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Journal articles on the topic 'Nannofossils'

Author: Grafiati
Published: 4 June 2021
Last updated: 31 July 2024

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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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2

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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3

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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4

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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5

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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6

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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7

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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8

Senemari, Saeedeh, Fabrizio Frontalini, Arman Jafarian, and Marziyeh Notghi Moghaddam. "Calcareous nannofossil distribution in the upper Maastrichtian–lower Thanetian interval in the Izeh zone (Southwest Iran): biostratigraphic framework and stage boundary identification in the Eastern Tethys." Stratigraphy 21, no. 1 (2024): 1–16. http://dx.doi.org/10.29041/strat.21.1.01.

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The distribution of calcareous nannofossil species in the upper part ofGurpi Formation and lower part of Pabdeh Formation has been investigated in the Karta section (northwest of Izeh in Zagros Basin, Iran, Eastern Tethys) to provide a biostratigraphic framework from Maastrichtian to Thanetian interval. In this study, 31 genera and 52 species of calcareous nannofossils have been identified and based on the recognized bioevents and the resulting biozones, the studied interval spans from the top of the nannofossil zone UC19TP to the base of the NP7 zone and covers ~10.8Myr. In this study, the Gurpi Formation spans from the upper UC19TP to NP4 zones, while the lowest part of Pabdeh Formation covers NP5, NP6 and NP7 zones. The studied sequence is continuous and encompasses Cretaceous-Paleogene (K/Pg), Danian/Selandian and Selandian/Thanetian boundaries. The K/Pg boundary is characterized by nannofossil assemblage recognized worldwide, such as the occurrence of Biantholithus, Cruciplacolithus, Braarudosphaera, Praeprinsius, and calcareous blooms of Thoracosphaera spp. Adecrease in the abundance of nannofossils is observed in the upper part of the Maastrichtian to the lower part of the Danian; poor to moderate preservation of nannofossils and low diversified nannofossil assemblages cover most of the studied samples. Here, as a result of species poor to moderate preservation, we observe patterns of stepwise extinctions upward in the top of CC25 zone, that culminate with the last occurrence of eight species, just prior to the base of the UC20bTP. We interpret these patterns to be mainly the result of diagenetic alteration. Our dataset provides a record over a long-lasting interval of stepwise extinctions toward the K/Pg boundary that was likely caused by the diagenetically-enhanced Signor-Lipps effect.
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9

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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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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11

Al-Salmani, Seham, and Omar Al-Badrani. "Calcareous Nannofossils Biostratigraphy of Gulneri Formation in Sulaimaniya, Northestern Iraq." Iraqi Geological Journal 56, no. 1E (May 31, 2023): 273–81. http://dx.doi.org/10.46717/igj.56.1e.21ms-2023-5-31.

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Investigations on the calcareous nannofossils of the Gulneri Formation are being done in the northern Iraqi of Dokan and Pushen areas, Sulimani, Northern Iraq. In this work, one biozone was established based on the results of a detailed examination used to identify fifty species of calcareous nannofossils; Quadrum gartneri Biozone (CC11) and Lucianorhabdus maleformis Biozone (CC12) in Dokan section, although in this study, three biozones were suggested; Microrhabdulus decoratus Biozone (CC10); Quadrum gartneri Biozone (CC11) and Lucianorhabdus maleformis Biozone (CC12) in Pushen section. According to correlations with other calcareous nannofossil biozones from local region we sagestion the Cenomanian to Turonian for Pushen section and Turonian for Dokan section.
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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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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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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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16

Farida, M., A. Jaya, A. Ahmad, N. Salsabilah, and T. Sato. "Biostratigraphy of calcareous nannofossils and their distribution in Tonasa Formation, Mallasoro area Jeneponto, South Sulawesi." IOP Conference Series: Earth and Environmental Science 1272, no. 1 (December 1, 2023): 012016. http://dx.doi.org/10.1088/1755-1315/1272/1/012016.

