Economic Geology
Almasi Alireza; Ghasem Nabatian; Amir Mahdavi; Qiuli Li
Abstract
The Maher abad and Khopik porphyry Cu deposits occurred in the Upper Eocene (39-37 Ma) in Lut block. All of them associated with intermediate (mostly monzonite) rocks. Porphyry deposits are closely associated with oxidized magmas. Oxygen fugacity (fO2) is a key factor that controls the formation of porphyry ...
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The Maher abad and Khopik porphyry Cu deposits occurred in the Upper Eocene (39-37 Ma) in Lut block. All of them associated with intermediate (mostly monzonite) rocks. Porphyry deposits are closely associated with oxidized magmas. Oxygen fugacity (fO2) is a key factor that controls the formation of porphyry Cu deposits. The composition of the major and trace elements of zircon grains related to several ore-bearing monzonite were measured in Maher abad and Khopik porphyry copper indices. Zircon grains show moderate to low Ce4+/Ce3+ with a range of 19 to 610 and an average of 155. The average of oxygen fugacity (logfO2) values of Meher abad and Khopik ore-bearing magmas, range ∆FMQ -3.2 to MFMQ -1.3 with mean ∆FMQ -2.2, indicate formation under moderate oxidation conditions (between Ni-NiO (NNO) and Faylite magnetite-quartz (FMQ) buffers, but magnetite-hematite (HM) buffer, which ), which is not ideal for the formation of porphyry deposits. This is supported by whole-rock and Sr-isotopic data, and absence of high oxidation minerals such as hematite, and the poor adakitic charactristic of rocks in both deposits, which are due to factors involved in magma origin such as rock type and partial melting rate (possibly peridotite with low participation of slab).
Economic Geology
Fatemeh Naderlou; Mir Ali asghar Mokhtari; Hossein Kouhestani; Ghasem Nabatian
Abstract
North Chargar Cu-Au mineralization located within the Tarom-Hashtjin sub-zone. This area composed of andesite and quartz-andesite lavas alternated with tuffaceouce rocks. The volcanic rocks have calc-alkaline nature and were formed in an active continental margin. Mineralization present as ore-bearing ...
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North Chargar Cu-Au mineralization located within the Tarom-Hashtjin sub-zone. This area composed of andesite and quartz-andesite lavas alternated with tuffaceouce rocks. The volcanic rocks have calc-alkaline nature and were formed in an active continental margin. Mineralization present as ore-bearing quartz vein-veinlets within a silicified zone. Based on mineralogical studies, chalcopyrite and pyrite are the main ore minerals, and malachite, covellite, chalcocite and goethite were formed by supergene processes. Quartz, barite and chlorite present as gangue minerals. Hydrothermal alterations include silicification, chloritization, sericitization and argillic. Ore and gangue minerals show disseminated, vein-veinlet, brecciated, cockade, comb, replacement, relict and open space filling textures. Based on field and microscopic studies, Cu-Au mineralization in the north Chargar can be divided into four stages: 1- the first stage is silicification of volcano-sedimentary host rock along with disseminated pyrite mineralization, 2- the second stage present as chalcopyrite and pyrite-bearing quartz vein-veinlets and hydrothermal breccia cement, 3- the third stage includes barite vein-veinlets crosscutting the previous stages of mineralization, 4- the last stage is related to supergene processes. Geological features, mineralogy and ore structure-textures in the north Chargar Cu-Au occurrence indicate most similarity with base metal epithermal (intermediate sulfidation) deposit type.
Economic Geology
Hossein Bagherpour; Mir Ali Asghar Mokhtari; Hossein Kouhestani; Ghasem Nabatian
Abstract
Qoyjeh Yeylaq volcanic rocks is located approximately in the 120 km southwest of Zanjan, within the Central Iranian zone. The rock units in this area belong to the Cenozoic which consist of mainly Oligo-Miocene volcanic (Basaltic- andesitic lavas) and sedimentary rocks. Based on geochemical classification, ...
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Qoyjeh Yeylaq volcanic rocks is located approximately in the 120 km southwest of Zanjan, within the Central Iranian zone. The rock units in this area belong to the Cenozoic which consist of mainly Oligo-Miocene volcanic (Basaltic- andesitic lavas) and sedimentary rocks. Based on geochemical classification, the mentioned volcanic rocks are basalt, basaltic andesite and andesite in composition, and have calc- alkaline to high-K calc-alkaline affinity. In the primitive mantle normalized spider diagrams, all of the volcanic rocks show similar patterns with enrichment in LILE (Ba, Th, K, Pb) and negative anomalies of HFSE (Nb, Ti). These rocks show LREE enrichment relative to HREE and high ratio of LREE/HREE. Based on tectonomagmatic discrimination diagrams these volcanic rocks were formed in a continental arc setting. Based on geochemical data, it seems that volcanic rocks of the Qoyjeh Yeylaq area were formed from 5-20 % partial melting of a garnet- spinel lherzolite enriched mantle by subduction of Neo-Tethys under the central Iran, within the Orumieh- Dokhtar magmatic arc.
