the presence of warmer waters, especially at Site 1263, and dissolution-resistant taxa increased in abundance. Benthic foraminiferal diversity decreased at both sites, but benthic foraminiferal accumulation rates declined dramatically at Site 1263, remaining stable at Site 1262. Ocean circulation may have changed during ETM3, resulting in the presence of a warmer (intermediate) water mass at Site 1263. More pronounced warming may have caused enhanced remineralization of organic matter, so less food reached the benthos. The biotic response to the X-event was less pronounced than that to earlier and more severe hyperthermal events, the Paleocene/Eocene Thermal Maximum and Eocene Thermal Maximum 2. The extent of the biotic response reflects the severity of the environmental disturbance but varies by location (e.g., paleodepth on Walvis Ridge). [ABSTRACT FROM AUTHOR]

Copyright of Iraqi Bulletin of Geology & Mining 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.)

Pelagic carbonates constitute the majority of the ocean sediments, particularly since the Jurassic, and record climatic and oceanic changes. Cenozoic sediments record glacial and interglacial periods, as well as thermal maxima, such as the PETM (Paleocene-Eocene Thermal Maximum) at ca. 56 Ma or the MECO (Middle Eocene Climatic Optimum) that dates back to ca. 40 Ma. The Paleogene period shows variations in seawater temperature and atmospheric CO 2 , as well as fluctuations of the carbonate compensation depth (CCD). In order to understand the actions and feedbacks between climate (regulated amongst others by temperature, partial pressure of CO 2 , and atmospheric belts), CCD fluctuations and pelagic carbonate producers, the fluxes, assemblages and sizes of calcareous nannofossils were studied from sediments dated between 48 and 39 Ma, including the MECO interval. Calcareous nannofossils were analysed in from the ODP (Ocean Drilling Project) Leg 198 Site 1209A, Shatsky Rise located in the tropical Pacific. The previously proposed age model for Site 1209 has been slightly modified based on new calcareous nannofossil biostratigraphy recalibrated according to the GTS 2012. In a long-term perspective, calcareous nannofossil assemblages and taxa size show significant changes during the middle Eocene. Our data suggest that relatively oligotrophic conditions occurred between 48 and 45 Ma, interrupted by higher trophic conditions between 45 and 39 Ma, although oligotrophy occurred again during the MECO. Discoaster spp. show smaller sizes from 48 to 39 Ma, mirroring the global temperature decrease. At 40 Ma, during the MECO, large-sized reticulofenestrids with a peak of Reticulofenestra umbilicus (> 14 μm) occurred, whereas smaller but heavily calcified Dictyococcites spp. peak in the aftermath of the MECO. Calcareous nannofossil fluxes show a significant increase with respect to background values during the CAEs (Carbonate Accumulation Event), although they are low during the MECO. Calcareous nannofossil fluxes seem to have had important impact on the oceanic carbon cycles, by creating a carbonate flux to the ocean interior, likely contributing to the CCD deepening. [ABSTRACT FROM AUTHOR]

Calcareous nannofossils were analyzed in 73 samples collected from the ANH-San Jacinto-1 cored-stratigraphic section drilled in the Sinú-San Jacinto Belt (SSJB) along the tectonic boundary of the South American and Caribbean plates in Colombia. Our quantitative results show that calcareous nannofossils were commonly abundant and moderately preserved. A total of 75 morphotypes, representing 13 genera and 55 species, were quantified. Calcareous nannofossil assemblages were dominated by Reticulofenestra spp., Sphenolithus spp., Coccolithus spp. and Helicosphaera spp. We recognized the standard biostratigraphic events highest occurrence (HO) of Reticulofenestra reticulata, HO of Discoaster saipanensis, lowest common occurrence (LCO) of Clausicoccus subdistichus , HO of Coccolithus formosus, HO of Reticulofenestra umbilicus, lowest occurrence (LO) of Sphenolithus distentus, LO of Sphenolithus ciperoensis, and LO of Discoaster druggii. This indicates that the studied deposits cover a stratigraphic range from zones NP19-20 (CNE19) to NN2 (CNM1) and encompass the 35.2 Ma to 22.5 Ma, interval from late Eocene (Priabonian) to Early Miocene (Aquitanian). The distribution patterns and age model show that the Eocene–Oligocene transition can be traced in the core and overlapping of bioevents as well as reworking of taxa suggest deep-sea stratigraphic unconformities formed during the late Eocene, early Oligocene and the Oligocene/Miocene. According to the duration of the hiatuses, ∼0.8 Myr, ∼2.2 Myr and ∼4.4 Myr, respectively, and the sedimentary context of the studied deposits, we suggest that these stratigraphic gaps represent downslope mass erosional episodes triggered by tectonic events and/or mud diapirism. • Calcareous nannofossils confirm a late Eocene to Early Miocene age. • The section spans from the NP19/NP20 to NN2 Zones. • The age model indicates unconformities formed during the late Eocene, early Oligocene and the O/M. • Stratigraphic gaps result from downslope mass erosional episodes. [ABSTRACT FROM AUTHOR]

