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Journal articles on the topic 'Calcite twinning'

Author: Grafiati

Published: 4 June 2021

Last updated: 25 May 2024

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1

Leiss, B., S. Siegesmund, and K. Weber. "Texture Asymmetries as Shear Sense Indicators in Naturally Deformed Mono- and Polyphase Carbonate Rocks." Textures and Microstructures 33, no. 1-4 (January 1, 1999): 61–74. http://dx.doi.org/10.1155/tsm.33.61.

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The microstructural and quantitative texture analyses of a naturally deformed calcite mylonite, a dolomite mylonite and a dolomitic calcite mylonite reveal different texture asymmetries for comparable deformation conditions. Calcite shows a c-axis maximum rotated against the shear sense with regard to the main shear plane. In contrast, the dolomite shows a c-axis maximum rotated with the shear sense. In accordance with the experimental and simulated textures from the literature, this difference proves e-twinning and r-slip for calcite and f-twinning and c-slip for dolomite as the main deformation mechanisms. The dolomitic calcite mylonite shows for both the calcite and the dolomite a c-axis maximum rotated against the shear sense. On account of the microstructure of this sample, the dolomite texture has been passively overtaken from the deformation texture of calcite during a late-deformative dolomitization. The results significantly contribute to the interpretation that the sampled shear zone is a transpressive strike–slip fault.

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2

Pokroy, B., M. Kapon, F. Marin, N. Adir, and E. Zolotoyabko. "Protein-induced, previously unidentified twin form of calcite." Proceedings of the National Academy of Sciences 104, no. 18 (April 25, 2007): 7337–41. http://dx.doi.org/10.1073/pnas.0608584104.

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Using single-crystal x-ray diffraction, we found a formerly unknown twin form in calcite crystals grown from solution to which a mollusc shell-derived 17-kDa protein, Caspartin, was added. This intracrystalline protein was extracted from the calcitic prisms of the Pinna nobilis shells. The observed twin form is characterized by the twinning plane of the (108)-type, which is in addition to the known four twin laws of calcite identified during 150 years of investigations. The established twin forms in calcite have twinning planes of the (001)-, (012)-, (104)-, and (018)-types. Our discovery provides additional evidence on the crucial role of biological macromolecules in biomineralization.

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3

Rocher, Muriel, Marc Cushing, Francis Lemeille, and Stéphane Baize. "Stress induced by the Mio-Pliocene Alpine collision in northern France." Bulletin de la Société Géologique de France 176, no. 4 (July 1, 2005): 319–28. http://dx.doi.org/10.2113/176.4.319.

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Abstract In most rocks, tectonic stress induces crystalline deformation, such as mechanical twinning. The inverse analysis of calcite twinning allows reconstruction of both directions and values of the paleostress field. The Etchecopar inverse method using calcite twinning has been improved in this paper, lowering the uncertainties on the calculated stress values. Calcite was sampled in the foreland of the western Alps, along a SE-NW section from the Jura Mountains to the Isle of Wight. The calcite twinning inversion has identified the successive Cenozoic tectonic events, named “Pyrenean” compression, “Oligocene” extension and “Alpine” compression. The distribution of the Mio-Pliocene Alpine orogenic stress was specified. This stress field varies in terms of stress regime, directions and values. The horizontal principal stress trends E-W in southern France, WNW in the centre, and NW in the North, which can be attributed to the Alpine indenter phenomenon. The tectonic stress regime roughly corresponds to a pure compression in the Jura and rapidly evolves to the NW to a strike-slip state of stress, then beyond the Paris basin’s centre to a perpendicular extension. Unlike the Pyrenean or Appalachian foreland stress, the Alpine differential stress does not significantly decrease from the Jura front to the far field (30 to 25 MPa). Moreover, stress values vary from one area to another, low in the Burgundy high, fractured and uprising during this tectonic event, and high in Paris basin centre, poorly fractured and subsiding during this event. Three possible explanations are proposed : variation in crust thickness, crustal buckling during the Mio-Pliocene, and pre-existing fractures.

