Thematische Bibliographien / Calcite twins

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Auswahl der wissenschaftlichen Literatur zum Thema „Calcite twins“

Autor: Grafiati

Veröffentlicht am 25. Mai 2024

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Zeitschriftenartikel zum Thema "Calcite twins"

Lacombe, Olivier, Camille Parlangeau, Nicolas E. Beaudoin und Khalid Amrouch. „Calcite Twin Formation, Measurement and Use as Stress–Strain Indicators: A Review of Progress over the Last Decade“. Geosciences 11, Nr. 11 (28.10.2021): 445. http://dx.doi.org/10.3390/geosciences11110445.

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Mechanical twins are common microstructures in deformed calcite. Calcite twins have been used for a long time as indicators of stress/strain orientations and magnitudes. Developments during the last decade point toward significant improvements of existing techniques as well as new applications of calcite twin analysis in tectonic studies. This review summarises the recent progress in the understanding of twin formation, including nucleation and growth of twins, and discusses the concept of CRSS and its dependence on several factors such as strain, temperature and grain size. Classical and recent calcite twin measurement techniques are also presented and their pros and cons are discussed. The newly proposed inversion techniques allowing for the use of calcite twins as indicators of orientations and/or magnitudes of stress and strain are summarized. Benefits for tectonic studies are illustrated through the presentation of several applications, from the scale of the individual tectonic structure to the continental scale. The classical use of calcite twin morphology (e.g., thickness) as a straightforward geothermometer is critically discussed in the light of recent observations that thick twins do not always reflect deformation temperature above 170–200 °C. This review also presents how the age of twinning events in natural rocks can be constrained while individual twins cannot be dated yet. Finally, the review addresses the recent technical and conceptual progress in calcite twinning paleopiezometry, together with the promising combination of this paleopiezometer with mechanical analysis of fractures or stylolite roughness.

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Parlangeau, Camille, Alexandre Dimanov, Olivier Lacombe, Simon Hallais und Jean-Marc Daniel. „Uniaxial compression of calcite single crystals at room temperature: insights into twinning activation and development“. Solid Earth 10, Nr. 1 (07.02.2019): 307–16. http://dx.doi.org/10.5194/se-10-307-2019.

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Abstract. E-twinning is a common plastic deformation mechanism in calcite deformed at low temperature. Strain rate, temperature and confining pressure have negligible effects on twinning activation which is mainly dependent on differential stress. The critical resolved shear stress (CRSS) required for twinning activation is dependent on grain size and strain hardening. This CRSS value may obey the Hall–Petch relation, but due to sparse experimental data its actual evolution with grain size and strain still remains a matter of debate. In order to provide additional constraints on twinning activation and development, new mechanical tests were carried out at room temperature on unconfined single crystals of calcite, with different sizes and crystallographic orientations. Uniaxial deformation was performed at a controlled displacement rate, while the sample surface was monitored using optical microscopy and a high-resolution CCD (charge-coupled device) camera. The retrieved macroscopic stress–strain behavior of the crystals was correlated with the surface observations of the deformation process. Results show (1) the onset of crystal plasticity with the activation of the first isolated mechanical twins during the strain hardening stage, and (2) the densification and thickening of twin lamellae during the steady-state flow stress stage. Such thickening of twin lamellae at room temperature emphasizes that calcite twin morphology is not controlled solely by temperature. The different values for the CRSS obtained for the activation of isolated twins and for the onset of twin densification and thickening raises questions regarding the appropriate value to be considered when using calcite twin data for stress inversion purposes.

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Schuster, Roman, Gerlinde Habler, Erhard Schafler und Rainer Abart. „Intragranular deformation mechanisms in calcite deformed by high-pressure torsion at room temperature“. Mineralogy and Petrology 114, Nr. 2 (07.01.2020): 105–18. http://dx.doi.org/10.1007/s00710-019-00690-y.

