scholarly journals Biotite from Čierna hora Mountains granitoids (Western Carpathians, Slovakia) and estimation of water contents in granitoid melts

2010 ◽  
Vol 61 (1) ◽  
pp. 3-17 ◽  
Author(s):  
Katarína Bónová ◽  
Igor Broska ◽  
Igor Petrík
Keyword(s):  
Lower Crust ◽  
Western Carpathians ◽  
Stability Equation ◽  
Ferromagnesian Mineral ◽  
Model Yield ◽  
Dissolution Model ◽  
Assimilation Process ◽  
Water Contents ◽  
Water Dissolution

Biotite from Čierna hora Mountains granitoids (Western Carpathians, Slovakia) and estimation of water contents in granitoid meltsBiotite is the dominant ferromagnesian mineral in different granites from the Čierna hora Mountains, in the Western Carpathians (Slovakia). A higher content of Fe3+(up to 20 %) is characteristic for the biotites from I-type Sokoľ and Sopotnica granitoid bodies in contrast to the biotites from S-type Ťahanovce granitoids showing decreased Fe3+amount (around 5 %). The Fe/(Fe + Mg) ratio in biotites from the Sokoľ and Sopotnica massifs between 0.47 and 0.54 is rather low with respect to that in biotite from the Ťahanovce [Fe/(Fe + Mg) = 0.55-0.63] and Miklušovce [Fe/(Fe + Mg) = 0.73-0.81] granite body. Water fugacities and contents calculated using Wones' (1981) calibration of biotite stability equation and Burnham's (1994) water dissolution model yield relatively similar values of 4-5 wt. % in remaining melts at 400 MPa and various levels of fo2and activities of annite for magnetite-bearing assemblages. This suggests an effective buffering role of biotite in both oxygen and water fugacities. Comparison of the peraluminosity index (A/CNK) of biotite with the same index in whole-rock shows distinctly higher A/CNK values for biotite indicating its aluminous character and important role as a significant aluminium carrier. The biotite composition indicates that granitoids in the Čierna hora Mts can be primarily derived from the lower crust; their protolith was influenced by mixing and/or assimilation process.

Role of water contents on microwave roasting of gold bearing high arsenic sulphide concentrate

2017 ◽  
Vol 161 ◽  
pp. 72-77 ◽  
Author(s):  
Nan Hu ◽  
Wei Chen ◽  
De-xin Ding ◽  
Feng Li ◽  
Zhong-ran Dai ◽  
...  
Keyword(s):  
Microwave Roasting ◽  
Water Contents ◽  
High Arsenic ◽  
Gold Bearing

scholarly journals The Role of Lower Crustal Rheology in Lithospheric Delamination During Orogeny

2021 ◽  
Vol 9 ◽  
Author(s):  
Lin Chen
Keyword(s):  
Lower Crust ◽  
Numerical Models ◽  
The Tibetan Plateau ◽  
Mantle Lithosphere ◽  
Laboratory Studies ◽  
Surface Uplift ◽  
Continental Lower Crust ◽  
Lower Crustal ◽  
Flow Laws

The continental lower crust is an important composition- and strength-jump layer in the lithosphere. Laboratory studies show its strength varies greatly due to a wide variety of composition. How the lower crust rheology influences the collisional orogeny remains poorly understood. Here I investigate the role of the lower crust rheology in the evolution of an orogen subject to horizontal shortening using 2D numerical models. A range of lower crustal flow laws from laboratory studies are tested to examine their effects on the styles of the accommodation of convergence. Three distinct styles are observed: 1) downwelling and subsequent delamination of orogen lithosphere mantle as a coherent slab; 2) localized thickening of orogen lithosphere; and 3) underthrusting of peripheral strong lithospheres below the orogen. Delamination occurs only if the orogen lower crust rheology is represented by the weak end-member of flow laws. The delamination is followed by partial melting of the lower crust and punctuated surface uplift confined to the orogen central region. For a moderately or extremely strong orogen lower crust, topography highs only develop on both sides of the orogen. In the Tibetan plateau, the crust has been doubly thickened but the underlying mantle lithosphere is highly heterogeneous. I suggest that the subvertical high-velocity mantle structures, as observed in southern and western Tibet, may exemplify localized delamination of the mantle lithosphere due to rheological weakening of the Tibetan lower crust.