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4

Parlangeau, Camille, Alexandre Dimanov, Olivier Lacombe, Simon Hallais, and Jean-Marc Daniel. "Uniaxial compression of calcite single crystals at room temperature: insights into twinning activation and development." Solid Earth 10, no. 1 (February 7, 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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5

Lacombe, Olivier, Camille Parlangeau, Nicolas E. Beaudoin, and Khalid Amrouch. "Calcite Twin Formation, Measurement and Use as Stress–Strain Indicators: A Review of Progress over the Last Decade." Geosciences 11, no. 11 (October 28, 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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6

Larsson, A. K., and A. G. Christy. "On twinning and microstructures in calcite and dolomite." American Mineralogist 93, no. 1 (January 1, 2008): 103–13. http://dx.doi.org/10.2138/am.2008.2520.

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7

Craddock, John P., Uwe Ring, and O. Adrian Pfiffner. "Deformation of the European Plate (58-0 Ma): Evidence from Calcite Twinning Strains." Geosciences 12, no. 6 (June 20, 2022): 254. http://dx.doi.org/10.3390/geosciences12060254.

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We present a data set of calcite twinning strain results (n = 209 samples; 9919 measured calcite twins) from the internal Alpine nappes northwestward across the Alps and Alpine foreland to the older extensional margin along the Atlantic coast in Ireland. Along the coast of Northern Ireland, Cretaceous chalks and Tertiary basalts are cross-cut by calcite veins and offset by calcite-filled normal and strike-slip faults. Both Irish sample suites (n = 16 with four U-Pb vein calcite ages between 70–42 Ma) record a sub-horizontal SW-NE shortening strain with vertical extension and no strain overprint. This sub-horizontal shortening is parallel to the margin of the opening of the Atlantic Ocean (~58 Ma), and this penetrative fabric is only observed ~100 km inboard of the margin to the southeast. The younger, collisional Alpine orogen (~40 Ma) imparted a stress–strain regime dominated by SE-NW sub-horizontal shortening ~1200 km northwest from the Alps preserved in Mesozoic limestones and calcite veins (n = 32) in France, Germany and Britain. This layer-parallel shortening strain (−3.4%, 5% negative expected values) is preserved across the foreland in the plane of Alpine thrust shortening (SE-NW) along with numerous outcrop-scale contractional structures (i.e., folds, thrust faults). Calcite veins were observed in the Alpine foreland in numerous orientations and include both a SE-NW layer-parallel shortening fabric (n = 11) and a sub-vertical NE-SW vein-parallel shortening fabric (n = 4). Alpine foreland strains are compared with twinning strains from the frontal Jura Mountains (n = 9; layer-parallel shortening), the Molasse basin (n = 26; layer-parallel and layer-normal shortening), Pre-Alp nappes (n = 39; layer-parallel and layer-normal shortening), Helvetic and Penninic nappes (Penninic klippe; n = 46; layer-parallel and layer-normal shortening plus four striated U-Pb calcite vein ages ~24 Ma) and calcsilicates from the internal Tauern window (n = 4; layer-normal shortening). We provide a chronology of the stress–strain history of the European plate from 58 Ma through the Alpine orogen.

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8

Lacombe, Olivier. "Calcite Deformation Twins: From Crystal Plasticity to Applications in Geosciences." Geosciences 12, no. 7 (July 17, 2022): 280. http://dx.doi.org/10.3390/geosciences12070280.

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9

Craddock, John, Junlai Liu, and Yuanyuan Zheng. "Twinning Strains in Synfolding Calcite, Proterozoic Sinian System, China." Geosciences 8, no. 4 (April 11, 2018): 131. http://dx.doi.org/10.3390/geosciences8040131.

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10

Rutter, Ernest, David Wallis, and Kamil Kosiorek. "Application of Electron Backscatter Diffraction to Calcite-Twinning Paleopiezometry." Geosciences 12, no. 6 (May 25, 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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11

Rez, Jiří. "TwinCalc: A multitool for calcite twinning based stress analysis." Applied Computing and Geosciences 5 (March 2020): 100020. http://dx.doi.org/10.1016/j.acags.2020.100020.

