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1
Al-Lhaebi, Safwan. "PALEOCLIMATIC INSIGHTS ON THE CENOMANIAN-TURONIAN OCEANIC ANOXIC EVENT (OAE2) FROM NORTHERN IRAQ BASED ON CALCAREOUS NANNOFOSSILS AND GEOCHEMICAL DATA." Iraqi Geological Journal 53, no. 2C (September 30, 2020): 68–86. http://dx.doi.org/10.46717/igj.53.2c.6rs-2020-09/06.
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Calcareous nannofossils, mineralogical and geochemical investigations are carried out on the Cenomanian-Turonian boundary of the Gulneri Formation in the Azmir, Dokan and Degala sections, northern Iraq. Regarding the calcareous nannofossil data CC11 and CC12 biozones were identified. A detailed investigation was carried out to identify calcareous nannofossils species. On the basis of their stratigraphic distribution, two biozones were proposed in this study; Quadrum gartneri Interval Biozone (CC11) part and Lucianrhabdus maleformis Interval Biozone (CC12) part. Correlation with other calcareous nannofossils biozones from regional schemes led to conclude that the age of the Gulneri Formation in the studied sections is the early Turonian. Mineralogical (X-ray diffraction XRD) and trace elements geochemistry (X-ray fluorescence XRF) data along with the dominance of calcareous nannofossil Watznauria that indicates warm and arid climatic condition prevailing in the Cenomanian-Turonian transition.
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Svobodová, Andrea, and Martin Kośák. "Calcareous nannofossils of the Jurassic/Cretaceous boundary strata in the Puerto Escano section (southern Spain) — biostratigraphy and palaeoecology." Geologica Carpathica 67, no. 3 (June 1, 2016): 223–38. http://dx.doi.org/10.1515/geoca-2016-0015.
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Abstract We obtained material from the Puerto Escano section (southern Spain) to study the Jurassic/Cretaceous (J/K) boundary interval. The same samples had already been processed for magnetostratigraphic studies and biostratigraphic zonation based on calpionellids and ammonites (Pruner et al. 2010), but not for calcareous nannofossils. The aim of this study was to process the samples using micropalaeontological analysis and to compare and calibrate results for calcareous nannofossils with existing magnetostratigraphic and other biostratigraphic data. The calcareous nannofossil assemblage was dominated by the genera Watznaueria, Cyclagelosphaera, Nannoconus, Conusphaera and Polycostella. Several nannofossil bioevents were recorded on the basis of the distribution of stratigraphically important taxa, including zonal and subzonal markers. Based on the lowest occurrences (LO) of M. chiastius, N. globulus minor, N. wintereri, N steinmanii minor, N. steinmannii steinmannii, N. kamptneri minor and N. kampteri kamptneri, two nannofossil subzones (NJT 15b, NJT 17a) and two nannofossil zones (NJT 16, NK-1) were recognized. The paper introduces new palaeoecological data based on geochemical analysis and macrofauna occurrences.
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Widiatama, Angga Jati, Lauti Dwita Santy, Rikza Nur Faqih An Nahar, Zulfiah, Winda Eka Mandiri Puteri, Adrianus Damanik, and Rubiyanto Kapid. "Calcareous Nanofossil of Post-Gondwana Sequence in Southern Banda Arc, Indonesia." Journal of Geoscience, Engineering, Environment, and Technology 6, no. 2 (June 8, 2021): 86–93. http://dx.doi.org/10.25299/jgeet.2021.6.2.6287.
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The presence of calcareous nannofossils in samples of the Post-Gondwana sequences (Kolbano and Viqueque sequence) gives guidance about the relative age of the study area located in the Outer Banda Arc, namely Timor, Rote, and Sawu Island. The study was carried out on six traverses, Timor Island traverse (Baun and Camplong), Rote Island traverse (Termanu and Central Rote), and Sawu Island traverses (West Sawu and East Sawu). There is 29 outcrop sample prepared using the smear slide method and observed using a polarizing microscope with 1000x magnification. The results of the study showed the presence of Cretaceous, Paleogene, and Neogen-Quarternary calcareous nannofossil. There are 82 species from 14 families identified in the post-Gondwana sequence. The results showed that the assemblage of calcareous nannofossil in Cretaceous characterized by the presence of Watznaueria fasciata, Watznaueria cynthae, Cyclagelosphaera brezae, Orastrum campanensis, and Micula concava. The assemblage of Paleogene calcareous nannofossil characterized by the presence of Coccolithus staurion, Chiasmolithus solitus, Discoaster minimus, Tawelus (?) magnicrassus, Chiasmolithus bidens, Prinsius africanus, Cyclicargolithus luminus, Spenolithus elongatus, Reticulofenestra umbilica, Cruciplacolithus vanheckae, and Helicospharea seminulum, and the assemblage of Neogene calcareous nannofossil characterized by the presence of Reticulofenestra pseudoumbilica, Discoaster quinqueramus, Helicosphaera princei, and Discoaster pansus. Quarternary calcareous nannofossil characterized by the presence of Ponthospaera indooceanica.
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Behdani, Ensieh, Fatemeh Hadani, Marziyeh Notghi Moghaddam, and Ahmadreza Khazaei. "Calcareous nannofossil biostratigraphy of Baghamshah Formation in Eastern Iran, Lut Block (Birg Section)." Revista Brasileira de Paleontologia 25, no. 1 (April 12, 2022): 51–60. http://dx.doi.org/10.4072/rbp.2022.1.04.
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Biostratigraphic studies of the Baghamshah Formation from the Birg section in the northwest of Birjand (Lut Block) are done here for the first time based on the calcareous nannofossils. In the studied section, 82 samples were taken, and smear slides were prepared. The examination of the collected samples resulted in the identification of 65 calcareous nannofossil and 11 didemnid ascidian spicules species belonging to 38 genera corresponding from CC1 to CC4b biozones with the age of early Berriasian to early Hauterivian, according to the Sissingh biozonation. The calcareous nannofossil assemblages are dominated by the following genera: Watznaueria, Nannoconus, Conusphaera, and Cyclagelosphaera. Keywords: Birjand, Baghamshah Formation, biozonation, Biostratigraphy, Early Berriasian, Early Hauterivian.
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Lokho, Kapesa, R. K. Saxena, D. S. N. Raju, and Ankit Kumar. "Middle Miocene calcareous nannofossils from the Upper Bhuban Formation of Mizoram, Indo-Burma Range." Micropaleontology 62, no. 5 (2017): 341–52. http://dx.doi.org/10.47894/mpal.62.5.01.
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The Indo-Burmamountain range represents an accretionary wedge which resulted from subduction of the Indian plate beneath the Eurasian plate. It is situated between the eastern Himalayan Namche Barwa syntaxis and the Sumatra–Andaman subduction zone.The rocks exposed in the Mizo Hills form a part of the Indo-Burma range. Although the geology of theMizo Hills has been studied for decades, fundamental aspects of age and paleoenvironment remain debatable. In this study, calcareous nannofossils have been used for refining the biostratigraphy and paleoenvironment of the Upper Bhuban Formation (UBF) of a part of Mizoram. A calcareous nannofossil assemblage comprising eleven species of eight genera have been recognized. Though the nannofossil yield is poor with a moderate to low preservation, their study is significant in determination of age and paleoenvironment. By integrating the calcareous nannofossil and known foraminiferal assemblage data, we constrain the studied succession to Calcareous Nannofossil Zone CNM7 of Backman et al. 2012 which is equivalent to early part of the middle Miocene. The relatively good abundance of Helicosphaera, presence of Discoasters and the published foraminiferal data indicate hemipelagic depositional setting for the UBF in Mizoram.
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Abdi, Asad, Emanuela Mattioli, and Beatriz Bádenas. "A New Calcareous Nannofossil Record from the Lower Jurassic of Kermanshah, Western Iran: Implications for Biostratigraphy and Evolutionary Reconstructions." Geosciences 12, no. 2 (January 27, 2022): 59. http://dx.doi.org/10.3390/geosciences12020059.
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Calcareous nannofossils are used here for the first time in order to establish a precise biostratigraphic framework for the Kermanshah Radiolarite Formation, an outcropping in Western Iran. The new data presented here challenge the previous tentative age interpretations (Pliensbachian to early Toarcian) based upon radiolarians. Calcareous nannofossil assemblages and events unequivocally indicated that the pelagic limestones and marls are late Sinemurian in age (NJT 3b nannofossil subzone), and that these are thrusted over shales and cherts dated as uppermost Sinemurian (NJT 3b-c nannofossil subzone) and lowermost Pliensbachian (NJT 4 nannofossil zone). This result leads not only to reconsideration of the age of the radiolarite formations, which are widespread in the Zagros orogenic system, but also a better understanding of the stratigraphic relationships between the various lithological units known in the area. Besides these new stratigraphic inferences, the calcareous nannofossil assemblages of the uppermost Sinemurian–lowermost Pliensbachian successions revealed the common presence of new morphologies of the Mitrolithus genus, never described before. These findings allow for the description of three new species, M. montgolfieri, M. pseudonannoconus, and M. tethysiensis, and reveal the existence of homeomorphy between the spine structure of conical Lower Jurassic coccoliths and the widespread Cretaceous nannoconids.