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AbstractPolycrystalline calcite was deformed to high strain at room-temperature and confining pressures of 1–4 GPa using high-pressure torsion. The high confining pressure suppresses brittle failure and allows for shear strains >100. The post-deformation microstructures show inter- and intragranular cataclastic deformation and a high density of mechanical e$$ \left\{01\overline{1}8\right\} $$011¯8 twins and deformation lamellae in highly strained porphyroclasts. The morphologies of the twins resemble twin morphologies that are typically associated with substantially higher deformation temperatures. Porphyroclasts oriented unfavorably for twinning frequently exhibit two types of deformation lamellae with characteristic crystallographic orientation relationships associated with calcite twins. The misorientation of the first deformation lamella type with respect to the host corresponds to the combination of one r$$ \left\{10\overline{1}4\right\} $$101¯4 twin operation and one specific f$$ \left\{01\overline{1}2\right\} $$011¯2 or e$$ \left\{01\overline{1}8\right\} $$011¯8 twin operation. Boundary sections of this lamella type often split into two separated segments, where one segment corresponds to an incoherent r$$ \left\{10\overline{1}4\right\} $$101¯4 twin boundary and the other to an f$$ \left\{01\overline{1}2\right\} $$011¯2 or e$$ \left\{01\overline{1}8\right\} $$011¯8 twin boundary. The misorientation of the second type of deformation lamellae corresponds to the combination of specific r$$ \left\{10\overline{1}4\right\} $$101¯4 and f$$ \left\{01\overline{1}2\right\} $$011¯2 twin operations. The boundary segments of this lamella type may also split into the constituent twin boundaries. Our results show that brittle failure can effectively be suppressed during room-temperature deformation of calcite to high strains if confining pressures in the GPa range are applied. At these conditions, the combination of successive twin operations produces hitherto unknown deformation lamellae.

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Mirijam, Vrabec, Rogan Šmuc Nastja und Vrabec Marko. „Calcite deformation twins in Pohorje marbles“. Geologija 61, Nr. 1 (20.07.2018): 73–84. http://dx.doi.org/10.5474/geologija.2018.005.

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Németh, Péter. „Diffraction Features from (101¯4) Calcite Twins Mimicking Crystallographic Ordering“. Minerals 11, Nr. 7 (04.07.2021): 720. http://dx.doi.org/10.3390/min11070720.

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During phase transitions the ordering of cations and/or anions along specific crystallographic directions can take place. As a result, extra reflections may occur in diffraction patterns, which can indicate cell doubling and the reduction of the crystallographic symmetry. However, similar features may also arise from twinning. Here the nanostructures of a glendonite, a calcite (CaCO3) pseudomorph after ikaite (CaCO3·6H2O), from Victoria Cave (Russia) were studied using transmission electron microscopy (TEM). This paper demonstrates the occurrence of extra reflections at positions halfway between the Bragg reflections of calcite in 0kl electron diffraction patterns and the doubling of d104 spacings (corresponding to 2∙3.03 Å) in high-resolution TEM images. Interestingly, these diffraction features match with the so-called carbonate c-type reflections, which are associated with Mg and Ca ordering, a phenomenon that cannot occur in pure calcite. TEM and crystallographic analysis suggests that, in fact, (101¯4) calcite twins and the orientation change of CO3 groups across the twin interface are responsible for the extra reflections.

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Rutter, Ernest, David Wallis und Kamil Kosiorek. „Application of Electron Backscatter Diffraction to Calcite-Twinning Paleopiezometry“. Geosciences 12, Nr. 6 (25.05.2022): 222. http://dx.doi.org/10.3390/geosciences12060222.

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Electron backscatter diffraction (EBSD) was used to determine the orientation of mechanically twinned grains in Carrara marble experimentally deformed to a small strain (≤4%) at room temperature and at a moderate confining pressure (225 MPa). The thicknesses of deformation twins were mostly too small to permit determination of their orientation by EBSD but it proved possible to measure their orientations by calculating possible twin orientations from host grain orientation, then comparing calculated traces to the observed twin traces. The validity of the Turner & Weiss method for principal stress orientations was confirmed, particularly when based on calculation of resolved shear stress. Methods of paleopiezometry based on twinned volume fraction were rejected but a practical approach is explored based on twin density. However, although twin density correlates positively with resolved shear stress, there is intrinsic variability due to unconstrained variables such as non-uniform availability of twin nucleation sites around grain boundaries that imposes a limit on the achievable accuracy of this approach.

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Lacombe, Olivier. „Calcite Deformation Twins: From Crystal Plasticity to Applications in Geosciences“. Geosciences 12, Nr. 7 (17.07.2022): 280. http://dx.doi.org/10.3390/geosciences12070280.

