TEMPERATURE AND STRAIN GRADIENTS ACROSS THE MAIN CENTRAL THRUST IN SOUTH-CENTRAL BHUTAN: IMPLICATIONS FOR THE ORIGIN OF INVERTED METAMORPHISM AND THE CONTRIBUTION OF TRANSPORT-PARALLEL STRETCHING TO CUMULATIVE MASS TRANSFER

2017 ◽  
Author(s):  
Sean P. Long ◽  
◽  
Stacia Gordon ◽  
John P. Young ◽  
Emmanuel Soignard
Keyword(s):  
Mass Transfer ◽  
Main Central Thrust ◽  
Strain Gradients ◽  
South Central ◽  
Inverted Metamorphism ◽  
Cumulative Mass

Cement Based Solidification / Stabilization of Industrial Contaminated Soil Using Various Cement Additives

2010 ◽  
Author(s):  
Grega E. Voglar ◽  
Domen Lestan
Keyword(s):  
Mass Transfer ◽  
Portland Cement ◽  
Contaminated Soils ◽  
Ordinary Portland Cement ◽  
Industrial Site ◽  
Toxicity Characteristic Leaching Procedure ◽  
Soil Extracts ◽  
Regulatory Limits ◽  
Cumulative Mass ◽  
Leaching Procedure

In a laboratory study, 15% (w/w) of ordinary portland cement (OPC), black portland cement (BPC) and puculanic cement (PC) combined with various cement additives were used for solidification/stabilization (S/S) of Cd, Pb, Zn, Cu, Ni and As contaminated soils from the former industrial site. Soil formed solid monoliths with all cements and cement additives. S/S effectiveness was assessed by measuring the mechanical strength of the monoliths, concentrations of metals in deionised water and TCLP (Toxicity Characteristic Leaching Procedure) soil extracts, and mass transfer of metals. Concentrations of Cd, Pb, Zn and Ni in water extracts from S/S soils generally decreased, while concentrations of As and Cu increased. Concentrations of Cd, Pb, Zn, Cu and Ni in the TCLP extracts from S/S mixes were lower than from original soil, while the extractability of As from S/S mixes increased. Overall, the concentration of metals in TCLP solution, obtained after extraction of the S/S mixes, was below the regulatory limits. S/S greatly reduced the mass transfer of Cd (up to 21.5-times), Pb (up to 114-times) and Zn (up to 999-times). Mass transfer of Ni was generally also reduced, while that of Cu and As increased in some S/S mixes. In general, monoliths made with OPC present higher cumulative mass of PTMs leached than those with BPC and PC.

scholarly journals Metabasites petrology and P-T evolution in the Lesser Himalaya, central Nepal

2011 ◽  
Vol 42 ◽  
pp. 21-40
Author(s):  
L. P. Paudel ◽  
T. Imayama ◽  
K. Arita
Keyword(s):  
Lesser Himalaya ◽  
Main Central Thrust ◽  
Himalayan Orogeny ◽  
Central Nepal ◽  
Inverted Metamorphism ◽  
The Matrix ◽  
T Path ◽  
Garnet Zone ◽  
Host Rocks ◽  
First Time

Petrological study was carried out for the first time on the metabasites of the Lesser Himalaya in central Nepal. The metabasites are mostly tholeiitic basalts emplaced in the elastic sediments as supracrustal dikes and sills, and later metamorphosed together with the host rocks. They contain almost a constant mineral assemblage of Ca-amphiboles + plagioclase + biotite + quartz ± epidote± chlorite + (Fe-Ti oxides). Amphiboles in the form of porphyroblasts show chemical zonation with actinolite/magnesio­homblende cores, tschermakite/ferro-tschermakite rims, and magnesio-hornblende margins. The cores of porphyroblasts are pre-kinematic and were probably formed prior to the Tertiary Himalayan orogeny. The porphyroblast rims and the matrix amphiboles are syn-kinematic and were formed during the Upper Main Central Thrust activity in the Tertiary period. The compositions of both the porphyroblast rims and matrix amphiboles change from actinolite in the chlorite zone to magnesium­ hornblende in the biotite zone and totschermakite/ferro-tschermakite in the garnet zone. The systematic changes in amphibole compositions as well as petrographic characteristics of metabasites confirm the classical concept of increasing metamorphic grade structurally upwards to the Upper Main Central Thrust in the Lesser Himalaya. Application of hornblende-plagioclase thermobarometry shows a coherent prograde P-T path in zoned amphiboles. The cores of amphibole porphyroblasts were formed at average peak temperature of ~540"C and at pressure of ~3 kbar. The porphyroblast rims and matrix amphiboles were recrystallized at average peak temperatures of ~570°C in the biotite zone and ~630°C in the garnet zone at pressure of ~6 kbar. The metabasites petrology is in favor of the tectono-metamorphic models that relate the inverted metamorphism with thrusting along the Upper Main Central Thrust and coeval inversion of isoiliem1S. It is suggested that published amphibole cooling ages from the Nepalese Lesser Himalaya based on simples, homogeneous mineralogy should be reinterpreted in view of the presence of polygenetic amphiboles with heterogeneous composition.

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