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Kasem, Atef M., Mahmoud Faris, Luigi Jovane, Taysir Abdelhamid Ads, Fabrizio Frontalini, and Amr S. Zaky. "Biostratigraphy and Paleoenvironmental Reconstruction at the Gebel Nezzazat (Central Sinai, Egypt): A Paleocene Record for the Southern Tethys." Geosciences 12, no. 2 (February 20, 2022): 96. http://dx.doi.org/10.3390/geosciences12020096.
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The variations in assemblages of calcareous nannofossils are tracked in the Dakhla and Tarawan Formations exposed at Gebel Nezzazat (central Sinai, Egypt). Five calcareous nannofossil biozones, namely NP2/3, NP4, NP5, NP6, and NP7/8 are identified. A distinct marker bed related to the Latest Danian Event (LDE) occurs within the Dakhla Fm. The earliest representative of fasciculiths, Lithoptychius schmitzii, first occurs just below the LDE distinct bed and is followed by the Los of Diantholitha alata, D. mariposa, L. varolii, L. felis, and L. collaris. The abundance of calcareous nannofossils drops within the LDE distinctive bed. The base of Selandian Stage is here approximated at the base of Zone NP5 in concurrence with a sudden drop in the abundance of calcareous nannofossils. No considerable lithological changes are noted across this transition. The absence of subsequent occurrences of L. ulii, L. janii, L. billii, and L. stegostus suggest inconsistent lowest occurrences (Los) of these taxa, insufficient sampling resolution, and/or a hiatus. The base of Thanetian is approximated with the base of Zone NP7/8 in the topmost of Dakhla Fm. No considerable changes in calcareous nannofossil assemblages are associated in correspondence to this transition except the LO of D. mohleri, lowest continuous occurrence (LctO) of Bomolithus megastypus, and the increase in abundance of Heliolithus kleinpellii as well as a sudden drop in abundance within Zone NP7/8. The variations in calcareous nannofossil assemblages at Gebel Nezzazat suggest prevailing warm-water and oligotrophic conditions during the Paleocene and particularly along the Danian Stage that are interrupted by minor fluctuations in paleoclimatic conditions. In particular, the Danian–Selandian transition marks a decrease in warm and oligotrophic conditions that persisted along the Selandian Stage. The Selandian–Thanetian transition shows an increase of warm and oligotrophic conditions prevailed in the Thanetian record. The sudden decrease in abundance of calcareous nannofossils in both the Selandian and Thanetian is likely resulted from an increase in dissolution of carbonates rather than variations in the paleotemperature and/or paleofertility.
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Nhung, Nguyen Thi Hong, Nguyen Thi Thuy, Nguyen Viet Hien, and Nguyen Huu Manh. "Quy trình gia công và phân tích hóa thạch Tảo vôi, áp dụng cho các trầm tích ven biển tỉnh Sóc Trăng." Tạp chí Khoa học và Công nghệ biển 19, no. 4 (March 27, 2020): 537–44. http://dx.doi.org/10.15625/1859-3097/19/4/12676.
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Calcareous nannofossils are very small microfossils composed of calcium carbonate. They are very good biostratigraphic markers within marine sediments by covering the Jurassic to present. The standard preparation of a sample for nannofossil analysis requires the collection of the largest quantity and the best fossils. Sample preparation accords to the following steps: i. Pounding sample; ii. Eliminating organic matter; iii. Washing sample; iv. Filter sample through the sieve; v. Eliminating clay; vi. Drying sample in an incubator; vii. Packing sample. Sample analysis accords to the following steps: i. Preparation of smear - slide; ii. Observation of morphology; iii. Determination; iv. Taking photo; v. Evaluating overall preservation and abundance of fossils; vi. Making analysis result sheet. This process is applied to study calcareous nannofossils within marine sediments in Soc Trang province. It makes much clear to understand middle Pleistocene-early Holocene ecosystem of calcareous nannofossil. In conclusion, this assemblage belongs to NN21 zone by the present of Emiliania huxleyi and Gephyrocapsa oceanica.
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Švábenická, Lilian, Xianghui Li, Lubomír Jansa, and Yushuai Wei. "Nannofossil biostratigraphy of the Lower Cretaceous Shadui Formation (Northern Tethyan Himalayas, Southern Tibet)." Geologica Carpathica 61, no. 5 (October 1, 2010): 383–91. http://dx.doi.org/10.2478/v10096-010-0023-2.
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Nannofossil biostratigraphy of the Lower Cretaceous Shadui Formation (Northern Tethyan Himalayas, Southern Tibet)Calcareous nannofossils of Aptian-Albian age were found in the basal part of the Shadui Formation, Northern Tethyan Himalayas, Southern Tibet. The predominantly shale strata are exposed near the northeastern tip of Yamdrock Tso Lake at the locality of Bangbu and they were previously considered to be of Late Cretaceous age. Occurrence of the nannofossil speciesPrediscosphaera columnataandCribrosphaerella ehrenbergiiindicates the Upper Aptian-Lower Albian Zone BC23. Nannofossil species of Late Albian, Cenomanian or younger Cretaceous age were not present in the studied part of the Shadui Formation. Nannofossils are badly preserved and hardly identifiable probably as a result of strong post mortem etching and dissolution during burial. The depositional setting of the Shadui Formation is interpreted as hemipelagic to pelagic. A horizon of dark shale in the lower part of the Shadui Formation may be stratigraphically correlated with ocean anoxic event OAE1b. The discovery of calcareous nannofossils at the Bangbu locality increases the stratigraphic precision in the correlation of Cretaceous strata between hemipelagic-pelagic facies and shelf depositional areas in the Tibetan Tethyan Himalayas.
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Oszczypko-Clowes, Marta. "Reworked nannofossils from the Lower Miocene deposits in the Magura Nappe (Outer Western Carpathians, Poland)." Geologica Carpathica 63, no. 5 (November 13, 2012): 407–24. http://dx.doi.org/10.2478/v10096-012-0032-4.
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Abstract Studies, based on calcareous nannofossils, proved that the level of reworked microfossils had so far been underestimated. More recently detailed quantitative studies of calcareous nannoplankton of the Magura, Malcov, Zawada and Kremna formations from the Magura Nappe in Poland documented a degree of nannofossil recycling among those formations. In the Late Eocene-Early Oligocene pelagic Leluchów Marl Member of the Malcov Formation the level of redeposition is very low (0-3.80 %), however, in the flysch deposits of the Malcov Formation reworking increased to 31.4 %. Late Oligocene through Early Miocene “molasse” type deposits of the Zawada and Kremna formations contain 43.7-69.0 % of reworked nannofossils. Quantitative analyses of the reworked assemblages confirmed the domination of Paleogene nannofossil species over Cretaceous ones. The most abundant, reworked assemblages belong to the Early- Middle Eocene age.
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Kędzierski, Mariusz. "Calcareous nannofossils from the Bathonian (Middle Jurassic) ore-bearing clays at Gnaszyn as palaeoenvironmental indicator, Kraków-Silesia Homocline, Poland." Acta Geologica Polonica 62, no. 3 (December 28, 2012): 421–37. http://dx.doi.org/10.2478/v10263-012-0024-9.
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ABSTRACT Kędzierski, M. 2012. Calcareous nannofossils from the Bathonian (Middle Jurassic) ore-bearing clays at Gnaszyn as palaeoenvironmental indicator, Kraków-Silesia Homocline, Poland. Acta Geologica Polonica, 62 (3), 421-437. Warszawa. Qualitative and quantitative studies on calcareous nannofossils have been carried out on the Middle-Upper Bathonian succession of Gnaszyn (Kraków-Silesia Homocline, Częstochowa region). The nannofossil assemblages are moderately or well-preserved and are dominated by Watznaueria britannica; also common are Staurolithiteslumina and Zeugrhabdotus erectus. The presence of delicate nannofossil forms together with dissolution- resistant taxa shows that the changes in composition of some of the nannoplankton assemblages reflect original variations. The frequency and diversity changes of the calcareous nannofossil assemblages have been interpreted in relation to fluctuations of sedimentation rate versus changes in trophic conditions within the photic zone. The highest diversity assemblages contain a high percentage of palaeofertility indicators, and are impoverished in the genus Watznaueria. This is interpreted as a reflection of a lower sedimentation rate and more stable, possibly mesotrophic conditions within the photic zone. On the other hand, W. britannica-dominated assemblages with low species diversity may represent more unstable environments with a high influx of terrestrial material related to a high sedimentation rate and a high nutrient influx, i.e. eutrophic conditions in the photic zone.
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Seefelt, Ellen L., Jean M. Self-Trail, and Arthur P. Schultz. "Comparison of three preservation techniques for slowing dissolution of calcareous nannofossils in organic-rich sediments." Micropaleontology 61, no. 3 (2015): 149–64. http://dx.doi.org/10.47894/mpal.61.3.01.