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Côté, A. S., R. Darkins und D. M. Duffy. „Deformation twinning and the role of amino acids and magnesium in calcite hardness from molecular simulation“. Physical Chemistry Chemical Physics 17, Nr. 31 (2015): 20178–84. http://dx.doi.org/10.1039/c5cp03370e.

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We employ classical molecular dynamics to calculate elastic properties and to model the nucleation and propagation of deformation twins in calcite, both as a pure crystal and with magnesium and aspartate inclusions.

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González-Casado, José M., und Carmen Garcı́a-Cuevas. „Calcite twins from microveins as indicators of deformation history“. Journal of Structural Geology 21, Nr. 7 (Juli 1999): 875–89. http://dx.doi.org/10.1016/s0191-8141(99)00081-4.

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Kang, Seong-Seung, Jun-Mo Kim und Bo-An Jang. „Paleostress fields from calcite twins in the Pyeongan Supergroup, South Korea“. Island Arc 14, Nr. 2 (Juni 2005): 137–49. http://dx.doi.org/10.1111/j.1440-1738.2005.00462.x.

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Dissertationen zum Thema "Calcite twins"

Bah, Boubacar. „Apport de l'analyse paléopiézométrique des macles de la calcite et des stylolites à la compréhension de l'histoire tectonique et d'enfouissement des bassins sédimentaires de la marge ouest-africaine de l'Atlantique Sud“. Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS081.

