Mise en place et pétrologie du granite associé au complexe ophiolitique de Thetford Mines, Québec

1984 ◽  
Vol 21 (10) ◽  
pp. 1114-1125 ◽  
Author(s):  
Roger Laurent ◽  
Mehmet F. Taner ◽  
Jean Bertrand
Keyword(s):  
Low Temperature ◽  
Mineral Assemblage ◽  
Shear Zones ◽  
Low Pressure ◽  
Late Ordovician ◽  
Calc Alkaline ◽  
Ophiolite Complex ◽  
Serpentinized Peridotite ◽  
Thrust Plane

Sheets of granite are confined to shear zones in the tectonite peridotite unit of the Thetford Mines ophiolite complex. Their orientation is parallel to the thrust plane at the base of the complex. The granite, which is calc-alkaline and rich in potassium, does not belong to the ophiolite sequence. We show that it was tectonically incorporated within the partially serpentinized peridotite during thrusting and emplacement of the complex.During this process, the granite was strongly deformed and recrystallized at low pressure (500 bar (50 MPa)) and low temperature (500 °C or less), which gave rise to the mineral assemblage orthoclase, albite, hydromuscovite, and hydrothermal biotite. This episode was followed by a rodingite alteration, characterized by the formation of grossular, which was associated with the development of economic chrysotile within the enclosing peridotite. The K–Ar ages of biotite, muscovite, and feldspar from the granite cluster around 450 Ma. These cooling ages suggest that the emplacement and alteration of the granite and peridotite had ended by Late Ordovician time.

Tectonic structures related to thrusting of ophiolitic complexes: the White Hills Peridotite, Newfoundland

1982 ◽  
Vol 19 (4) ◽  
pp. 709-722 ◽  
Author(s):  
J. Girardeau
Keyword(s):  
Low Temperature ◽  
High Stress ◽  
Metamorphic Rocks ◽  
Tectonic Structures ◽  
Ophiolite Complex ◽  
Fine Grained ◽  
Thrust Plane ◽  
Basal Portion ◽  
Ophiolitic Complex

The White Hills Peridotite and its underlying metamorphic rocks represent the basal portion of a partly eroded ophiolitic complex. At the contact with the metamorphic rocks, the peridotites display low-temperature–high-stress mylonitic textures, which grade upwards to fine-grained porphyroclastic textures indicative of higher temperatures and lower stresses. Petrological and structural evidence indicates that the mylonitic peridotites and underlying metamorphic rocks have been deformed during the oceanic thrusting of the lithosphere. The analysis of the main tectonic structures observed in the peridotites shows that the complex has been thrust northwestward along a southeast-dipping thrust plane. The data are compared with those obtained from the Bay of Islands ophiolite complex.

Field ion microscopy

1988 ◽  
Vol 46 ◽  
pp. 434-435
Author(s):  
Gert Ehrlich
Keyword(s):  
Low Temperature ◽  
Sample Surface ◽  
Low Pressure ◽  
Radius Of Curvature ◽  
Field Ion Microscopy ◽  
Phosphor Screen ◽  
Ion Microscopy ◽  
Field Ion Microscope

The field ion microscope, devised by Erwin Muller in the 1950's, was the first instrument to depict the structure of surfaces in atomic detail. An FIM image of a (111) plane of tungsten (Fig.l) is typical of what can be done by this microscope: for this small plane, every atom, at a separation of 4.48Å from its neighbors in the plane, is revealed. The image of the plane is highly enlarged, as it is projected on a phosphor screen with a radius of curvature more than a million times that of the sample. Müller achieved the resolution necessary to reveal individual atoms by imaging with ions, accommodated to the object at a low temperature. The ions are created at the sample surface by ionization of an inert image gas (usually helium), present at a low pressure (< 1 mTorr). at fields on the order of 4V/Å.