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In an attempt to halt or reduce dissolution of calcareous nannofossils in organic and/or pyrite-rich sediments, three different methods of short-term storage preservation were tested for efficacy: vacuum packing, argon gas replacement, and buffered water. Abundance counts of calcareous nannofossil assemblages over a six month period showed that none of the three preservation methods were consistently effective in reducing assemblage loss due to dissolution. In most cases, the control slides made at the drill site had more abundant calcareous nannofossil assemblages than those slides made from sediments stored via vacuum packing, argon gas replacement, or buffered water. Thin section and XRD analyses showed that in most cases, <1% pyrite was needed to drive the oxidation-reduction reaction that resulted in dissolution, even in carbonate-rich sediments.
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Raffi, Isabella, and Jan Backman. "The role of calcareous nannofossils in building age models for Cenozoic marine sediments: a review." Rendiconti Lincei. Scienze Fisiche e Naturali 33, no. 1 (February 17, 2022): 25–38. http://dx.doi.org/10.1007/s12210-022-01048-x.
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AbstractThis review paper has been thought to emphasize the role of Biostratigraphy in Geosciences and, specifically, of calcareous nannofossils as dating tool. This group of calcareous plankton occurs in Mesozoic and Cenozoic carbonate-bearing marine sediments in all depositional settings and is routinely used for stratigraphic purposes. The importance of calcareous nannofossils in relative dating of marine sediments is due to their abundance, taxonomic diversity, rapid evolution and wide distribution in marine environments. Nannofossil biostratigraphy improved over the last few decades due to the use of accurate methods for data gathering, including acquisition of semiquantitative census data on high-resolution samples. These microfossils contribute to obtain reliable biostratigraphic classification in various time-intervals in the last 66 m.y. and often provide the key to the interpretation of other stratigraphic records. Nannofossil biohorizons can be used as control points for constructing cyclostratigraphic composite sections, and for identification of magnetostratigraphic intervals, and have provided a basis for age models subsequently developed into orbitally tuned cyclostratigraphies or used for chronological revision of polarity timescale. Graphic abstract
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Granchovski, Georgi. "Quantitative analysis of calcareous nannofossil assemblages across the Campanian/Maastrichtian boundary interval at Kladorub (NW Bulgaria): preliminary results." Review of the Bulgarian Geological Society 82, no. 3 (December 2021): 109–11. http://dx.doi.org/10.52215/rev.bgs.2021.82.3.109.
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An investigation of the variations in calcareous nannofossil abundances across the Campanian/Maastrichtian boundary interval at Kladorub (NW Bulgaria) has been carried out. The section has an established detailed biostratigraphic framework, based on calcareous nannofossils, and also contains the Campanian–Maastrichtian Boundary Event. The analysis shows that the nannofloras are dominated by Prediscosphaera cretacea, followed by Watznaueria barnesiae, Micula staurophora, Arkhangelskiella spp. and Cribrosphaerella ehrenbergii.
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Preto, N., C. Agnini, M. Rigo, M. Sprovieri, and H. Westphal. "The calcareous nannofossil <i>Prinsiosphaera</i> achieved rock-forming abundances in the latest Triassic of western Tethys: consequences for the <i>δ</i><sup>13</sup>C of bulk carbonate." Biogeosciences 10, no. 9 (September 23, 2013): 6053–68. http://dx.doi.org/10.5194/bg-10-6053-2013.
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Abstract. The onset of pelagic biomineralization was a milestone in the history of the long-term inorganic carbon cycle: as soon as calcareous nannofossils became major limestone producers, the pH and supersaturation state of the global ocean were stabilized (the so-called mid-Mesozoic revolution). But although it is known that calcareous nannofossils were abundant already by the end of the Triassic, no estimates exist on their contribution to hemipelagic carbonate sedimentation. With this work, we estimate the volume proportion of Prinsiosphaera, the dominant late Triassic calcareous nannofossil, in hemipelagic and pelagic carbonates of western Tethys. The investigated Upper Triassic lime mudstones are composed essentially of microspar and tests of calcareous nannofossils, plus minor bioclasts. Prinsiosphaera had become a significant component of lime mudstones since the late Norian, and was contributing up to ca. 60% of the carbonate by the late Rhaetian in periplatform environments with hemipelagic sedimentation. The increasing proportion of Prinsiosphaera in upper Rhaetian hemipelagic lime mudstones is paralleled by an increase of the δ13C of bulk carbonate. We interpreted this isotopic trend as related to the diagenesis of microspar, which incorporated respired organic carbon with a low δ13C when it formed during shallow burial. As the proportion of nannofossil tests increased, the contribution of microspar with low δ13C diminished, determining the isotopic trend. We suggest that a similar diagenetic effect may be observed in many Mesozoic limestones with a significant, but not yet dominant, proportion of calcareous plankton.
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Preto, N., C. Agnini, M. Rigo, M. Sprovieri, and H. Westphal. "The calcareous nannofossil <i>Prinsiosphaera</i> achieved rock-forming abundances in the latest Triassic of western Tethys: consequences for the δ<sup>13</sup>C of bulk carbonate." Biogeosciences Discussions 10, no. 5 (May 14, 2013): 7989–8025. http://dx.doi.org/10.5194/bgd-10-7989-2013.
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Abstract. The onset of pelagic biomineralization marked a milestone in the history of the long term inorganic carbon cycle: as soon as calcareous nannofossils became major limestone producers, the pH and supersaturation state of the global ocean were stabilized (the so-called Mid Mesozoic Revolution). But although it is known that calcareous nannofossils were abundant already by the end of the Triassic, no estimates exist on their contribution to hemipelagic carbonate sedimentation. With this work, we estimate the volume proportion of Prinsiosphaera, the dominant Late Triassic calcareous nannofossil, in hemipelagic and pelagic carbonates of western Tethys. The investigated Upper Triassic lime mudstones are composed essentially of microspar and tests of calcareous nannofossils, plus minor bioclasts. Prinsiosphaera became a significant component of lime mudstones since the late Norian, and was contributing up to ca. 60% of the carbonate by the late Rhaetian in periplatform environments with hemipelagic sedimentation. The increasing proportion of Prinsiosphaera in upper Rhaetian hemipelagic lime mudstones is paralleled by a increase of the δ13C of bulk carbonate. We interpreted this isotopic trend as related to the diagenesis of microspar, which incorporated respired organic carbon with a low δ13C when it formed during shallow burial. As the proportion of nannofossil tests increased, the contribution of microspar with low δ13C diminished, determining the isotopic trend. We suggest that a similar diagenetic effect may be observed in many Mesozoic limestones with a significant, but not yet dominant, proportion of calcareous plankton.
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Ghiță, Daniela, and Vasile Șindilar. "UPPER BURDIGALIAN-MIDDLE SARMATIAN CALCAREOUS NANNOFOSSILS FROM TOTEA-VĂLENI AREA (GETIC DEPRESSION, ROMANIA)." Acta Palaeontologica Romaniae, no. 17 (2) (April 30, 2021): 75–82. http://dx.doi.org/10.35463/j.apr.2021.02.05.
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This work presents the calcareous nannofossils identified in samples recovered from 7 boreholes drilled on the western side of the Olt River, in the Totea, Colibasi, Radinesti and Valeni areas, within the central-southern part of the Getic Depression. These boreholes crossed upper Burdigalian–middle Sarmatian sediments. The identified assemblages are typical for the following calcareous nannofossil biozones: upper part of NN 3 – lower part of NN 4, corresponding to the late Burdigalian time interval, upper part of NN 4, corresponding to the early Badenian, NN 5, spanning the middle Badenian, and, respectively, NN 6-NN 8, covering the late Badenian – middle Sarmatian interval. The diversity and abundance of the identified nannofossil assemblages allow palaeoenvironmental reconstructions
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Abdelghany, Osman, and Mahmoud Faris. "Early Oligocene calcareous nannofossils, planktonic and larger foraminifera from the United Arab Emirates, Oman Mountains." Micropaleontology 63, no. 6 (2018): 445–56. http://dx.doi.org/10.47894/mpal.63.6.06.
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The Lower Oligocene Asmari Formation occupies the western and eastern flanks of the Jabal Hafit anticline and the western limb of the Jabal Malaqet-Mundassah anticline in the southeast of the United Arab Emirates near the Oman border. In this area the Asmari Formation unconformably overlies the Upper Eocene Dammam Formation. In this study an Early Oligocene characteristic assemblage of calcareous nannofossils, foraminifera, corals, calcareous algae, bryozoa, mollusks and echinoids is described from the carbonate rocks of the Asmari Formation. The Asmari stratigraphic succession is dated by analysis of the calcareous nannofossil assemblages and planktonic and larger foraminifera. The results of this study indicate that the succession falls within the Early Oligocene Zones NP24 and P20-P21. About seventeen nannofossil species are documented for the first time in this formation, along with three planktonic and larger foraminiferal species. The Oligocene rocks in the study area provide results consistent with a shallow-water inner shelf within the photic zone.
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Lakova, Iskra, Jacek Grabowski, Kristalina Stoykova, Silviya Petrova, Daniela Reháková, Katarzyna Sobień, and Petr Schnabl. "Direct correlation of Tithonian/Berriasian boundary calpionellid and calcareous nannofossil events in the frame of magnetostratigraphy: new results from the West Balkan Mts, Bulgaria, and review of existing data." Geologica Balcanica 46, no. 2 (November 2017): 47–56. http://dx.doi.org/10.52321/geolbalc.46.2.47.