The Eocene and Oligocene deposits of the southwestern region of the Sinú-San Jacinto Belt (SSJB) in NW South America were formed in marine environments influenced by fluvial discharges from the northern Andes of Colombia. However, these deposits are not well-exposed on the surface, which has limited the study of micropaleontological assemblages that could improve our understanding of the chronostratigraphic and paleoenvironmental characteristics of these rocks. In this study, we analyzed two cores of one of the thickest Cenozoic stratigraphic sections in the Caribbean region, from the ANH-TIERRALTA-2-X-P stratigraphic well, using palynomorphs and calcareous nannofossils. Our analysis allowed us to determine the age of deposition and understand the biostratigraphic patterns of marine and terrestrial microfossils in these nearshore deposits. We found that the first cored interval, from 2122 m to 2026.9 m, corresponds to marine rocks accumulated between the middle and late Eocene. The second interval, from 1130 m to 731.6 m, showed patterns of terrestrial and marine microfossils, which indicate the middle-late Eocene to the Early Miocene age. Palynological and calcareous nannofossil biostratigraphy were consistent in the middle to upper Eocene and Lower Miocene deposits, but discrepancies were observed in the Oligocene deposits. We attributed this to reworking or broader biostratigraphic ranges of certain palynological markers used in the biozones. Determining the age of the middle to upper Eocene and upper Eocene to lower Oligocene deposits was challenging due to the limited number of well-calibrated biostratigraphic markers. As a result, accurate correlation with the late Eocene – early Oligocene stratigraphic record from other parts of the SSJB is hindered, demonstrating that regional stratigraphic correlations based on biostratigraphy alone are problematic. • Middle-upper Eocene to Lower Miocene deposits of the ANH-TIERRALTA-2-X-P stratigraphic well of the Sinú-San Jacinto Belt. • Integrated palynomorph and calcareous nannofossil biostratigraphy of Colombian Caribbean region. • Integrated biostratigraphic age model of the ANH-TIERRALTA-2-X-P. • Biostratigraphic patterns of terrestrial and marine microfossils in fluvio-deltaic deposits. [ABSTRACT FROM AUTHOR]

The Sinú-San Jacinto Belt (SSJB) is a set of folded and faulted onshore deposits in the Caribbean region of Colombia near the tectonic boundary of the Caribbean and South American plates. Previous studies relied on biostratigraphic data from mollusks, benthic and subsequently planktonic foraminifera to establish a tectonostratigraphic framework from the Late Cretaceous to Pleistocene for these deposits. In this study, we collected over 10 years of new biostratigraphic information from calcareous nannofossils, an oceanic micropaleontological group with well-calibrated biostratigraphy, providing us the opportunity to evaluate the prior age determinations and to refine the tectonostratigraphic framework of these deposits. We found that the recovery of calcareous nannofossils varied, observing that large barren intervals affected chronostratigraphic constrains on southwestern deposits accumulated in nearshore environments. However, despite this limitation, the occurrences of biostratigraphic markers allowed us to establish that lower Eocene, upper Eocene, Oligocene, Lower Miocene and Upper Miocene deposits occur in different localities of the belt, whereas Upper Cretaceous and upper Paleocene are scarcer. Our results support the previous chronostratigraphic framework, but also indicate that the duration and origin of the hiatuses can vary with location in the belt, complicating regional correlations of the tectonostratigraphic boundaries. We suggest that integrated biostratigraphic and sedimentologic studies from additional cored sections and outcrops would help to understand the polygenetic origin of unconformities that affect the stratigraphic record in the Caribbean region of Colombia. • Calcareous nannofossil stratigraphy used to establish chronostratigraphic framework in Sinú-San Jacinto Belt. • Marine sedimentation observed during early Eocene, late Eocene-Early Miocene, and Late Miocene-Pliocene intervals. • Variable sedimentation rates found in the belt. • Hiatuses in sedimentation suggest a polygenetic origin, requiring further study. • Reworked nannofossils indicate erosion of upper Paleocene deposits and Oligocene to Middle Miocene rocks during Late Miocene-Pliocene interval. [ABSTRACT FROM AUTHOR]