CHEMISORPTION OF CO AND METHANATION ON Rh SURFACES AT LOW TEMPERATURE AND LOW PRESSURE, AN ATOM-PROBE FIM STUDY

1987 ◽  
Vol 48 (C6) ◽  
pp. C6-487-C6-492
Author(s):  
W. Liu ◽  
D. M. Ren ◽  
C. L. Bao ◽  
T. T. Tsong
Keyword(s):  
Low Temperature ◽  
Atom Probe ◽  
Low Pressure

scholarly journals Petrogenesis of a late-stage calc-alkaline granite in a giant S-type batholith: geochronology and Sr–Nd–Pb isotopes from the Nomatsaus granite (Donkerhoek batholith), Namibia

2021 ◽  
Author(s):  
S. Aspiotis ◽  
S. Jung ◽  
F. Hauff ◽  
R. L. Romer
Keyword(s):  
Partial Melting ◽  
Mineral Assemblage ◽  
Central Zone ◽  
Calc Alkaline ◽  
Pb Isotope ◽  
Alkaline Granite ◽  
Ti Oxides ◽  
Eu Anomaly ◽  
Environment Characteristic ◽  
Southern Central

AbstractThe late-tectonic 511.4 ± 0.6 Ma-old Nomatsaus intrusion (Donkerhoek batholith, Damara orogen, Namibia) consists of moderately peraluminous, magnesian, calc-alkalic to calcic granites similar to I-type granites worldwide. Major and trace-element variations and LREE and HREE concentrations in evolved rocks imply that the fractionated mineral assemblage includes biotite, Fe–Ti oxides, zircon, plagioclase and monazite. Increasing K2O abundance with increasing SiO2 suggests accumulation of K-feldspar; compatible with a small positive Eu anomaly in the most evolved rocks. In comparison with experimental data, the Nomatsaus granite was likely generated from meta-igneous sources of possibly dacitic composition that melted under water-undersaturated conditions (X H2O: 0.25–0.50) and at temperatures between 800 and 850 °C, compatible with the zircon and monazite saturation temperatures of 812 and 852 °C, respectively. The Nomatsaus granite has moderately radiogenic initial 87Sr/86Sr ratios (0.7067–0.7082), relatively radiogenic initial εNd values (− 2.9 to − 4.8) and moderately evolved Pb isotope ratios. Although initial Sr and Nd isotopic compositions of the granite do not vary with SiO2 or MgO contents, fSm/Nd and initial εNd values are negatively correlated indicating limited assimilation of crustal components during monazite-dominated fractional crystallization. The preferred petrogenetic model for the generation of the Nomatsaus granite involves a continent–continent collisional setting with stacking of crustal slices that in combination with high radioactive heat production rates heated the thickened crust, leading to the medium-P/high-T environment characteristic of the southern Central Zone of the Damara orogen. Such a setting promoted partial melting of metasedimentary sources during the initial stages of crustal heating, followed by the partial melting of meta-igneous rocks at mid-crustal levels at higher P–T conditions and relatively late in the orogenic evolution.

Epitaxial growth of Co3O4 films by low temperature, low pressure chemical vapour deposition

2001 ◽  
Vol 231 (1-2) ◽  
pp. 242-247 ◽  
Author(s):  
K. Shalini ◽  
Anil U. Mane ◽  
S.A. Shivashankar ◽  
M. Rajeswari ◽  
S. Choopun
Keyword(s):  
Low Temperature ◽  
Epitaxial Growth ◽  
Chemical Vapour Deposition ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Low Pressure ◽  
Pressure Chemical

Silicide Based Low Temperature and Low Pressure Bonding of TI/SI for Microfludic and Hermetic Selaling Application

2018 ◽  
Author(s):  
C Hemanth Kumar ◽  
Asisa Kumar Pnaigrahi ◽  
Nirupam Paul ◽  
Satish Bonam ◽  
Siva Rama Krishna Vanjari ◽  
...  
Keyword(s):  
Low Temperature ◽  
Low Pressure

In situ optical monitoring of AlAs wet oxidation using a novel low-temperature low-pressure steam furnace design

1998 ◽  
Vol 10 (2) ◽  
pp. 197-199 ◽  
Author(s):  
S.A. Feld ◽  
J.P. Loehr ◽  
R.E. Sherriff ◽  
J. Wiemeri ◽  
R. Kaspi
Keyword(s):  
Low Temperature ◽  
Low Pressure ◽  
Wet Oxidation ◽  
Optical Monitoring ◽  
Furnace Design ◽  
Pressure Steam
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