دکتر حمایت جمالی

The Barout Aghaji gold deposit is located ∼90 km northwest of Zanjan, within the Takab-Takht-e-Soleyman subzone of the Sanandaj-Sirjan metamorphosed-deformed zone. Ore-bearing quartz veins are hosted by Neoproterozoic amphibolite and Eocene to Oligocene granitic gneisses. Oligo-Miocene Upper Red Formation unconformably overlies the amphibolite and granitic gneisses. Field observations and petrographic studies show that two deformation stages occurred in this area. The first deformation stage was ductile, producing mylonitic and proto-mylonitic microstructures, but the second one was brittle, represented by sheeted quartz veins and veinlets. In the first stage, barren milky quartz veins occurred containing minor sulfide minerals, but dark to light gray ore-bearing quartz veins and veinlets are formed in the latter stage. The mineralized veins appear as massive microcrystalline quartz cut by sheeted quartz veins with comb, druse, and crustiform textures. The gold-bearing quartz veins contain as much as 3% sulfide minerals. Pyrite is the main sulfide mineral and is associated with minor chalcopyrite. Sulfides are commonly altered to hematite, goethite, and rarely malachite. Hydrothermal alteration around the quartz veins consists of silicification, pyritization, and sericitization. The whole-rock geochemistry of the collected samples from the granitic gneisses and quartz veins shows that Au is enriched in the quartz veins (average of 114 ppb) relative to host rocks (average of 22.5 ppb). Au shows strong positive correlations with As, Ba, Mo, Pb, Sc, Tl, Ag, and negative correlations with Cu, Bi, Se, and Te in the granitic gneisses. It also shows strong positive correlations with S, Hg, Th, Co, Bi, Pb, and Ag and negative correlations with P, V, Te, W, Sc, Zn in quartz veins. Four types of primary fluid inclusions were identified, including type I, two-phase aqueous-rich fluid inclusions (liquid > vapor; LV); type II, two-phase vapor-rich fluid inclusions (gas > liquid; VL); type III, three-phase fluid inclusions containing CO2 with clathrate formation (L1L2V); and type IV three-phase fluid inclusions (aqueous, vapor, and solid; LVS). The homogenization temperatures of fluid inclusions in auriferous quartz veins range from 199 −446 with a mode of 270–300 °C. Salinities range from 0.8 to 49.02 wt% NaCl Equiv. with two distinct populations at 0.8–8.5 and 31.1–49.02 wt% NaCl Equiv. The large variations in the homogenization temperatures and salinities can be attributed to the cooling and isothermal mixing of fluids. The δ34S values for four pyrites separated from auriferous quartz veins range from +2.9 to +7.1‰, with an average of 4.5‰. δ34S values of fluids in equilibrium with pyrite were calculated from +3.5 to +7.3‰, with an average of 5.4‰, indicating a metamorphic source for the sulfur using temperatures estimated from the fluid inclusion study. The Field observations, vein textures, mineralogy, ore geochemistry, fluid inclusion studies, and sulfur isotope data indicate that gold mineralization in the Barout Aghaji area has many similarities to orogenic and intrusion-related gold deposits, such that low salinity fluids derived from metamorphic rocks are mixed with high salinity fluid inclusions possibly derived from granitic gneisses during syn to post tectonic magmatism. © 2023 The Author(s)

Origin and evolution of the ore-forming fluids in the southern Abbas Abad iron skarn deposit, NE Isfahan, Central Iran: Insights from geology, fluid inclusions, and C-O isotopes

( Article . )

Masoumipour, Zahra, Jamali, Hemayat, Masoumipour, Z., Jamali, H., Harris C., Lentz, D.R., Yousefi, F.