scholarly journals Genetic aspects of barite mineralization related to rocks of the teschenite association in the Silesian Unit, Outer Western Carpathians, Czech Republic

2017 ◽  
Vol 68 (2) ◽  
pp. 119-129 ◽  
Author(s):  
Jakub Jirásek ◽  
Zdeněk Dolníček ◽  
Dalibor Matýsek ◽  
Tomáš Urubek
Keyword(s):  
Aqueous Fluid ◽  
Western Carpathians ◽  
Rock Matrix ◽  
Multiple Sources ◽  
Two Phase ◽  
Sulphur Isotope ◽  
Outer Western Carpathians ◽  
Supergene Processes ◽  
Homogenization Temperatures

AbstractBarite is a relatively uncommon phase in vein and amygdule mineralizations hosted by igneous rocks of the teschenite association in the Silesian Unit (Western Carpathians). In macroscopically observable sizes, it has been reported from 10 sites situated only in the Czech part of the Silesian Unit. Microscopic barite produced by the hydrothermal alteration of rock matrix and also by the supergene processes is more abundant. We examined four samples of barite by mineralogical and geochemical methods. Electron microprobe analyses proved pure barites with up to 0.038 apfu Sr and without remarkable internal zonation. Fluid inclusion and sulphur isotope data suggests that multiple sources of fluid components have been involved during barite crystallization. Barite contains primary and secondary aqueous all-liquid (L) or less frequent two-phase (L+V) aqueous fluid inclusions with variable salinity (0.4-2.9 wt. % NaCl eq.) and homogenization temperatures between 77 and 152 °C. The higher-salinity fluid endmember was probably Cretaceous seawater and the lower-salinity one was probably diagenetic water derived from surrounding flysch sediments during compaction and thermal alteration of clay minerals. The δ34S values of barite samples range between -1.0 ‰ and +16.4 ‰ CDT suggesting participation of two sources of sulphate, one with a near-zero δ34S values probably derived from wall rocks and another with high δ34S values being most probably sulphate from the Cretaceous seawater. All results underline the role of externally derived fluids during post-magmatic alteration of bodies of rock of the teschenite association.

Some Considerations on the Role of Water in Thin Layer Chromatography of Inorganic Anions

1984 ◽  
Vol 39 (2) ◽  
pp. 186-189
Author(s):  
Takaya Iida ◽  
Kaname Ito
Keyword(s):  
Thin Layer ◽  
Partition Coefficient ◽  
Thin Layer Chromatography ◽  
Partition Coefficients ◽  
Ionic Radius ◽  
Stationary Phases ◽  
Partial Charge ◽  
Layer Chromatography ◽  
Water Contents

The volume ratios of the mobile and stationary phases in thin layer chromatography, and the partition coefficients of halide and halate anions and some other anions between these phases were obtained by developing the ions simultaneously with a series of metaphosphates. The water contents of the developing solvents influenced the volume ratios very much, but not so much the partition coefficients. The logarithm of the partition coefficient of the halide anions is proportional to the reciprocal of their ionic radius, and that of the halate anions and oxoanions to the partial charge on the oxygens of them.

scholarly journals Rifted margins: Ductile deformation, boudinage, continentward-dipping normal faults and the role of the weak lower crust

2018 ◽  
Vol 53 ◽  
pp. 20-40 ◽  
Author(s):  
Camille Clerc ◽  
Jean-Claude Ringenbach ◽  
Laurent Jolivet ◽  
Jean-François Ballard
Keyword(s):  
Lower Crust ◽  
Ductile Deformation ◽  
Normal Faults ◽  
Rifted Margins
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