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Статті в журналах з теми "Calcareous fossils"
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Anderson, T. F., B. N. Popp, L. Z. HO, and A. C. Williams. "The carbon and oxygen isotopic records of fossils from the Lower Oxford Clay." Paleontological Society Special Publications 6 (1992): 7. http://dx.doi.org/10.1017/s2475262200005670.
Повний текст джерелаАнотація:
The excellent preservation of calcareous invertebrates and phosphatic vertebrates in the Lower Oxford Clay provides a good opportunity for paleooceanographic reconstruction based on stable isotopic abundances. We present here our initial results and interpretations on carbon and oxygen isotopic analyses on fossils of different depth habitats. Benthic fossils include epifaunal oysters and infaunal nuculacean bivalves. We also analyzed “pendant” bivalves whose depth habitat is uncertain. Fossil nekton are represented by ammonites and belemnites. Organisms that inhabited the uppermost part of the water column are represented by marine reptiles, such as icthyosaurs and plesiosaurs, and probable pelagic fish.The oxygen isotopic compositions of calcareous benthos and nekton overlap substantially (δ180 = −2 to +1 permil vs. PDB). The wide scatter in δ180 values probably reflects physiological (non-equilibrium) effects in calcification rather than paleoenvironmental variations. Mean δ180 values for oysters, pendant bivalves, and belemnites (all calcitic) and nuculacean bivalves (aragonitic) correspond to precipitation at isotopic equilibrium with non-glacial seawater at temperatures of 15°-18°. The mean isotopic paleotemperature for ammonites (aragonitic) is slightly higher (20°) but is probably not significantly different from those for other calcareous macro-invertebrates. Preliminary oxygen isotopic results on phosphate extracted from bones, teeth, and gill rays correspond to paleotemperatures of 20°–25°.Carbon isotopic results are limited to data from calcareous benthos and nekton. δ 13C values for individual taxa are quite variable (+2 to +5 permil for aragonitic fossils, 0 to +3 permil for calcitic fossils), suggesting physiological isotope effects. Nonetheless, mean δ 13C values are consistent with calcification in seawater having a carbon isotopic composition similar to that of modern average seawater. The presumably high flux of 13C-depleted CO2 into bottom waters from the diagenesis of sedimentary organic matter is not recorded in the carbon isotopic composition of benthic fossils.Thermal stratification implied by the oxygen isotopic record suggests the penetration of cool, nutrient-rich waters into the Lower Oxford Clay sea. Upward advection of deep waters together with runoff from adjacent landmasses must have provided sufficient nutrients to maintain the inferred high productivity of surface waters. The influence of productivity on the carbon isotopic composition of surface waters will be tested by the analysis of calcareous phytoplankton.
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Bengtson, Stefan. "Early skeletal fossils." Paleontological Society Papers 10 (November 2004): 67–78. http://dx.doi.org/10.1017/s1089332600002345.
Повний текст джерелаАнотація:
The Precambrian-Cambrian transition saw the burgeoning of diverse skeletal organisms (“small shelly fossils”), represented in the fossil record by spicules, tubes, tests, conchs, shells, and a variety of sclerites and ossicles. Whereas calcareous biomineralization as such may have been facilitated by changes in ocean chemistry at this time, the utilization of biominerals in mineralized skeletons is a different process. The massive appearance of skeletons is most likely an epiphenomenon of the general radiation of body plans and tissues. The “choice” of biominerals (mainly calcium carbonates, calcium phosphates, and silica) may reflect the environmental conditions under which the particular skeleton first evolved.
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Wilson, J. "Approaches to the preparation and development of calcareous fossils from calcareous matrices." Geological Curator 4, no. 7 (February 1987): 447–50. http://dx.doi.org/10.55468/gc12.
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Miller, Kelly B., and Sara H. Lubkin. "Calicovatellus petrodytes, a new genus and species of primitive vatelline diving beetle (Coleoptera: Dytiscidae: Hydroporinae: Vatellini) from the Miocene Barstow Formation, southern California, USA." Journal of Paleontology 75, no. 4 (July 2001): 890–94. http://dx.doi.org/10.1017/s0022336000016991.
Повний текст джерелаАнотація:
Relatively few fossil dytiscids have been described. This is unfortunate since fossils can provide useful phylogenetic and evolutionary information including unique character combinations not present in extant taxa and minimum ages for divergences. However, even when fossils are found, important characters are often not visible since they may be poorly preserved or obscured. The fossil insects present in calcareous nodules from the Miocene Barstow Formation of the Calico Mountains in Southern California are exceptionally well preserved (Palmer, 1957). The original organisms are replaced by silica or other minerals and when the nodules are dissolved in formic acid, the three-dimensional fossil can be retrieved from the resulting residue. These nodules have yielded a wide variety of fossils, including larvae of the dytiscid species Schistomerus californense Palmer, 1957 and numerous other terrestrial and fresh-water arthropods (Palmer, 1957). The purposes of this paper are to describe a new dytiscid genus and species from an exceptionally well-preserved specimen from the Barstow Formation and to present a hypothesis of the phylogenetic placement of the new taxon.
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Turner, Judith. "Sponge Gemmules from Lake Sediments in the Puget Lowland, Washington." Quaternary Research 24, no. 2 (July 1985): 240–43. http://dx.doi.org/10.1016/0033-5894(85)90010-9.
Повний текст джерелаАнотація:
Gemmules of five species of freshwater sponge found in deposits at Cedar Mountain bog in the southeastern Puget Lowland were used to infer that during the late-glacial period the water was calcareous, was not deficient in SiO2, was aerobic, and had a pH in the range 6.6–8.5. This is consistent with plant fossil data. In view of their paleoenvironmental potential it is worth looking for gemmules when extracting other fossils from lake sediments.