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Abstract The age studies of the Tonasa Formation have been carried out from various relative ages, including using large foraminifera, small foraminifera, and nannofossil. Field and laboratory data were collected to observe the age and distribution of nannofossils in the study area. The results of observations from nannofossils in the Mallasoro section of the Jeneponto area are as many as 20 species were identified and examined in three markers of Sphenolithus pseudoradians (NP.22-NP.24), and the Last Occurrence of Dictyococcites scrippsae (NP.25-NN. 1). The age zonation of Tonasa Formation in this area is determined from the three datums is the Late Oligocene to Early Miocene (NP. 21 – NN.1) or correlated to CP.16c – CP.19a. The nannofossil abundances are distributed from bottom to top of the section is common to a few species, they are Cyclicargolithus floridanus, Sphenolithus moriformis, and Sphenolithus predistentus, respectively. Then followed by Zygrhabilithus bijugatus, Discoaster deflandrei, Dictyococcites scrippsae, and Coccolithus pelagicus in rare to present distributions and the others are present to single.
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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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18

Adnan Hakeem Mohammed Ameen, Mahfoudh Abdulla Al-Hadeedy, and Omar Ahmed Al-Badrani. "Calcareous nannofossils biostratigraphy and Paleoclimatology of the Bekhme Formation, Bekhere anticline, Dhouk area, Kurdistan region, Northern Iraq." Tikrit Journal of Pure Science 28, no. 2 (April 27, 2023): 73–82. http://dx.doi.org/10.25130/tjps.v28i2.1338.

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A Detailed Calcareous nannofossil study conducted on the Bekhme Formation that is cropped out at the Southern limb of the Bekhere anticline, eastern ward of the Dohuk city near Bajlur village, northern Iraq. The Bekhme Formation is composed of marly limestone, Organic limestone and fossiliferous limestone. The nannopaleontological classification of these calcareous nannofossils led us to determine thirty-four genus/species belonging to nine families. The nannobiostratigraphic analysis suggested three calcareous nannofossils biozones from oldest to youngest are: (1) Quadrum sissinghii Interval Zone; (2) Quadrum trifidum Interval Zone; (3) Tranolithus phacelosus Interval Zone. These biozones suggest that the studied section from the Bekhme Formation is the Middle to Late Campanian, and it refers to temperature fluctuations which considered as possible warm time period at subtropical areas.
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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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20

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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21

Harris, W. Burleigh, and Jean M. Self-Trail. "Late Cretaceous base level lowering in Campanian and Maastrichtian depositional sequences, Kure Beach, North Carolina." Stratigraphy 3, no. 3 (2006): 195–216. http://dx.doi.org/10.29041/strat.03.3.02.

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Campanian through Maastrichtian mixed carbonate and siliciclastic sediments in a 422 m continuous core drilled at Kure Beach, NC provide a record of sea-level change. Based on lithology and stratigraphy, depositional sequences are defined, and calcareous nannofossil zones and 87Sr/86Sr ratios and corresponding ages using the LOWESS Table determined. Campanian and Maastrichtian sediments comprise six depositional sequences. The oldest is Tar Heel 1 and contains calcareous nannofossils that indicate assignment to the upper part of Zones CC18a, CC18c and the lower part of CC19. 87Sr/86Sr ratios indicate ages from 83.2 to 80.0 Ma or lower Campanian. Tar Heel II contains calcareous nannofossils that indicate assignment to the upper part of Zone CC19 and CC20. 87Sr/86Sr ratios indicate ages from 78.0 to 76.3 Ma or middle Campanian. Donoho Creek I and II are thin and contain calcareous nannofossils referable to upper Zone CC21 and Zone CC22, and to CC23, respectively. The top of Donoho Creek II marks the Campanian-Maastrichtian boundary. Donoho Creek I 87Sr/86Sr ratios cluster into two groups, and provide ages from 78.0 to 76.2 Ma and 73.7 to 72.3 Ma, respectively. 87Sr/86Sr ratios in Donoho Creek II indicate ages from 71.4 to 69.6 Ma. Two Maastrichtian sequences are present; the lowermost Peedee I contains calcareous nannofossils that place it in Zones CC25a and CC25b. 87Sr/86Sr r ratios indicate an age from 69.3 to 66.9 Ma or late Maastrichtian. Peedee II is assigned to calcareous nannofossil Zone CC26a. 87Sr/86Sr ratios indicate ages from 66.4 to 65.2 Ma or late Maastrichtian. The four Campanian sequences correlate to three depositional sequences in New Jersey; the sequence boundary between upper Campanian Donoho Creek I and Donoho Creek II is not recognized in New Jersey. This boundary is interpreted to result from Gulf Stream impingement and subsequent erosion on the outer shelf. The two Maastrichtian sequences recognized in the Kure Beach core correlate to the two identified Maastrichtian sequences in New Jersey. These data support base-level lowering of sea-level during the Campanian-Maastrichtian, and suggest that the western margin of the North Atlantic may contain one of the best Late Cretaceous records of sea-level change.
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22