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12

Shelley, David. "Calcite twinning and determination of paleostress orientations: three methods compared." Tectonophysics 206, no. 3-4 (June 1992): 193–201. http://dx.doi.org/10.1016/0040-1951(92)90376-h.

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13

Bueble, S., and W. W. Schmahl. "Mechanical twinning in calcite considered with the concept of ferroelasticity." Physics and Chemistry of Minerals 26, no. 8 (September 29, 1999): 668–72. http://dx.doi.org/10.1007/s002690050232.

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14

Craddock, John P., David H. Malone, Jakob Wartman, Megan J. Kelly, Liu Junlai, Maura Bussolotto, Chiara Invernizzi, Jeff Knott, and Ryan Porter. "Calcite twinning strains from syn-faulting calcite gouge: small-offset strike-slip, normal and thrust faults." International Journal of Earth Sciences 109, no. 1 (December 4, 2019): 1–42. http://dx.doi.org/10.1007/s00531-019-01783-x.

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15

Németh, Péter. "Diffraction Features from (101¯4) Calcite Twins Mimicking Crystallographic Ordering." Minerals 11, no. 7 (July 4, 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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16

Rowe, K. J., and E. H. Rutter. "Palaeostress estimation using calcite twinning: experimental calibration and application to nature." Journal of Structural Geology 12, no. 1 (January 1990): 1–17. http://dx.doi.org/10.1016/0191-8141(90)90044-y.

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17

Côté, A. S., R. Darkins, and D. M. Duffy. "Deformation twinning and the role of amino acids and magnesium in calcite hardness from molecular simulation." Physical Chemistry Chemical Physics 17, no. 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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18

Parlangeau, Camille, Alexandre Dimanov, and Simon Hallais. "In-Situ Evolution of Calcite Twinning during Uniaxial Compression of Carrara Marble at Room Temperature." Geosciences 12, no. 6 (May 31, 2022): 233. http://dx.doi.org/10.3390/geosciences12060233.

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Calcite twinning is a dominant deformation mechanism at low temperatures. It is often used to reconstruct paleostresses: orientations of the principal stress axes, stress ratios and differential stress. Despite numerous studies, on single crystals and aggregates, questions remain about the initiation and evolution of the twinning. In particular, the existence of a critical value for the activation of twin planes is debated. In this study, Carrara marble samples were uniaxially deformed at low temperature. The experiments were monitored in situ in an SEM (Scanning Electron Microscope) and a deformation analysis was performed at regular intervals using image correlation. Image correlation analysis shows the link between the overconcentration of strains and the appearance of the first twinned planes. This is followed by a densification and a gradual thickening of the twin lamellae. Fracturing only appears in a third stage as a precursor to the collapse of the sample. The inversion, using the CSIT-2 technique, showed that the twinned planes are globally related to the applied macroscopic stress. The inversion allows one to retrieve the macroscopic stress tensor. Schmid factors were extracted from this analysis and correlated to the loading curves. For crystals of about 200 µm diameter, the threshold value is in between 6.75 and 8.25 MPa.

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19

Covey-Crump, S. J., P. F. Schofield, and E. C. Oliver. "Using neutron diffraction to examine the onset of mechanical twinning in calcite rocks." Journal of Structural Geology 100 (July 2017): 77–97. http://dx.doi.org/10.1016/j.jsg.2017.05.009.

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20

Craddock, John P., David W. Farris, and Aimee Roberson. "Calcite-twinning constraints on stress-strain fields along the Mid-Atlantic Ridge, Iceland." Geology 32, no. 1 (2004): 49. http://dx.doi.org/10.1130/g19905.1.

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21

Richards, R. Peter. "Calcite Crystals from the Old Faylor-Middlecreek Quarry, Winfield, Pennsylvania: Crystal Habits & Twinning." Rocks & Minerals 69, no. 4 (August 1994): 260–70. http://dx.doi.org/10.1080/00357529.1994.9925600.