Economic Geology
Maryam Honarmand; Ghasem Nabatian; Mahtab Aflaki; Mohammad Ebrahimi
Abstract
Geology, geochronology and tectonic setting of the Moghanlou mylonite gneiss and granite bodies, west of Zanjan Abstract The Moghanlou mylonite gneiss and granite assemblage is located in the west of Zanjan forming a part of the magmatic-metamorphic association in the Takab area. The Moghanlou assemblage ...
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Geology, geochronology and tectonic setting of the Moghanlou mylonite gneiss and granite bodies, west of Zanjan Abstract The Moghanlou mylonite gneiss and granite assemblage is located in the west of Zanjan forming a part of the magmatic-metamorphic association in the Takab area. The Moghanlou assemblage comprises of leucogranite and biotite granite intrusions which have surrounded the gneiss body. The zircon U-Pb dating shows the ages of 563±6.5 Ma for the mylonite gneiss, 576±13 Ma for the biotite granite and 559±6 Ma for the leucogranite intrusions. Moreover, the samples from the Moghanlou assemblage display high-K calc-alkaline and slightly peraluminous affinities, except those from the leucogranite which are low potassium samples due to the sodic alteration and albitization of the K-feldspars. The trace element patterns suggest LILE and LREE enrichment and HFSE and HREE depletion as well negative anomaly of Nb, Ta and Ti. In general, the geochemical features of the Moghanlou intrusions are comparable with the melts formed from crustal partial melting in magmatic arc environment. The Moghanlou assemblage is analogues to other Late Neoproterozoic-Early Cambrian igneous and metamorphic associations in Iran and Turkey which are related to the igneous activity along the Cadomian magmatic arc, in north of Gondwana supercontinent.
Economic Geology
Amir Naderi; Ghasem Nabatian; Maryam Honarmand; Hossein Kouhestani
Abstract
Halab manganese deposit is located in the Sanandaj- sirjan zone, 100 km southwest of Zanjan. The rock units in the study area include Precambrian Kahar and Jangoutaran marble Formations. Manganese mineralization in the Halab area, occurred as veins and massive in the Jangoutaran marble and minor amount ...
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Halab manganese deposit is located in the Sanandaj- sirjan zone, 100 km southwest of Zanjan. The rock units in the study area include Precambrian Kahar and Jangoutaran marble Formations. Manganese mineralization in the Halab area, occurred as veins and massive in the Jangoutaran marble and minor amount in the schist unit. The main important minerals in the Halab manganese mineralization consist of pyrolusite, psilomelane, manganite and goethite, which calcite and quartz occurred as associated gangue minerals. The ore textures include cloform, vein-veinlets, massive, comb, dogtooth, botryoidal, replacement and relict. Actinolite, carbonate and silicic are the main important alterations in this area. Primitive mantle normalized of the rare earth elements (REE) patterns in the orebody and hydrothermal carbonate samples show that the samples relatively enrichmed in light REE. The analyzed samples show significant negative anomaly in Ce and weak negative anomalies in Eu. Furthermore, the primitive mantle normalized pattern of trace elements in the orebody and hydrothermal carbonate show significant enrichment in Ba, U, La, Pb, Sr and negative anomaly in Rb, Th, Nb, Ce, P, Zr and Ti. The field and microscopic studies as well geochemical evidences suggest that the mineralization formed by hydrothermal fluids. The circulation of meteoric and/or magmatic fluids within the Precambrian units provide the important elements such as Mn, Fe and Ca for mineralization. When the mineralizing fluid contact with reactable rocks, caused the formation of Mn mineralization in the Halab area.
Economic Geology
Fattaneh Pourmohammad; Hossein Kouhestani; Amir Morteza Azimzadeh; Ghasem Nabatian; Mir Ali Asghar Mokhtari
Abstract
Mianaj Fe ore occurrence is located in the Takab-Angouran-Takht-e-Soleyman metallogenic zone, 100 km southwest of Zanjan. In this area, Fe mineralization occurs as lens-shaped bodies parallel to the foliation of schist and rhyolitic meta-tuff units (equal to Kahar Formation). Based on mineralography, ...