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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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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24

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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Tangunan, Deborah N., Alyssa M. Peleo-Alampay, Jamila B. Abuda, Lara Angeli T. Mambuay, Camille Regina A. Ramos, Allan Gil S. Fernando, Carla B. Dimalanta, Decibel V. Faustino-Eslava, Chelo S. Pascua, and Edmundo P. Vargas Vargas. "Post-Collision Deposition of Balanga Formation in northwest Mindoro, Philippines: Calcareous Nannofossil Evidence." Stratigraphy 11, no. 3-4 (2014): 235–43. http://dx.doi.org/10.29041/strat.11.3.02.

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This study investigates the calcareous nannofossil assemblage and composition of 62 field samples collected from a calcareous sedimentary sequence exposed in Mamburao, Occidental Mindoro, Philippines. The sequence consisting of foraminifera-rich, alternating beds of mudstones and fine- to medium-grained sandstones was subjected to stratigraphic logging and detailed calcareous nannofossil analysis. The nannofossils were used to interpret the biostratigraphic assignment of the sequence relative to the identified formations in the study area. Index calcareous nannofossil species reveal a Late Pliocene to Early Pleistocene age (~1.67 to 4.13 Ma) of the sequence, which suggests it was formed from continuous sedimentation after the Miocene collision of the Palawan-Mindoro Block with the Philippine Mobile Belt. Based on its lithologic description and age, the sequence represents the northwest extension of the Balanga Formation, a sedimentary unit reported to be extensively distributed in southeast Mindoro.
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26

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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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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28

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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Preiss-Daimler, Inga, Karl-Heinz Baumann, and Rüdiger Henrich. "Carbonate budget mass estimates for Neogene discoasters from the Equatorial Atlantic (Ceara Rise: ODP Site 927)." Journal of Micropalaeontology 31, no. 2 (July 1, 2012): 169–78. http://dx.doi.org/10.1144/0262-821x11-014.

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Abstract. Mass estimates for Late Miocene and Pliocene (8.6–3.25 Ma) Discoaster species and Sphenolithus are determined using samples of the equatorial Atlantic (Ceara Rise: ODP Site 927). Based on morphometric measurements, 3D computer models were created for 11 Discoaster species and their volumes calculated. From these, shape factors (ks) were derived to allow calculation of mass for different-sized discoasters and Sphenolithus abies. The mass estimates were then used to calculate the contribution of nannofossils to the total nannofossil carbonate. The discoaster contribution ranges from 10% to 40%, with a decreasing trend through the investigated interval. However, our estimates of total nannofossil carbonate from size-corrected abundance data are consistently 30–50% lower than estimates from grain-size measurement; this suggests that data based on mass estimates need to be interpreted with caution.
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30

Forniaciari, Eliana, Claudia Agnini, Rita Catanzariti, Domenico Rio, Eleonora M. Bolla, and Elisabetta Valvasoni. "Mid-Latitude calcareous nannofossil biostratigraphy and biochronology across the middle to late Eocene transition." Stratigraphy 7, no. 4 (2010): 229–64. http://dx.doi.org/10.29041/strat.07.4.01.

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Calcareous nannofossil biostratigraphic studies are presented from 11 sedimentary sections, nine located in the Mediterranean area and one each from the middle latitude North and South Atlantic, respectively. The distribution patterns of middle to late Eocene calcareous nannofossils are studied by means of quantitative and semiquantitative methods. Our main goal was to test the biostratigraphic reproducibility of bioevents used in two classical standard biozonations, and to introduce new biostratigraphically useful biohorizons, resulting in a series of new middle latitude biostratigraphic events. The new zonal scheme substantially improves the available biochronologic resolution, doubling the current partioning based on the classical standard zonations. This study extends the terminal Eocene and Oligocene calcareous nannofossil zonal scheme proposed for the Mediterranean area (Catanzariti et al. 1997), into the middle Eocene. New age estimates are provided, which highlight the need to revise the present middle-late Eocene calcareous nannofossil biochronology. Two new species are described: Cribrocentrum erbae sp. nov. and Cribrocentrum isabellae sp. nov.
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31

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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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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33

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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34

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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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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36

Omar A. Al-Badrani, Mahfoud A. Al-Hadeedy, and Ibrahim Y. Al-Shareefi. "Calcareous Nannofossils from the Shiranish Formation at Bekhaer anticline, Dhouk area, Northern Iraq." Tikrit Journal of Pure Science 27, no. 3 (November 30, 2022): 19–30. http://dx.doi.org/10.25130/tjps.v27i3.54.