Deltaic depositional systems are characterized by a complex interaction of physical, chemical, and biological factors. Although fluvial-, wave- and tidal-dominated deltaic environments have been extensively studied, evaluation of the processes in tropical mixed sedimentary systems has not been fully documented. Tropical regions with active margins are tectonic environments where these multiple factors act on the development of coastal systems. An onshore well-core from this tropical setting (Sinú-San Jacinto Basin, Colombian Caribbean) revealed that a middle-upper Eocene?-lower Oligocene coarse-grained deltaic setting is replaced by a thick coal-bearing mixed-energy fine-grained deltaic succession from the Oligocene to Early Miocene. The integrated analysis of facies associations, ichnological data, and terrestrial/marine micropaleontological assemblages (palynomorphs, foraminifera, and calcareous nannofossils) of this well-core allowed us to identify changes in dominance and influence of coastal processes (fluvial-, wave- and tide) and shoreline evolution. Using this information, as well as the sediment supply and accommodation space ratio, we were able to distinguish three intervals from the bottom to the top of the siliciclastic succession: (i) middle-late Eocene?–early Oligocene, prograding, fluvial-dominated, wave- and tide-influenced coarse-grained deltas with amalgamation of hyperpycnal-dominated mouth bars with hyperconcentrated flow input, (ii) Oligocene, retrograding to prograding, hyperpycnal-dominated heterolithic delta deposits punctuated by transgressive pulses, and (iii) late Oligocene to Early Miocene, aggradational, coal-bearing fine-grained delta plain with a higher proportion of transgressive phases over the continental environment. The complete succession represents long-term (∼14 Myr) mixed-energy nearshore siliciclastic systems, showing different lithological arrangements and sedimentation styles. A long-term evolution is observed from a middle-late Eocene? steep, short and coarse-grained sedimentary system with tropical humid lowland forest and punctual development of macrobenthic tracemaker communities (Interval I) to an Early Miocene gently (poorly drained), well-developed delta plain with mangroves and wave- and storm-influence record through trace fossils assemblages (Interval III). A combination of factors, including subsidence, relief uplifting, and possible relative sea level changes, are interpreted as the main controls on the stratigraphic evolution of sedimentary styles throughout the entire succession. Minor-order sedimentary successions into each interval (e.g., prograding distributary mouth-bar channel) revealed short-term cycles presumably controlled by an internal delta dynamic. Multidisciplinary analysis is essential for recognizing the influence of fluvial, wave, and tidal processes on tropical deltas, where high spatial and temporal variability makes it difficult to determine dominant processes for long periods of time. • Integrated sedimentological/ichnological/micropaleontological analysis. • Subsidence, relief uplifting, and possible relative sea level changes in tropical mixed-energy coastal systems. • Amalgamated mouth bars settings during middle-late Eocene? to early Oligocene. • Retrograding to prograding, hyperpycnal-dominated heterolithic delta deposits during the Oligocene. • Gently (poorly drained), well-developed delta plain during Oligocene to Early Miocene. [ABSTRACT FROM AUTHOR]

Core OS-28 located in central Jordan offers an expanded record of calcareous nannofossils and benthic foraminifera for the early Eocene of the southern Tethys. The oil shale succession of the studied interval covers calcareous nannofossil biozones NP10, NP11, NP12 and NP13. Microfossils document the biotic response of calcareous nannofossils and benthic foraminifera to short and long term warming trends of the early Eocene following the Paleocene-Eocene Thermal Maximum (PETM). On a global scale, two early Eocene short term shifts to higher atmospheric CO 2 concentration are recorded by negative δ 13 C excursions. These are known as Eocene Thermal Maximum 2 and 3 (ETM2, ETM3). Stable isotope records (δ 13 C org , δ 13 C carb , δ 18 O carb ) from the study area do not show these negative excursions, which elsewhere can be correlated with the two hyperthermal events known from early Eocene successions. The absence of negative δ 13 C signals otherwise typical for ETM2 and ETM3 is explained by a diagenetic alteration of the isotope signal after deposition. High abundances of the nannofossil taxon Sphenolithus spp. in biozone NP10 indicate less fertile conditions for this interval than for the overlying biozone NP11. Throughout biozones NP11 to NP13 Coccolithus pelagicus and Toweius spp. are the dominant taxa of the assemblages, suggesting a mesotrophic environment. Surface waters experienced a temperature change from warm to moderate-warm. The benthic foraminifera in calcareous nannofossils biozone NP10 and in the lower part of NP11 reflect oligo-mesotrophic and moderate to well oxygenated bottom water conditions. Throughout the upper part of biozones NP11, NP12 and NP13, the benthic foraminifera are characterized by an increasing abundance of Anomalinoides zitteli , Lenticulina spp. and Valvulineria scrobiculata . This coincides with enriched total organic matter content (TOC), indicating a shift to mesotrophic conditions and a moderate oxygen supply of the bottom waters. Based on the micropaleontological observations made in core OS-28 the early Eocene is first characterized by an increase and subsequently by a decrease of nutrients and oxygen. The composition of both, benthic and planktic communities was rather controlled by variations of regional environmental parameters than by global ones. These include strong runoff, climatic variability and the architecture of the basin. [ABSTRACT FROM AUTHOR]

The Ypresian/Lutetian boundary duration calcareous nannofossil biostratigraphy and bioevents from three sections, two from Sinai, Egypt (Wadi Ferian and El Mishatii; west-central and north-east Sinai, respectively) and one from Jordan (Outherite), are presented for the first time. Fifty-three calcareous nannofossil species are identified from 86 samples, spanning the calcareous nannofossil Zone NP14 (= Zone CP12; early‒middle Eocene). In the present study, the early/middle Eocene (Ypresian/Lutetian) boundary is defined by the Lowest Occurrence (LO) of Blackites inflatus , positioned at the base of NP14b/CP12b zones. The LO of B. inflatus is slightly above the LO of Turborotalia frontosa. In general, the present data is largely consistent with what is known from the GSSP (Gorrondatxe section, Spain, Basque Provinces) of the base of Lutetian, where the LO of B. inflatus also marks the base of NP14b/CP12b subzones. In the present study, the LO of B. inflatus is reaffirmed as a reliable marker for correlating the base of the Lutetian. Discoaster sublodoensis , D. saiipenensis , D. bifax , D. martini and Tribrachiatus orthostylus show diachronous occurrences. • Calcareous nannofossil biostratigraphy and bioevents across the Ypresian/Lutetian boundary in Egypt and Jordan • The Ypresian/Lutetian boundary is defined by the Lowest Occurrence (LO) of Blackites inflatus. • The LO of B. inflatus is slightly above the LO of Turborotalia frontosa. • The LO of B. inflatus is reaffirmed as a reliable marker for correlating the base of the Lutetian. [ABSTRACT FROM AUTHOR]

