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.

scholarly journals 40Ar/39Ar thermochronology in the Ios basement terrane resolves the tectonic significance of the South Cyclades Shear Zone

2019 ◽  
Vol 487 (1) ◽  
pp. 291-313 ◽  
Author(s):  
Marnie Forster ◽  
Oleg Koudashev ◽  
Ruoran Nie ◽  
Sonia Yeung ◽  
Gordon Lister
Keyword(s):  
Shear Zone ◽  
High Vacuum ◽  
Aegean Sea ◽  
Potassium Feldspar ◽  
Ultra High Vacuum ◽  
The South ◽  
Directed Movement ◽  
Mineral Growth ◽  
Diffusion Parameters ◽  
Time Histories

AbstractWe conducted 39Ar diffusion experiments using potassium feldspar from the South Cyclades Shear Zone on Ios, in the Cyclades, Aegean Sea, Greece. Irradiated samples were step-heated in an ultra-high-vacuum resistance furnace attached to a mass spectrometer, thus also allowing 40Ar/39Ar geochronology. Conjoint inversion of these datasets allowed estimation of the relevant diffusion parameters, which were then used to forward model the effect of arbitrary temperature–time histories. Simulations used Monte Carlo methods to improve approximations to the observed age spectra. Two periods of rapid cooling could be inferred. The South Cyclades Shear Zone commenced operation during or shortly after the Eocene–Oligocene transition. Episodes of south-directed movement continued into Early Miocene time, however, with the footwall still hot enough to cause biotite ± garnet metamorphic mineral growth at the base of the overlying, already substantially exhumed, eclogite–blueschist unit. Since its footwall continued to cool, the South Cyclades Shear Zone was an extensional shear zone during both episodes of its operation.

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>

scholarly journals Petrology of the Garnet Amphibolites from the Tejici Village - Povlen Mt., Western Serbia

2002 ◽  
pp. 187-198 ◽  
Author(s):  
Danica Sreckovic-Batocanin ◽  
Dragan Milovanovic ◽  
Kadosa Balogh
Keyword(s):  
Metamorphic Grade ◽  
Metamorphic Rocks ◽  
Temperature Conditions ◽  
The Village

Different metamorphic rocks discovered near the village of Tejici (Povlen Mt., Western Serbia) represent members of the olistostrome m?lange metamorphosed during the obduction/emplacement of some still hot ultramafic body. They occupy the area of about 2 km2. The garnet amphibolites are of highest metamorphic grade in the area of Tejici and were chosen as the most convenient rocks for determination the pressure-temperature conditions of metamorphism and of ultramafics during their emplacement.

Geochemistry of Archean meta-igneous rocks, Lake Despair area, Wabigoon Subprovince, northwestern Ontario

1980 ◽  
Vol 17 (8) ◽  
pp. 1046-1063 ◽  
Author(s):  
Fred J. Longstaffe ◽  
Robert H. McNutt ◽  
Henry P. Schwarcz
Keyword(s):  
Trace Element ◽  
Partial Melting ◽  
Metamorphic Grade ◽  
Igneous Rocks ◽  
Rock Types ◽  
Northwestern Ontario ◽  
Metavolcanic Rocks ◽  
Plutonic Complex ◽  
Tectonic Settings ◽  
Amphibole Fractionation

The Lake Despair area, northwestern Ontario, is underlain by a series of igneous and meta-igneous rocks including mafic and felsic metavolcanic rocks, gneisses (Footprint gneiss), and plutonic granitoids (Jackfish Lake Plutonic Complex; Northwest Bay Complex). The metavolcanic sequence consists of a bimodal suite of interlayered metabasalts of tholeiitic character and metadacites with metamorphic grade ranging from greenschist to amphibolite facies. Trace element studies of the metabasalt, while indicating an oceanic provenance, do not uniquely distinguish between possible oceanic tectonic settings. The metadacites, the Footprint gneiss, and the Northwest Bay Complex are chemically similar to the high Al tonalitic rocks common in other Archean terrains. The Footprint gneiss, which forms part of the gneissic core of the Rainy Lake batholith, was derived from an igneous parent, and was quasi-isochemically metamorphosed.The youngest major intrusion, the Na-alkalic Jackfish Plutonic Complex, is composed of hornblende diorite and monzodiorite with minor leucodiorite, quartz monzodiorite, granodiorite, and Na-syenite. The diorite and monzodiorite crystallized from an intermediate magma formed by partial melting of a garnet and (or) amphibole-rich basaltic parent. Remaining residual liquids, enriched in alkalis and silica by amphibole fractionation, crystallized to form the more leucocratic rock types. Perthitic microcline megacrysts, characteristic of the quartz monzodiorite and granodiorite, formed near the end of magmatic processes. The Na-syenite was emplaced as a separate pulse of magma or possibly was produced by the interaction of alkalis and the upper portions of the solidified rim of the magma chamber.

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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