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Lorcher, Fritz, and Thomas Keller. "Preparation Techniques for Material From The Posidonienschiefer (Lias Epsilon, Upper Liassic) of Germany." Geological Curator 4, no. 3 (July 1985): 164–68. http://dx.doi.org/10.55468/gc749.
Повний текст джерелаАнотація:
The authors describe methods of mechanical and chemical treatment of fossils from the Posidonienschiefer (Lias epsilon, Upper Liassic, Lower Jurassic, south-western Germany). Special tools and techniques are discussed. The use of acids in the preparation of vertebrate fossils from calcareous layers gives very good results, better than any mechanical method of preparation.
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R. Nimnu, J., G. O Aigbadon, and F. Ogbikaya. "Foraminiferal biostratigrpahy of oshi-13 field, coastal and central swamp depobelt, Niger delta basin, Nigeria." International Journal of Advanced Geosciences 6, no. 1 (May 30, 2018): 127. http://dx.doi.org/10.14419/ijag.v6i1.10907.
Повний текст джерелаАнотація:
A high resolution Foraminiferal biostratigrpahic study has been carried out using data from three wells located in the Coastal and Central Swamp depobelts of Niger Delta.The study defined six (N6-N15) Foraminiferal zones for the early to middle Miocene Niger Delta on the basis of index Foraminiferal and this was correlated to Blow, 1969 and Bergreen et al., 1995. Foraminiferal analysis shows that Oshi-13Field is very rich in calcareous and araneceous benthics, calcareous and planktic foraminiferal. The abudance of fossils and index fossils are responsible for constructing the biostratigraphic chart and hydrocarbon saturation in the field. The biostratigraphy chart constructed act as a basis in establishing the ages of sediments/ sequence in the studied field.
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Nhung, Nguyen Thi Hong, Nguyen Thi Thuy, Nguyen Viet Hien та 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, № 4 (27 березня 2020): 537–44. http://dx.doi.org/10.15625/1859-3097/19/4/12676.
Повний текст джерелаАнотація:
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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Hochuli, Peter A. "‘Organic nannofossils’: a new type of palynomorph from the Palaeogene of the North Sea." Journal of Micropalaeontology 19, no. 2 (December 1, 2000): 153–58. http://dx.doi.org/10.1144/jm.19.2.153.
Повний текст джерелаАнотація:
Abstract. Organic microfossils of regular dodecahedral shape are found in the Palaeogene (Lower Oligocene) of the central and northern parts of the Norwegian North Sea. The shape and structure of these fossils are very similar to coccospheres of the calcareous nannoplankton genus Braarudosphaera. The individual pentagonal plates show the same morphological features as replicas of the inner surface of pentaliths forming calcareous coccospheres. It is the first evidence that a representative of calcareous nannoplankton (Haptophyta, Coccolithophorales) is found to produce acid-resistant organic microfossils. The organic remains might have been produced by an undescribed species of the genus Braarudosphaera or represent an unknown stage in the life cycle of species which normally produce calcareous plates.
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Onken, Beth R., and Philip W. Signor. "Lidaconus palmettoensis n. gen. and sp.: an enigmatic Early Cambrian fossil from western Nevada." Journal of Paleontology 62, no. 2 (March 1988): 172–80. http://dx.doi.org/10.1017/s0022336000029826.
Повний текст джерелаАнотація:
Lidaconus palmettoensis n. gen. and sp. is a recently discovered fossil from the Lower Cambrian Harkless Formation (Bonnia–Olenellus Zone) in Esmeralda County, Nevada. The conoidal fossils were originally calcareous and have been replaced by silica. The cones are distinctive in their consistent morphology, the presence of weak annulations, and the lack of any internal structures such as septa, tabulae, or dissepiments. Because of the paucity of diagnostic characters due to the simple morphology and the lack of original microstructure, taxonomic affinities are uncertain.
Дисертації з теми "Calcareous fossils"
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Baky, Alaaeldin Mohamed Abdel. "Maastrichtian to early Eocene calcareous nannofossils from Egypt." Thesis, University College London (University of London), 1988. http://discovery.ucl.ac.uk/1317747/.
Повний текст джерелаАнотація:
A study of calcareous nannofossils from the Maastrichtian-Early Eocene from Egypt has resulted in the recognition of four Maastrichtian and seven Early Tertiary biostratigraphic zones. These nannoplankton zones are based upon local ranges and compared with the zones proposed by Martini (1971), Sissingh (1977), Verbeek (1977) and Romein (1979). A new zone, the Fasciculithus ragaae Zone is described and the E1lipsolithus macellus Zone and the Fasciculithus tympaniformis Zone are emended. Study of the vertical ranges of the species provided many markers (including the zonal markers) with distinctive first and/or last occurrence levels. The uppermost Maastrichtian and Lower Danian are missing in the study sections. There is no change in the lithology at the Cretaceous-Tertiary boundary as observed in the Esh Mellaha area, but biostratigraphic evidence shows that there is a time gap and the boundary missing. This boundary is, however, marked by a conglomerate band at Gebel Urn El Ghanayem, a thin bed of black non-calcareous shale at Gebel Duwi and a change in the lithology from chalky limestone (upper part of Sudr Chalk Formation) of Maastrichtian age to shale (lower part of Esna Shale Formation) of Early Palaeocene age at Wadi Tarfa. No continuous Cretaceous-Tertiary boundary sequence was analysed. The palaeoenvironment during the Maastrichtian-Early Eocene according to the nannofossil assemblages, was a warm open marine inner to outer shelf, although the absence of late Maastrichtian and early Danian age sediments limits observation and comment. One hundred and sixty five species have been identified. Descriptions, remarks and figures as well as schematic drawings of many species are presented. A new family RHOMBOASTERACEAE, a new genus Diadochiastozygus, five new species Fasciculithus ragaae, F. gelelii, Discoaster atefii, D. duwiensis and D. amrii are described. New combinations for Bomolithus megastypus, B. cantabriae, Diadochiastozygus imbriei, D. saepes, D. eosaepes, Tranolithus tarboulensis, Vekshinella dorfii and V. compacta are proposed. The evolution of some Cretaceous and Early Tertiary nannofloral groups is discussed and a link between the Bomolithus and Discoaster groups proposed.