We integrate previous Bayesian and astronomically tuned age calibrations of the calcareous nannofossils events with our large-scale correlations to discuss using the standard calcareous nannofossil zonal schemes in the SW Neo-Tethys platform during a period of significant paleoceanographic, tectonic, and paleoclimatic perturbations (middle Eocene to early Oligocene). Two marine on-land sections extend from NP15 (Nanno-Plankton zone) to lower NP23, equivalent to upper CNE9 (Calcareous Nannofossil of the Eocene) to lower CNO3 (Calcareous Nannofossil of the Oligocene), are studied. Calcareous nannofossils have been investigated at less than 96 kyr resolution between 45.55 Ma and 31.9 Ma. The Souar section covers the Top (T) of the Nannotetrina alata group zone (CNE9, Lutetian) to the Isthmolithus recurvus zone (CNE18, Priabonian) in the Pelagic facies of the Tunisian dorsal. The El Rahma section extends from the Helicosphaera compacta zone (CNE21) to the Reticulofenestra umbilicus (CNO2) zone in the Cap Bon peninsula. The distribution patterns were studied through semi-quantitative counts to test the reliability of the biohorizons used in the standard biozonations schemes (Martini, 1971; Agnini et al., 2014). We discuss 14 biohorizons that span 13.65 Myr to highlight the limitations (absence/scarcity) of the Chiasmolithus group, particularly Ch. grandis, Ch. oamaruensis , and Ch. solitus, as biohorizons in the SW Neo-Tethys. Our study shows that Sphenolithus furcatolithoides , Dictyococcites bisectus, Sphenolithus obtusus, and Reticulofenestra erbae are reliable horizons for large-scale correlations with the northern margins of the Neo-Tethys. Calcareous nannofossils from the SW Neo-Tethys margin were highly affected by the paleo-circulation changes due to the episodic restriction of the westward subtropical Eocene Neo-Tethys (STENT) current (Jovane et al., 2009), followed by the closure of the eastern Neo-Tethys. • Calcareous nannofossil biostratigraphy at time resolution below 96 kyr. • Correlation of calcareous nannofossils events between the SW Neo-Tethys and Northern Neo-Tethys (Italy and Turkey). • Reliability of 14 early Paleogene biohorizons between 45.55 Ma to 31.9 Ma. • Sphenolithus furcatolithoides and Sphenolithus obtusus are reliable horizons for correlations with the northern Neo-Tethys. • C hiasmolithus grandis, Ch. oamaruensis , and Ch. solitus are diachronous and inconsistent in the SW Neo-Tethys. [ABSTRACT FROM AUTHOR]

The Caribbean area is currently considered a frontier basin for hydrocarbon exploration; however, the knowledge of the Cenozoic geological evolution is controversial and requires to be reviewed as new information becomes available. This study integrates for the first-time calcareous microfossils and palynomorphs and proposes a biostratigraphic framework for the early Eocene (Ypresian), in two marine sequences obtained from the ANH Piedras Blancas 1-X and ANH San Cayetano 1-X wells drilled in the Sinu-San Jacinto basin. This information was compared with palynological publications in the Llanos, Llanos Foothills, Middle Magdalena Valley, Catatumbo, and Maracaibo basins. The new information from the Caribbean suggests that the marine palynomorph events reported in the Llanos are diachronic, but they concur with global records in low-middle latitude. Similarly, we extend the biostratigraphic range of some terrestrial palynomorphs considered traditionally of Oligocene-Miocene until Ypresian. In the studied wells lateral changes of facies (turbiditic fan to outer fan-abyssal plain) seem to control the preservation and abundance of calcareous microfossils (calcareous nannofossils and planktonic foraminifera), however, the terrestrial palynology did not show stronger variation. • Integrated biostratigraphy of calcareous microfossils and palynomorphs for the Ypresian in the Caribbean Colombian. • The palynology from the early Eocene in basins from north of South America was compared. • New reports of the Adnatospharidium Acme for the Ypresian in the Colombian Caribbean. • Contributions about to age range of some palynomorphs for the north of South America. [ABSTRACT FROM AUTHOR]

A quantitative study of calcareous nannofossils, planktonic, and benthic foraminiferal assemblages have been performed on fifty six samples collected from ∼40 m interval across the Paleocene/Eocene transition at Nag El-Quda section in Upper Nile Valley, Egypt. I study this interval to evaluate the faunal and floral changes across the P/E transition. Four biozones of calcareous nannofossils and seven planktonic biozones have been recorded. The benthic foraminifera extinction event (BFEE) and the characteristic datum of both calcareous nannofossils, planktonic foraminifera, have been recognized. The absence of deep-sea benthic foraminifera ( Stensioeina beccariiformis), the low abundance of ( Angulogavelinella avnimelechi and Gavelinella rubiginosus) and increasing dominance of shallow-marine taxa (buliminids, Loxostomoides applinae) indicate deposition of the interval in shallow water environments (100-150 m depth). The benthic foraminiferal assemblages are dominated by Loxostomoides applinae, buliminids, and Lenticulina spp and indicate dysoxic conditions. Quantitative analyses have revealed a change in the species richness and fluctuations in abundance of foraminifera and calcareous nannofossils. [ABSTRACT FROM AUTHOR]