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La présente thèse a pour objectif d'éprouver des méthodologies permettant de reconstituer l'évolution des propriétés réservoirs et de la pression subit par un réservoir. Ce manuscrit présente (1) une caractérisation pétrologique des roches réservoirs avec une estimation du calendrier de l'évolution de la porosité, (2) les résultats une étude paléopiézométrique, et (3) une évolution des contraintes effectives et potentielles (sur)pressions de fluides ayant prévalu dans le réservoir carbonaté au cours de son évolution. Ces éléments permettent de reconstituer l'histoire d'enfouissement et les paléocontraintes subies par des réservoirs carbonatés dans un contexte de marge passive. Pour cela ce travail s'est basé sur une approche couplée de deux outils paléopiézométrique complémentaires combinant l'inversion des macles de la calcite et l'inversion de la rugosité des stylolites. Cette approche a été combinée avec des analyses pétrographiques, géochimiques, géomécaniques et géochronologiques pour bien caractériser le réservoir. Le matériel étudié lors de cette thèse consiste en des carottes de forage offshore récupérées de puits profonds fournis par TotalEnergies situés dans les bassins du Bas Congo et de Kwanza sur la marge ouest africaine de l'océan Atlantique Sud. Ces bassins ont subi un épisode de rifting au Crétacé inférieur (145.5 - 112 Ma). L'étude de la destruction de la porosité des réservoirs pré-sel de la formation TOCA syn-rift d'âge Barrémien (130-125 Ma) à partir de carottes prélevées dans le bassin du Bas Congo a révélé que la porosité initiale avait été réduite à sa valeur actuelle de 4-8% au cours des 35 premiers Ma de son histoire d'enfouissement, atteignant ~10% après seulement 10 Ma, i.e. dans les 400-500 premiers mètres d'enfouissement et que la porosité actuelle n'avait pas évolué de manière significative depuis 95 Ma (fin de la stylolitisation). Cette étude a ainsi montré que les propriétés des réservoirs dans les formations carbonatées bioclastiques telles que la formation TOCA peuvent être largement contrôlés par des processus diagénétiques précoces et très superficiels plutôt que par des réactions mésogénétiques qui se produisent ultérieurement en profondeur dans l'histoire de l'enfouissement. Une étude paléopiézométrique a été réalisée dans le but de reconstituer l'histoire d'enfouissement et des paléocontraintes des formations carbonatées de la TOCA (syn-rift) du Barrémien et Sendji (post-rift) de l'Albien sur la marge ouest africaine. La paléopiézométrie basée sur l'inversion de la rugosité des stylolites et l'inversion des macles de calcite a été combinée à l'analyse de la fracturation, à la datation géochronologique U-Pb du ciment calcitique et à la modélisation de l'enfouissement des deux formations pour reconstruire les orientations et les grandeurs des contraintes horizontales et verticales ayant affecté les deux formations au cours du temps. L'inversion des macles de la calcite réalisée sur des ciments précoces a révélé que les carbonates syn-rift et post-rift avaient enregistré une histoire des paléocontraintes polyphasée, incluant (1) des régimes de contraintes extensifs liés à l'ouverture l'océan Atlantique Sud (145.5-112 Ma), avec un σ3 orienté NE-SW à E-W, et à l'échelle du bassin des failles normales orientées N-S et NE-SW. Cette phase d'extension n'est observée que dans les formations syn-rift. (2) des régimes de contraintes extensifs associés à une tectonique salifère locale affectant les formations post sel, trouvés uniquement dans la formation Sendji (101 à 80 Ma) avec un σ3 orienté ~N-S et ~E-W. (3) Des régimes de contraintes compressifs et décrochants avec un σ1 horizontal orienté ~N-S à NE-SW probablement liés à la collision Afrique-Eurasie. (4) Des régimes de contraintes compressifs et décrochants avec un σ1 horizontal orienté ~E-W que nous avons proposé d’attribuer à la poussée à la ride médio-Atlantique et qui prévalent depuis ~15 - 10 Ma
This thesis aims to test methodologies allowing the reconstruction of the evolution of reservoir properties and their pressure. This manuscript presents (1) a petrological characterization of the reservoir rocks with an estimation of the timing of porosity evolution, (2) the results of a paleopiezometric study, and (3) an evolution of effective stresses and potential fluid (over)pressures that prevailed in the carbonate reservoir during its evolution. These tools allow the reconstruction of the burial history and the paleostresses experienced by carbonate reservoirs in a passive margin. For this purpose, this work was based on a coupled approach of two complementary paleopiezometric tools combining the inversion of calcite twin data and stylolite roughness data. This approach was combined with petrographic, geochemical, geomechanical and geochronological analyses to fully characterize the reservoir. The studied material during this thesis consists of offshore cores recovered from deep wells provided by TotalEnergies located in the Lower Congo and Kwanza basins on the West African margin of the South Atlantic Ocean. These basins underwent a rifting event in the early Cretaceous times (145.5 - 112 Ma). The study of the porosity destruction of the pre-salt reservoirs of the syn-rift TOCA formation of Barremian age (130-125 Ma) from offshore core located in the Lower Congo basin revealed that the initial porosity was reduced to its current value of 4-8% during the first 35 Ma of its burial history, reaching ~10% after only 10 Ma, i.e. in the first 400-500 meters of burial and that the current porosity has not evolved significantly since 95 Ma (end of stylolitization). This study has shown that the outcome of reservoir properties in bioclastic carbonate formations such as the TOCA formation may be largely controlled by early and very shallow diagenetic processes rather than by mesogenetic reactions that occur later in the burial history. A paleopiezometric study was carried out in order to reconstruct the burial and paleostress history of the TOCA (syn-rift) Barremian and Sendji (post-rift) Albian carbonate formations on the West African margin. Paleopiezometry based on stylolite roughness inversion and calcite twins inversion was combined with fracture analysis, U-Pb geochronological dating of the calcite cement and burial modelling of the both formations to unravel the orientations and magnitudes of horizontal and vertical stresses that affected the TOCA and Sendji formations over time. The inversion of calcite macles on early diagenetic cements revealed that syn-rift and post-rift carbonates recorded a complex, polyphase paleostress history, (1) extensional stress regimes related to the opening of the South Atlantic ocean (145.5-112 Ma), with a σ3 oriented NE-SW to E-W, and at the basin scale N-S and NE-SW oriented normal faults. This extensional phase is only recorded by the TOCA syn-rift formation. (2) Extensional stress regimes associated with local salt tectonics that affect the post-salt formations, only found in the Sendji formation (101 to 80 Ma) with a σ3 oriented ~N-S and ~E-W. (3) Compressional and strike-slip stress regimes with horizontal σ1 oriented ~N-S to NE-SW probably related to the Africa-Eurasia collision at ~67-60 Ma. (4) Compressional stress regimes with horizontal σ1 oriented ~E-W that we proposed to attribute to the mid-Atlantic ridge push and that have prevailed since 15-10 Ma onwards

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Ess, J. W. „Characterization of dispersive and distributive mixing in a co-rotating twin-screw compounding extruder“. Thesis, Brunel University, 1989. http://bura.brunel.ac.uk/handle/2438/5239.