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Magnetostratigraphy, calpionellid and calcareous nannofossil biostratigraphy of the upper Tithonian and lower Berriasian of section Barlya in the West Balkan Mts are herein presented. The studied interval comprises the magnetozones from M21r to M17r, with a large interval of partial remagnetization. It has been directly correlated with a continuous succession of the calpionellid Chitinoidella, Praetintinnopsella, Crassicollaria and Calpionella zones, and with the nannofossil zones from NJT 15b to NK-1. The accumulated evidence in the last twenty years on the magnetostratigraphy, calpionellid and calcareous nannofossil biostratigraphy and events across the J/K boundary in the European Tethys has provoked the authors to plot the main micropalaeontological events against magnetostratigraphic column in order to assess the extent of diachronism of these events. Data from Slovakia, Poland, Italy, Austria, Hungary, France, Spain and Bulgaria has shown specific behaviour of different calpionellid and nannofossil events with respect to the column of the magnetic polarity chrons, which have been considered as ‘isochronous’ or at least less diachronous than the microfossil events. Thus, some rather consistent events have appeared, such as the first occurrences (FOs) of calpionellids Calpionella grandalpina, Crassicollaria brevis, Calpionella minuta and Remaniella ferasini, and the FOs of calcareous nannofossils Nannoconus globulus minor, Hexalithus geometricus, Nannoconus wintereri, Nannoconus steinmannii minor and Nannoconus kamptneri minor. The J/K boundary, as widely accepted, has been traced in section Barlya at the base of the Calpionella alpina Subzone.Financial support from the Synthesys Program at the National History Museum, Stockholm, is gratefully acknowledged.
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Hunnig Bom, Marlone H., Rodrigo do Monte Guerra, Andrea Concheyro, and Gerson Fauth. "Methodologies for recovering calcareous nannofossils from bituminous claystone." Micropaleontology 61, no. 3 (2015): 165–70. http://dx.doi.org/10.47894/mpal.61.3.02.
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The usual methods applied to recover calcareous nannofossils from claystones are extremely simple, cost-effective and fast. Some samples, however, exhibit heterogeneous mixtures of biogenic materials, detrital particles and other aggregates that visually mask the coccoliths under the microscope. For instance, a high content of organic matter in associationwith calcareous nannofossil specimens was observed in outcrop samples of the Vaca Muerta Formation (Neuquén Basin, Argentina). To solve this problem, traditional preparation techniques are herein improved to aid better visualization of calcareous nannofossils. Sixteen tests were qualitatively and quantitatively evaluated, testing the efficiency of some chemicals and physicals methods such as the addition of a solvent (oxidizing agent) in the smear slide technique, as well as the use of ultrasound in the random decantation technique.
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Stoykova, Kristalina, and Marin Ivanov. "Calcareous nannoplankton response model of the global warming at the Paleocene-Eocene boundary in Riben section, Northern Bulgaria." Review of the Bulgarian Geological Society 83, no. 3 (December 2022): 157–60. http://dx.doi.org/10.52215/rev.bgs.2022.83.3.157.
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We present a model of calcareous nannoplankton response of the global warming at the PETM, based on studies of Bulgarian sections. New data acquired from forams’carbon and oxygen isotopes, as well as high-resolution quantitative study of calcareous nannofossils suggest 3 phases of the event: pre-PETM, core of PETM and recovery phase. During the core phase, a significant increase in warm-water nannofossil species was registered, as well as signs of acidification and higher salinity of the surface waters (dissolution of carbonate skeletons of nannofossils). In the recovery phase, the cold-water species from pre-event conditions gradually return, however g. Fasciculithus completely disappears.
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Xinrong, Cheng. "Calcareous Nannofossils in Surface Sediments of the Central and Northern Parts of the South China Sea." Journal of Micropalaeontology 11, no. 2 (December 1, 1992): 167–76. http://dx.doi.org/10.1144/jm.11.2.167.
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Abstract. Taxonomic composition and quantitative distribution of calcareous nannofossils in the nothern and central parts of the South China Sea were studied in 146 samples of surface sediments taken from estuary, continental shelf, continental slope and deep-water basin. This paper reports distribution patterns of nannofossils in the area, including nannofossil abundance, species, assemblages and specimen size. Abundance increases from shelf to slope, with a decrease from the lower part of the slope towards the abyssal plain. The assemblages are dominated by Emiliania huxleyi, Gephyrocapsa oceanica and Florisphaera profunda. Ecologically the effects of water temperature, and nutrient inputs can be detected in the distribution of nannofossils, while dilution by terrigenous materials and deep sea carbonate dissolution influence the sedimentological aspect of the samples. The composition of the South China Sea nannofossil assemblage enables it to be grouped with the central zone of the North Pacific in biogeographic zonations of nannoplankton.
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Bown, Paul R. "Late Triassic-Early Jurassic Calcareous Nannofossils of the Queen Charlotte Islands, British Columbia." Journal of Micropalaeontology 11, no. 2 (December 1, 1992): 177–88. http://dx.doi.org/10.1144/jm.11.2.177.
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Abstract. Sediments of the Kunga and Maude groups (Early Norian-Aalenian) from the Queen Charlotte Islands, British Columbia, have yielded the first records of early Mesozoic calcareous nannofossils in North America. These occurrences are the only record of Triassic nannofossils away from the recent discoveries in the Tethyan area (Austria, Indonesia, and the northwestern Australian margin). The nannofossil assemblages from the Queen Charlotte Islands are generally poor to moderately preserved, with species diversities typical for this time interval (2–10 species). The assemblages are comparable to those from northwest Europe, for the Lower Jurassic, and to those from Austria, Indonesia, and the Australian margin, for the Upper Triassic. They show compatible stratigraphical ranges, allowing the application of existing biostratigraphical zonations. Palaeobiogeographical interpretations are inconclusive and fail to positively confirm a low latitude (Tethyan) position for the Queen Charlotte Islands, as indicated by macrofossil data. However, Triassic nannofossil assemblages have yet to be described from high palaeolatitude locations. In addition, certain features of the Lower Jurassic assemblages may indicate Tethyan affinities but also distinguish these assemblages from those which have been previously documented. These features include the absence of Schizosphaerella punctulata, which occurs abundantly in the circum-Mediterranean region and was previously thought to be “cosmopolitan” in distribution; and the absence of Mitrolithus jansae which characterizes “Tethyan” assemblages in the circum-Mediterranean area. The Queen Charlotte Islands results are compared with new nannofossil data from Argentina, Timor and North America.
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Toffanin, Federica, Claudia Agnini, Domenico Rio, Gary Acton, and Thomas Westerhold. "Middle Eocene to early Oligocene calcareous nannofossil biostratigraphy at IODP Site U1333 (equatorial Pacific)." Micropaleontology 59, no. 1 (2013): 69–82. http://dx.doi.org/10.47894/mpal.59.1.04.
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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).
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Chira, Carmen Mariana, Carlo Aroldi, Mirela Violetta Popa, Sergiu-Nicolae Șerban, Traian-Ioachim Suciu, and Raluca Bindiu-Haitonic. "BIOSTRATIGRAPHY (CALCAREOUS NANNOFOSSILS AND MOLLUSCS) OF THE PANNONIAN DEPOSITS FROM TRANSYLVANIA, ROMANIA (GUŞTERIŢA QUARRY – SIBIU)." Acta Palaeontologica Romaniae, no. 17 (2) (April 17, 2021): 63–73. http://dx.doi.org/10.35463/j.apr.2021.02.04.
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Three sections from the upper Miocene (Pannonian) of the Guşteriţa quarry – Sibiu (the southern border of the Transylvanian Basin) were investigated in detail. The main part of the research was based on calcareous nannofossil analysis to which some aspects on molluscs and ostracods fauna, together with sedimentological remarks were added. The calcareous nannofossil assemblages from Guşteriţa quarry were compared with seven other previously analyzed sections from the western border of the Transylvanian Basin: Aiud area (Geoagiu, Gârbova, Gârboviţa, Lopadea exposures and Decea quarry) and Sibiu area (Vurpăr and Apoldu exposures). The Pannonian calcareous nannofossil assemblages are abundant at some levels and contain mostly species of the genera Isolithus and Noelaerhabdus.
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Palliani, Raffaella Bucefalo, and Emanuela Mattioli. "High resolution integrated microbiostratigraphy of the Lower Jurassic (late Pliensbachian–early Toarcian) of central Italy." Journal of Micropalaeontology 17, no. 2 (December 1, 1998): 153–72. http://dx.doi.org/10.1144/jm.17.2.153.
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Abstract. The integrated use of calcareous nannofossil and dinoflagellate cyst events in a study of the late Pliensbachian–early Toarcian interval in central Italy has yielded a high resolution biostratigraphy. The use of both the first and last occurrences of selected taxa belonging to the two phytoplankton groups allows the dating of the sediments with a very refined detail, even when lithologies are unfavourable to the preservation of one fossil group. The evolutionary history of calcareous nannofossils and dinoflagellate cysts during the early Jurassic and its links with global events are responsible for the high potential of this integrated biostratigraphy.