This work aims to put an end to the controversies about the occurrences of the upper Eocene in west-central Sinai by using the calcareous nannofossils. The Eocene calcareous nannofossil zones NP15 to NP18 were identified in Wadi Thal, west-central Sinai. Although the late Eocene Isthmolithus recurvus is recorded here for the first time, the base of NP19-20 zones is not delineated because the first occurrence of this taxon is considered a diachronous bioevent. The Zone NP18 is unconformably overlain by the lower marine Miocene NN2 Zone. Many calcareous nannofossil bioevents such as the last occurrence of Chiasmolithus grandis, the acme beginning of Cribrocentrum erbae , and the last occurrence of Neococcolithes dubius are used to approximate the Priabonian in west-central Sinai. It is recorded in the Tanka and Tayiba formations and probably in the uppermost part of the Thal Formation. Sea shallowness during the late Eocene due to uplifting in west-central Sinai might be responsible for the absence of many microfauna characterizing this stage/age. This suggestion is supported by the increased abundance of the nearshore nannofossil indicators, Lanternithus minutus, Zygrhablithus bijugatus and the shallow water Micrantholithus and Braarudosphaera from the upper part of Thal Formation through the overlain Tanka and Tayiba formations. • Calcareous nannofossil zones NP15 to NP18 were identified in west central Sinai. • The late Eocene Isthmolithus recurvus is recorded for the first time. • The nannofossil bioevents support the upper Eocene occurrence in west central Sinai. • A major hiatus occurs between Zone NP18 and the overlain lower Miocene NN2 Zone. • Sea shallowness during the late Eocene is suggested from the nannofossil assemblage. [ABSTRACT FROM AUTHOR]

Biostratigraphy and paleoenvironment of seventy surface samples were studied based on calcareous nannofossils along the Upper Maastrichtian – Eocene sequence at Gebel Duwi and Gebel Ghanima sections, Egypt. This succession includes three rock units, arranged from base to top as follow: Dakhla, Tarawan and Esna formations. Seven calcareous nannofossil biozones have been recorded, arranged as follow: CC 25c, CC 26, NP 2/3, NP 4, NP 5, NP 6 and NP 9b, discussed and compared with their counterpart in and outside Egypt. Four present stage boundaries have been discussed; the Cretaceous/Paleogene boundary, it seems to be incomplete in the Gebel Duwi section due to the absence of the biozone NP 1. The Danian/Selandian boundary, it can be determined in the Gebel Ghanima section based on the FO of Fasciclithus tympaniformis. The Selandian/Thanetian boundary, it was difficult to trace in the Gebel Ghanima section, where the topmost part of Zone NP 6 was missed. The Paleocene/Eocene boundary, it cannot be accurately determined in the Gebel Ghanima section, owing to the presence of a small hiatus represented by the absence of the Subzone NP 9a. There is predominance in assemblages' taxa and were relatively warm-water temperature during the Late Danian in the Gebel Duwi section and highly warm-water temperature around the Paleocene-Eocene boundary in the Gebel Ghanima section. There are two ecozones have been recognized in our study. In the Gebel Duwi, the sediments of ecozone (A) are deposited in cool-water, and transitional states between eutrophic and oligotrophic environments, while that of ecozone (B) are deposited in warm-water and also transitional states between eutrophic and oligotrophic environments. The sediments of ecozone (B) in the Gebel Ghanima are deposited in warm-water and mainly oligotrophic environments. • This work concerns the study of the Upper Maastrichtian- Eocene sequence at Eastern and Western Deserts, Egypt. • The sequence was represented by three rock units arranged from the base to top as: Dakhla, Tarawan, and Esna formations. • Seven calcareous nannofossil biozones were defined (CC25c, CC26, NP2/3, NP4, NP5, NP6 and NP9b zones). • Stage boundaries along the Upper Maastrichtian- Eocene sequence were discussed and determined as possible. • Our study gives remarks about the paleoenvironment and ecozones of the most identified taxa. [ABSTRACT FROM AUTHOR]

A detailed analysis of calcareous nannofossil assemblages was carried out across the Paleocene-Eocene transition in four outcrops in Egypt (the Gebel Matulla, Markha, El-Quss Abu Said, and Gebel Duwi sections) that span the Discoaster multiradiatus (NP9) to Discoaster binodosus (NP11) zones. The Paleocene-Eocene (P/E) boundary is placed in the lower part of the Esna Shale Formation based on the LOs of the Calcareous Nannofossil Excursion Taxa (CNET or RD) that define the base of NP9b. The studied sections are considered complete and document the Paleocene-Eocene Thermal Maximum (PETM). The occurrences of long-armed and asymmetrical discoasters (e.g., D. araneus, D. anartios) and rhomboasters (e.g., R. intermedia, R. bitrifidia, and R. spineus) are characteristic of the PETM interval. A sharp decrease in the diversification of Fasciculithus is noted at the onset of PETM. The abundance of Zygrhablithus bijugatus increases and corresponds with the dramatic decline in the oligotrophic Fasciculithus above the Paleocene/ Eocene boundary and appears to be a significant global event. The Discoaster, Fasciculithus, and Rhomboaster species reflect relatively warm and, probably, oligotrophic surface waters. A minor hiatus in most of the studied sections near the upper part of Zone NP10 has been recorded in many parts of the world and reflects a global sea level drop. [ABSTRACT FROM AUTHOR]