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Street, Christianne. "Palaeobiogeography of Early Cretaceous calcareous nannoplankton." Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322002.
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Van, Niel Brigitta E. "Early Cretaceous Nannoconus (Calcareous nannofossil, Incertae sedis) in NW Europe." Thesis, University College London (University of London), 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307692.
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Windley, Dawn Elizabeth. "Calcareous nannofossil applications in the study of cyclic sediments of the Cenomanian." Thesis, University College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306898.
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Hairie, Clara. "La dégradation de Byne : efflorescences de sels de calcium sur les collections de micropaléontologie." Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPAST084.
Повний текст джерелаАнотація:
L'apparition d'efflorescences cristallines sur des objets calcaires stockés dans des environnements pollués, communément appelée "dégradation de Byne", résulte de l'émission de composés organiques volatils (COV) acides par les matériaux de stockage. Ces acides réagissent avec le carbonate de calcium en formant des sels organiques de calcium, dont des acétates et des sels mixtes acétate-formiate, qui provoquent une détérioration irréversible du substrat. Jusqu'à présent, seuls des objets macroscopiques subissant la dégradation de Byne avaient été décrits dans la littérature.Ce travail vise à comprendre comment la dégradation de Byne peut aussi affecter des spécimens calcaires microscopiques présents dans les collections de micropaléontologie. Il a été initié par la numérisation de la collection de foraminifères d'Alcide d'Orbigny (1802-1857), conservée au Muséum national d'Histoire naturelle (MNHN), qui a révélé des dommages importants liés à la présence d'efflorescences salines.Un constat d'état a été mené sur l'ensemble de la collection d'Orbigny (plus de 3600 spécimens), mettant en évidence que les altérations, à la fois anciennes et évolutives, sont influencées par la cristallinité des tests et l'origine des lieux de prélèvement des foraminifères. Des collections voisines ont été examinées à titre comparatif et des recherches en archives ont permis de retracer l'histoire de la collection depuis son entrée au MNHN. Elles mettent en évidence de nombreux déménagements et des accidents tels que la crue de la Seine de 1910, qui expliquerait l'humidité particulièrement élevée à l'intérieur des tubes où sont conservés les foraminifères. Des variations importantes de température, combinées à la présence de matériaux émetteurs de COV introduits à la fin du XIXe siècle dans le montage des spécimens, sont ainsi à l'origine de la pollution acide et de la prolifération des sels.Parallèlement à cela, une procédure de vieillissement artificiel a été élaborée pour reproduire la dégradation de Byne sur des foraminifères sains. Les produits de dégradation formés sur les spécimens vieillis, ainsi que sur une sélection représentative de spécimens historiques, ont été analysés de manière non invasive et sans contact par spectroscopie micro-Raman et par diffraction des rayons X sur rayonnement synchrotron. Ces analyses ont mis en évidence des phases minéralogiques différentes de celles observées dans la littérature sur les collections macroscopiques. Ce sont ainsi des formiates de calcium qui prédominent, et tout particulièrement le polymorphe tétragonal [β-Ca(HCOO)2] connu pour être instable lorsqu'il est synthétisé en laboratoire. Aucun acétate ou sel mixte de calcium n'a pu être identifié sur les foraminifères de la collection d'Orbigny. Les vieillissements montrent que l'humidité relative et la taille des spécimens jouent un rôle primordial dans la formation des sels : des conditions humides favorisent la cristallisation du formiate de calcium sur le spécimen, tandis que l'acétate, très hygroscopique, est sujet aux cycles de déliquescence-cristallisation qui le conduisent à se disperser autour de l'échantillon lorsque celui-ci est de très petite taille.Enfin, pour mieux comprendre la prédominance du formiate de calcium [β-Ca(HCOO)2], différentes solutions de formiate de calcium ont été laissées à évaporer et placées dans des environnements à humidité variée afin d'étudier la transformation vers la phase stable [α-Ca(HCOO)2]. L'analyse semi-quantitative des produits montre que la présence d'ions tels que ceux trouvés dans les coquilles de foraminifères (Mg2+, Sr2+...) favorise la formation de la phase métastable, et ralentit la transition β-->α.Ce travail montre que la nature des sels formés par la dégradation de Byne n'est pas seulement tributaire des COV présents mais dépend aussi de la taille des spécimens, leur composition, la cristallisation de leur test et des cycles d'humidité et de température auxquels ils ont été soumisThe appearance of crystalline efflorescence on calcareous objects stored in polluted environments is commonly referred to as "Byne's decay". It results from the emission of acidic volatile organic compounds (VOCs) from storage materials, which react with calcium carbonate to form organic calcium salts. This includes acetates and mixed acetate-formate salts that cause irreversible deterioration of the substrate. Until now, only macroscopic objects undergoing Byne's decay had been reported in the literature.This work focuses on how Byne's decay can also affect microscopic calcareous specimens from micropaleontology collections. It was initiated by the digitization of the foraminifera collection of Alcide d'Orbigny (1802-1857), housed at the Muséum national d'Histoire naturelle (MNHN), which revealed significant damage due to the presence of saline efflorescences.A condition report was carried out on the whole of the d'Orbigny collection (more than 3600 specimens), highlighting that the alterations, both ancient and evolutionary, are influenced by the crystallinity of the tests and the origin of the places where the foraminifera were collected. Similar collections closely located were examined for comparison and archival research was conducted to trace the material history of