Petrology
Ismail KhanChuban; Behzad Haj alilou; Mohsen Moayyed; Mohamadreza Hosseinzadeh; Morovat Faridazad
Abstract
In the Gezeldash_daghi region, there is a significant outcrop of Miocene volcanic activity with andesitic composition associated with pyroclastic deposits including tuff, breccia and agglomerate. These rocks have porphyry to microporphyry texture with coarse crsytals of pagioclase, and matrix includes ...
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In the Gezeldash_daghi region, there is a significant outcrop of Miocene volcanic activity with andesitic composition associated with pyroclastic deposits including tuff, breccia and agglomerate. These rocks have porphyry to microporphyry texture with coarse crsytals of pagioclase, and matrix includes plagioclase, hornblende and minor biotite. Zoning, sieve texture in the coarse crystals of these lavas is an indicative of unstable conditions during magma solidification. These lavas have calc-alkaline nature. The geochemical characteristics of Gezeldash_daghi lavas such as LREE enrichment than HREE as well as enrichment of LILE elements with negative Nb, Ti and P anomalies indicate their affilliation to subduction setting. These rocks contain high amounts of SiO2, Sr, Sr / Y and La / Yb, and lower values of Y, MgO, and Yb than classic calc-alkaline volcanic rocks, and may indicate lava adakitic features. Based on the geochemical data, these lavas had formed partial melting of subducted oceanic crust. The depletion of rare earth elements indicates a residue containing garnet and hornblende in the source area.
Economic Geology
Behzad Hajalilou; M. Razmara; Nasim Hajalilou
Abstract
The placer ore deposit of Ataeieh is located in south west of Mashhad and central Iranian microplate. The petrography and mineralography studies of VTM placer ore deposit, showed that the main ores in this area from high to low amounts are: magnetite, titanomagnetite, hematite and ilmenite. It revealed ...
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The placer ore deposit of Ataeieh is located in south west of Mashhad and central Iranian microplate. The petrography and mineralography studies of VTM placer ore deposit, showed that the main ores in this area from high to low amounts are: magnetite, titanomagnetite, hematite and ilmenite. It revealed that the ultramafic and gabbros are the main source for opak minerals by mineralography Studies. The SEM-EDS, EPMA and XRM studies on the placer ore deposit and their origion presentaded remarkable results. The SEM investigation showed that, in the magma crystallization the solid soulution is formed between titanomagnetite and ilmenite at 800°C and then with the decreasing of temperature up to 600°C the ilmenite and magnetite exsolution lamella segreqates and separated from titanomagnetite phase either the ophiolite sequence is the source of this deposit. Titaniumand Vanadium enter to the ilmenite and titanomagnetite in gabbroic rocks whit continuing of magma crystallization. The EPMA analysis on gabbroic units showed that these rocks are origion for Ti and V in placers.