Two records of the crust laminae from the Marcus-Wake Seamounts and the Magellan Seamount were biostratigraphically studied. Based on biological imprints of the calcareous nannofossils, the geological ages of the two records were determined, with CM1D03 from the Marcus-Wake Seamounts being of late Paleocene to Pleistocene and CM3D06 from the Magellan Seamount of Late Cretaceous (more than 70.0 Ma). There are the obvious temporal-spatial differences in the initial formation period and enrichment characteristics of the cobalt-rich crusts of the two seamount chains and differences in the combination and distribution of microfossils in the inner crust layers between the seamounts. These differences are due to the adaptabilities of oceanic species in different environments. Ecological research was carried out in terms of population size of the calcareous nannofossils preserved in the crustal layers to discern the relation of the geological events at the Eocene-Oligocene (E/O) transition. The results show the transitions and recombination of species in the biotic community during the E/O transition obviously corresponded to 25 mm depth in the CM1D03 crust and 58 mm depth in the CM3D06 crust. The changes in biological species and the formation of particular ecological structures indicate the adaptive response of the paleo-biological community in the western Pacific Ocean to the global cold-climate events and the close correlation between the formation of the crust and the global climate change. [ABSTRACT FROM AUTHOR]

Large distance correlation of sedimentary organic rich facies units in Jordan has been established by means of calcareous nannofossil biostratigraphy. Based on a biostratigraphic framework, a better understanding of the deposition and distribution of Maastrichtian to Eocene oil shales is obtained. A total of 812 samples representing 29 wells located across Jordan were studied for calcareous nannofossil biostratigraphy. The results reveal major regional changes in paleogeography leading to a change in oil shales distribution in time. The tectonic settings have been determined for four different oil shale sequences of Maastrichtian, Paleocene, Early Eocene and Middle Eocene age. Large variations in thickness over short distances indicate syndepositional subsidence control in several fault bound sedimentary sub-basins. During the Early Maastrichtian transgression, a thick oil shale dominated succession was accumulated in the south of Jordan. This transgression continued into the Paleocene as represented by a thick sequence of oil shales in nannofossil Zone NP 3. In the Late Paleocene, the gradual progradation of the oil shale facies from south to north coincided with an uplift of the Sirhan Sub-basin in east Jordan. Accordingly, the oil shale distribution varies locally and shows a scattered geographic distribution in the Late Paleocene. An up to 60 m thick succession of Early Eocene oil shales was found in central Jordan. Localized restricted conditions, which prevailed during the Ypresian–Lutetian transition (nannofossil Zone NP 14), were caused by the subsidence of the Azraq-Hamza and Sirhan sub-basins. These movements resulted in thick oil shale accumulation in the southeastern and central parts of Jordan. A gradual relative sea level fall during the Bartonian resulted in a prograding and thinning of the oil shale facies from west to east in central Jordan. [ABSTRACT FROM AUTHOR]

The Eocene sequence exposed at Gebel Naalun (Fayum-Nile divide), Guta section-I (West of Birket Qarun near Guta Village) and Guta section-II (Northwest of Birket Qarun near Guta Village) is differentiated, from base to top, into two formations; Gehannam Formation (Middle–Late Eocene) and Birket Qarun Formation (Late Eocene), respectively. Two calcareous nannofossil zones were recognized from the Eocene succession at Gebel Naalun; Discoaster saipanensis (NP17) and Chiasmolithus oamaruensis (NP18) zones as well as one planktonic foraminiferal zone; Truncorotaloides ( Acaranina ) rohri (P14) zone. However, at Guta section-I, two nannofossil zones were defined; Discoaster saipanensis (NP17) and Chiasmolithus oamaruensis (NP18) zones; the preservation of planktonic foraminiferal assemblage is too poor to enable us to recognize marker species as a result of many diagenetic processes. At Guta section-II, two nannofossil zones; Chiasmolitus oamaruensis (NP18) and Isthmolithus recurvus (NP19) and two planktonic foraminiferal zones; T. pseudoampliapertura zone and G. semiinvoluta zone are recorded. Several authors found that the lowest occurrence of Chiasmolithus oamaruensis is a poor criterion for defining the base of NP18 Zone, which is confirmed here. The same criticism has been applied to the lowest occurrence of Isthmolithus recurvus which defines the NP18/NP19 zonal boundary. It is generally agreed that NP19 Zone falls in the Priabonian (Late Eocene). As a result of the occurrence of the nannofossil marker species; Isthmolithus recurvus only in side views below and above the first appearance of Chiasmolithus oamaruensis at both Naalun and Guta section-I, this species is not reliable to define the NP18/NP19 zonal boundary. At Guta section-II, the Middle/Upper Eocene boundary can be delineated by the first appearance of Globigerinatheka semiinvoluta above the first occurrence of Isthmolithus recurvus in both plane and side views. [ABSTRACT FROM AUTHOR]