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Calcareous nannofossils are examined up on the Shiranish Formation from the Bekhaer anticline in Northern Iraq. The study area includes about 55 meters to find calcareous nannofossils assemblages, from which (36) species have identified. Three biozones are postulated based on the above studied assemblages, in order of biozones: Tranolithus phacelosus biozone; Reinhardites levis biozone; Arkhangelskiella cymbiformis biozone. From a regional perspective, these biozones were connected with other calcareous nannofossils biozones, leading to the conclusion that the section is Late Campanian-Maastrichtian in age.
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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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38

Al-Hadeedy, Mahfoudh, Omar Al-Badrani, and Faris Hassan. "Nannobiostratigraphy of The Mushorah Formation in (AZ.29) well, Ain Zalah oil field, Northwestern Iraq." Journal of Zankoy Sulaimani - Part A 25, no. 1 (June 20, 2023): 12. http://dx.doi.org/10.17656/jzs.10908.

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A Detailed calcareous nannofossils study for the Mushorah Formation from subsurface section at Az. (29) well, Ain Zalah oil field, Northwestern Iraq. This is the first documentation of calcareous nannofossils in the Mushorah Formation, the Paleontological classification of this flora led to determine forty species. The nannobiostratigraphic analysis suggested three calcareous nannofossils biozones these are: (1) Calculites obscurus Interval Biozone; (2) Broinsonia parca Interval Biozone;(3) Misceomarginatus pleniporus Interval Biozone. These biozones concluded that the age of studied section of the Mushorah Formation is Early to Middle Campanian.
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39

Burnett, Jackie, and Alan Lord. "Nannofossils and their applications. Proceedings of the International Nannofossil Association Conference, London 1987." Cretaceous Research 10, no. 4 (December 1989): 359–61. http://dx.doi.org/10.1016/0195-6671(89)90011-6.

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40

Švábenická, Lilian. "Nannofossil record across the Cenomanian-Coniacian interval in the Bohemian Cretaceous Basin and Tethyan foreland basins (Outer Western Carpathians), Czech Republic." Geologica Carpathica 63, no. 3 (June 1, 2012): 201–17. http://dx.doi.org/10.2478/v10096-012-0018-2.

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Nannofossil record across the Cenomanian-Coniacian interval in the Bohemian Cretaceous Basin and Tethyan foreland basins (Outer Western Carpathians), Czech Republic Nannofossil biostratigraphy and mutual correlation was worked out for the Cenomanian-Coniacian deposits of the Bohemian Cretaceous Basin (BCB) and Outer Western Carpathians (OWC) in the territory of the Czech Republic. Similar assemblages of the BCB and from sediments deposited on the SE slopes of West European Platform, Waschbergždánice-Subsilesian Unit, OWC support the hypothesis that the two areas were connected by a sea way (nowadays the Blansko trough). The nannoflora of the Silesian Unit, OWC show more afinity to high latitudes as is documented by the presence of Marthasterites furcatus in the Lower Turonian, UC6b and UC7 Zones. Turonian and Coniacian deep-water flysch sediments of the Silesian Unit and Magura Group of Nappes provide nannofossils on rare occassions. Strongly atched nannofossils dominated by W. barnesiae from Cenomanian black shales of the BCB are comparable to those of the Silesian Unit and reflect a similar shallow nearshore sea. In the BCB, uppermost Cenomanian is marked by the last occurrence (LO) of Axopodorhabdus albianus and first occurrence (FO) of Quadrum intermedium (6 and 7 elements) and lowermost Turonian by a sudden quantitative rise in nannoflora and by the FO Eprolithus octopetalus. First Eiffellithus eximius and thus the base of the UC8 Zone was recorded in the upper part of ammonite Zone Collignoniceras woollgari in the lower Middle Turonian. Lithastrinus grillii is the stratigraphically youngest nannofossil species in this region and indicates the uppermost Coniacian. In the OWC, the Albian-Cenomanian boundary was recorded in the Silesian Unit and is marked by the LO Crucicribrum anglicum and FO Prediscosphaera cretacea and Corollithion kennedyi in the uppermost Albian. The Turonian-Coniacian boundary found both in the BCB and Waschberg-Ždánice-Subsilesian Unit, OWC is indicated by the FO Broinsonia parca expansa and by the base of the interval with common Marthasterites furcatus. In both areas, events were found closely below the FO inoceramid species Cremnoceramus waltersdorfensis. The Coniacian-Santonian boundary interval (Waschberg-Ždánice-Subsilesian and Foremagura Units, OWC) is indicated by Lithastrinus grillii occasionally accompanied by Lucianorhabdus ex gr. cayeuxii, Hexalithus sp. and Arkhangelskiella specillata.
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41