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22

Chen, Kai, Martin Kunz, Nobumichi Tamura, and Hans-Rudolf Wenk. "Deformation twinning and residual stress in calcite studied with synchrotron polychromatic X-ray microdiffraction." Physics and Chemistry of Minerals 38, no. 6 (March 20, 2011): 491–500. http://dx.doi.org/10.1007/s00269-011-0422-7.

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23

Craddock, John P., and Ben A. van der Pluijm. "Sevier–Laramide deformation of the continental interior from calcite twinning analysis, west-central North America." Tectonophysics 305, no. 1-3 (May 1999): 275–86. http://dx.doi.org/10.1016/s0040-1951(99)00008-6.

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24

Schmahl, W. W., J. Lastam, X. Yin, E. Griesshaber, A. Checa, I. Sánchez-Almazo, M. Kucera, J. Erez, M. Hess, and P. Walther. "Fractal morphology and non-classical twinning of calcite in the hydrogel matrices regulating foraminiferal chamber growth." Acta Crystallographica Section A Foundations and Advances 79, a2 (August 22, 2023): C1183. http://dx.doi.org/10.1107/s2053273323084383.

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25

Rocher, Muriel, Stéphane Baize, Stéphane Jaillet, Edward Marc Cushing, Yannick Lozac'h, and Francis Lemeille. "Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)." Comptes Rendus Geoscience 335, no. 8 (August 2003): 701–8. http://dx.doi.org/10.1016/s1631-0713(03)00115-9.

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26

Craddock, John P., Thomas Klein, Gotthard Kowalczyk, and Gernold Zulauf. "Calcite twinning strains in Alpine orogen flysch: Implications for thrust-nappe mechanics and the geodynamics of Crete." Lithosphere 1, no. 3 (June 2009): 174–91. http://dx.doi.org/10.1130/l31.1.

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27

Craddock, John P., Suzanne D. Craddock, Alex Konstantinou, Andrew R. C. Kylander-Clark, and David H. Malone. "Calcite twinning strain variations across the Proterozoic Grenville orogen and Keweenaw-Kapuskasing inverted foreland, USA and Canada." Geoscience Frontiers 8, no. 6 (November 2017): 1357–84. http://dx.doi.org/10.1016/j.gsf.2017.01.006.

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28

Lacombe, O., K. Amrouch, F. Mouthereau, and L. Dissez. "Calcite twinning constraints on late Neogene stress patterns and deformation mechanisms in the active Zagros collision belt." Geology 35, no. 3 (2007): 263. http://dx.doi.org/10.1130/g23173a.1.

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29

Schuster, Roman, Gerlinde Habler, Erhard Schafler, and Rainer Abart. "Intragranular deformation mechanisms in calcite deformed by high-pressure torsion at room temperature." Mineralogy and Petrology 114, no. 2 (January 7, 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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30

Ong, P. F., B. A. van der Pluijm, and R. Van der Voo. "Early rotation and late folding in the Pennsylvania salient (U.S. Appalachians): Evidence from calcite-twinning analysis of Paleozoic carbonates." Geological Society of America Bulletin 119, no. 7-8 (July 1, 2007): 796–804. http://dx.doi.org/10.1130/b26013.1.

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31

Rocher, Muriel, Marc Cushing, Francis Lemeille, Yannick Lozac'h, and Jacques Angelier. "Intraplate paleostresses reconstructed with calcite twinning and faulting: improved method and application to the eastern Paris Basin (Lorraine, France)." Tectonophysics 387, no. 1-4 (August 2004): 1–21. http://dx.doi.org/10.1016/j.tecto.2004.03.002.

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32

Harris, John H., and Ben A. Van Der Pluijm. "Relative timing of calcite twinning strain and fold-thrust belt development; Hudson Valley fold-thrust belt, New York, U.S.A." Journal of Structural Geology 20, no. 1 (January 1998): 21–31. http://dx.doi.org/10.1016/s0191-8141(97)00093-x.

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33

Hnat, James S., and Ben A. van der Pluijm. "Foreland signature of indenter tectonics: Insights from calcite twinning analysis in the Tennessee salient of the Southern Appalachians, USA." Lithosphere 3, no. 5 (October 2011): 317–27. http://dx.doi.org/10.1130/l151.1.