JOURNAL OF GEOCHEMICAL EXPLORATION (03756742)248

The southern Abbas Abad iron skarn deposit is located in the western part of the Central Iran zone, SW edge of the Urumieh-Dokhtar magmatic arc. The skarn alteration occurred mainly at the contact of the Abbas Abad gabbro and Triassic Nayband Formation. The Triassic Nayband Formation in the southern Abbas Abad area consists of limestone, shale, siltstone, and marl with interlayers of tuff. The Abbas Abad gabbro is calc-alkaline with adakitic signatures and continental arc setting affinity. Four iron ore bodies occur along the NW-SE trending normal fault along the southern margin of Abbas Abad gabbro within sedimentary host rocks of the Nayband Formation. Three main paragenetic stages of skarnification and ore deposition have been recognized: i) prograde stage, ii) retrograde stage, and iii) supergene stage. Spinel, garnet, and pyroxene formed during the prograde stage. Epidote, tremolite-actinolite, calcite and ore minerals, such as magnetite, hematite-I, pyrite, and minor chalcopyrite formed the retrograde stage assemblage. Magnetite is the main economic ore mineral, which is diverse in terms of fabric and texture, including massive, disseminated, needle-like, blade-like, prismatic, crustification, and cubes. Stable isotope data from Abbas Abad iron skarn deposit indicated that the interaction of non-magmatic brine (connate) fluids with Triassic carbonate host rocks at high temperature and its mixing with meteoric water has led to changes in the isotopic composition of the mineralizing fluid. Subsequently, garnet and magnetite with relatively high estimated fluid delta 18O values (average 12.3 and 14.6 parts per thousand, respectively) formed from this modified fluid. The estimated delta 18O values of fluid in equilibrium with calcite decreased as a result of the greater influx of the meteoric water into the hydrothermal system in the late stages of ore formation. Fluid in-clusion data from this iron skarn deposit are consistent with minor boiling during the prograde stage, although cooling and dilution seem to be principally responsible for Fe precipitation. The petrogenetic model proposed for the Southern Abbas Abad iron skarn deposit suggests that during the Eocene a gabbroic stock intruded the sedimentary rocks of the Nayband Formation and acted as a heat source for the non-magmatic brine (connate and meteoric) fluids convection cells, then reacted with cooler Triassic carbonate rocks. In this model, leaching of the gabbroic rock provided the iron, whereas carbon came from degassing and dissolution of carbonate rocks during contact metamorphism-metasomatism.

2020

Spatial-temporal relationship of mineralization and magmatism in the Mazraeh polymetallic deposit (north of Ahar, Eastern Azarbaijan province)

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Jamali, H.

Petrological Journal (22285210)11(3)pp. 65-84

2019

Exhalative deposits in eocene volcano-sedimentary rocks in the middle part of the Urumieh-Dokhtar magmatic belt: Detailed evidence from nabar deposit, west of Kashan, Urumieh – Dokhtar Magmatic Belt

( Article . )

Jamali, H., Zohouri, F.S., Tabatabaei manesh, S.M.

Journal of African Earth Sciences (1464343X)154pp. 120-135

Meso-Cenozoic magmatic belt of Urumieh–Dokhtar resulted from subduction of Neothetys oceanic crust beneath the Central Iran Block with Gondwanic signature is dominated by calc-alkaline to alkaline igneous rocks. The magmatic rocks has mainly occurred in submarine environments as volcanic-volcanoclastics with interlayers of sedimentary rocks in the Eocene, while it has occurred as intrusive and subvolcanics in the Neogene. In the Nabar area volcano-sedimentary rocks of Eocene have been covered unconformably by Oligo-Miocene sedimentary rocks (Qom Formation). The Eocene and Oligo-Miocene sequences are intruded by Middle-Upper Miocene intrusive and subvolcanic bodies. Igneous rocks of Eocene and Middle-Upper Miocene are of I-type and calc-alkaline belonging to arc and post-collisional setting of continental margin, respectively. The mineralization consists of pyrrhotite, pyrite, minor chalcopyrite and sphalerite, mainly hosted by Eocene volcanoclastics and particularly by the contact metamorphic halos of Qom formation. Irregular veinlets (stringer zone) in the lower part change to massive lenses upward which conformable with Eocene enclosing rocks, and have sharp contact with overlying Qom formation. Low grad ores with irregular shape (patches, veinlets, cavity and fracture filling) which are resulted from remobilization of previous mineralization, occurred within the contact metamorphic halos of Middle-Upper Miocene intrusions. According to geochemical analysis and mineralogical studies, iron, copper, gold, silver, arsenic, lead and zinc are enriched in the ore zone. Two types of fluid inclusion (L-V and L-V[sbnd]S) were distinguished in quartz veinlets. The homogenization temperature and salinity of fluid inclusions vary from 121 °C – 537 °C and 9–45 wt% NaCl equivalent, respectively. These data indicating the mixing of magmatic water with meteoric water in the later stage of mineralization. The δ 34 S values of pyrite and pyrrhotite which varies from 10.5 to 11.6 wt% compatible with massive sulfide and skarn type deposits. Field observations, mineralogical, geochemical, fluid inclusion and isotopic data suggest that, the Nabar deposit is probably a Kuroko type massive sulfide deposit which has been partly changed to skarn during penetration of Middle-Upper Miocene subvolcanic intrusions. The Kuroko type barite deposit of Dorreh and exhalative Mn deposit of Venarch and Shahrestanak were formed at the same time, within the Eocene volcanoclastic sequences. © 2019

