Tectonic discontinuity, partial melting and exhumation in the Garhwal Himalaya (Northwest India): Constrains from spatial and temporal pressure-temperature conditions along the Bhagirathi valley

Lithos ◽  
2021 ◽  
pp. 106488
Author(s):  
Ryoichi Kawabata ◽  
Takeshi Imayama ◽  
Narayan Bose ◽  
Keewook Yi ◽  
Yui Kouketsu
Keyword(s):  
Partial Melting ◽  
Garhwal Himalaya ◽  
Temperature Conditions ◽  
Temporal Pressure ◽  
Northwest India

Structural and metamorphic development of migmatites in the Svecokarelides, near Tampere, Finland

1980 ◽  
Vol 71 (4) ◽  
pp. 185-200 ◽  
Author(s):  
D. S. Campbell
Keyword(s):  
Partial Melting ◽  
Potassium Feldspar ◽  
Metamorphic Grade ◽  
Temperature Conditions ◽  
Mineral Growth ◽  
Metamorphic Development ◽  
Areal Variation

ABSTRACTFive generations of structures (F1–F5), excluding faults, can be recognised in granitoid and trondhjemitoid migmatites with quartzofeldspathic neosome development associated with F1–F4 structures. Areal variation in metamorphic grade is shown by the zonal development of muscovite-sillimanite, potassium feldspar-sillimanite and potassium feldspar-cordierite assemblages in the palaeosomes. The climactic metamorphism, associated with MS2–MP2 mineral growth, occurred at between 675°C, 4 kb and 825°C, 6·5 kb. These pressure-temperature conditions are consistent with at least some neosome development having resulted from partial melting. The occurrence of a relatively shallow metamorphic geotherm and the resultant products are assessed in relation to metamorphic conditions known from elsewhere in the Svecokarelides.

Impact of forest degradation on streamflow regime and runoff response to rainfall in the Garhwal Himalaya, Northwest India

2017 ◽  
Vol 62 (7) ◽  
pp. 1114-1130 ◽  
Author(s):  
Nuzhat Q. Qazi ◽  
L. Adrian Bruijnzeel ◽  
Shive Prakash Rai ◽  
Chandra P. Ghimire
Keyword(s):  
Forest Degradation ◽  
Garhwal Himalaya ◽  
Streamflow Regime ◽  
Northwest India

Archean granitoids of the Aravalli Craton, northwest India

2020 ◽  
Vol 489 (1) ◽  
pp. 215-234 ◽  
Author(s):  
Iftikhar Ahmad ◽  
M. E. A. Mondal ◽  
Md Sayad Rahaman ◽  
Rajneesh Bhutani ◽  
M. Satyanarayanan
Keyword(s):  
Partial Melting ◽  
Continental Crust ◽  
Mantle Wedge ◽  
Nd Isotope ◽  
Oceanic Plateau ◽  
Slab Breakoff ◽  
Northwest India ◽  
Aravalli Craton ◽  
Metasomatized Mantle ◽  
Asthenospheric Upwelling

AbstractThe Archean granitoids of the Aravalli Craton (NW India) are represented by orthogneisses (3.3–2.6 Ga) and undeformed granitoids (c. 2.5 Ga). Here we present whole-rock geochemical (elemental and Nd-isotope) data of the granitoids from the Aravalli Craton with an aim of understanding the evolution of the continental crust during the Archean. These Archean granitoids have been classified into three compositional groups: (1) TTG – tonalite–trondhjemite–granodiorite; (2) t-TTG – transitional TTG; and (3) sanukitoids. Based on the geochemical characteristics, it is proposed that the TTGs have formed from the partial melting of subducting oceanic plateau. The t-TTG formed owing to reworking of an older continental crust (approximately heterogeneous) in response to tectonothermal events in the craton. For the formation of the sanukitoids, a two-stage petrogenetic model is invoked which involves metasomatization of the mantle wedge, followed by slab breakoff and asthenospheric upwelling, which leads to the melting of asthenosphere and the metasomatized mantle wedge. It is also proposed that subducted sediments contributed to the genesis of sanukitoid magma.

Timescales of partial melting in the Himalayan middle crust: insight from the Leo Pargil dome, northwest India

2013 ◽  
Vol 166 (5) ◽  
pp. 1415-1441 ◽  
Author(s):  
Graham W. Lederer ◽  
John M. Cottle ◽  
Micah J. Jessup ◽  
Jackie M. Langille ◽  
Talat Ahmad
Keyword(s):  
Partial Melting ◽  
Middle Crust ◽  
Northwest India

scholarly journals Partial melting as an efficient mechanism to produce rare metal granite?