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A new design of closely intermeshing co-rotating twin-screw compounding extruder, developed at Brunel University, has been utilized in the development of quantitative techniques for characterization of dispersive and distributive mixing in thermoplastics materials prepared by extrusion compounding. Image analysis procedures were used to quantify mixing of polypropylene composites containing calcium carbonate filler using reflected light microscopy on polished surfaces, and transmitted light microscopy of microtomed pigmented sections. Stereological statistics have been applied to raw sample data; results are discussed in relation to mechanistic phenomena influencing particle agglomeration, dispersion and distribution of fillers in thermoplastics. Dispersive or intensive mixing determined from calcium carbonate filled polypropylene specimens showed that processing parameters had no significant influence except when filler was added midway along the machine although the melting zone was highlighted as having a marked effect on the rate of filler dispersion. Premixing of filler and polymer introduced additional agglomeration into the filler. A series of model experiments were undertaken to assess the influence of specific parameters. In this context moisture content emerged as having the single most important effect on filler compaction. Distributive or extensive mixing of carbon black pigmented specimens was very significantly affected by the presence of segmented disc elements at the end of the screws. These elements produced more than a six-fold increase in distributive mixing in the extrudate.

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Leligny, Henri. „Etude des cristaux hydrates isoles dans les diagrammes cdcl::(2)-h::(2)o, cdbr::(2)-h::(2)o et cdcl::(2)-cacl::(2)-h::(2)o : structures atomiques et proprietes cristallochimiques“. Caen, 1987. http://www.theses.fr/1987CAEN2022.

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Determination par diffraction rx des arrangements atomiques de neuf phases cristallines hydratees. Les polyedres de coordination des cations s'organisent en trois types structuraux : chaines simples (cd); empilement en couches (cd); chaines mixtes (cd,ca). Quatre phases possedent des structures caracterisees par une pseudo-symetrie marquee. Les macles et les transformations orientees, observees sur certains cristaux, sont interpretees par l'existence de pseudo-symetrie locale et de parentes structurales entre blocs atomiques des hydrates concernes

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Burgin, Hugo Bonython. „A Multiscale Approach towards the Characterisation of Upper Crustal Deformation at Passive Continental Margins: A Case Study on the Otway Basin, Australia“. Thesis, 2019. http://hdl.handle.net/2440/120858.

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This thesis presents a multiscale structural analysis of upper crustal deformation at a passive continental margin, using the Jurassic - Quaternary Otway Basin along Australia’s southern margin as a case study. Techniques of structural analyses across the micro (calcite twin, magnetic and porefabric analyses), meso (wellbore and outcrop natural fracture analysis) and macroscales (three-dimensional seismic interpretation) providing an effective means of characterising stress and strain across space and time. The integration of these investigative methods at a passive continental margin for the first time, has assisted in reducing structural uncertainty for basin evolution models, delivering original insights into the evolution of stress within these tectonic environments. The results of this study show magnitudes of maximum differential stress as high as 69MPa during extension and continental breakup, in contrast to magnitudes as low as 13MPa during basin inversion. The influence of high extensional stresses during continental break up, resulting in layer parallel stretching (LPSt), a microstructural strain which may develop in layered rock, characterised by an azimuth of stretching or thinning, orthogonal to the orientation of regional extensional faults. LPSt occurs in the early stages of extension, prior to the development of calcite twins, natural fractures, and faults which occur progressively as the intensity and duration of extension increases. This is evidenced in the Otway Basin, where Late Cretaceous aged NE-SW and N-S oriented LPSt is co-axial with extensional azimuths during that time, derived from the stress inversion of seismic scale faults, calcite twins and natural fractures from the outcrop and wellbore. The neotectonic preservation of LPSt in the Otway Ranges, an uplifted section of Early Cretaceous sediments in the Otway Basin, suggests that early grain-scale extensional strain can be preserved during ensuing phases of inversion at continental margins. As during the process of inversion, stress is primarily released through the reactivation of previously formed extensional fault and detachment systems. A process of deformation that results in low levels of coupling between the basement and cover, an observation that is supported by the low magnitudes of compressional stress (13MPa) calculated during the same period. Additionally, the results of this study have improved our understanding of sub-surface fluid flow in the Otway Basin. Geomechanical modelling demonstrating that low contemporary magnitudes of effective normal stress, acting on NW-SE oriented faults, striking parallel to the orientation of maximum horizontal stress, results in a high risk of fault dilation. This suggests that future efforts of exploration for conventional oil and gas systems within the Otway Basin, are best focused where E-W, N-S and NE-SW striking faults interact with the major NW-SE fabric, or where the influence of basin inversion is most pronounced. A major outcome of this study is a new structural framework for the Otway Basin, one that is defined by a consistent pattern of NW-SE striking faults across much of the basin, in contrast to the previous structural model of opposing fault trends in the west and east. The new framework characterises a structural trend that is consistent with faulting patterns in sedimentary provinces to the west and east along Australia’s southern margin.
Thesis (Ph.D.) -- University of Adelaide, Australian School of Petroleum, 2019