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Giraud, Fabienne, Bernard Courtinat, Jean-Pierre Garcia, François Baudin, François Guillocheau, Gilles Dromart, François Atrops, and Claude Collete. "Palynofacies and calcareous nannofossils in the Upper Kimmeridgian, southeastern Paris basin (France)." Bulletin de la Société Géologique de France 176, no. 5 (September 1, 2005): 457–66. http://dx.doi.org/10.2113/176.5.457.
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AbstractThe Upper Kimmeridgian Members “Calcaires blancs supérieurs” and the “Marnes à exogyres supérieures” of the southeastern Paris basin were investigated for their palynofacies and calcareous nannofossils. These members display alternating limestone-marl lithotypes and represent shallow marine palaeoenvironments. The lower carbonate member is interpreted as a proximal palaeoenvironment (palaeobathymetry = 5 to 10 m), where storm and swell deposits were prevalent and the salinity was occasionally weak. The relative richness of brown phytoclasts in this part is favoured by good preservation related to restricted conditions. These conditions would explain the dominance of the nannofossil Cyclagelosphaera margerelii in the nannofossil assemblages. The palynological data as those of the nannofossil assemblages show variations in the shift from carbonate member to marly member. The dominance of brown phytoclasts over black phytoclasts, the presence of amorphous organic matter (AOM), and the highest abundance and diversity observed within the nannofossil assemblages suggest that the maximum of distality occurred during this transition, at the basal part of the Marnes à Exogyres supérieures. The upper part of the section (marly member) characterized by storm deposits and storm-coquina beds is deeper (palaeobathymetry probably between 10 and 40 m depth) than the lower part. Oxidizing depositional conditions prevailed and explained the abundance of black particles found in this upper part, while proximate cysts and elevated non-placolith coccolith abundances indicate that relationships with the open sea were probably more significant compared to the lower part. Towards the top of the section, recurrences of restricted conditions are reflected by relatively elevated amounts of AOM and the abundance peak of the nannofossil Biscutum ellipticum. This study shows that micropalaeontological signals can be well recorded in vast lagunal domains. We speculate that salinity, nutrient supply, and oxygenation of the waters control microfossil associations. In shallow environments, these parameters are particularly fluctuating, especially when freshwater dilutes marine waters in surface, on the occasion of rainy periods or of intense arrival of continental waters.
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Crux, Jason A. "Early Jurassic calcareous nannofossil biostratigraphic events." Newsletters on Stratigraphy 17, no. 2 (July 5, 1987): 79–100. http://dx.doi.org/10.1127/nos/17/1987/79.
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Baldassini, Niccolo’, Roberto Mazzei, Luca Maria Foresi, Federica Riforgiato, and Gianfranco Salvatorini. "Calcareous plankton bio-chronostratigraphy of the Maltese Lower Globigerina Limestone member." Acta Geologica Polonica 63, no. 1 (March 1, 2013): 105–35. http://dx.doi.org/10.2478/agp-2013-0004.
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Abstract Baldassini, N., Mazzei, R., Foresi L.M., Riforgiato, F. and Salvatorini, G. 2012. Calcareous plankton bio-chronostratigraphy of the Maltese Lower Globigerina Limestone member. Acta Geologica Polonica, 63 (1), 105-135. Warszawa. The planktonic foraminifera and calcareous nannofossil biostratigraphy of the Maltese Lower Globigerina Limestone member has been investigated. The member was dated to early planktonic foraminiferal P22 Zone and nannofossil NP25 Zone (upper Chattian). A climate-stratigraphic approach, based on the quantitative analyses of calcareous nannofossils, was used additionally to achieve a more precise chronology. The species Coccolithus pelagicus (diameter £11 μm) and the genus Umbilicosphaera were selected for the recognition of cold and warm surface waters intervals respectively. The ratio of their percentages enabled the construction of a Climatic Factor (CLF) curve. The CLF values were consistent with a warm climatic phase, which is probably represented by the portion of the oxygen stable isotope curve of Miller et al. above the Oi2c event and below the beginning of the cooling trend that culminates in the Mi1 event. Considering these two climatic events and the upper boundary of the NP25 Zone, it can be inferred that the deposition of the Lower Globigerina Limestone member took place between 25.1 and 24.3 Ma.
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Ćorić, Stjepan. "Calcareous nannofossils from the middle/upper Miocene succession of Pécs-Danitzpuszta, southern Hungary: cosmopolitan Paratethys and endemic Lake Pannon assemblages." Földtani Közlöny 151, no. 3 (December 4, 2021): 253–65. http://dx.doi.org/10.23928/foldt.kozl.2021.151.3.253.
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Quantitative analyses on calcareous nannofossils were carried out on 109 middle/late Miocene (Sarmatian/ Pannonian) samples from the section at Pécs-Danitzpuszta sand pit (Hungary). The lower part of the section, which can be assigned to the Sarmatian, contains normal marine low-diversity assemblages dominated by Calcidiscus leptoporus, Reticulofenestra pseudoumbilicus, Sphenolithus moriformis and Syracosphaera spp. accompanied by didemnid ascidian spicules (Perforocalcinela fusiformis). The middle/late Miocene (Sarmatian/Pannonian) boundary is characterized by the last occurrences of normal marine calcareous nannofossils. The upper part of the section (Pannonian) can be subdivided into intervals characterized by monospecific endemic nannofossils Isolithus spp. and ascidians, respectively. A short interval with common endemic coccoliths belonging to the family Noelaerhabdaceae (Bekelithella echinata, Noelaerhabdus bozinovicae, N. jerkovici, Praenoelaerhabdus banatensis) in the upper part of the profile was also documented. The drastic change in nannofossil assemblages at the Sarmatian/Pannonian boundary is a result of paleoenvironmental stress caused by the isolation of the Central Paratethys from the Eastern Paratethys.
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Roy, Lopamudra, Amit K. Ghosh, Ajoy Kumar Bhaumik, Arindam Chakraborty, Sarajit Sensarma, and Stuti Saxena. "Diatom assemblages from the Tortonian of northeast Indian Ocean (NGHP- 01- 17A): correlation with significant radiolarian and calcareous nannofossil events." Micropaleontology 68, no. 1 (2022): 51–84. http://dx.doi.org/10.47894/mpal.68.1.03.
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The present study has been carried out from the NGHP sediment core (NGHP-01-17A) of northeast Indian Ocean on different siliceous microfossils represented by diatoms and radiolarians along with calcareous nannofossils. Samples from the bottommost subunit Ic of the sediment core (684.09 mbsf to 369.62 mbsf) have been analysed. This contribution is the first comprehensive account on the Tortonian diatom assemblages from the offshore of northeast Indian Ocean that has been integrated with the radiolarian zonations. For determining the relative age of the sequence more precisely the obtained dataset also have been correlated to the calcareous nannofossil zones and eventually an attempt has been made to establish an integrated biostratigraphy. Detailed taxonomic analysis of the diatoms reveals the presence of 118 diatom taxa belonging to 49 genera. Three diatom biozones have been determined using CONISS cluster analysis. Based on the index radiolarian taxa in the studied samples, the entire sequence is assignable to RN6, RN7 and RN8 zones. The samples also contain stratigraphic marker taxa of calcareous nannofossils that allow identifying NN9, NN10 and NN11 zones corresponding to CNM13 - CNM16 zones. The ages of the bottommost and topmost sample of the analysed section of the core have been estimated < 10.49 Ma and > 7.39 Ma respectively. To estimate the sedimentation rate an age-depth model has been proposed using diatom, radiolarian and calcareous nannofossil events. All the microfossil assemblages of the present study have been correlated with the known assemblages of late Miocene, specifically Tortonian from DSDP, ODP, IODP expeditions and onshore sediments of Indian Ocean as well as equatorial Pacific Ocean. Diversity analysis has been carried out to quantitatively estimate the diversity and dominance of the diatom taxa. Planktic/benthic ratio of the diatoms has been calculated to evaluate the water depth.
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Farouk, Sherif, and Mahmoud Faris. "Calcareous nannofossil and foraminiferal bio-events of the Danian-Selandian transition of the Quseir area, northwestern Red Sea margin, Egypt." Micropaleontology 59, no. 2-3 (2013): 201–22. http://dx.doi.org/10.47894/mpal.59.2.10.