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34

Craddock, John P., Kimberly J. Nielson, and David H. Malone. "Calcite twinning strain constraints on the emplacement rate and kinematic pattern of the upper plate of the Heart Mountain Detachment." Journal of Structural Geology 22, no. 7 (July 2000): 983–91. http://dx.doi.org/10.1016/s0191-8141(00)00017-1.

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35

Bruno, Marco, Francesco Roberto Massaro, Marco Rubbo, Mauro Prencipe, and Dino Aquilano. "(10.4), (01.8), (01.2), and (00.1) Twin Laws of Calcite (CaCO3): Equilibrium Geometry of the Twin Boundary Interfaces and Twinning Energy." Crystal Growth & Design 10, no. 7 (July 7, 2010): 3102–9. http://dx.doi.org/10.1021/cg100233p.

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36

Shafiei, SH, S. A. Alavi, and M. Mohajjel. "Calcite twinning constraints on paleostress patterns and tectonic evolution of the Zagros hinterland: the Sargaz complex, Sanandaj–Sirjan zone, SE Iran." Arabian Journal of Geosciences 4, no. 7-8 (April 29, 2010): 1189–205. http://dx.doi.org/10.1007/s12517-010-0140-3.

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37

Lindgren, Paula, Mark C. Price, Martin R. Lee, and Mark J. Burchell. "Constraining the pressure threshold of impact induced calcite twinning: Implications for the deformation history of aqueously altered carbonaceous chondrite parent bodies." Earth and Planetary Science Letters 384 (December 2013): 71–80. http://dx.doi.org/10.1016/j.epsl.2013.10.002.

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38

Hnat, James S., Ben A. van der Pluijm, Rob Van der Voo, and William A. Thomas. "Differential displacement and rotation in thrust fronts: A magnetic, calcite twinning and palinspastic study of the Jones Valley thrust, Alabama, US Appalachians." Journal of Structural Geology 30, no. 6 (June 2008): 725–38. http://dx.doi.org/10.1016/j.jsg.2008.01.012.

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39

Klein, T., J. P. Craddock, and G. Zulauf. "Constraints on the geodynamical evolution of Crete: insights from illite crystallinity, Raman spectroscopy and calcite twinning above and below the ‘Cretan detachment’." International Journal of Earth Sciences 102, no. 1 (June 21, 2012): 139–82. http://dx.doi.org/10.1007/s00531-012-0781-4.

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40

Craddock, J. P., D. H. Malone, J. Magloughlin, A. L. Cook, M. E. Rieser, and J. R. Doyle. "Dynamics of the emplacement of the Heart Mountain allochthon at White Mountain: Constraints from calcite twinning strains, anisotropy of magnetic susceptibility, and thermodynamic calculations." Geological Society of America Bulletin 121, no. 5-6 (April 27, 2009): 919–38. http://dx.doi.org/10.1130/b26340.

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41

Craddock, John P., Kim Neilson, Cameron Petersen, Ryan Porter, and David H. Malone. "Calcite twinning fabrics along the Middle America trench, Costa Rica and the Motagua sinistral fault, Honduras and Jamaica: Tectonic implications for the Caribbean plate." Journal of South American Earth Sciences 104 (December 2020): 102816. http://dx.doi.org/10.1016/j.jsames.2020.102816.

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42

Paulsen, Timothy S., Terry J. Wilson, Christie Demosthenous, Cristina Millan, Rich Jarrard, and Andreas Läufer. "Kinematics of the Neogene Terror Rift: Constraints from calcite twinning strains in the ANDRILL McMurdo Ice Shelf (AND-1B) core, Victoria Land Basin, Antarctica." Geosphere 10, no. 5 (October 2014): 828–41. http://dx.doi.org/10.1130/ges01002.1.

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Craddock, John, Maria Princen, Jakob Wartman, Haoran Xia, and Junlai Liu. "Calcite Twinning in the Ordovician Martinsburg Formation, Delaware Water Gap, New Jersey, USA: Implications for Cleavage Formation and Tectonic Shortening in the Appalachian Piedmont Province." Geosciences 6, no. 1 (February 19, 2016): 10. http://dx.doi.org/10.3390/geosciences6010010.

