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Wyszukujesz frazę "Sanandaj-Sirjan Zone" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Mineral chemistry and thermobarometry of plutonic, metamorphic and anatectic rocks from the Tueyserkan area (Hamedan, Iran)
Autorzy:
Sepahi, A. A.
Borzoei, K.
Salami, S.
Powiązania:
https://bibliotekanauki.pl/articles/2060560.pdf
Data publikacji:
2013
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Alvand Pluton
Hamedan
Iran
mineral chemistry
Sanandaj-Sirjan zone
thermobarometry
Opis:
The study area is a part of the NW to SE striking Sanandaj–Sirjan metamorphic belt in western Iran. The Alvand Pluton, consisting of rocks that range in composition from gabbro to granite, is the major magmatic rock complex of this area. Gabbroic rocks include olivine gabbro, gabbro norite, norite and gabbro. Rocks around the Alvand Pluton were subjected to different P–T conditions due to polymetamorphism. Common metamorphic rocks are meta-pelites, but some meta-psammites, meta-basites and meta-carbonates also occur. Slates, phyllites, schists, migmatites and hornfelses are major rock units of meta-pelites in the metamorphic sequence. Based on mineral chemistry, the highest temperature of crystallisation (1300°C) was determined for the olivine gabbros, and the lowest temperature (950°C) was calculated for the hornblende-bearing gabbros. Clinopyroxene–plagioclase barometry suggests that pressures near 5 to 6 kbars prevailed during the crystallisation of the various mafic rocks. P–T estimates yield maximum temperatures of 700–750°C at 5–6 kbars for the high-grade metamorphic rocks from the metamorphic aureole around the pluton. These results indicate that the heat released from the Alvand Pluton (T = 950–1300°C), which intruded the metamorphic rocks at middle and upper crustal levels, was sufficient to cause partial melting leading to formation of the metatexites, diatexites and restite-rich S-type granites. During this process, part of the deep-seated gabbro-dioritic rocks were transported to higher crustal levels by viscous, enclave- and crystal-rich granitic magmas of the partial melting zone.
Źródło:
Geological Quarterly; 2013, 57, 3; 515--526
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geochemistry and fluid-inclusion microthermometry of the Farsesh barite deposit, Iran
Autorzy:
Zarasvandi, A.
Zaheri, N.
Pourkaseb, H.
Chrachi, A.
Bagheri, H.
Powiązania:
https://bibliotekanauki.pl/articles/94476.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
hydrothermal barite
ICP-MS analysis
geochemistry
fluid inclusions
Sanandaj-Sirjan zone
Iran
hydrotermalny baryt
ICP-MS
geochemia
inkluzje fluidalne
Opis:
The Permian carbonate-hosted Farsesh barite deposit is located southeast of the City of Aligudarz in the prov-ince of Lorestan, Iran. Structurally, this deposit lies in the Zagros metallogenic belt and the Sanandaj-Sirjan Zone. Barite mineralisations occur as open-space filling veins, and as massive and replacement ores along fractures, faults and shear zones of the Permian carbonate host rocks. In order to determine the structure, in addition to pe-trographic and fluid-inclusions studies, an ICP-MS analysis was carried out in order to measure the major as well as the trace and rare earth elements. The Farsesh barite deposit has a simple mineralogy, of which barite is the main mineral, followed by calcite, dolomite, quartz, and opaque minerals such as Fe-oxides. Replacement of bar-ite by calcite is common and is more frequent than space-filling mineralisation. Sulphide minerals are minor and mainly consist of chalcopyrite and pyrite, which are altered by weathering to covellite, malachite and azurite. Petrographic analysis and micro-thermometry were carried out on the two-phase liquid/vapour inclu-sions in ellipsoidal or irregularly shaped minerals ranging in size from 5–10 μm. The measurements were conducted on fluid inclusions during the heating and subsequent homogenisation in the liquid phase. The low homogenisation temperatures (200–125°C) and low to moderate salinity (4.2–20 eq wt% NaCl) in-dicate that the barite had precipitated from hydrothermal basinal water with low to moderate salinity. It appears from the major and trace elements that geochemical features such as Ba and Sr enrichment in the barite samples was accompanied by depletion of Pb, Zn, Hg, Cu and Sb. The geochemistry of the rare earth elements, such as low ΣREE concentrations, LREE-enrichment chondrite-normalised REE patterns, the negative Ce and positive Eu anomalies, the low Ce/La ratio and the positive La and Gd anomalies, suggest that the Farsesh barite was deposited from hydrothermally influenced sea water. The Farsesh deposit contains low-temperature hydrothermal barite. The scatter plots of the barite (close to sea water) in different areas on the CeN/SmN versus CeN/YbN diagram support the possibility that the barite was formed from seawater-bearing hydrothermal fluids.
Źródło:
Geologos; 2014, 20, 3; 201-214
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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