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Integration between calcareous nannofossil and the planktonic foraminifera investigations of two exposed section (Gebel Duwi and Gebel Hamadat) from the Quseir area, northwestern Red Sea margin, Egypt allow to divided the calcareous nannofossil Zone NP4 into NTp6, NTp7A, NTp7B, NTp8A, NTp8B, and NTp8C subzones, which reflects continuous, well preserved, and very diverse calcareous microplankton bio-events across the Danian/Selandian boundary. The Danian/Selandian boundary is bracketed at the base of Subzone NTp8B within P3b Subzone below a level close to a sequences planktonic foraminiferal bioevents from older to younger: LO of Igorina albeari, Morozovella occulsa, M. aequa, M. acuta, M. velascoensis, and Subbotina velascoensis. Small specimens (<125ìm) of Globanomalina pseudomenardii first appear within the upper part of nannofossil NP4 Zone near the base of Selandian that differ from those previously documented. Comparison of the calcareous nannofossil and planktonic foraminiferal bio-events noted in the different paleolatitudes revealed variations in the stratigraphic range across the Danian /Selandian boundary. This variation in the timing of the first appearances of planktonic foraminifera is primarily due to taxonomically different concepts and/or climatic changes in different paleogeographic setting. Astrong drop in the relative sea-level during the late Danian associated with Neoeponides duwi benthic assemblage was identified resulting from eustatic sea level changes.
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Lupi, Claudia, Valeria Luciani, and Miriam Cobianchi. "Integrated calcareous nannofossil and planktonic foraminiferal bioevents of the last 1.07 Ma: a case study from the East New Zealand Pacific Ocean." Micropaleontology 54, no. 5 (2008): 463–76. http://dx.doi.org/10.47894/mpal.54.5.05.
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The core MD97-2114 (42°22.32’S; 171°20.42’W) on the northern slope of the submarine Chatham Rise (east of New Zealand, 1935m water depth), is a significant case-study for the improvement of the resolution of the mid-late Pleistocene integrated calcareous nannofossil and planktonic foraminiferal biostratigraphy. Quantitative data of calcareous nannofossils and planktonic foraminifera, well preserved and abundant throughout the core, are correlated with magnetostratigraphy and oxygen isotope stratigraphy and indicate that the studied core contains a sedimentary record of the past ca. 1.07 Ma. Several standard nannofossil events were documented and their correlation with Marine Isotope Stages (MIS) is consistent with previous calibrations. Moreover, some subsidiary events are here recorded thus improving the biostratigraphic resolution. The identification of one standard and a number of additional foraminiferal bioevents have been achieved by using climatically/ ecologically controlled entries/exits or variations in abundance. The integrated scheme obtained includes 17 bioevents, calibrated with magneto-isotope stratigraphy, and provides a biostratigraphic resolution of ca 63kyr. The bioevents of the two investigated groups of calcareous plankton appear closely spaced in two selected intervals in the lower part of the core, placed at the middle-lower part of the Brunhes Chron and at the top of the Jaramillo Subchron. The implications for the recognition of the chronostratigraphic lower-middle and middle-upper Pleistocene boundaries are discussed.
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Marini, Mattia, Luca Maria Foresi, Viviana Barbagallo, Michelangelo Bisconti, Agata Di Stefano, Giovanni Muttoni, and Ivan Martini. "Age and Depositional Environment of Whale-Bearing Sedimentary Succession from the Lower Pliocene of Tuscany (Italy): Insights from Palaeomagnetism, Calcareous Microfossils and Facies Analyses." Journal of Marine Science and Engineering 11, no. 2 (February 19, 2023): 455. http://dx.doi.org/10.3390/jmse11020455.
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A c. 31 m thick section straddling the fossil find of an Early Pliocene baleen whale (“Brunella”, hereafter), made in 2007 in the sedimentary fill of the Middle Ombrone Basin of Tuscany, is investigated for depositional age and environment combining palaeomagnetic, micropalaeontological (Foraminifera and calcareous nannofossils) and sedimentary facies analyses. Resting unconformably onto Late Miocene continental deposits, the Early Pliocene marine deposits include, from bottom to top, a coarse-grained wave-winnowing lag, the few metres-thick fossiliferous sandstone bedset from which Brunella was unearthed, and several metres of clays. The stratigraphic organisation of these deposits indicate deposition in a deepening upward inner shelf environment. Successful isolation of characteristic remanent magnetisation and calcareous nannofossil content indicate the investigated marine section was deposited during the interval of polarity Chron C3n.2n corresponding to the basal part of the Mediterranean nannofossil zone MNN13 (between Helicosphaera sellii Base common and the Amaurolithus primus Top) and allow estimating the depositional age of Brunella to c. 4.6 Ma. Sedimentary facies, benthic Foraminifera association and anisotropy of magnetic susceptibility characterising the deposits that embedded Brunella suggest deposition above the fair-weather base level.
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Kadar, Adi P., Thomas De Keyser, Nilotpaul Neog, and Khalaf A. Karam. "Calcareous nannofossil zonation and sequence stratigraphy of the Jurassic System, onshore Kuwait." GeoArabia 20, no. 4 (October 1, 2015): 125–80. http://dx.doi.org/10.2113/geoarabia2004125.
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ABSTRACT This paper presents the calcareous nannofossil zonation of the Middle and Upper Jurassic of onshore Kuwait and formalizes current stratigraphic nomenclature. It also interprets the positions of the Jurassic Arabian Plate maximum flooding surfaces (MFS J10 to J110 of Sharland et al., 2001) and sequence boundaries in Kuwait, and correlates them to those in central Saudi Arabia outcrops. This study integrates data from about 400 core samples from 11 wells representing a nearly complete Middle to Upper Jurassic stratigraphic succession. Forty-two nannofossil species were identified using optical microscope techniques. The assemblage contains Tethyan nannofossil markers, which allow application of the Jurassic Tethyan nannofossil biozones. Six zones and five subzones, ranging in age from Middle Aalenian to Kimmeridgian, are established using first and last occurrence events of diagnostic calcareous nannofossil species. A chronostratigraphy of the studied formations is presented, using the revised formal stratigraphic nomenclature. The Marrat Formation is barren of nannofossils. Based on previous studies it is dated as Late Sinemurian–Early Aalenian and contains Middle Toarcian MFS J10. The overlying Dhruma Formation is Middle or Late Aalenian (Zone NJT 8c) or older, to Late Bajocian (Subzone NJT 10a), and contains Lower Bajocian MFS J20. The overlying Sargelu Formation consists of the Late Bajocian (Subzone NJT 10b) Sargelu-Dhruma Transition, and mostly barren Sargelu Limestone in which we place Lower Bathonian MFS J30 near its base. The lower part of the overlying Najmah Formation consists of the Najmah Shale, which is subdivided into three subunits: (1) barren Najmah-Sargelu Transition, (2) Late Bathonian to Middle Callovian (lower Zone NJT 12) Lower Najmah Shale, and (3) Middle Callovian to Middle Oxfordian (upper Zone NJT 12 to NJT 13b) Upper Najmah Shale. Middle Callovian MFS J40 and Middle Oxfordian MFS J50 are positioned near the base and top of the Upper Najmah Shale. The upper part of the Najmah Formation is represented by the Late Oxfordian (Subzone NJT 13b) Najmah Limestone, and is overlain by the Kimmeridgian (Zone NJT 14) Jubaila Formation. Early Kimmeridgian MFS J60 and Late Kimmeridgian MFS J70 are positioned near the base and top of the Jubaila Formation. The positions of Late Jurassic MFS J80, J90 and J100 are not constrained by our biostratigraphic data and are positioned in the Gotnia Formation. The Upper Tithonian MFS J110 and the Jurassic/Cretaceous boundary are positioned in the Makhul Formation.
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Monechi, Simonetta, Eugenia Angori, and Katharina von Salis. "Calcareous nannofossil turnover around the Paleocene/Eocene transition at Alamedilla (southern Spain)." Bulletin de la Société Géologique de France 171, no. 4 (July 1, 2000): 477–89. http://dx.doi.org/10.2113/171.4.477.
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Abstract A high resolution biostratigraphic study of calcareous nannofossil assemblages has been performed on the Alamedilla section in southern Spain across the Paleocene/Eocene transition. The identification of numerous and well differentiated events together with a major calcareous nannofossil turnover suggest the Alamedilla section to represent one of the most expanded and continuous sections straddling the P/E boundary. Quantitative analyses have revealed a change in the species richness and fluctuations in abundance of important paleoecological species.
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Villa, Giuliana, Jackie A. Lees, and Paul R. Bown. "Calcareous nannofossil palaeoecology and palaeoceanographic reconstruction." Marine Micropaleontology 52, no. 1-4 (August 2004): 1–3. http://dx.doi.org/10.1016/j.marmicro.2004.05.001.
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Wimbledon, William A. P., Daniela Reháková, Andrzej Pszczółkowski, Cristina E. Casellato, Eva Halásová, Camille Frau, Luc G. Bulot, et al. "An account of the bio- and magnetostratigraphy of the Upper Tithonian—Lower Berriasian interval at Le Chouet, Drôme (SE France)." Geologica Carpathica 64, no. 6 (December 1, 2013): 437–60. http://dx.doi.org/10.2478/geoca-2013-0030.
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Abstract This paper discusses the results of a study of the Le Chouet section, its lithologies, facies, magnetic properties and fossil record (ammonites, calcareous nannofossils, calpionellids and calcareous dinoflagellates). Data obtained have been applied to give a precise biostratigraphy for this carbonate sequence as well as a paleoenvironmental reconstruction. Its relationship to magnetostratigraphy, based on a modern study of a French site, is important. Investigation of the micro- and macrofossils shows that the site comprises a sedimentary sequence in the Microcanthum to Jacobi ammonite Zones, and the Chitinoidella, Crassicollaria and Calpionella Zones. Several calpionellid and nannofossil bioevents have been recorded on the basis of the distribution of stratigraphically important planktonic organisms. The site allows us to calibrate the levels of various biomarkers and biozonal boundaries, and correlate them with the magnetozones M20n, M19r and M19n.