the collection since its entry into the MNHN. They highlight several moves and accidents such as the flooding of the Seine in 1910, which would explain the particularly high levels of humidity inside the tubes where the foraminifera are kept. Significant variations in temperature, combined with the presence of VOC-emitting materials introduced at the end of the 19th century in the assembly of the specimens, are thus at the origin of the acid pollution and the proliferation of salts.At the same time, an artificial aging procedure was developed to reproduce Byne's decay on unaltered specimens. The degradation products formed on the aged specimens, as well as on a representative selection of historical ones, were analysed non-invasively and without contact by using micro-Raman spectroscopy and synchrotron X-ray diffraction. These analyses revealed mineralogical phases different from those observed in the literature on macroscopic collections. Thus, calcium formates and especially the tetragonal polymorphic phase [β-Ca(HCOO)2] known to be unstable when synthesized in laboratory conditions, predominate. No calcium acetate or mixed salt could be identified on d'Orbigny's foraminifera. Aging shows that the relative humidity and the size of the specimens play a primordial role in the formation of the salts: humid conditions favour the crystallization of calcium formate directly on the specimen, while acetate, very hygroscopic, is subject to deliquescence-crystallization cycles that lead to its redispersion around micrometer-scale specimens.Finally, to better understand the predominance of calcium formate [β-Ca(HCOO)2], different calcium formate solutions were left to evaporate and placed in environments with different humidity to study the transformation towards the stable phase [α-Ca(HCOO)2]. Semi-quantitative analysis of the products shows that the presence of ions such as those found in foraminiferal shells (Mg2+, Sr2+…) favours the formation of the metastable phase and slows down the transition β-->α.This work shows that the nature of the salts formed by Byne's decay is not only dependent on the VOCs present, but also on the size of the specimens, their composition, their test crystallization, and the moisture and temperature cycles to which they were exposed
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Gaillot, Jérémie. "The late Permian-early Triassic Khuff formation in the Middle-East : sequence biostratigraphy and palaeoenvironments by means of calcareous algae and foraminifers." Lille 1, 2006. http://www.theses.fr/2006LIL10162.
Повний текст джерелаАнотація:
Les carbonates et évaporites de la formation Khuff (Permien supérieur) de la plate-forme arabique abritent un des plus grands réservoirs de gaz au monde. Le matériel étudié comprend 6000 échantillons de subsurface ou d'affleurements et provient du Golfe persique, de Turquie, d'Arabie Seoudite et de Chine du Sud. Les objectifs de l'étude étaient de: (1) construire un cadre biostratigraphique robuste à partir de l'étude systématique détaillée des algues calcaires et des foraminifères, (2) caractériser les environnements de dépôt et leur succession dans le temps à la fin du Permien et au Trias basal. La comparaison des différents assemblages a permis de subdiviser l'intervalle étudié en 8 unités distinctes limitées par des niveaux d'importants renouvellements biotiques. A la fin du Permien, le Zagros (Iran), le Taurus (Turquie), la Chine du Sud et même le Japon partagent un assemblage de foraminifères similaire et constituaient des provinces paléogéographiques périodiquement interconnectées. L'étude paléoécologique montre que les points hauts relatifs contrôlés structuralement ont été successivement ennoyés et que le système a évolué depuis une plate-forme barrée vers une rampe très faiblement inclinée. Les unités oolithiques majeures (réservoirs) se sont développées à la fin du Wuchiapingian (partie supérieure du réservoir k4) et au début du Trias (réservoir k2), et sont piégées à l'intérieur de zones plus fortement subsidentes. La subsidence thermique liée à l'ouverture de l'Océan Neotethys est sans doute le facteur majeur contrôlant la sédimentation sur la plate-forme arabique et a joué un rôle important durant les phases successives d'extinction de la fin du PermienThe carbonates and evaporites of the late Permian Khuff formation form widespread reservoirs across the Arabian plate and concentrate the biggest gas resources in the world. The material studied includes 6000 samples from subsurface and outcrops in the Persian gulf, Turkey, Saudi Arabia and South China. The objectives of the study were (1) to build a robust biostratigraphic framework based on a detailed description of algal-foraminiferal biotic content, (2) to characterize the depositional environments and their temporal successions during the late Permian and early Triassic. By comparison of fossils distribution, the middle/late Permian Khuff deposits are divided into 8 units limited at their tops by turnovers levels, corresponding to significant reshapings of biotic assemblages. During the late Permian, Zagros (Iran), Taurus (Turkey), South China and even Japan share similar foraminiferal assemblages and represent intermittently connected palaeobiogeographic provinces. Palaeoecological results show that the structurally controlled palaeohighs are successively drowned and that the system evolves progressively from a rimmed platform towards an almost uniformly flat ramp. The major oolitic units (reservoirs) developed within high-subsiding areas by sediment volume funneling, mainly during the late Wuchiapingian (upper k4 reservoir) and early Triassic (k2 reservoir). The thermal subsidence during the Neotethyan spreading is likely the main factor that drove the Khuff deposition on the Arabian platform and can be related to the demise of the regional Permian fauna
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Campbell, Robert John. "Calcareous nannofossil and foraminiferal analysis of the middle to upper cretaceous Bathurst Island Group, Northern Bonaparte Basin and Darwin Shelf, Northern Australia." University of Western Australia. School of Earth and Geographical Sciences, 2003. http://theses.library.uwa.edu.au/adt-WU2003.0025.