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Bücher zum Thema "Calcite twins"

Charles, Emmanuel. Calcite-twin fabric as an indicator of progressive shortening in the Gros Ventre Range, Wyoming. 1989.

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Charles, Emmanuel. Calcite-twin fabric as an indicator of progressive shortening in the Gros Ventre Range, Wyoming. 1989.

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Buchteile zum Thema "Calcite twins"

Pascal, Christophe. „Inversion of calcite twins“. In Paleostress Inversion Techniques, 155–69. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-12-811910-5.00002-6.

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„Calcite Twin Plane“. In Nanoscale. The MIT Press, 2009. http://dx.doi.org/10.7551/mitpress/8166.003.0026.

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Wark, John. „Calcium, Other Nutrients, Exercise and Bone Health in Twins“. In Diet, Nutrients, and Bone Health. CRC Press, 2011. http://dx.doi.org/10.1201/b11228-29.

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Paton, Lynda, Thomas Beck, Caryl Nowson, Melissa Cameron, Susan Kantor, Heather McKay, Mark Forwood und John D. Wark. „A Co-Twin calcium intervention Trial in Premenarcheal Girls“. In Nutritional Aspects of Osteoporosis, 35–43. Elsevier, 2004. http://dx.doi.org/10.1016/b978-012141704-8/50042-8.

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Craddock, John P., David H. Malone, Alex Konstantinou, John Spruell und Ryan Porter. „Calcite twinning strains associated with Laramide uplifts, Wyoming Province“. In Tectonic Evolution of the Sevier-Laramide Hinterland, Thrust Belt, and Foreland, and Postorogenic Slab Rollback (180–20 Ma). Geological Society of America, 2022. http://dx.doi.org/10.1130/2021.2555(06).

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ABSTRACT We report the results of 167 calcite twinning strain analyses (131 limestones and 36 calcite veins, n = 7368 twin measurements)t from the Teton–Gros Ventre (west; n = 21), Wind River (n = 43), Beartooth (n = 32), Bighorn (n = 32), and Black Hills (east; n = 11) Laramide uplifts. Country rock limestones record only a layer-parallel shortening (LPS) strain fabric in many orientations across the region. Synorogenic veins record both vein-parallel shortening (VPS) and vein-normal shortening (VNS) fabrics in many orientations. Twinning strain overprints were not observed in the limestone or vein samples in the supracrustal sedimentary veneer (i.e., drape folds), thereby suggesting that the deformation and uplift of Archean crystalline rocks that form Laramide structures were dominated by offset on faults in the Archean crystalline basement and associated shortening in the midcrust. The twinning strains in the pre-Sevier Jurassic Sundance Formation, in the frontal Prospect thrust of the Sevier belt, and in the distal (eastern) foreland preserve an LPS oriented approximately E-W. This LPS fabric is rotated in unique orientations in Laramide uplifts, suggesting that all but the Bighorn Mountains were uplifted by oblique-slip faults. Detailed field and twinning strain studies of drape folds identified second-order complexities, including: layer-parallel slip through the fold axis (Clarks Fork anticline), attenuation of the sedimentary section and fold axis rotation (Rattlesnake Mountain), rotation of the fold axis and LPS fabric (Derby Dome), and vertical rotations of the LPS fabric about a horizontal axis with 35% attenuation of the sedimentary section (eastern Bighorns). Regional cross sections (E-W) across the Laramide province have an excess of sedimentary veneer rocks that balance with displacement on a detachment at 30 km depth and perhaps along the Moho discontinuity at 40 km depth. Crustal volumes in the Wyoming Province balance when deformation in the western hinterland is included.