Integrated litho- and bio-stratigraphic investigations were conducted on the Paleocene-Eocene successions (P-E) of El-Ballas area (Qena region, Egypt) to map the Dababiya Quarry Member (DQM). Three formations include Dakhla, Tarawan, and Esna were recorded in three sections (El-Ballas-1, El-Ballas-2, and El-Ballas-3). The age of the studied interval was estimated based on the calcareous nannofossils and the planktonic foraminifera. Six planktonic foraminifera and seven calcareous nannofossil zones/subzones were recorded covering the Paleocene-Eocene interval. The paleoenvironmental interpretations were established based on the calcareous nannofossils and benthic foraminifera. The deposition of the DQM was characterized by warm oligotrophic conditions in an outer neritic setting. In addition, the DQM which encompasses the Paleocene/Eocene boundary at El-Ballas-1 resembles the Global Stratotype Section and Point, despite its reduced in thickness. The absence of the lower part of the DQM (beds 1–3) and the presence of 5 cm of sandstone and pebbles beds at the El-Ballas-2 in addition to the sharp upper base of DQM at the El-Ballas-3 indicate subaerial erosion or deposition in a submarine channel. • The Dababiya Quarry Member (DQM) is traced in three sections in El-Ballas area. • The DQM at El-Ballas-1 section resembled the GSSP with reduce in the thickness. • Warm oligotrophic condition marks the deposition of the DQM in outer neritic setting. • Variation of the DQM may be due to the effect of syn-sedimentary tectonic. • A deposition in submarine channel may be interpreting this variation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Maastrichtian–Eocene rocks in Kharga and Dakhla Oases were divided into three formations. [•] Integrated eight planktonic and eight nannofossil biozones have been recognized. [•] Stage boundaries have been delineated based on fossils datum events. [•] Cooling around M/Da and warming around Da/Se boundaries were suggested. [•] A warm-water paleotemperatures at the P/E boundary is detected. [Copyright &y& Elsevier]

We focus on an active continental margin related to northwards subduction during the Eocene in which sedimentary melange (‘olistostromes’) forms a key component. Maastrichtian – Early Eocene deep-marine carbonates and volcanic rocks pass gradationally upwards into a thick succession (<800 m) of gravity deposits, exposed in several thrust sheets. The lowest levels are mainly siliciclastic turbidites and debris-flow deposits. Interbedded marls contain Middle Eocene planktonic/benthic foraminifera and calcareous nannofossils. Sandstones include abundant ophiolite-derived grains. The higher levels are chaotic debris-flow deposits that include exotic blocks of Late Palaeozoic – Mesozoic neritic limestone and dismembered ophiolite-related rocks. A thinner sequence (<200 m) in one area contains abundant redeposited Paleogene pelagic limestone and basalt. Chemical analysis of basaltic clasts shows that some are subduction influenced. Basaltic clasts from unconformably overlying alluvial conglomerates (Late Eocene – Oligocene) indicate derivation from a supra-subduction zone ophiolite, including boninites. Taking account of regional comparisons, the sedimentary melange is interpreted to have formed within a flexurally controlled foredeep, floored by continental crust. Gravity flows including large limestone blocks, multiple debris flows and turbidites were emplaced, followed by southwards thrust imbrication. The emplacement was possibly triggered by the final closure of an oceanic basin to the north (Alanya Ocean). Further convergence between the African and Eurasian plates was accommodated by northwards subduction beneath the Kyrenia active continental margin. Subduction zone rollback may have triggered collapse of the active continental margin. Non-marine to shallow-marine alluvial fans prograded southwards during Late Eocene – Oligocene time, marking the base of a renewed depositional cycle that lasted until latest Miocene time. [ABSTRACT FROM PUBLISHER]

The study of nannofossils, dinocysts, and foraminifera from Paleogene deposits of the Urma Plateau of Central Dagestan revealed the Paleocene-Eocene age of the Gray Formation, to apply zonations based on of all three groups of microplankton, and to correlate the regional dinocyst and planktonic foraminifer zonations to the standard nannofossil scale. Nannofossil zonation of O. Varol's (1989) is shown to be successfully applied for subdivision of Danian deposits. The large foraminifer assemblage found in the lower Eocene deposits is correlated to the NP12-NP13 zones of the nannofossil scale. [ABSTRACT FROM AUTHOR]

Paleogene turbidite deposits that outcrop at the SE Aegean (Karpathos Island, SE Greece) were investigated using sedimentological, biostratigraphical, and organic geochemical techniques. Results indicate that turbidite sedimentation in the area took place from the Early Eocene (NP12-14) to Late Eocene-Early Oligocene (NP20-21). Six different units were recognized in the turbidite succession based on sedimentological characteristics, outcropping in 2 major areas of the island (1 in the north and 1 in the south) and having a thickness of less than 1000 m. Deposition and spatial arrangement of sedimentary facies was affected by the already deformed carbonate substratum and changes in the prevailing sediment source between siliciclastic and carbonate sources. Tectonic activity was mainly responsible for the evolution of the turbidite system, but a eustatic sea level lowstand during the Early Eocene also affected sedimentation. The Late Eocene was characterized by the deposition of lenticular sand-rich fan sediments containing terrigenous organic material. High density (hyperpycnal) flows caused by direct river input of sediment largely contributed to the observed sand-rich fan sedimentation, which is closely related with tectonic activity. Organic geochemical analysis of organic rich samples from the Late Eocene sand-rich fan sediments reveals source rock potential for gaseous hydrocarbons of mature/postmature stage. The time span and the tectonic setting of deposition reveal similarities with turbidite sedimentation of the Pindos and/or Pelagonian Zones of southern Greece and also with Eocene turbidite deposits outcropping in the area of the Lycian Nappes (SW Turkey). Based on the latter, the present study cautiously highlights the need for correlation of the studied sediments with age-equivalent clastic deposits in SW Turkey (Yavus Thrust Sheet/Yavuz-Elmalı turbidites), closely related with the advance of the Lycian Nappes during the Eocene-Early Oligocene. [ABSTRACT FROM AUTHOR]