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Kaya Ozer, Caner, and Yakup Kilic. "The calcareous nannofossil record of the uppermost Maastrichtian-lower Palaeocene in the Kırıkkale Basin, in the Central Anatolian Region (Turkey)." Geologia Croatica 75, no. 3 (October 26, 2022): 365–80. http://dx.doi.org/10.4154/gc.2022.30.
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The Late Cretaceous–Early Paleogene (K–Pg) was a critical period of transition in geological time. This period encompassed short-term climatic fluctuations on a global scale, changes in ocean circulation, and sudden and large extinctions of marine and terrestrial organisms. In the study area, located in the mid to low latitudes, the Late Cretaceous and Early Paleogene were very tectonically active due to the positioning of the site close to the collision zone of two large continents. The impacts of the global K–Pg crisis can be observed in the study area. In this study, the calcareous nannofossil contents of late Maastrichtian–Danian sediments were studied, and the nannofossil biostratigraphy determined, from samples from the Samanlık and Dizilitaşlar Formations, deposited in the Kırıkkale Basin. From three stratigraphic sections, 26 nannofossil genera and 36 nannofossil species were identified from the Late Maastrichtian UC20aTP and UC20bTP biozones and the NP1 and NP2 biozones of the Danian. Additionally, it was determined that the K–Pg boundary was not continuous in the study area. In the Kırıkkale Basin, relatively low abundances of Micula decussate Vekshina, 1959 signals a diagenetic effect and stressful environment in the Late Maastrichtian, whereas the relatively low abundances of Thoracosphaera operculata Bramlette & Martini, 1964, Braarudosphaera bigelowii (Gran & Braarud, 1935) Deflandre, 1947 and Futyania petalosa (Ellis & Lohmann, 1973) Varol, 1989 in the Danian assemblages indicate unstable environmental conditions and major environmental perturbations that reflect tectonic activity in the region. No nannofossils were encountered in those samples taken from turbiditic levels, which contained high proportions of sand.
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Galeotti, Simone, Eugenia Angori, Rodolfo Coccioni, Gabriella Ferrari, Bruno Galbrun, Simonetta Monechi, Isabella Premoli Silva, Robert Speijer, and Bruno Turi. "Integrated stratigraphy across the Paleocene/Eocene boundary in the Contessa Road section, Gubbio (central Italy)." Bulletin de la Société Géologique de France 171, no. 3 (May 1, 2000): 355–65. http://dx.doi.org/10.2113/171.3.355.
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Abstract An integrated stratigraphic study of the upper Paleocene to lower Eocene Scaglia limestones of the Contessa Road section has allowed us to identify the classical markers of the Paleocene-Eocene transition. The section provides a good magnetostratigraphic record as well as a continuous calcareous nannofossil and foraminiferal biostratigraphy. A negative Carbon Isotopic Excursion (CIE) occurs in the lower part of Chron C24r. The calibration to calcareous plankton zonation indicates that the CIE occurs in the lowermost part of calcareous nannofossil Zone NP10 and the upper part of Zone CP8, that is in the planktonic foraminiferal Zone P5. In the same stratigraphic interval, a distinct turnover in the calcareous benthic foraminifera and a sharp change in the Deep Water Agglutinated Foraminiferal (DWAF) assemblages have been recognised. The record of DWAF, however, indicates a gradual initiation of such a change beginning some 150 k.y. before the CIE and BEE.
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Chaumeil Rodríguez, Micaela, Emanuela Mattioli, and Juan Pablo Pérez Panera. "Lower Jurassic calcareous nannofossil taxonomy revisited according to the Neuquén Basin (Argentina) record." Journal of Micropalaeontology 41, no. 1 (April 26, 2022): 75–105. http://dx.doi.org/10.5194/jm-41-75-2022.
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Abstract. Standard Early Jurassic biostratigraphic studies were performed in the boreal and Tethys realms (western Europe and northern Africa), and biozonations from these areas are the most accurate of the world. Comparatively, investigations in the Pacific realm are scarce, and, in Argentina, they are limited to contributions based on oil-industry subsurface and outcrop reports for the Los Molles Formation. A focused systematic analysis was not previously addressed in the area. The Neuquén Basin in west–central Argentina offers a unique opportunity to study the Early Jurassic calcareous nannofossil history in the south-eastern Pacific Ocean. Calcareous nannofossil assemblages from El Matuasto I section (Los Molles Formation) represent one of the earliest records for the Early Jurassic in the Neuquén Basin and one of the few for the eastern Pacific realm. A detailed systematic analysis allowed the recognition of major bioevents and a comparison with worldwide associations and biostratigraphic schemes. A thorough taxonomic discussion of the Early Jurassic nannofossil species of the Neuquén Basin is presented for the first time. Herein, the taxonomic features of coccoliths recorded in the Neuquén Basin are settled. The age of the calcareous nannofossil assemblages recorded in El Matuasto I is early–late Pliensbachian, covering the NJT4a to NJT4c subzones. Similarities between the Neuquén Basin and localities from the proto-Atlantic region suggest an effective connection between the Pacific and Tethyan basins during the Pliensbachian.
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Chaumeil Rodríguez, Micaela, Emanuela Mattioli, and Juan Pablo Pérez Panera. "Lower Jurassic calcareous nannofossil taxonomy revisited according to the Neuquén Basin (Argentina) record." Journal of Micropalaeontology 41, no. 1 (April 26, 2022): 75–105. http://dx.doi.org/10.5194/jm-41-75-2022.
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Abstract. Standard Early Jurassic biostratigraphic studies were performed in the boreal and Tethys realms (western Europe and northern Africa), and biozonations from these areas are the most accurate of the world. Comparatively, investigations in the Pacific realm are scarce, and, in Argentina, they are limited to contributions based on oil-industry subsurface and outcrop reports for the Los Molles Formation. A focused systematic analysis was not previously addressed in the area. The Neuquén Basin in west–central Argentina offers a unique opportunity to study the Early Jurassic calcareous nannofossil history in the south-eastern Pacific Ocean. Calcareous nannofossil assemblages from El Matuasto I section (Los Molles Formation) represent one of the earliest records for the Early Jurassic in the Neuquén Basin and one of the few for the eastern Pacific realm. A detailed systematic analysis allowed the recognition of major bioevents and a comparison with worldwide associations and biostratigraphic schemes. A thorough taxonomic discussion of the Early Jurassic nannofossil species of the Neuquén Basin is presented for the first time. Herein, the taxonomic features of coccoliths recorded in the Neuquén Basin are settled. The age of the calcareous nannofossil assemblages recorded in El Matuasto I is early–late Pliensbachian, covering the NJT4a to NJT4c subzones. Similarities between the Neuquén Basin and localities from the proto-Atlantic region suggest an effective connection between the Pacific and Tethyan basins during the Pliensbachian.
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Bown, P. R., and M. K. E. Cooper. "New Calcareous Nannofossil taxa from the Jurassic." Journal of Micropalaeontology 8, no. 1 (June 1, 1989): 91–96. http://dx.doi.org/10.1144/jm.8.1.91.
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Abstract. Four biostratigraphically significant new calcareous nannofossil species are described, Biscutum davyi, Lotharingius contractus, Lotharingius velatus and Retecapsa incompta, together with three new combinations.
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Buls, Toms, Kresten Anderskouv, Ida L. Fabricius, Patrick L. Friend, Charlotte E. L. Thompson, and Lars Stemmerik. "Production of Calcareous Nannofossil Ooze For Sedimentological Experiments." Journal of Sedimentary Research 85, no. 10 (October 1, 2015): 1228–37. http://dx.doi.org/10.2110/jsr.2015.80.
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Abstract: The notion of fine-grained pelagic carbonates as uniform, monotonous sequences of sediments settled in a quiescent environment has been challenged over the past few decades. Fine-grained pelagic carbonates can undergo substantial reworking after their first deposition, as illustrated by an abundance of sedimentary structures, such as drifts, moats, sediment waves, and channels documented in the Upper Cretaceous Chalk Group of NW Europe. Despite chalk being a major hydrocarbon reservoir rock of the North Sea, surprisingly little is known about the physical behavior of the pelagic carbonate sediment from which the chalk formed—calcareous nannofossil ooze. This poses a serious challenge to the understanding of the depositional system and the properties of facies distribution. Experimental tests, such as those performed in laboratory flumes, are necessary to provide empirical data on this subject. However, the use of modern calcareous nannofossil ooze as an analogue for Cretaceous ooze is associated with a number of disadvantages such as generally higher noncarbonate content and smaller coccolith size of modern oozes. Here, we document a preparation method for the production of calcareous nannofossil ooze for the purpose of physical experiments, based on disaggregation of Upper Cretaceous chalk through repeated freezing and thawing. We further document the textural characteristics of the ooze compared to the original chalk, based on quantitative backscatter scanning electron image analysis, laser diffraction granulometry, and smear slides. The Upper Cretaceous chalk chosen for disaggregation is highly friable due to delicate contact cement and has a low noncarbonate content (< 2 wt %), a high porosity, friability, and good nannofossil and microfossil preservation. These characteristics allowed an effective disaggregation of the chalk matrix into its basic nannofossil and microfossil components, which show good preservation through the disaggregation process. Textural analysis of chalk used for disaggregation and the produced ooze shows no significant differences between the two, thus validating the use of the freeze–thaw method for production of experimental ooze to model the basic depositional behavior of Cretaceous chalk.