Повний текст джерелаАнотація:
[Truncated abstract] The Northern Bonaparte Basin and adjacent Darwin Shelf form part of a major petroleum province on the northwestern margin of Australia. The middle to Late Cretaceous Bathurst Island Group consists of siliciclastic and pelagic carbonate strata that form the regional seal to underlying Upper Jurassic and Lower Cretaceous reservoir sandstones. The Bathurst Island Group has previously been subdivided into four stratigraphic sequences or ‘play intervals’ bound by regional disconformities in the Valanginian (KV horizon), Lower Aptian (KA horizon), upper Lower Cenomanian (KC horizon), Middle Campanian (KSC horizon), and at the CretaceousPaleocene boundary (T horizon). Correlation of these sedimentary packages and stratigraphic surfaces requires high-resolution calcareous microfossil biostratigraphy, while palaeobathymetric determinations based on benthonic foraminiferal assemblages are important for determining the subsidence history of the area and relative sea-level changes. This study presents the first detailed stratigraphic distributions, taxonomic lists and illustrations of foraminifera and calcareous nannofossils from the Bathurst Island Group of the Northern Bonaparte Basin and Darwin Shelf. A biostratigraphic framework has been constructed for the study area incorporating ‘standard’ (Tethyan) Cretaceous planktonic foraminiferal and calcareous nannofossil events where applicable, and integrating locally defined events where necessary. This framework allows Cretaceous strata to be correlated regionally across the study area and to the global chronostratigraphic scale. Correlation of the Northern Bonaparte Basin and Darwin Shelf strata to the Cretaceous Stages and international time scale is based on recent ties of nannofossil and foraminiferal events to macrofossil zones and palaeomagnetic polarity chrons at ratified and proposed Global Stratotype Sections and Points (GSSPs). Calcareous nannofossil events recorded in the study area that are critical for defining stage boundaries include the lowest occurrences of Prediscosphaera columnata, Micula decussata, Lithastrinus grillii, and Aspidolithus parcus parcus, and the highest occurrences of Helenea chiastia, Lithastrinus moratus, Aspidolithus parcus constrictus, and Eiffellithus eximius. Important planktonic foraminiferal events for correlation include the lowest occurrences of Rotalipora gr. globotruncanoides, and Dicarinella asymetrica, and the highest occurrences of Planomalina buxtorfi, Rotalipora cushmani, and Dicarinella asymetrica. During the middle to Late Cretaceous the Northern Bonaparte Basin and Darwin Shelf occupied mid-high palaeolatitudes between 35ºS to 45ºS. These palaeolatitudes are reflected in the transitional character of the planktonic microfossil assemblages, which combine elements of the low-latitude, warm-water Tethyan Province to the north and the cool-water high-latitude Austral Province to the south. ‘Standard’ Tethyan zonations are most applicable for uppermost AlbianMiddle Campanian strata because equator-to-pole temperature gradients were weakly developed, and global climate was warm and equable during this interval. These conditions resulted in broad latitudinal distributions for Tethyan marker species, and consequently most UC calcareous nannofossil zones and European-Mediterranean planktonic foraminiferal zones are recognised. In contrast, the EarlyLate Albian and the late Middle CampanianMaastrichtian were intervals of greater bioprovinciality and stronger palaeotemperature gradients. In these intervals application of the Tethyan zonations is more difficult, and a number of the Tethyan biostratigraphic markers are absent from the study area (e.g. Ticinella species in the Albian and Radotruncana calcarata in the Late Campanian). Cretaceous palaeobathymetric reconstruction of the study area is based on comparison of the foraminiferal assemblages with those of previous Cretaceous palaeobathymetric studies. Marginal marine assemblages consist solely of low diversity siliceous agglutinated foraminifera (e.g. Trochammina). Inner and middle neritic water depths (0-100 m) contain rare to common planktonic foraminifera (mainly globigerine forms), robertinids (e.g. Epistomina), siliceous agglutinates, lagenids, buliminids (e.g. Neobulimina), and rotaliids. The outer neritic zone (100-200 m water depth) contains abundant planktonic foraminifera (keeled and globigerine), calcareous agglutinates (e.g. Dorothia), and diverse lagenids, buliminids, and rotaliids. Upper-middle bathyal water depths (200-1000 m) are characterised by abundant planktonic foraminifera, common siliceous agglutinated taxa (e.g. Glomospira), rare to common Osangularia, and globular species of Gyroidinoides, Pullenia, and Paralabamina.
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Petrocchi, Francesca. "Paleo- ecologia dei Foraminiferi in ambiente estremo: un caso di studio in Antartide." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/9763/.
