The Sheeted Dike Layer of the Betts Cove Ophiolite Complex does not Represent Spreading

1974 ◽  
Vol 11 (1) ◽  
pp. 208-210 ◽  
Author(s):  
P. W. G. Brock
Keyword(s):  
Plastic Deformation ◽  
Brittle Fracture ◽  
Ultramafic Rocks ◽  
Surface Cool ◽  
Ophiolite Complex ◽  
Near Surface ◽  
Mafic Rocks

Dikes of the sheeted dike layer are conspicuously chilled against the underlying mafic and layered ultramafic rocks, indicating that the older rocks were relatively cool when the dikes were intruded. Cool mafic rocks could spread only by brittle fracture and infilling by dike material. Near-surface, cool ultramafic rocks could spread by brittle fracture or, possibly, by plastic deformation. The absence of significant infilling, and the preservation of cumulate textures in the extensive layering indicate that spreading did not take place.

Felsic plutonic rocks from the southern portion of the New Caledonian Ultramafic Belt

1973 ◽  
Vol 110 (5) ◽  
pp. 431-446 ◽  
Author(s):  
K. A. Rodgers
Keyword(s):  
New Caledonia ◽  
Ultramafic Rocks ◽  
Calc Alkaline ◽  
Mafic Rocks ◽  
Alkaline Magma ◽  
Southwest Pacific ◽  
Plutonic Rocks

SummaryGranodiorite stocks were intruded into the alpine peridotites of southern New Caledonia in the Eocene following overthrusting of the ultramafics onto the sialic core of the island. Strong zoning, from mela-diorite to granodiorite, is developed in one pluton and is believed to be the result of assimilation of ultramafic and mafic rocks by the calc-alkaline magma. Evidence in favour of a consanguineous relationship between the felsic and ultramafic rocks is largely circumstantial. In their petrography, mineralogy and chemistry, the rocks show few differences from other felsic plutonics of Tertiary age in the southwest Pacific.

scholarly journals Petrological implications for the production of methane and hydrogen in hyperalkaline springs from the Othrys ophiolite, Greece.

2013 ◽  
Vol 47 (1) ◽  
pp. 449
Author(s):  
B. Tsikouras ◽  
G. Etiope ◽  
E. Ifandi ◽  
S. Kordella ◽  
G. Papatheodorou ◽  
...  
Keyword(s):  
Low Temperature ◽  
Co2 Hydrogenation ◽  
Ultramafic Rocks ◽  
Mafic Rocks ◽  
Silica Activity ◽  
High Silica ◽  
Greenhouse Gas Budget ◽  
The Origin Of Life ◽  
Life On Earth ◽  
Shed Light

Altered mafic and ultramafic rocks were studied in correspondence with hyperalkaline, CH4-bearing and very low-hydrogen spring waters in the Othrys ophiolite, whose chemical features are typical of present day serpentinisation. The H2 paucity is interpreted as the result of the incorporation of high-silica, aqueous fluids, probably derived from mafic rocks. The vein assemblage of serpentine + magnetite is related to circulation of low-silica fluids whereas serpentine + talc, tremolite after garnet and Fe-rich serpentine in the interior of serpentine veins reflect a late circulation of low-temperature (likely below 120 °C), high silica activity fluids. The highsilica conditions might have limited or interrupted the production of H2, which was subsequently consumed by CO2 hydrogenation to produce CH4. The lack of H2 could also be due to peridotite alteration by CO2-rich fluids. This would imply that the Othrys peridotites, among similar methane-bearing peridotites, may be considered as terrestrial analogues of Martian ultramafic rocks, which are thought to contribute to methane emission in the atmosphere of Mars. Understanding the mechanism of methane abiotic production will likely shed light to the details of some crucial aspects as the greenhouse-gas budget, the production of hydrocarbons and the origin of life on Earth.

Leka Ophiolite Complex as analogy to the serpentinization-carbonation system on Mars.