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USTINOVA, Maria A. "Calcareous nannofossils from the uppermost Oxfordian and lowermost Kimmeridgian of Staffin Bay, Isle of Skye, northern Scotland." Volumina Jurassica XV, no. 1 (September 6, 2018): 63–72. http://dx.doi.org/10.5604/01.3001.0012.4595.
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Twenty six samples from the sections at Flodigarry and Digg at Staffin Bay, Isle of Skye, northern Scotland, spanning the stratigraphical interval from the uppermost Oxfordian to the lowermost Kimmeridgian were examined for their calcareous nannofossil content. The study revealed the presence of an assemblage typical of the nannofossil zone NJ15 of the northern European zonation.
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Stoykova, Kristalina, Vyara Idakieva, Marin Ivanov, and Daniela Reháková. "Calcareous nannofossil and ammonite integrated biostratigraphy across the Jurassic – Cretaceous boundary strata of the Kopanitsa composite section (West Srednogorie Unit, southwest Bulgaria)." Geologica Carpathica 69, no. 2 (April 1, 2018): 199–219. http://dx.doi.org/10.1515/geoca-2018-0012.
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AbstractCalcareous nannofossil, calpionellid and ammonite occurrences have been directly constrained across the Jurassic–Cretaceous boundary interval in the section of Kopanitsa, SW Bulgaria. This section reveals a continuous and expanded sedimentary record through the Upper Tithonian and Lower Berriasian, besides an excellent calcareous nannofossil and ammonite record. The topmost part of the NJT 16b and the base of NJT 17a nannofossil Subzones correspond to the ammonite Microcanthum / Transitorius Subzone. The major part of the NJT 17a Subzone equates to the Durangites spp. ammonite Zone, whereas the NJT 17b Subzone correlates to the lower part of the B. jacobi ammonite Zone. The NKT nannofossil Zone approximately corresponds to the upper part of the B. jacobi Zone and the NK-1 nannofossil Zone correlates at least to the lowest part of the T. occitanica Zone. The FOs ofNannoconus globulus minor, N. wintereri, N. kamptneri minor, N. steinmannii minor, N. kamptneri kamptneriandN. steinmannii steinmanniiare confirmed as reliable bio-horizons for correlations in the Mediterranean Tethys area. The first occurrence ofNannoconus wintereriis regarded as an almost concomitant event with the first occurrence ofBerriasella jacobi. We suggest it could be the most useful nannofossil proxy for approximating the base of the B. jacobi Zone. Rare, but relatively well preserved calpionellids and calcareous dinoflagellates together with microfacies analysis were used additionally for stratigraphical and palaeoenvironmental interpretations. The investigated sediments are typical for the steep slope of a steepened ramp, with accumulation of hemipelagic and gravitational deposits.
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Da Gama, Rui O. B. P., Paul R. Bown, and M. Cristina Cabral. "Calcareous nannofossil biostratigraphy of an outcrop section of Aptian sediments of west-central Portugal (Lusitanian Basin)." Journal of Micropalaeontology 28, no. 2 (November 1, 2009): 153–60. http://dx.doi.org/10.1144/jm.28.2.153.
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Abstract. The present work is the first study of nannofossils from the Ponta Alta and Praia da Lagoa members of the Cresmina Formation and provides a new approach to establishing the age of these sediments. Nannofossil biostratigraphy improves previous age assignments: the Ponta Alta Member is placed within the latest Early Aptian, the passage between the Ponta Alta to the Praia da Lagoa members is assigned an early Late Aptian age and the Praia da Lagoa member is assigned an age not younger than the early Late Aptian. The lower half of the Rodísio Formation is assigned an age not younger than the Albian.The integration of the nannofossil results with isotope stratigraphy provides support for the age attributions and calibration with more open-marine sections. The low abundance of nannoconids observed within the Ponta Alta Member coincides with the OAE 1a carbon isotope excursion and is possibly a manifestation of the ‘nannoconid crisis’ event. The subsequent increase in the abundance of nannoconids in the upper Ponta Alta Member coincides with the highest values of the δ13C isotope anomaly and may reflect a position above the ‘nannoconid crisis’ event in the early Late Aptian.
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Lima, Francisco Henrique de Oliveira, and Eduardo A. M. Koutsoukos. "Towards an integrated stratigraphy of the Gramame Formation (Maastrichtian), CIPASA quarry, Pernambuco-Paraíba Basin, NE Brazil." Anuário do Instituto de Geociências 29, no. 1 (January 1, 2006): 81–94. http://dx.doi.org/10.11137/2006_1_81-94.
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This study presents the integrated biostratigraphic (calcareous nannofossils and foraminifera), petrographic, geochemical and ichnological analyzes of the Gramame Formation (Maastrichtian) at the CIPASA Quarry section, in the Pernambuco-Paraíba Basin, northeastern Brazil. A high resolution calcareous nannofossil biostratigraphic study has been carried out, allowing to subdivide the studied section into three subzones of Maastrichtian age: CC25A, CC25B, and CC25C. Each biostratigraphic unit was further characterized by petrographic, geochemical and ichnological parameters. During the Maastrichtian the area was characterized by a dry and warm climate with low influx of terrigenous sediments. These conditions were fundamental to the widespread development of a carbonate ramp system in an outer neritic to bathyal setting, with deposition of alternating calcareous mudstones and argillaceous mudstones of the Gramame Formation. The Gramame Formation belongs to the transgressive system tract of second-order type, characteristic of a Passive Margin Sequence. The studied section consists of part of a third order deposicional cycle, which is arranged in a transgressive systems tract and a highstand systems tract. The lowstand systems tract was not characterized.
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Jolkicev, Nikola. "The Cretaceous/Paleogene (K/Pg) boundary in the Mezdra and Lyutidol syncline, Vratza District (West-Fore Balkan, Bulgaria)." Annales g?ologiques de la Peninsule balkanique, no. 67 (2006): 41–49. http://dx.doi.org/10.2298/gabp0667041j.
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This paper discusses the unjustified assignment (based on calcareous nannofossils) of a large portion of the Maastrichtian strata in the Mezdra and Lyutidol synclines (West Fore Balkan, Bulgaria) to the Paleogene. The co-occurrence of Paleocene nannofossils, reported by some authors, and Maastrichtian macrofossil taxa in these sections indicates diachronism in the appearance of macro- and nannofossils across the K/Pg boundary. Thus, this boundary cannot be precisely localized except if the Maastrichtian fossils are assumed to have been redeposited, but there is no evidence of resedimentation. Maastrichtian macrofossils are found not only within the range of the Paleogene nannofossil zones, but also in sections overlying them in the Kajl?ka Formation where new Maastrichtian macrofossil taxa, such as the echinoid Hemipneustes striatoradiatus (LESKE), appear and some inoceramid and cephalopod taxa range into this unit. These facts shed doubt over the applicability of nannofossils in determining the K/Pg boundary where this has already been firmly documented by macrofauna.
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Thomsen, Erik, Tine L. Rasmussen, and Annette Hastrup. "Calcareous nannofossil, ostracode and foraminifera biostratigraphy of Plio-Pleistocene deposits, Rhodes (Greece), with a correlation to the Vrica section (Italy)." Journal of Micropalaeontology 20, no. 2 (December 1, 2001): 143–54. http://dx.doi.org/10.1144/jm.20.2.143.
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Abstract. The Kalithea Bay section is situated on the southeastern coast of the island of Rhodes. The section comprises a sedimentary sequence ranging from brackish water gravel and nearshore sand to deep-water clay. The brackish water and nearshore deposits are assigned to the Kritika Formation, while the deep-water deposits are assigned to the Lindos Bay clay. Calcareous nannofossil biostratigraphy shows that the age of the marine sequence is Early Pleistocene. The brackish water sediments cannot be dated with any degree of certainty. The marine deposits are rich in ostracodes and foraminifera and several species have been recognized, which previously have been used as biostratigraphic markers in the Plio-Pleistocene deposits of Rhodes. Biostratigraphic correlation between the Kalithea Bay section and the Plio-Pleistocene boundary stratotype at Vrica, southern Italy, shows that the ostracodes and foraminifera events generally are diachronous relative to the calcareous nannofossil events. The only exception is the first occurrence of the benthic foraminifera Hyalinea balthica. As calcareous nannofossil events are thought to be virtually synchronous within the Mediterranean region, it is concluded that the diachroneity is due to a relative delay in the appearance of ostracodes and foraminifera at Kalithea, caused by differences in the palaeobathymetric settings between the two sites.