Повний текст джерелаАнотація:
Nel presente lavoro sono state analizzate le distribuzioni quantitative dei Foraminiferi planctonici e bentonici presenti in una carota e in un box core prelevati nel Mare di Ross in Antartide durante la campagna KOPRI ANTA03 nel Febbraio 2013 nell’ambito del progetto di ricerca congiunto Corea- Italia finanziato dal Progetto Nazionale di Ricerca in Antartide (PNRA). Scopo del lavoro è stato quello di comprendere l’evoluzione ambientale dell’area in base alla distribuzione quantitativa e qualitativa delle associazioni a Foraminiferi nel tardo Quaternario. In base alla distribuzione quantitativa dei Foraminiferi identificati, la sequenza sedimentaria della carota C2 è stata suddivisa in tre intervalli corrispondenti a tre principali fasi paleoceanografiche/paleoclimatiche. La prima fase, più antica di 18 ka, caratterizzata dall’assenza o rarità di forme documenta un ambiente con presenza di copertura glaciale. La seconda, depositatasi tra 18 ka e ~8 ka è caratterizzata da una maggiore variabilità intraspecifica e riflette un miglioramento delle condizioni climatiche. La terza, corrisponde ad un periodo compreso tra ~8 ka e ~2 ka. La presenza di forme agglutinanti e l’assenza di Foraminiferi a guscio calcareo suggeriscono la presenza di condizioni di dissoluzione carbonatica sul fondale in un ambiente marino libero da copertura glaciale. La documentazione di numerosi individui allo stadio giovanile di Neogloboquadrina pachyderma durante l’intervallo B ha reso possibile avanzare ipotesi riguardo la strategia di sopravvivenza di questa specie in ambiente estremo quale il ghiaccio antartico. La somiglianza morfologica tra individui giovanili di Neogloboquadrina pachyderma riscontrata durante il nostro studio nei sedimenti a livello fossile nella carota con individui giovanili della stessa specie provenienti da campioni di ghiaccio marino antartico documentati in bibliografia, ha permesso di supportare la tesi dello sviluppo di tali forme nei pori del “microghiaccio”.
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Findlay, CS. "Living and fossil calcareous nannoplankton from the Australian sector of the Southern Ocean: Implications for Paleoceanography." Thesis, 1998. https://eprints.utas.edu.au/17686/1/findlay_thesis.pdf.
Повний текст джерелаАнотація:
This study documents the distribution of calcareous nannoplankton in
the waters and surface sediments of the Australian Sector of the Southern
Ocean, and applies the information to core samples from the region to
infer past changes in the ocean between 41 os and 64°S. The preservation
of calcite plates produced by these phytoplankton are preserved in pelagic
sediments and are useful in paleoceanography.
Water column samples show that calcareous nannoplankton can be
separated into five distinct assemblages associated with properties of the
water mass, i.e., temperature, salinity, light and nutrients. In general the
abundance and diversity of nannoplankton decrease poleward from
subtropical to polar waters.
The surface sediments show an abundance and diversity of calcareous
nannoplankton different from living assemblages in the water column.
Surface sediments are dominated by a single assemblage including C.
pelagicus, a species not found in water column samples. The absence of C.
pelagicus suggests a1recent extinction in the Southern Ocean. Of 45
surface sediment s~mples, only eight were identified as younger than 73
ka BP based on currently recognised biostratigraphy, indicating erosion
and disturbance of sediments in the region. Preferential preservation of
larger, more robust species of nannoplankton in the surface sediments
suggests that chemical dissolution of calcite is significant.
Calcareous nannoplankton biost~atigraphy from a 5.1-metre core (GC07;
45°S; 146°E; 3307m water depth), coupled with 14C dates, oxygen isotope
ratios and %CaC03 data show that the core spans the interval of about 129
ky (from the beginning of the last interglacial) to Late Holocene. Changes
in fossil assemblages with time are related to glacial and interglacial
intervals, suggesting that the nannoplankton are useful as paleoclimatic indicators. A change from dominance by Gephyrocapsa muellerae to
dominance by Emiliania huxleyi occurred at about 11 ka BP, suggesting
that the commonly used date for this reversal (73 ka BP) is not applicable
for the Sub-Antarctic. The presence of Miocene and Pliocene species in
the core samples indicates that reworking of sediments is commori in the
region.
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Young, Marty. "The distribution of organic-and calcareous-walled dinoflagellate cysts from the eastern Indian Ocean : a proxy for late Quaternary palaeo-oceanographic reconstructions." Phd thesis, 2005. http://hdl.handle.net/1885/151086.
Повний текст джерелаКниги з теми "Calcareous fossils"
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Aubry, Marie-Pierre. Handbook of Cenozoic calcareous nannoplankton. New York: Micropaleontology Press, American Museum of Natural History, 1987.
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2
Robert, Riding, and International Symposium on Fossil Algae (4th : 1987 : Cardiff, Wales), eds. Calcareous algae and stromatolites. Berlin: Springer-Verlag, 1991.
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3
Kleijne, A. Morphology, taxonomy and distribution of extant coccolithophorids (calcareous nannoplankton). [s.l: s.n.], 1993.
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4
Finks, Robert M. Some new genera of Paleozoic calcareous sponges. Lawrence, Kansas: University of Kansas, 1995.
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5
Driever, B. W. M. Calcareous nannofossil biostratigraphy and paleoenvironmental interpretation of the Mediterranean Pliocene. Utrecht, Netherlands: U.M.B., 1988.
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Bybell, Laurel M. Cenozoic calcareous nannofossil biostratigraphy of the Dover Je32-04 drillhole, Kent County, Delaware. [Reston, Va?]: Dept. of the Interior, U.S. Geological Survey, 1995.
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Bybell, Laurel M. Calcareous nannofossils and planktic foraminifers from Enewetak Atoll, western Pacific Ocean. Washington: U.S. G.P.O., 1991.