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Sierra, F., A. Schedl, C. McCabe, and D. R. Robbins. "Deformation and magnetization of the Hudson Valley, eastern New York: Results of a study of calcite twinning and anisotropy of magnetic remanence in the Onondaga Limestone." Tectonophysics 217, no. 3-4 (January 1993): 321–29. http://dx.doi.org/10.1016/0040-1951(93)90013-a.

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Juroszek, Rafał, Biljana Krüger, Irina Galuskina, Hannes Krüger, Yevgeny Vapnik, and Evgeny Galuskin. "Siwaqaite, Ca6Al2(CrO4)3(OH)12·26H2O, a new mineral of the ettringite group from the pyrometamorphic Daba-Siwaqa complex, Jordan." American Mineralogist 105, no. 3 (March 1, 2020): 409–21. http://dx.doi.org/10.2138/am-2020-7208.

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Abstract A new mineral, siwaqaite, ideally Ca6Al2(CrO4)3(OH)12·26H2O [P31c, Z = 2, a = 11.3640(2) Å, c = 21.4485(2) Å, V = 2398.78(9) Å3], a member of the ettringite group, was discovered in thin veins and small cavities within the spurrite marble at the North Siwaqa complex, Lisdan-Siwaqa Fault, Hashem region, Jordan. This complex belongs to the widespread pyrometamorphic rock of the Hatrurim Complex. The spurrite marble is mainly composed of calcite, fluorapatite, and brownmillerite. Siwaqaite occurs with calcite and minerals of the baryte-hashemite series. It forms hexagonal prismatic crystals up to 250 μm in size, but most common are grain aggregates. Siwaqaite exhibits a canary yellow color and a yellowish-gray streak. The mineral is transparent and has a vitreous luster. It shows perfect cleavage on (1010). Parting or twinning is not observed. The calculated density of siwaqaite is 1.819 g/cm3. Siwaqaite is optically uniaxial (–) with ω = 1.512(2), ε = 1.502(2) (589 nm), and non-pleochroic. The empirical formula of the holotype siwaqaite calculated on the basis of 8 framework cations and 26 water molecules is Ca6.01(Al1.87Si0.12)Σ1.99[(CrO4)1.71(SO4)1.13(SeO4)0.40]Σ3.24(OH)11.63·26H2O. X-ray diffraction (XRD), Raman, and infrared spectroscopy confirm the presence of OH- groups and H2O molecules and absence of (CO3)2– groups. The crystal structure of this Cr6+-analog of ettringite was solved by direct methods using single-crystal synchrotron XRD data. The structure was refined to an agreement index R1 = 4.54%. The crystal structure of siwaqaite consists of {Ca6[Al(OH)6]2·24H2O}6+ columns with the inter-column space (channels) occupied by (CrO4)2–, (SO4)2–, (SeO4)2–, and (SO3)2– groups and H2O molecules. The tetrahedrally coordinated site occupied by different anion groups is subjected to disordering and rotation of these tetrahedra within the structure. The temperature of siwaqaite formation is not higher than~70–80 °C, as is evident from the mineral association and as inferred from the formation conditions of the natural and synthetic members of the ettringite group minerals, which are stable at conditions of T < 120 °C and pH = 9.5–13. The name siwaqaite is derived from the name of the holotype locality—Siwaqa area, where the mineral was found.

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CHATZARAS, V., P. XYPOLIAS, and T. DOUTSOS. "Exhumation of high-pressure rocks under continuous compression: a working hypothesis for the southern Hellenides (central Crete, Greece)." Geological Magazine 143, no. 6 (September 18, 2006): 859–76. http://dx.doi.org/10.1017/s0016756806002585.

