Economic Geology
Majid Hafez Darbani; Ali Abedini; Farhang Aliyari; Ali Asghar Calagari
Abstract
The Kuh-Baba iron ore deposit is located in ~70 km south of Hashtroud, East-Azarbaidjan province, NW Iran. The lithologic units cropped out around this deposit include Oligo-Miocene volcanic-sedimentary rocks, Pliocene intrusive rocks, and Pliocene dacitic domes. The principal host rocks for the Fe mineralization ...
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The Kuh-Baba iron ore deposit is located in ~70 km south of Hashtroud, East-Azarbaidjan province, NW Iran. The lithologic units cropped out around this deposit include Oligo-Miocene volcanic-sedimentary rocks, Pliocene intrusive rocks, and Pliocene dacitic domes. The principal host rocks for the Fe mineralization include units of gabbro-norite, pyroxene hornblende gabbro-norite, and monzo-diorite. Remote sensing investigations (using Sentinel satellite images) display the presence of lineaments, NE-SW trending fault structures, and various alteration zones. The dominant hydrothermal alteration in inner parts of the deposit is mainly propylitic (epidote, chlorite, sericite) which gradually changes to argillic outward toward the peripheral parts. Based upon field relations and microscopic examinations, the ores show massive, vein/veinlet, brecciated, and disseminated textures. In the propylitic zone, magnetite is accompanied by epidote and actinolite. The geochemical studies revealed that the FeT content in the diamond drill core samples varies from 3.85 wt% to 63.2 wt%. Ground magnetic survey was conducted in the area and also, the maps of total magnetic field, reduced to pole magnetic, analytic signal, first vertical derivative, and upward continuation were prepared in an attempt to identify the potential deep and shallow subsurface mineralized zones. The obtained results show that two anomalies, one in the north and the other in the central parts of the study area, were recognized which almost correspond with the location of the intrusive bodies.
Economic Geology
S. Maleki; A. A. Calagari; K. Siahcheshm; S. Alirezaei
Abstract
Khak Sorkh iron deposit located about 42 km northwest of Nadushan town in Yazd Province. Host rock include upper Triassic-Jurassic limestone which are intruded by Oligo-Miocene granitoid bodies. Mineralization is dominated by magnetite, and serpentine is the main waste mineral. Skarn mineral assemblages ...
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Khak Sorkh iron deposit located about 42 km northwest of Nadushan town in Yazd Province. Host rock include upper Triassic-Jurassic limestone which are intruded by Oligo-Miocene granitoid bodies. Mineralization is dominated by magnetite, and serpentine is the main waste mineral. Skarn mineral assemblages include clinopyroxene, garnet, tremolite phlogopite and epidote. The characteristics of mineralization are: magnetite mineralization in two generations, presence of serpentine as the main waste mineral, hornfelsed greywacke units which come between intrusive bodies and skarned limestone units, absence of obvious zoning in endoskarn and exoskarn parts, presence of Ni-Co-As sulfides, high amount of Zn, As, Co and Mn in magnetite geochemical results and the increasing Fe along with decreasing Mg contents in magnetite at both deposit and crystal scales from primary to secondary types. Minor elements contents of geochemical results have been used for distinguishing of different mineral deposits (e.g, Dare et al., 2012; Dupuis and Beaudoin, 2011; Nadoll et al., 2012) and they are in good accordance to hydrothermal and skarn type deposits like: low contents of Cr (less than 10 ppm), high contents of Mg (2.2 to 7.5 ppm), low TiO2 (from 0.01 to 0.3 ppm), low amounts of incompatible elements including Ag (
Sh Fatahi; A.A Calagari; A Abedini
Abstract
Neyestanak bentonite deposit is located in northwest of Naeen, Isfehan province. This deposit is an alteration product of Oligocene tuff breccias. Mineralogical considerations of this deposit show that montmorillonite, kaolinite, and quartz are the principal minerals which are accompanied by lesser amounts ...