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Ehrendorfer, Thomas Wolfgang. Late cretaceous (Maestrichtian) calcareous nannoplankton biogeography: With emphasis on events immediately preceding the cretaceous/paleocene boundary. Woods Hole, Mass: Woods Hole Oceanographic Institution, 1993.
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Bybell, Laurel M. Evolutionary, biostratigraphic, and taxonomic study of calcareous nannofossils from a continuous Paleocene-Eocene boundary section in New Jersey. Washington: U.S. G.P.O., 1994.
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Dowsett, Harry J. Documentation of the Santonian-Campanian and Austinian-Tayloran stage boundaries in Mississippi and Alabama using calcareous microfossils. Washington, DC: U.S. Government Printing Office, 1989.
Знайти повний текст джерелаЧастини книг з теми "Calcareous fossils"
1
Keupp, H. "Fossil Calcareous Dinoflagellate Cysts." In Calcareous Algae and Stromatolites, 267–86. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-52335-9_14.
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2
Wu, X. "Fossil Udoteaceae and Gymnocodiaceae." In Calcareous Algae and Stromatolites, 146–66. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-52335-9_9.
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3
Ledger, P. W., and W. C. Jones. "On the Structure of Calcareous Sponge Spicules." In Fossil and Recent Sponges, 341–59. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-75656-6_27.
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Rigby, J. K. "Evolution of Paleozoic Heteractinid Calcareous Sponges and Demosponges — Patterns and Records." In Fossil and Recent Sponges, 83–101. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-75656-6_8.
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Reitner, J. "Phylogenetic Aspects and New Descriptions of Spicule-Bearing Hadromerid Sponges with a Secondary Calcareous Skeleton (Tetractinomorpha, Demospongiae)." In Fossil and Recent Sponges, 179–211. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-75656-6_15.
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Wagreich, Michael. "A review of low-latitude “Tethyan” calcareous nannoplankton assemblages of the Cretaceous." In New Aspects on Tethyan Cretaceous Fossil Assemblages, 45–55. Vienna: Springer Vienna, 1992. http://dx.doi.org/10.1007/978-3-7091-5644-5_4.
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Rosenthal, Yair. "Chapter Nineteen Elemental Proxies for Reconstructing Cenozoic Seawater Paleotemperatures from Calcareous Fossils." In Developments in Marine Geology, 765–97. Elsevier, 2007. http://dx.doi.org/10.1016/s1572-5480(07)01024-x.
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Rosenthal, Y., and B. Linsley. "PALEOCEANOGRAPHY, PHYSICAL AND CHEMICAL PROXIES | Mg/Ca and Sr/Ca Paleothermometry from Calcareous Marine Fossils." In Encyclopedia of Quaternary Science, 871–83. Elsevier, 2013. http://dx.doi.org/10.1016/b978-0-444-53643-3.00290-9.
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Braga, J. C., and R. Riding. "FOSSIL PLANTS | Calcareous Algae." In Encyclopedia of Geology, 428–36. Elsevier, 2005. http://dx.doi.org/10.1016/b0-12-369396-9/00951-5.
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Beauchamp, Benoit, Charles M. Henderson, Elinda Dehari, Daniela Waldbott Von Bassenheim, Sean Elliot, and Daniel Calvo González. "Carbonate Sedimentology and Conodont Biostratigraphy of Late Pennsylvanian–Early Permian Stratigraphic Sequences, Carlin Canyon, Nevada: New Insights into the Tectonic and Oceanographic Significance of an Iconic Succession of the Basin and Range." In Late Paleozoic and Early Mesozoic Tectonostratigraphy and Biostratigraphy of Western Pangea, 34–71. SEPM (Society for Sedimentary Geology), 2022. http://dx.doi.org/10.2110/sepmsp.113.14.
Повний текст джерелаАнотація:
The Gzhelian (Upper Pennsylvanian) to Kungurian (Lower Permian) succession around Carlin Canyon, northern Nevada, in the Basin and Range province of the western USA is a relatively undeformed wedge of fossiliferous marine carbonate and fine-grained calcareous and cherty clastic rocks that rests with profound angular unconformity on Mississippian to mid-Pennsylvanian sedimentary rocks that had been uplifted, faulted, folded, and eroded prior to the Late Pennsylvanian transgression. This wedge of sediments, which tapers over less than 2 km from 1341 m in the west to 588 m in the east, comprises the Strathearn, Buckskin Mountain, and lower part of the Beacon Flat formations. These units form a second-order sequence within which five third-order unconformity-bounded transgressive–regressive sequences are nested. These sequences are Gzhelian, early to late Asselian, latest Asselian to late Sakmarian, latest Sakmarian to late Artinskian, and latest Artinskian to late Kungurian in age based on the determination and biostratigraphic interpretation of 26 conodont taxa, including two new species (Adetognathus carlinensis n. sp. and Sweetognathus trexleri n. sp.). Each sequence records sedimentation on a westward-dipping ramp along which significant facies change occurs with inner-ramp coarse-grained algal and bioclastic photozoan grainstone to the east passing westward into mid- to outer-ramp heterozoan carbonate, and ultimately into deep-water fine-grained mixed clastic–carbonate facies with no fossils except sponge spicules, representing deep-water sedimentation in a basinal area that underwent repeated episodes of rapid subsidence associated with each sequence. Accommodation during sedimentation of Gzhelian–Kungurian sequences around Carlin Canyon was repeatedly created in response to flexural subsidence caused by tectonic loading west of the study area. Each sequence recorded the simultaneous foundering of the basinal area in the west and uplift of the basin margin in the east. Individual sequences overlap the underlying sequence to the east, while flexural subsidence from the Gzhelian to the earliest Artinskian led to a basin in the west that became deeper over time. A lull in tectonic activity associated with each sequence allowed carbonates to prograde from east to west, partially filling the basinal area until the early Artinskian, and completely filling it to sea level during the late Artinskian and then again in the late Kungurian. The Gzhelian–Kungurian carbonate succession of the Carlin Canyon area bears much resemblance with the coeval succession that occurs all along the northwest margin of Pangea, from Nevada in the south to the Canadian Arctic islands in the north, and down from the Barents Sea to the central Urals to the east. That broad area was affected by the same oceanographic events, the most significant of which was the earliest Sakmarian closure of the Uralian seaway, which prevented warm water from the Tethys Ocean from reaching the northwestern Pangea margin as it did before; this led to much cooler oceanic conditions all along western North America, even in the low tropical paleolatitudes where northern Nevada was located, in spite of a globally warming climate following the end of the late Paleozoic ice age.
