Review for "Paragenesis of secondary Ca–Al silicates during hydrothermal alteration of Proterozoic granitic rocks (SE Sweden)"

2020 ◽  
Author(s):  
JYOTISANKAR RAY
Keyword(s):  
Hydrothermal Alteration ◽  
Granitic Rocks

HYDROTHERMAL ALTERATION OF MAGMATIC TITANITE: EVIDENCE FROM PROTEROZOIC GRANITIC ROCKS, SOUTHEASTERN SWEDEN

2009 ◽  
Vol 47 (4) ◽  
pp. 801-811 ◽  
Author(s):  
S. Morad ◽  
M. A.K. El-Ghali ◽  
M. A. Caja ◽  
K. Al-Ramadan ◽  
H. Mansurbeg
Keyword(s):  
Hydrothermal Alteration ◽  
Granitic Rocks

scholarly journals How Do Secondary Minerals in Granite Help Distinguish Paleo- from Present-Day Permeable Fracture Zones? Joint Interpretation of SWIR Spectroscopy and Geophysical Logs in the Geothermal Wells of Northern Alsace

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-20 ◽  
Author(s):  
Carole Glaas ◽  
Jeanne Vidal ◽  
Patricia Patrier ◽  
Jean-François Girard ◽  
Daniel Beaufort ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Absorption Band ◽  
Hydrothermal Alteration ◽  
Granitic Rocks ◽  
Upper Rhine Graben ◽  
Fracture Zones ◽  
Band Area ◽  
Resistivity Logs ◽  
Geothermal Wells ◽  
Geophysical Logs

The investigation of permeable hydrothermally altered and fractured zones and their distribution is a key issue for the understanding of fluid circulation in granitic rocks, on which the success of geothermal projects relies. Based on the use of short-wave infrared (SWIR) spectroscopy applied to rock cuttings coupled with interpretation of geophysical logs, we propose an investigation of the clay signature of fault and fracture zones (FZ) inside the granitic basement. This methodology was applied to two geothermal wells: GRT-2 from the Rittershoffen and GPK-1 from the Soultz-sous-Forêts (Soultz) geothermal sites, both located in the Upper Rhine Graben (URG). A total of 1430 SWIR spectra were acquired and analysed. Variations in the 2200 nm absorption band area are correlated with hydrothermal alteration grades. The 2200 nm absorption band area is found to reflect the illite quantity and its variations in the granitic basement. Low, stable values are observed in the unaltered granite facies, showing good reproducibility of the method, whereas scattered high values are associated with high hydrothermal alteration and FZs. Variations in the 2200 nm absorption band area were correlated with the gamma ray and electrical resistivity logs. This procedure allowed us to confirm that illite mainly controls the resistivity response except inside the permeable FZs, where the resistivity response is controlled by the geothermal brine. Thus, the architecture of these permeable FZs was described precisely by using a combination of the 2200 nm absorption band area data and the electrical resistivity log. Moreover, by correlation with other geophysical logs (temperature (T), porosity, and density), paleo-permeable and currently permeable FZs inside the reservoir were distinguished. The correlation of SWIR spectroscopy with electrical resistivity logs appears to be a robust tool for geothermal exploration in granitic reservoirs in the URG.

Author response for "Paragenesis of secondary Ca–Al silicates during hydrothermal alteration of Proterozoic granitic rocks (SE Sweden)"

2020 ◽  
Author(s):  
Howri Mansurbeg ◽  
Mohammad A. K. El‐Ghali ◽  
Salahedin Shahrokhi ◽  
Jaroslav Reif ◽  
Hossein S. Hussein ◽  
...  
Keyword(s):  
Hydrothermal Alteration ◽  
Granitic Rocks ◽  
Author Response

Author response for "Paragenesis of secondary Ca–Al silicates during hydrothermal alteration of Proterozoic granitic rocks (SE Sweden)"

2020 ◽  
Author(s):  
Howri Mansurbeg ◽  
Mohammad A. K. El‐Ghali ◽  
Salahedin Shahrokhi ◽  
Jaroslav Reif ◽  
Hossein S. Hussein ◽  
...  
Keyword(s):  
Hydrothermal Alteration ◽  
Granitic Rocks ◽  
Author Response

Geochemical and Sr and Nd isotopic constraints on the origin of late Proterozoic volcanics and associated tin-bearing granites from the Franklin Mountains, west Texas

1987 ◽  
Vol 24 (4) ◽  
pp. 830-839 ◽  
Author(s):  
David I. Norman ◽  
Kent C. Condie ◽  
Robert W. Smith ◽  
W. F. Thomann
Keyword(s):  
Field Strength ◽  
Hydrothermal Alteration ◽  
High Field ◽  
Granitic Rocks ◽  
High Field Strength ◽  
Late Proterozoic ◽  
West Texas ◽  
Depleted Mantle ◽  
Fluoride Complexes ◽  
Back Arc

Late Proterozoic volcanic and granitic rocks from the Franklin Mountains in west Texas define a continuous tholeiitic trend from rhyolite (granite) to trachyte with a small compositional gap between trachyte and basalt. Volcanics and granitic rocks have immobile-element geochemical affinities with volcanics from continental-margin-arc systems and associated back-arc basins. Felsic volcanics and granitic rocks appear to have formed by fractional crystallization of basalt during which REE and high-field-strength elements were stabilized as fluoride complexes and concentrated in late or post-magmatic fluids.A Rb–Sr isochron from nonhematized samples (1064 ± 5 Ma, i = 0.7034) falls within the error of reported U–Pb zircon dates and probably dates a period of hydrothermal alteration. εNd values (0.7–2.5 at 1065 Ma) fall below a depleted mantle growth curve and probably reflect contamination of the fractionating magmas with older continental crust. Changes in the isotopic composition of Nd during hydrothermal alteration may also contribute to the spread in εNd values.

Hydrothermal alteration of plagioclase in granitic rocks from Proterozoic basement of SE Sweden

2010 ◽  
Vol 45 (1) ◽  
pp. 105-116 ◽  
Author(s):  
S. Morad ◽  
M. A. K. El-Ghali ◽  
M. A. Caja ◽  
M. Sirat ◽  
K. Al-Ramadan ◽  
...  
Keyword(s):  
Hydrothermal Alteration ◽  
Granitic Rocks ◽  
Proterozoic Basement
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