2021 ◽  
Author(s):  
benjamin bultel ◽  
Agata M. Krzesinska ◽  
Damien Loizeau ◽  
François Poulet ◽  
Håkon O. Astrheim ◽  
...  
Keyword(s):  
Near Infrared ◽  
Nir Spectroscopy ◽  
Ground Truth ◽  
Ultramafic Rocks ◽  
Ophiolite Complex ◽  
Spectral Parameters ◽  
Thin Sections ◽  
Accessory Minerals ◽  
Mineral Assemblages ◽  
Alteration Minerals

<p>Serpentinization and carbonation have affected ultramafic rocks on Noachian Mars in several places called here serpentinization-carbonation systems (SCS). Among the most prominent SCS revealing mineral assemblages characteristic of serpentinization/carbonation is the Nili Fossae region [1]. Jezero crater – the target of the Mars 2020 rover –hosted a paleolake which constitutes a sink for sediments from Nili Fossae [1]. Thanks to the near infrared spectrometer onboard Mars2020 [2], the mission has the potential to offer ground truth measurement for other putative serpentinization/carbonation system documented on Mars. Several important aspects that may be addressed are: Do carbonates result from primary alteration of olivine-rich lithologies or are they derived by reprocessing of previous alteration minerals [3]? What is the composition? and nature of the protolith, which appear to be constituted of considerable amounts of olivine [4]? To reveal critical information regarding the conditions of serpentinization/carbonation, accessory minerals need detailed studies [1; 5]. In case of Jezero Crater, and serpentinization on Mars in general, the main alteration minerals are identified, but little is known about the accessory minerals.</p> <p>The Nili Fossae-Jezero system has potential analogues in terrestrial serpentinized and carbonated rocks, such as the Leka Ophiolite Complex, Norway (PTAL collection, https://www.ptal.eu). Here, distinct mineral assemblages record different stages of hydration and carbonation of ultramafic rocks [6].</p> <p>We perform petrological and mineralogical analyses on thin sections to characterize the major and trace minerals and combine with Near Infrared (NIR) spectroscopy measurements. A set of spectral parameters are defined and compare to spectral parameters previously used on CRISM and OMEGA data [1, 4, 7, 8]. We study the significance of the mineralogical assemblages including nature of accessory minerals. Effect of the presence of accessory minerals on the NIR signal is investigated and their potential incidence on the amount of H<sub>2</sub>/CH<sub>4</sub> production in mafic or ultramafic system is discussed [5].</p> <p>We started to apply the newly defined spectral parameters on several SCS on Mars. Results confirm local carbonation of earlier serpentinized rocks and suggest that different protoliths could have led to diversity of mineralogical associations in SCS on Mars. Multiple detection of brucite are also suggested for the first time on Mars. Altogether our results help to better describe key geochemical conditions of the SCS on Mars for habitability potential of the martian crust and Mars’s evolution.</p> <p><strong> </strong></p> <p>References:</p> <ul> <li>Brown, A. J., et al. <em>EPSL</em>1-2 (2010): 174-182.</li> <li>Wiens, R.C., et al.  <em>Space Sci Rev</em><strong>217, </strong>4 (2021).</li> <li>Horgan, B., et al. <em>Second International Mars Sample Return</em>. Vol. 2071. 2018.</li> <li>Ody, A., et al. <em>JGR: Planets</em>2 (2013): 234-262.</li> <li>Klein, F., et al. <em>Lithos</em>178 (2013): 55-69.</li> <li>Bjerga, A., et al. <em>Lithos</em>227 (2015): 21-36.</li> <li>Viviano-Beck et al, <em>JGR: Planets 11</em>8.9 (2013)</li> <li>Viviano-Beck et al, <em>JGR: Planets 119.6</em> (2014)</li> </ul>

Reaction of Sn to Nanocrystalline Surface Layer of Cu by Near Surface Severe Plastic Deformation

2007 ◽  
pp. 115-120
Author(s):  
Yoritoshi Minamino ◽  
Yuichiro Koizumi ◽  
Nobuhiro Tsuji ◽  
Y. Nakamizo ◽  
Toshiya Shibayanagi ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Surface Layer ◽  
Severe Plastic Deformation ◽  
Near Surface

scholarly journals Elastic-plastic-brittle transitions of potassium dihydrogen phosphate crystals: characterization by nanoindentation

2020 ◽  
Vol 8 (4) ◽  
pp. 447-456
Author(s):  
Yong Zhang ◽  
Ning Hou ◽  
Liang-Chi Zhang ◽  
Qi Wang
Keyword(s):  
Plastic Deformation ◽  
Brittle Fracture ◽  
Optical Switching ◽  
Potassium Dihydrogen Phosphate ◽  
Machining Process ◽  
Fracture Mechanisms ◽  
Dihydrogen Phosphate ◽  
Kdp Crystal ◽  
Potassium Dihydrogen ◽  
Kdp Crystals