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Combined kinematic, structural and palaeostress (calcite twinning, fault-slip data) analyses are used to study the exhumation mechanism of the high-pressure rocks exposed on the island of Crete (southern Aegean, Greece). Our study shows that the evolution of windows in central Crete was controlled by two main contractional phases of deformation. The first phase (D1) was related to the ductile-stage of exhumation. NNW–SSE compression during D1 caused layer- and transport-parallel shortening in the upper thrust sheets, resulting in nappe stacking via low-angle thrusting. Synchronously, intracontinental subduction led to high-pressure metamorphism which, however, did not affect the most external parts of the southern Hellenides. Subsequent upward ductile extrusion of high-pressure rocks was characterized by both down-section increase of strain and up-section increase of the pure shear component. The second phase (D2) was associated with the brittle-stage of exhumation. D2 was governed by NNE–SSW compression and involved conspicuous thrust-related folding, considerable tectonic imbrication and formation of a Middle Miocene basin. The major D2-related Psiloritis Thrust cross-cuts the entire nappe pile, and its trajectory partially follows and reworks the D1-related contact between upper and lower (high-pressure) tectonic units. Eduction and doming of the Talea Window was accompanied by gravity sliding of the upper thrust sheets and by out-of-the-syncline thrusting. Late-orogenic collapse also contributed to the exhumation process. Therefore, it seems that the high-pressure rocks of central Crete were exhumed under continuous compression and that the role of extension was previously overestimated.

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Beaudoin, Nicolas, Daniel Koehn, Olivier Lacombe, Alexandre Lecouty, Andrea Billi, Einat Aharonov, and Camille Parlangeau. "Fingerprinting stress: Stylolite and calcite twinning paleopiezometry revealing the complexity of progressive stress patterns during folding-The case of the Monte Nero anticline in the Apennines, Italy." Tectonics 35, no. 7 (July 2016): 1687–712. http://dx.doi.org/10.1002/2016tc004128.

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Hawthorne, F. C., M. A. Cooper, D. I. Green, R. E. Starkey, A. C. Roberts, and J. D. Grice. "Wooldridgeite, Na2(P2O7)2(H2O)10: A new mineral from Judkins Quarry, Warwickshire, England." Mineralogical Magazine 63, no. 1 (February 1999): 13–16. http://dx.doi.org/10.1180/002646199548268.

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AbstractWooldridgeite, ideally Na2(P2O7)2(H2O)10, orthorhombic, a = 11.938(1), b = 32.854(2), c = 11.017(1) Å , V = 4321.2(8) Å3, a:b:c = 0.3634:1:0.3353, space group Fdd2, Z = 8, is a new mineral from Judkins Quarry, Nuneaton, Warwickshire, England. Associated minerals are calcite, chalcopyrite, bornite and baryte. It occurs as equant crystals forming rhombic dipyramids; no twinning was observed. It is transparent blue-green with a very pale-blue streak, a vitreous lustre, and does not fluoresce under long- or short-wave ultraviolet light. Wooldridgeite has a Mohs hardness of 2–3, is brittle with an irregular fracture, and has no cleavage. The calculated density is 2.279 g/cm3. In transmitted light, wooldridgeite is colourless, non-pleochroic, and shows no dispersion. It is biaxial negative with α = 1.508(1), β = 1.511(1), γ = 1.517(1), 2V(meas.) = 76.2(5), 2V(calc.) = 71(10)8, X = b, Y = c, Z = a. The strongest five reflections in the X-ray powder diffraction pattern are [d(Å), (I), (hkl)]: 8.23(30)(040), 6.52(100)(131), 4.05(40)(260), 3.255(40)(262); 2.924(40)(371). Electron-microprobe analysis of wooldridgeite gave P2O5 39.37, CuO 20.24, MgO 0.24, CaO 7.73, Na2O 8.33, K2O 0.17, H2O(calc.) 24.72, sum 100.80 wt.%; the corresponding unit formula (based on 24 anions) is (Na1.96K0.03)Ca1.00(Cu1.85Mg0.04)P4.04O14(H2O)10 where the H2O groups were assigned from knowledge of the crystal structure; the infrared absorption spectrum also indicates the presence of H2O in the structure. The mineral is named for James Wooldridge (1923–1995), a fervent amateur mineral collector who discovered this mineral.

