نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه زمینشناسی، دانشکده علوم پایه، دانشگاه هرمزگان، بندرعباس، ایران
2 موسسه تحقیقاتی پاساد، کالیفرنیا، آمریکا
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Introduction
The evolutionary history of the Sanandaj-Sirjan zone has been influenced by two extensional and
compressional regimes that have caused rifting, subduction, collision and its final closure. The study area is
located in Esfandabad city of Yazd province. The sequence contains dark colored andesitic, rhyolitic and
basaltic lava with interlayers of volcanoclastic and sedimentary units. The volcanic rocks detected contain
aphanitic textures and have dark gray to black color with oxidized surface, fractures and pores. These
volcanic rocks have a layered flow and are mostly seen as dome-shaped structures and are sometimes in the
form of dikes. Another characteristic of this group of rocks is the green color obtained from the secondary
minerals of chlorite and epidot, as a result of the alteration applied to them. The volcanoclastic rocks are
mainly fine-grained and welded purple tufts.
Materials and Methods
In order to achieve the aim of this study, after descriptive studies, field operations were performed in three
stages and 100 samples were taken from the desired outcrops and thin sections were prepared. After
petrographic studies, less altered samples were selected and sent to the GeoLeb Laboratory in Canada for
geochemical analyzing using XRF, ICP-MS and ICP-IAS methods. Age studies have been conducted at the
Caltech Institute in California.
Results and Discussion
In microscopic studies, the dominant texture in basaltic rock is porphyry, consisting of plagioclase, olivine
and pyroxene in a fine-grained matrix composed of plagioclase, epidote, chlorite, sphene and opaque
minerals. Andesitic rocks have microporphyric and seriate textures consisting of plagioclase, in a fine
grained matrix consisting of plagioclase, pyroxene, quartz, epidote, carbonate and chlorite alteration
products and opaque minerals. Rhyolite rocks have a microcrystalline to hyalline texture consisting of quartz,
alkali feldspar and plagioclase. Evidence such as sosoritization of plagioclase, filling of cavities by chlorite
and zeolite, idingitizated or chlorinated olivine and uralite pyroxene crystals indicate the performance of
metamorphic phenomena in the studied rocks.
Conclusion
In microscopic studies, the dominant texture in basaltic rock is porphyry, consisting of plagioclase, olivine and
pyroxene in a fine-grained matrix composed of plagioclase, epidote, chlorite, sphene and opaque minerals.
Andesitic rocks have microporphyric and seriate textures consisting of plagioclase, in a fine grained matrix
consisting of plagioclase, pyroxene, quartz, epidote, carbonate and chlorite alteration products and opaque
minerals. Rhyolite rocks have a microcrystalline to hyalline texture consisting of quartz, alkali feldspar and
plagioclase. Evidence such as sosoritization of plagioclase, filling of cavities by chlorite and zeolite, idingitizated
or chlorinated olivine and uralite pyroxene crystals indicate the performance of metamorphic phenomena in the
studied rocks.
کلیدواژهها [English]