The early Eocene is marked by prominent short warming episodes that are globally documented. The present study provides a well-established micropaleontological record of the calcareous nannofossils, planktonic, and benthonic foraminifera in order to evaluate the impact of the environmental perturbations across the early Eocene generally and particularly throughout these short warming events. This study has been conducted on two expanded lower Eocene successions at the Dababiya and the El-Ballas sections, southern Egypt. The recorded benthonic foraminifera indicate a deposition in a middle-outer neritic setting for El-Ballas, while at the Dababiya section, the lower part is deposited in an inner-middle neritic setting that changed upward to middle-outer neritic due to sea-level oscillation. The detailed analyses of the identified calcareous nannofossils and foraminifera allow definition of four early Eocene hyperthermal events. These events are the Post-Paleocene Eocene Thermal Maximum (Post-PETM), Eocene Thermal Maximum-2 (ETM-2), H2, and Eocene Thermal Maximum-3 (ETM-3). These events are indicated by a remarkable shift of the calcareous planktonic warm water indicators. The benthonic foraminifera assemblages that were recorded throughout these events reflect partially dysoxic/suboxic marine conditions associated with increased eutrophication probably of mesotrophic marine conditions. The calcareous planktonic and benthonic foraminifera record indicates evidence of minor dissolution across these events. Unlike the PETM, these events had a lesser impact on the environmental marine condition. The integrated data of the present study show that the magnitude of these events was greater and more pronounced at the shallower site at the Dababiya than at the deeper El-Ballas section. • Micropaleontological record indicates four early Eocene hyperthermal events. • Mesotrophy associated with dysoxic/suboxic conditions characterize these events. • The impact of these events affect the shallower site more than the deeper one. [ABSTRACT FROM AUTHOR]

Calcareous nannofossil assemblages from middle to upper Eocene sediments of the western Tarim Basin indicate two important episodes of marine incursion into the basin. The first episode represents a period of shallowing upward in the Wulagen Formation, which is dated as Zone CNE13 (Lutetian) by the co-occurrence of Discoaster bifax, Chiasmolithus solitus , and common Reticulofenestra umbilicus. The presence of a diverse assemblage of discoasters in the basal Wulagen suggests deposition occurred in oligotrophic, warm water with a connection to the open ocean. Progressive shallowing over time led to the formation of a restricted basin in which only Coccolithus pelagicus could survive. The second major episode of marine incursion is preserved in the middle part of the Bashibulake Formation, which is dated as Zone CNE17 (Bartonian/Priabonian) based on the presence of common Cribrocentrum erbae. The interval between the two marine incursions was dominated by subaerial exposure and evaporation, resulting in the deposition of gypsum at the top of the Wulagen Formation. Although maximum regression at the end of the Lutetian is followed by sea-level rise at the beginning of the Bartonian globally, it is clear that local tectonics played a crucial role in regional marine incursions into the Tarim Basin during deposition of the Wulagen Formation. • Age of Wulagen and Bashibulake formations confirmed. • Upwards shallow environment observed in the Bashibulake section. • Three stages of nannofossil assemblages identified. • Nannofossil paleoecology confirmed and contrasted. [ABSTRACT FROM AUTHOR]

We present a biostratigraphic and biochronologic study of calcareous nannofossils of middle Eocene - early Oligocene age recovered during IODP Expedition 320, at Hole U1333C in the equatorial Pacific Ocean. The study succession encompasses nannofossil Zones NP16-NP21 (equivalent to CP13-CP16) and Chrons C20r-C12r (middle Eocene-early Oligocene). The distribution patterns of calcareous nannofossil taxa are studied by means of relative abundance and semiquantitative counts with the final aim to test the reliability of biohorizons used in the Paleogene standard biozonations (Martini 1971; Okada and Bukry 1980) and check alternative bioevents included in a more recent mid-latitudes biostratigraphic scheme (Fornaciari et al. 2010). Calibration ages are estimated based on the ranges of the biozones relative to a detailed magnetostratigraphy constructed for the site. Of particular biostratigraphic significance, our study shows that the Top of Sphenolithus furcatolithoides, the Base of common and continuous occurrence (Bc) of Dictyococcites bisectus and the total range of Sphenolithus obtusus can be used to better constrain the middle Eocene interval. The studied sediments cover the crucial time period that followed maximum Cenozoic warmth and led up to the initial major glaciation on Antarctica, including two important climatic events, the Middle Eocene Climatic Optimum (MECO), a transient episode of global warming during a long-term cooling trend, and the Oi-1 event. The peculiar regime in sedimentation observed in the equatorial Pacific, which roughly consists of alternating phases of Carbonate Accumulation Events (CAE) and crashes in carbonate content, are correlated with increases and decreases in calcareous nannofossil abundances. A more detailed comparison indicates that the MECO corresponds to an interval with very low carbonate in between CAE3 and CAE4. This event is correlative with the Top of S. furcatolithoides, the Bc of D. bisectus and a prominent increase in the relative abundance of heavy calcified nannofossils (e.g., discoasters). [ABSTRACT FROM AUTHOR]