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ROCHER, MURIEL, ALAIN TREMBLAY, DENIS LAVOIE, and ANDRÉ CAMPEAU. "Brittle fault evolution of the Montréal area (St Lawrence Lowlands, Canada): rift-related structural inheritance and tectonism approached by palaeostress analysis." Geological Magazine 140, no. 2 (March 2003): 157–72. http://dx.doi.org/10.1017/s0016756803007283.

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The Montréal area belongs to the St Lawrence Lowlands, a Cambrian Early Ordovician passive margin of the Iapetus Ocean, later covered by Appalachian Middle to Upper Ordovician foreland deposits. A structural and palaeostress analysis has been carried out in order to reconstruct its tectonic evolution. The structural map has been revised with new data. Palaeostresses are reconstructed based on inversion of fault slip data, and these results are independently corroborated by the microstructural study of calcite mechanical twinning. Field relationships are used to establish the relative chronology of fractures and to deduce the motion on regional faults. The reconstructed structural and tectonic evolution brings to light some relationships between structural inheritance and tectonic events that have affected the area since Early Palaeozoic times. An early NW–SE extension is responsible for N040-trending faults along the northern border of the St Lawrence Lowlands, and for N090- and N120-trending faults cross-cutting the Montréal area. This extension is followed by WNW–ESE and NNW compressions, which have induced reverse motion on pre-existing faults and generated strike-slip conjugate faults. Subsequent NE–SW and NNW–SSE-directed extensions have reactivated previous faults with normal to strike-slip motions. A late NE–SW compression is recorded in the Monteregian plutons. Compressions in WNW–ESE and NNW directions are consistent with Appalachian collisional tectonism, but N040- and N090-trending faults cross-cut Appalachian folds and foreland deposits. Although the early NW–SE extension is consistent with the collapse of the Iapetan margin in Early Palaeozoic times, most of the present geometry of the St Lawrence Lowlands could be attributed to Mesozoic tectonism, recorded as nearly N–S-directed extensional events.

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Wilton, Derek H. C., Gary M. Thompson, and Dawn Evans-Lamswood. "MLA-SEM Characterization of Sulphide Weathering, Erosion, and Transport at the Voisey’s Bay Orthomagmatic Ni-Cu-Co Sulphide Mineralization, Labrador, Canada." Minerals 11, no. 11 (November 4, 2021): 1224. http://dx.doi.org/10.3390/min11111224.

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The Voisey’s Bay nickel-copper-cobalt (Ni-Cu-Co) sulphide deposits constitute a significant resource of orthomagmatic mineralization. The deposits are not exposed at the surface except for in a small ferruginous gossan (Discovery Hill). The subsequent geophysical surveys and diamond drilling led to the discovery of the Ovoid ore body, buried beneath 20 m of till, and other deeper deposits in the bedrock. This study was initiated to characterize the sulphide mineralogy of these deposits through various stages of weathering, erosion, and transport. Because the samples ranged from bedrock through to a variety of surficial sediment types, the automated SEM-based identification provided by the MLA-SEM system was the ideal technique to quantitatively evaluate mineral distributions in the different media. The derived MLA-SEM data indicate that, aside from the Discovery Hill gossan, the surface sulphide mineralization at Voisey’s Bay was weathered in a pre-glaciation regolith at the Mini-Ovoid deposit and, on the surface of the Ovoid deposit, the massive sulphide was unoxidized due to a thin calcite-cemented clay cover. Pentlandite is very preferentially oxidized compared to other sulphides in the Voisey’s Bay ore, to depths of up to 10 m in bedrock. Conversely, within the coarse reject samples of crushed drill cores stored in sealed plastic bags, pyrrhotite was altered, whereas pentlandite and chalcopyrite are stable, presumably due to anaerobic reactions. The MLA-SEM detected trace amounts of minute sulphide grains in surficial sediments, but their contents abruptly decreased with distance from the sulphide mineralization. Microtextures such as troilite and pentlandite exsolution or twinning in pyrrhotite, however, could be observed in the fine sulphide grains from till, suggesting a derivation from orthomagmatic sulphide material, such as the Voisey’s Bay mineralization.

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