Siamak Karimi; Mehrdad Behzadi; Iraj Rasa; Amir Masoud Ghazvinizadeh
Volume 3, Issue 12 , March 2013, , Pages 33-50
Abstract
The IIeh Iron ore deposit is located about 250 km SE of Mashhad and 49 km SW of Taibad (Khorasan Razavi province). The oldest exposed rock unit belong to late Proterozoic and are meta ...
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The IIeh Iron ore deposit is located about 250 km SE of Mashhad and 49 km SW of Taibad (Khorasan Razavi province). The oldest exposed rock unit belong to late Proterozoic and are meta volcano-sedimentary complexes with metamorphic grade of green schist facies. The other outcrops are granites with Upper Eocene age which cut the complex. The granitic bodies are calc-alkaline, high-K, peraluminous to meta aluminous, and characterized by negative Eu anomaly, the magnetite- series (I-Type) granites, are related to continental- margin subduction zones with the lower crust source. The homogenization temperatures (Th) obtained from fluid inclusions in calcite and quartz ranges from 200-385 ºC with mode of 300-320 ºC. Two salinity ranges of 4-6 and 28-38 NaCl eq. Wt% are observed in quartz and calcite, respectively, implying an possible fluid-mixing event. The occurrence of hematite could be taken as evidence for extremely oxidizing conditions and the possible derivation from a magmatic source during the trapping event. Based on XRD and thin- section studies, the altered rocks around ore deposits show sericitization, chloritization, illitization, kaolinitization, silicification and montmorillonitization are the main alteration types. This study suggestsa K-Fe-Mg-Si-Ca composition for the ore-bearing fluids. Further proof for the hydrothermal-origin of the ore-bearing fluids is indicated by the positive Eu anomaly in the respected REE abundance pattern of ore samples.