AbstractPotassium dihydrogen phosphate (KDP) crystals are widely used in laser ignition facilities as optical switching and frequency conversion components. These crystals are soft, brittle, and sensitive to external conditions (e.g., humidity, temperature, and applied stress). Hence, conventional characterization methods, such as transmission electron microscopy, cannot be used to study the mechanisms of material deformation. Nevertheless, understanding the mechanism of plastic-brittle transition in KDP crystals is important to prevent the fracture damage during the machining process. This study explores the plastic deformation and brittle fracture mechanisms of KDP crystals through nanoindentation experiments and theoretical calculations. The results show that dislocation nucleation and propagation are the main mechanisms of plastic deformation in KDP crystals, and dislocation pileup leads to brittle fracture during nanoindentation. Nanoindentation experiments using various indenters indicate that the external stress fields influence the plastic deformation of KDP crystals, and plastic deformation and brittle fracture are related to the material’s anisotropy. However, the effect of loading rate on the KDP crystal deformation is practically negligible. The results of this research provide important information on reducing machining-induced damage and further improving the optical performance of KDP crystal components.

The Fracture Microphology of the Ceramics by Strong Laser Shock Processing

2006 ◽  
Vol 532-533 ◽  
pp. 137-140 ◽  
Author(s):  
Ling Feng Zhang ◽  
Yong Kang Zhang ◽  
Ai Xin Feng
Keyword(s):  
Plastic Deformation ◽  
Brittle Fracture ◽  
Radial Crack ◽  
Laser Energy ◽  
High Energy ◽  
Laser Shock ◽  
Main Mode ◽  
Laser Shock Processing ◽  
Strong Laser ◽  
Shock Processing

The laser shocking to the Al2O3 ceramics was proceeded, and the fracture microphology that formed from the strong laser shock processing (LSP) was analyzed by the Scanning electron microscopy (SEM). It was discovered that the feature of ceramics responds differently when the laser energy was changed. The brittle fracture that consists of intergranular fracture and cleavage fracture was the main mode under high energy laser shocking (laser pulse enegry: 42J); the macroscopical fracture characteristic was the radial crack. When the laser energy reduced to a fit level (25J), the brittle fracture of ceramics appears to the characteristic of plastic deformation, its fracture microphology appears lots of slippage lines, and the macroscopical feature of radial crack under 42J become subulate crack. While the energy reduced to 15J, the Al2O3 ceramics did not fracture, its micro-hardness ascended, a feature of micro-plastic deformation was existed under the low energy. The reason of the brittle materials appears to the feature of plastic deformation was analyzed.

scholarly journals Slicing Ceramics on Material Removed by a Single Abrasive Particle

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4324
Author(s):  
Yao-Yang Tsai ◽  
Ming-Chang Wu ◽  
Yunn-Shiuan Liao ◽  
Chung-Chen Tsao ◽  
Chun-Yao Hsu
Keyword(s):  
Mathematical Model ◽  
Plastic Deformation ◽  
Brittle Fracture ◽  
Material Removal ◽  
Equations Of Motion ◽  
Abrasive Particle ◽  
Brittle Materials ◽  
Machining Parameters ◽  
Wire Saw ◽  
Cutting Model

Multi-wire saw machining (MWSM) used for slicing hard-brittle materials in the semiconductor and photovoltaic industries is an important and efficient material removal process that uses free abrasives. The cutting model of single-wire saw machining (SWSM) is the basis of MWSM. The material removal mechanism of SWSM is more easily understood than MWSM. A mathematical model (includes brittle fracture and plastic deformation) is presented in this paper for SWSM ceramic with abrasives. This paper determines the effect of various machining parameters on the removal of hard-brittle materials. For brittle fracture of SWSM ceramics, the minimum strain energy density is used as a fracture criterion. For plastic deformation of SWSM ceramics, the material removal is calculated using equations of motion. Actual wire-sawing experiments are conducted to verify the results of the developed mathematical model. The theoretical results agree with experimental data and practical experience. From the developed mathematical model, brittle fracture plays a major role in material removal of SWSM ceramics. Wire speed (S) and working load (P) are positively correlated with material removal of SWSM ceramics. The coefficient of friction is low, a lateral crack, which propagates almost parallel to the working surface, leads to more brittle fracture and material removal is increased.

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