Schaaf, André. "Nannofossils and their applications." Geobios 22, no. 6 (January 1989): 855. http://dx.doi.org/10.1016/s0016-6995(89)80079-8.

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42

Gartner, Stefan. "Nannofossils and their applications." Palaeogeography, Palaeoclimatology, Palaeoecology 91, no. 1-2 (January 1992): 184–85. http://dx.doi.org/10.1016/0031-0182(92)90042-4.

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43

Hay, William W. "Nannofossils and their applications." Marine Geology 106, no. 1-2 (April 1992): 166–67. http://dx.doi.org/10.1016/0025-3227(92)90062-m.

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44

Hine, N. "Nannofossils and their applications." Marine and Petroleum Geology 10, no. 6 (December 1993): 634–35. http://dx.doi.org/10.1016/0264-8172(93)90069-5.

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45

Cepek, P. "Nannofossils and their applications." Earth-Science Reviews 31, no. 3-4 (October 1991): 295–97. http://dx.doi.org/10.1016/0012-8252(91)90036-f.

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46

Young, J. R. "Computer illustration of nannofossils." Journal of Nannoplankton Research 9, no. 3 (1987): 116–19. http://dx.doi.org/10.58998/nina2285.

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47

Lemos, João Paulo da Silva, and Geize Carolinne Correia Andrade Oliveira. "Nanofósseis calcários do Mioceno da Bacia do Baixo Tejo, Portugal." Revista Brasileira de Paleontologia 24, no. 1 (January 30, 2021): 47–61. http://dx.doi.org/10.4072/rbp.2021.1.04.

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Calcareous nannofossils of the Lower Tejo Basin Miocene, Portugal. This study presents the taxonomy, biostratigraphy, and paleoecology of calcareous nannofossils from an outcrop on the border of Foz da Fonte beach, geologically setting in the Neogene of the Lower Tejo Basin, Portugal. The taxonomic description allowed us to identify 19 calcareous nannofossils species belonging to ten genera (Helicosphaera, Pontosphaera, Reticulofenestra, Cyclicargolithus, Coccolithus, Discoaster, Sphenolithus, Umbilicosphaera, Calcidiscus, and Thoracosphaera). Based on the stratigraphic range of Discoaster druggii, Reticulofenestra lockeri, and Helicosphaera ampliaperta the section was defined in the NN2 and CN1 biozones, within the Burdigalian (lower Miocene). Quantitative analysis showed a significant variation in species diversity as a function of depth, as well as a relationship between species richness and the calcium carbonate content present in these rocks. According to these data, mainly due to the abundance of Reticulofenestra spp., Coccolithus spp. and Helicosphaera spp., it is possible to infer that this was a nutrient-rich nearshore marine environment (eutrophic) influenced by warm water conditions. Keywords: calcareous nannofossils, taxonomy, biostratigraphy, paleoecology, Neogene, Lower Tejo Basin.
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48

Ratumanan, R. C. F., V. Isnaniawardhani, and B. Muljana. "Nannofossil Biostratigraphy of Elat Formation, Kei Besar Island, Southeast Maluku." IOP Conference Series: Earth and Environmental Science 1148, no. 1 (March 1, 2023): 012027. http://dx.doi.org/10.1088/1755-1315/1148/1/012027.