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Noda, Masafumi, Tomomi Ito, Yoshio Gonda, Hisashi Mori und Kunio Funami. „Texture, Microstructure, and Mechanical Properties of Calcium- Containing Flame-Resistant Magnesium Alloy Sheets Produced by Twin-Roll Casting and Sequential Warm Rolling“. In Magnesium Alloys - Properties in Solid and Liquid States. InTech, 2014. http://dx.doi.org/10.5772/58940.

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Konferenzberichte zum Thema "Calcite twins"

White, Samuel, und Jeffrey Rahl. „AN EBSD-BASED APPROACH TO CALCULATING PALEOSTRESSES USING CALCITE TWINS: AN EXAMPLE FROM THE ARBUCKLE MOUNTAINS, OK“. In GSA Connects 2022 meeting in Denver, Colorado. Geological Society of America, 2022. http://dx.doi.org/10.1130/abs/2022am-378667.

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Arboit*, Francesco, Khalid Amrouch, Alan S. Collins, Rosalind King* und Christopher Morley. „Determination of Stress and Strain Evolution From Faults and Calcite Twins on the Western Margin of the Indochina Block“. In International Conference and Exhibition, Melbourne, Australia 13-16 September 2015. Society of Exploration Geophysicists and American Association of Petroleum Geologists, 2015. http://dx.doi.org/10.1190/ice2015-2210784.

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Amrouch, K., O. Lacombe, J. M. Daniel, P. Robion, J. P. Callot und N. Bellahsen. „Quantification of Stress and Strain Using Calcite Twins and Anisotropy of Physical Rock Properties in a Folded/Fractured Reservoir“. In 1st International Petroleum Conference and Exhibition Shiraz 2009. Netherlands: EAGE Publications BV, 2009. http://dx.doi.org/10.3997/2214-4609.20145867.

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Konovalchik, Nicholas A., und Jeffrey M. Rahl. „USING ELECTRON BACKSCATTER DIFFRACTION TO PERFORM CALCITE TWIN PALEOSTRESS ANALYSIS: METHODOLOGY AND APPLICATION TO THE ARBUCKLE MOUNTAINS“. In Joint 69th Annual Southeastern / 55th Annual Northeastern GSA Section Meeting - 2020. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020se-345360.

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Jiang, Guo, und Hanxiong Huang. „Effect of Flow Field on Online Shear Viscosity of PP/nano-CaCO3 Composites“. In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-15808.

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Polymer nanocomposites have been regarded as a new category of engineering materials and attracted technical and scientific interest. Recently rheological analysis became an effective tool for investigating the microstructures of nanocomposites. However, the online rheological property of nanocomposites during compounding was seldom studied. In this work, two types of screw configurations in twin-screw extruder were selected, one provides high shearing intensity and the other provides high shearing/mixing intensity. In addition, chaotic mixing was induced by installing a single screw extruder with a convective screw at the end of the twin-screw extruder to compound the nanocomposites. The online melt shear viscosity of nanocomposite was measured using Haake ProFlow online rheometer. Effects of high shearing, high shearing/mixing, and chaotic mixing on the online shear viscosity for polypropylene (PP)/nano-calcium carbonate (nano-CaCO3) composites were investigated. The study showed that the chaotic mixing facilitates the processing of the nanocomposite.

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Huang, Han-Xiong, und Jian-Kang Wang. „Microcellular PP-CaCO3 Nanocomposites: Relationship Between Nanocomposite Morphology and Foam Morphology“. In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-80846.

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Polymeric nanocomposites exhibit high potential as a new material for carbon dioxide (CO2) foaming. In this paper, a polypropylene (PP)/nano-calcium carbonate (nano-CaCO3) composite was selected to investigate the relationship between nanocomposite morphology and foam morphology. Nanocomposites were prepared using a twin-screw extruder with screw including both shearing and mixing elements. Nanocomposites with different morphology via changing the nano-CaCO3 content were then foamed by using supercritical CO2 in a batch system. Effect of nano-CaCO3 content on the volume expansion ratio, and cell coalescence were studied.

