S. Zandifar; M. V. Valizadeh; M. A. Barghi; M. R. Foroodi Jahromi
Abstract
In the west and north west of Hassan-Abaad village of Yazd, massive dikes of alkali andesite in the diorite, quartz diorite and granodiorite are observed. Clinopyroxene phenocrysts in these rocks have obvious zoning. Reconnaissance work indicates that groundmass pyroxenes in the alkaline rocks are similar ...
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In the west and north west of Hassan-Abaad village of Yazd, massive dikes of alkali andesite in the diorite, quartz diorite and granodiorite are observed. Clinopyroxene phenocrysts in these rocks have obvious zoning. Reconnaissance work indicates that groundmass pyroxenes in the alkaline rocks are similar to the more evolved phenocryst rims. Obtained data from core to rim of Clinopyroxene phenocrysts by SEM point analysis, show that Clinopyroxene composition, contains Chrome-diopsides, Salites-ferrosalites and Titanaugite. Clinopyroxene zoning formed during crystal growth. These pyroxenes are believed to record an intricate history of stop-start differentiation, magma-mixing, entry or disappearance of high-pressure precipitates. The salitic and ferrosalitic crystals of the Hassan-Abaad andesite also represent accidental fragments of anomalous upper mantle wall rocks.
S. Zandifar; M.V. Valizadeh; M. A. Barghi; M. R. Foroodijahromi
Abstract
The crystallization history of a rock is recorded by the size and the distribution of its minerals. The porphyroblast crystal size in metamorphic rocks can give notable information about its growing medium. Considering the varieties of mineralogy in the Hassan-Abad's skarn and high frequency of garnet ...
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The crystallization history of a rock is recorded by the size and the distribution of its minerals. The porphyroblast crystal size in metamorphic rocks can give notable information about its growing medium. Considering the varieties of mineralogy in the Hassan-Abad's skarn and high frequency of garnet porphyroblasts in different metamorphic zones and special different sizes in the first metamorphic zone of the NE skarn, the crystal size distributions of this mineral is studied. With regard to this, digital photos of cutting surface were provided and analyzed by JMicrovision software. It has been expected, two different slopes can show three suspections: 1- parent rock composition effect; 2- crystal growing time; 3- fluid flow around plutonic rock. According to the presence of clintonite, vesuvianite and garnet and as many as joints in the region, the role of fluid in growing the size of garnet porphyroblast in part of the first metamorphic zone seem to be noticeable.