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Abstract The first detailed mapping and recording of nannofossils was carried out on Kei Besar Island, Southeast Maluku. This area is mostly composed of the Elat Formation, which is mainly composed by intercalated calcarenite and calcareous claystone. Total 48 samples were taken on three measured sections (Hollat, Ngurdu and Mata Hollat). Samples were prepared using smear slide method, then observed under a polarized microscope at 1000 x magnification. Total 48 species of nannofossils were identified. Several index species were selected to define biostratigraphic zones based on their first and last occurrence. Three zones of nannofossils are identified, starting with the oldest those are: Reticulofenestra umbilica zone (NP16; 43.06 to 38.7 million years ago), Helicosphaera compacta zone (NP17; 38.7 to 37.9 Mya) and Helicosphaera eupratis zone (NP18-NP19; 37.9-36.8 Mya). It can be concluded that Elat Formation is deposited in Middle to Late Eocene (43.06 to 35.4 Mya). The Middle-Late Eocene boundary can be clearly defined based on nannofossils assemblages in the section of the Kei Besar Island.
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49

Minoletti, Fabrice, Silvia Gardin, Elisabeth Nicot, Maurice Renard, and Silvia Spezzaferri. "Mise au point d'un protocole experimental de separation granulometrique d'assemblages de nannofossiles calcaires; applications paleoecologiques et geochimiques." Bulletin de la Société Géologique de France 172, no. 4 (July 1, 2001): 437–46. http://dx.doi.org/10.2113/172.4.437.

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Abstract Calcareous nannofossils play an important role in biostratigraphy and paleoecology, though their study is often complicated by their reduced size. The methodology presented herein allows to separate the nannofossil assemblage into granulometrically and taxonomically homogeneous fractions. This method permits :a) the concentration of rare taxa in order to simplify their morphometric study; b) the geochemical analysis (stable isotopes and trace elements) of these fractions. The latter is helpful in many cases, especially when the analysis of major or minor taxa constituent of the assemblage is greatly complicated by the reduced particles dimensions. In this way, it will be possible to bring light to the ecological parameters of these taxa, as calcification temperature and other ecological requirements (salinity, nutrient concentrations).
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50

Gradstein, Felix M., Zehui Huang, Inger L. Kristiansen, and James G. Ogg. "Optimum microfossil sequences and cyclic sediment patterns in Early Cretaceous pelagic strata." Canadian Journal of Earth Sciences 30, no. 2 (February 1, 1993): 391–411. http://dx.doi.org/10.1139/e93-029.

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Three sequencing methods were used to calculate the most likely biozonation and the periodicity of sedimentary cycles in Lower Cretaceous pelagic strata of the Atlantic and Indian oceans.A database was built of 378 first and last stratigraphic occurrences of calcareous nannofossils, dinocysts, foraminifers, and geomagnetic reversals in highest Jurassic through Lower Cretaceous deep marine strata at 10 Atlantic Ocean and 3 Indian Ocean drilling sites. There are 135 different events in total, about one third of which are unique to either ocean. Using the complete data set, the quantitative stratigraphy methods STRATCOR and RASC calculated closely comparable optimum sequences of average first- and last-occurrence positions. The preferred zonal solution, based on the STRATCOR method, includes 56 events, each of which occurs at three or more sites. The events comprise 6 geomagnetic reversals, 25 nannofossils, 5 planktonic foraminifera, 8 benthic foraminifera, and 12 dinocysts occurrences. Nine assemblage zones have been recognized of Tithonian through Albian age. All but 2 of 18 nannofossil events in the Atlantic Ocean optimum sequence were reported in the same stratigraphic order in a standard Mesozoic nannofossil zonation.Our quantitative examination, using Walsh spectral analysis, of the Lower Cretaceous cyclic sequences at three Deep Sea Drilling Project (DSDP) sites in the Atlantic Ocean generally supports the hypothesis that they are the product of cyclic climatic changes controlled by the Milankovitch orbital cycles. The peaks in the power spectra usually can be related to obliquity and precession cycles; some peaks seem to correspond to the eccentricity cycle. Obliquity seems to be the most important and persistent orbital element responsible for cyclic sedimentation in the Early Cretaceous Atlantic Ocean.The actual pelagic sedimentation rates were calculated for some cores using the results of spectral analysis. The correlation of the actual pelagic sedimentation rate with cyclic patterns and the occurrence of calcareous turbidites indicate that the changes in cycle pattern are the reflection of changes in the oceanographic setting. The changes in oceanographic setting are related to relative-sea-level fluctuations. The intervals dominated by laminated limestone were deposited during higher sea-level periods.
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