2021 ◽  
Author(s):  
Alexis Plunder ◽  
Eric Gloaguen ◽  
Saskia Erdmann ◽  
Fabrice Gaillard ◽  
Josselyn Garde ◽  
...  
Keyword(s):  
Partial Melting ◽  
Rare Metal ◽  
Silicate Melts ◽  
Efficient Mechanism ◽  
Rare Metal Granite ◽  
Temperature Conditions ◽  
Critical Metal ◽  
Low Degree ◽  
Peraluminous Granites ◽  
Crystallization Experiment

<p>Rare metal (HFSE such Sn, W, Ta, Nb and LILLE such Li, Rb) granite represent the most enriched magmatic rocks on Earth. This is especially true for some elements that belongs either to the European list of critical raw materials and/or the conflict minerals (eg. Li, Sn, W, Nb, Ta). Rare metal granites generally emplace in the vincinity of S-type granites during late orogenic stages. The fraction crystallisation mechanism is postulated to be the unique way to produce enriched silicate melt that later leads to ore deposits due to a combination of magmatic/hydrothermal processes. However, some problems persist in the explanation of the genesis of rare metal granite: crystal fractionation alone does not lead to the very high rare metal concentrations; field discrepancies exist between rare metal granites and their supposed parent peraluminous granites that in some cases are unknown. An alternative model - based on the integration of geochemical, experimental, paleogeographical and structural studies – suggests that low degree partial melting could be an efficient mechanism to produce critical metals enriched silicate melts enriched. To test whether this hypothesis makes sense, we present a study of the behaviour of W, Sn, Nb and Ta in metamorphic minerals from various metapelitic rocks. The selected samples do not present anomalous bulk concentrations of these elements with respect to an average continental crust. They formed at different pressure temperature conditions, in different orogenic belts. The rock collection comprises (i) amphibolite-facies staurolite bearing rocks, (ii) sillimanite-bearing rocks and (iii) granulite-facies orthopyroxene-bearing rocks. These samples represent the three main stages of the classical evolution of a collisional gradient leading to partial melting: they respectively belong to the muscovite + biotite domain, the muscovite-out reaction and the biotite-out reaction. We first estimate pressure-temperature conditions of formation of the rocks using pseudosection modelling. We then expose a set of LA-ICP-MS data to identify the critical metal carriers minerals in our samples. Meanwhile, we investigate the behaviour of W, Sn, Nb and Ta during the muscovite out reaction with two piston cylinder experiments (a partial melting experiment and a crystallization experiment). The protolith consists of a staurolite-bearing metapelite that did not suffer partial melting. In the light of these new data, we discuss the framework of the production of critical metal enriched silicate melts. We show that the main carrier of W is muscovite (up to 30 ppm) and that biotite handle Sn at high temperature (up to 40ppm). Using both the data from the natural sample and the experiments, we highlight that muscovite releases W during its destabilisation ant that Sn enters in biotite until the mineral breaks. We finally discuss the implication of multiple low degree partial melting / melt extraction as efficient way to produce enriched silicate melts.</p>

Pengaruh Penambahan Molases Pada Kulit Pisang Kapendis Untuk Media Produksi Xilanase B.Stearothermophillus DSM 22

2019 ◽  
Vol 15 (3) ◽  
Author(s):  
Trismillah
Keyword(s):  
Enzyme Activity ◽  
Ammonium Sulfate ◽  
Banana Peel ◽  
Partial Purification ◽  
Temperature Conditions ◽  
Cavendish Banana ◽  
Working Volume ◽  
Initial Ph ◽  
Xylanase Enzyme

Cavendish banana peel can be used as a substitute for the expensive xylan, while molasses than as a source of carbon as well as nitrogen, minerals and nutrients needed for the growth of microbes that can produce the enzyme. Xylanase produced from Bacillus stearothermopillus DSM 22, using media cavendish banana peels with the addition of molasses 1%, 2%, and 3%. Fermentation is done in a shaker incubator at 550C temperature conditions, initial pH 8, and 250 rpm agitation. The result showed the highest enzyme activity of 4,14 ± 0,16 U/mL min., on the addition 2% molasses after 24 hours. Further fermentation carried out in the fermenter working volume of 3.5 liters, with the condition of temperature 550C, pH 8, aeration 1 vvm, agitation 250 rpm, the highest spesific enzyme of activity of 51,62 ± 0,16 U/mg after 24 hours. Partial purification of xylanase enzyme fermentation is done with the results of microfiltration, ultrafiltration, ammonium sulfate (0-80%) and dialysis. There is an increase in the purity of the enzyme at each stage of purification, the highest purity on dialysis 3.23 times of crude enzymes.Kulit buah pisang kapendis dapat digunakan sebagai pengganti xilan yang harganya mahal, sementara molases selain sebagai sumber karbon serta nitrogen, mineral dan nutrisi dibutuhkan untuk pertumbuhan mikroba yang dapat menghasilkan enzim. Xilanase yang dihasilkan dari Bacillus stearothermopillus DSM 22, menggunakan media kulit pisang kapendis dengan penambahan molase 1%, 2%, dan 3%. Fermentasi dilakukan dalam shaker inkubator pada temperatur 550C, pH awal 8, dan agitasi 250 rpm. Hasilnya menunjukkan aktivitas enzim tertinggi 4,14 ± 0,16 U/mL min., pada penambahan 2% molases setelah 24 jam. Selanjutnya fermentasi dilakukan di dalam fermentor, volume kerja dari 3,5 liter, dengan kondisi temperatur 550C, pH 8, aeration 1 vvm, agitasi 250 rpm, aktivitas spesifik tertinggi 51,62 ± 0,16 U/mg setelah 24 jam. Pemurnian parsial fermentasi enzim xilanase dilakukan dengan hasil mikrofiltrasi, ultrafiltrasi, amonium sulfat (0-80%) dan dialisis. Ada peningkatan kemurnian enzim pada setiap tahap pemurnian, kemurnian tertinggi pada dialisis 3,23 kali dari enzim kasar.Keywords: Xylanase, B. stearothermophillus DSM 22, Cavendish banana peel, molasses, enzyme activity

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