Тези доповідей конференцій з теми "Calcareous fossils"
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Putri, D. ,. A. ,. L. ,. A. "Morphotectonic Analysis of Tanjung Bungo Area Based on Geological Structure Control, Central Sumatera Basin." In Digital Technical Conference. Indonesian Petroleum Association, 2020. http://dx.doi.org/10.29118/ipa20-sg-254.
Повний текст джерелаАнотація:
Tectonic activity in an area could result in various impacts such as changes in elevation, level of slope percentages, river flow patterns and systems, and the formation of geological structures both locally and regionally, which will form a new landscape. The tectonic activity also affects the stratigraphic sequences of the area. Therefore, it is necessary to study morphotectonic or landscape forms that are influenced by active tectonic activities, both those occur recently and in the past. These geological results help provide information of the potential of natural resources in and around Tanjung Bungo area. Morphological data are based on three main aspects including morphogenesis, morphometry, and morphography. The data are collected in two ways, the first is field survey by directly observing and taking field data such as measuring geological structures, rock positions, and outcrop profiles. The second way is to interpret them through Digital Elevation Model (DEM) and aerial photographs by analyzing river flow patterns and lineament analysis. The field measurement data are processed using WinTensor, Dips, and SedLog Software. The supporting data such as Topographic Maps, Morphological Elevation Maps, Slope Maps, Flow Pattern Maps, and Lineament Maps are based on DEM data and are processed using ArcGis Software 10.6.1 and PCI Geomatica. Morphotectonically, the Tanjung Bungo area is at a moderate to high-class level of tectonic activity taken place actively resulted in several joints, faults, and folds. The formation of geological structures has affected the morphological conditions of the area as seen from the development of steep slopes, structural flow patterns such as radial, rectangular, and dendritic, as well as illustrated by rough surface relief in Tanjung Bungo area. This area has the potential for oil and gas resources as indicated by the Telisa Formation, consisting of calcareous silts rich in planktonic and benthonic fossils, which may be source rocks and its contact with the Menggala Formation which is braided river system deposits that could be good reservoirs. Further research needs to be done since current research is only an interpretation of surface data. Current natural resources being exploited in Tanjung Bungo region are coals. The coals have thicknesses of 5-7 cm and are classified as bituminous coals.
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Qu, Hai, Xiangjun Chen, Ying Liu, Xu Liu, and Zhijun Zeng. "Nuclear Magnetic Resonance Experimental Study on Pore Structure Effect of Deep Shale Under Liquid Nitrogen Freezing." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0384.
Повний текст джерелаАнотація:
ABSTRACT The freezing of liquid nitrogen (LN2) can affect the rock's structure, which can be used in the extraction of natural gas from deep shale formations. However, its effect on the pore structure of the shale remains unclear. To address this issue, this study subjected three different types of deep shale: Carbonaceous (C) shale, siliceous (Si) shale and calcareous (Ca) shale. The mineral composition was determined by X-ray diffraction (XRD). And the physical properties of deep shale were analyzed by nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM). The evolution of porosity of shale samples under LN2 cooling by different lithology, rock temperature and cyclic cooling were compared to explore the effect of LN2 freezing on the pore structure. The results of this study indicated that LN2 fluid would be a promising source of longitudinal and bedding fractures in carbonaceous shales. And the resulting fractures would increase the permeability of the shale. In addition, repeated freezing also lead to the formation of conductive fractures in the shale. In conclusion, since LN2 has low-temperature properties, has a freeze-damaging effect on reservoir rocks and promotes microfracture development, it is important to inject LN2 as fracturing fluid during the reservoir process to improve the effect of fracturing transformation. INTRODUCTION As an important component of unconventional oil and gas resources, shale gas has played an important role in recent years in meeting the growing global demand for fossil energy (Alfi et al., 2019; Qu, Hu, et al., 2022; Wu et al., 2017). As shale gas reservoirs are characterized by low pore permeability and large burial depth, corresponding production enhancement measures need to be implemented to achieve effective extraction of shale gas. In response to the problems of water scarcity and environmental pollution caused by hydraulic fracturing, the liquid nitrogen (LN2) waterless fracturing proposed in recent years can be one of the key technologies for effective development of deep shale gas and alleviating water scarcity (Qu, Tang, et al., 2022). The cold impact effect of LN2 on the rock is used to reduce the difficulty of rock fracturing, thus improving the fracturing effect of the reservoir (Qu et al., 2023). Therefore, it is important to clarify the study of the fracturing mechanism of low-temperature LN2 on deep shale rocks and explore the feasibility of LN2 fracturing in deep shale rocks for the guidance of shale gas development (Qu, Liu, et al., 2022; Wu et al., 2019; Yang et al., 2021).