2018

Mineralogy, alteration, fluid inclusion and geochemical constraints of the Tappeh-Khargoosh Cu-Au deposit (SW Ardestan)

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Hashemian, E., Jamali, H., Ahmadian, J.

Journal of Economic Geology (20087306)10(2)

2017

The behavior of rare-earth elements, zirconium and hafnium during magma evolution and their application in determining mineralized magmatic suites in subduction zones: Constraints from the Cenozoic belts of Iran

( Article . )

Jamali, H.

Ore Geology Reviews (01691368)81pp. 270-279

2015

Relationships between arc maturity and Cu-Mo-Au porphyry and related epithermal mineralization at the Cenozoic Arasbaran magmatic belt

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Jamali, H., Mehrabi, B.

Ore Geology Reviews (01691368)65(P2)pp. 487-501

The actual study deals with the temporal and geochemical evolution of the arc magmatism and the Cu-Mo-Au mineralization in the Neo-Tethyan belt of the Arasbaran region in northwestern Iran. The magmatic activity in this section of the Neo-Tethyan belt periodically occurred from Upper Cretaceous to Quaternary. The Cretaceous magmatic rocks are calc-alkaline to tholeiitic in nature without any mineralization in the Arasbaran region. Cenozoic magmatism begins with alkaline (shoshonitic) volcanism at an early stage and is followed by alkaline to calc-alkaline plutonism. No significant mineralization is associated with the early stage alkaline magmatism and the most porphyry and epithermal mineralizations are related to the late stage adakite-like, calc-alkaline magmatism. The subsequent, post-collisional alkaline magmatism follows in the Plio-Quaternary. Magmatism and the related mineralization decrease in age from the north to the south, and the mineralization changes in time and space from a Cu-Mo to a Cu-Au association.Mineralization stages at the Arasbaran region consist of (a) Upper Oligocene to Lower Miocene (~. 20. Ma) Cu-Mo porphyry and intrusion mineralization, and (b) Upper Miocene (~. 10. Ma), Cu-Au porphyry and epithermal Cu-Au mineralization. Although the exact timing of the porphyry mineralization relative to the final collision is unclear, the presence of most porphyry and epithermal mineralizations in the Upper Oligocene to Upper Miocene, post-collisional, adakite-like intrusions, is related to crustal thickening and delamination of lower crust suggesting that they formed at a late stage of the Arasbaran magmatic arc evolution following a major volcanic stage in the Eocene. Mineralogical and geochemical characteristics of the mineralized porphyry bodies in Arasbaran region indicate that significant amounts of hornblende was fractionated prior to plagioclase crystallization as a consequence of high magmatic water contents. In contrast, the earlier, barren plagioclase-phyric magmas were relatively dry. Fertile plutonic suites in Arasbaran region may be recognized by their relatively late timing with respect to the voluminous Eocene volcanism. Widespread presence of hornblende phenocrysts, and major and trace element compositions with relatively high Sr/Y and La/Yb ratios, high Sr (>. 400. ppm) and Nd (≥. 20. ppm) indicate a long-lived mature arc setting. © 2014 Elsevier B.V.

2010

Metallogeny and tectonic evolution of the Cenozoic Ahar-Arasbaran volcanic belt, northern Iran

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Jamali, H., Dilek, Y., Daliran, F., Yaghubpur, A., Mehrabi, B.

International Geology Review (00206814)52(4-6)pp. 608-630