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Huang, Han-Xiong, Guo Jiang und Shan-Qiang Mao. „Effect of Flow Fields on Morphology of PP/Nano/CaCO3 Composite and Its Rheological Behavior“. In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-80830.

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Polypropylene (PP)/nano-calcium carbonate (nano-CaCO3) composite was prepared using a co-rotating, intermeshing twin-screw extruder. The effect of flow fields on the morphology of the nanocomposite was investigated. Transmission electron microscopy (TEM) was used for the determination of the morphology in the nanocomposite. The crystallization behavior of the nanocomposite was studied by using differential scanning calorimetry (DSC) and the melt shear viscosity was investigated by a melt flow index tester. The study showed that the flow field, through appropriately combining the type of the screw elements in this work, plays an important role in developing morphology of the nanocomposite. In addition, it was shown that the melt viscosity for the nanocomposite at the filler content less than 10 wt% is lower than that of neat PP.

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Huang, Han-Xiong, Xiao-Hui Sun und Jian-Kang Wang. „Effect of Nano-Particles on Cellular Structure of Foamed PP-HDPE Blend Using Supercritical Fluid“. In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43906.

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Microcellular foaming of general polypropylene (PP) is a hot subject, but there are some difficulties in its foaming due to its low melt strength, narrow foaming temperature window, and so on. This work attempted to the improvement of PP microcellular foaming by adding nano-montmorillonite and nano-calcium carbonate into PP-high-density polyethylene (HDPE) blend. The nanocomposites were prepared using a twin-screw extruder. The foaming was carried out by a batch process with supercritical carbon dioxide as a blowing agent. Microstructure of the nanocomposites was examined using transmission electron microscopy. The cellular structure of foams was examined using a scanning electron microscope. The effects of nano-particle concentration and type on the cellular structure, cell density, cell diameter, and sample density were investigated. The results showed that the main factor controlling the cellular structure of foamed nanocomposites is the distribution of nano-particles.

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Dimitrova, Violeta, Sonya Damyanova und Dimitar Dimitrov. „STOCKS OF CHEMICAL ELEMENTS IN LITTERFALL IN BEECH (FAGUS SYLVATICA L.) FORESTS IN WESTERN STARA PLANINA“. In 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023/3.1/s14.40.

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The litterfall (fallen leaves, flowers, fruits and twigs) in the forests represents part of dead plant mass. The quantity and quality of litterfall in forests plays an important role in their state. Through it, a large part of chemical elements is returned to the cycle of the ecosystem, it is an essential carbon depot, it affects regeneration, soil moisture, fertility, composition, fauna and flora. The study presents data on stocks of chemical elements in annual literfall of Western Stara planina. The sample plots are located on the territory of the Petrohan LTER site. The average total quantity of litterfall was 481.17 g.m-2. The leaves were 54%, cupulas were 23%, seed were 21% and the fraction of branches had the smallest share - from 2%. The total annual amount of elements returned to the beech forest ecosystem with leaves was 1569.42 kg.ha-1, of which macroelements are 1560.98 kg.ha-1, and microelements - 8.46 kg.ha-1. The predominant elements were: carbon - about 80%, hydrogen - about 13%, nitrogen - 3% and calcium - 2%. The remaining elements were represented in very small amounts � less than 1%. Microelements were presented in the following sequence: Mg >Mn >Fe >Zn >Pb >Cu. 790.88 kg.ha-1 elements were returned annually through the seeds and 582.21 kg.ha-1 elements were annually returned through the cupules.

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Kulikowski, David, Khalid Amrouch, Khalda Hamed Mohammed Al Barwani, Wei Liu und Dennis Cooke. „Insights Into the Tectonic Stress History and Regional 4-D Natural Fracture Distribution in the Australian Cooper Basin Using Etchecopar's Calcite Twin Stress Inversion Technique, 2-D/ 3-D Seismic Interpretation and Natural Fracture Data From Image Logs and Core“. In International Conference and Exhibition, Melbourne, Australia 13-16 September 2015. Society of Exploration Geophysicists and American Association of Petroleum Geologists, 2015. http://dx.doi.org/10.1190/ice2015-2224164.

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