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Mianaj Fe ore occurrence is located in the Takab-Angouran-Takht-e-Soleyman metallogenic zone, 100 km southwest of Zanjan. In this area, Fe mineralization occurs as lens-shaped bodies parallel to the foliation of schist and rhyolitic meta-tuff units (equal to Kahar Formation). Based on mineralography, ore mineral is magnetite, and quartz present as gangue mineral at Mianaj. The ore minerals show disseminated, laminated, banded, massive, vein-veinlet and replacement textures. Three stages of mineralization can be distinguished at Mianaj. The first stage is recognized as stratiform and stratabound lenses, laminated and disseminated crystals of magnetite parallet to the foliation of host rocks. Stage-2 mineralization is recognized by folding of ore bands, σ microfabric and boudinage of magnetite crystals, quartz pressure shadows and surrounding of foliation around magnetite crystals, and recrystallization of quartz and magnetite crystals. Stage-3 is recognized by quartz vein-veinlets that cut previous mineralization stages. Chondrite-nonmineralized REE pattern of host rocks and the mineralized samples indicate that mineralized samples are depleted in REE. This signature indicates mobility of REE by Cl and F-rich oxidized fluids during mineralization processes. Characteristics of Mianaj occurrence are comparable with metamorphosed and deformed volcano-sedimentary type of iron deposits.
Economic Geology
Mahin Zolfaghari; Ghasem Nabatian; Amir Morteza AzimZadeh; Maryam Honarmand; P. Azizi
Abstract
Pirgheshlagh Cu-Zn-Pb deposit is located in the Central Iranian zone, north-east of the Mahneshan in the Zanjan province. The Kahar Formation with Precambrian age is the oldest Formation in the area which cutted by the granitic dykes. The Pirgheshlagh Cu-Zn-Pb mineralization occurred mainly as tabular-shape ...
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Pirgheshlagh Cu-Zn-Pb deposit is located in the Central Iranian zone, north-east of the Mahneshan in the Zanjan province. The Kahar Formation with Precambrian age is the oldest Formation in the area which cutted by the granitic dykes. The Pirgheshlagh Cu-Zn-Pb mineralization occurred mainly as tabular-shape within the metamorphosed sandstones, meta-andesitic tuff, meta-crystal lithic tuff and meta-andesite rocks. Based on the field and microscopic studies, the main minerals consist of chalcopyrite, sphalerite, galena, pyrite, arsenopyrite and minor magnetite. The ore textures consist of disseminated, laminated, massive and veinlet which the veinlet texture is occurred mainly in the lower part of deposit. Secondary minerals such as smithsonite, cerrusite, chalcocite, covellite, malachite, azurite, goethite and lepidochrosite have formed during supergene processes. The main alterations in the Pirgheshlagh deposit include silicic, sericitic, chlorite and carbonate. The results of this study suggest that the Cu-Zn-Pb mineralization in the Pirgheshlagh deposit is a Besshi-type valcogenic massive sulfide (VMS) mineralization.
Gh Nabatian; M Ghaderi
Abstract
Iron oxide - apatite deposits are one of the most important REE resources that occurred in the Posht-e-Badam and Zanjan regions of Iran. REE mineralization in the Zanjan region is associated with Sorkhe Dizaj, Aliabad, Morvarid, Zaker, Oskand and Golestanabad iron oxide-apatite mineralization. The deposits ...
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Iron oxide - apatite deposits are one of the most important REE resources that occurred in the Posht-e-Badam and Zanjan regions of Iran. REE mineralization in the Zanjan region is associated with Sorkhe Dizaj, Aliabad, Morvarid, Zaker, Oskand and Golestanabad iron oxide-apatite mineralization. The deposits are located in the Tarom area, which is a part of western Alborz - Azarbaijan zone. The Eocene volcanic sequences such as olivine basalt, trachyandesite, andesite as well as volcanoclastic rocks are the main units in the area which are intruded by the late Eocene plutonic rocks. Plutonic rocks in the region include porphyric micro-quartzdiorite and quartz-monzonite to quartz-monzodiorite. Magnetite-apatite mineralization in the Zanjan region is related to quartz-monzonitic to quartz-monzodioritic rocks. The mineralization is observed in the form of vein and stockwork (irregular veins and veinlets of magnetite-apatite). In the Tarom magnetite-apatite deposits, apatite crystals are associated with magnetite some of which have sizes up to 20 cm. Monazite is the main REE-bearing mineral at these deposits occurring as inclusion in the apatite. The apatite minerals contain 0.4-1.6 wt% REE, and have an REE distribution pattern with a strange LREE/HREE enrichment. The results of this research indicate that the iron oxide - apatite mineralization in the Zanjan region is formed by a quartz-monzonitic magma with calk-alkaline affinity, which occurred in a magmatic arc setting. This research shows that the magnetite - apatite mineralization in the Zanjan region is an important REE concentration in Iran.