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Neyestanak bentonite deposit is located in northwest of Naeen, Isfehan province. This deposit is an alteration product of Oligocene tuff breccias. Mineralogical considerations of this deposit show that montmorillonite, kaolinite, and quartz are the principal minerals which are accompanied by lesser amounts of anorthite, calcite, chlorite, illite, albite, dolomite, microcline, orthoclase, sanidine, and halite. Mineral chemistry investigations testify to the similarity of this deposit with Wyoming-type bentonite deposits. Geochemical studies reveal that bentonitization of tuff breccias at Neyestanak is accompanied by depletion of Ba, Co, Zn, Y, Ni, Sr, Au, Ca, Fe, Mg, Mn, P, Ti, and Na, enrichment of Si, Th, As, Hf, Nb, and U, and leaching-fixation of K, Pb, Cs, Rb, Zr, and Cu. Geochemical analyses make clear that variation of Eu and Ce anomalies in this deposit were controlled by the degree of alteration of feldspars and oxidation potential of the environment, respectively. By considering the results obtained from this study, it seems that factors such as differences in degree of alteration intensity of parent materials, physico-chemical conditions of the environment, adsorption, incorporation in crystal structure, access to complexing ligands, and differences in degree of resistance of the primary minerals against alteration played prominent role in mobilization, distribution, and concentration of elements in this deposit.
Gh Sohrabi; M.R Hosseinzadeh; A.A Calagari; B Hadjalilu
Abstract
The study area is located in north of East-Azarabaidjan (northwest of Iran). The most important intrusive bodies in the area include the Gharehdagh and Shivardagh batholiths and porphyry stocks of Sungun and Haftcheshmeh. The petrological and petrographical studies show that the composition of intrusives ...
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The study area is located in north of East-Azarabaidjan (northwest of Iran). The most important intrusive bodies in the area include the Gharehdagh and Shivardagh batholiths and porphyry stocks of Sungun and Haftcheshmeh. The petrological and petrographical studies show that the composition of intrusives varies from gabbro through diorite, monzonite, and granodiorite to granite. All bodies are I-type and mostly metaluminous and calc-alkaline with medium to high potassium belonging to volcanic arcs. The most important alterations in ore-bearing areas include silicic, potassic, propylitic, phyllic, and argillic. Mo mineralization occurred mostly in quartz veins and veinlets within the potassic zone in porphyry systems and veins and also in endoskarn associated with garnet skarns. The amount of Mo increases in differentiated and biotite-bearing acidic bodies that have high values of Si, K, Rb, and REEs. The intrusive bodies enriched with K, Rb, and Ba and depleted in Zr, Ta, Y, Yb, and Nb elements indicate metasomatism of the upper mantle by subducting oceanic crust and subsequent generation of magma and its passes through relatively thick crust. The bodies bearing Mo mineralization are located mainly in the center of batholiths and have quartz monzonitic and granodioritic compositions.
Sh Fatahi; A.A Calagari; A Abedini; H Bagheri
Abstract
Chahreeseh bentonite deposit is located at ~55 km northeast of Isfahan, structural zone of Central Iran. This deposit has layered and massive form and includes six discrete outcrops. The field observations showed that the ores are genetically related to Oligo-Miocene tuff breccia. The mineralogical studies ...
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Chahreeseh bentonite deposit is located at ~55 km northeast of Isfahan, structural zone of Central Iran. This deposit has layered and massive form and includes six discrete outcrops. The field observations showed that the ores are genetically related to Oligo-Miocene tuff breccia. The mineralogical studies testified to the presence of minerals such as montmorillonite, saponite, beidellite, cristobalite, anorthite, calcite, dolomite, albite, vermiculite, actinolite, pyrophyllite, quartz, sanidine nontronite, orthoclase, microcline, tridymite, and hematite in rock-forming quantities in the bentonitic samples. Based on the minerals chemistry considerations, the Chahreeseh bentonite deposit can be classified as the Wyoming type. The results of mass change calculations (with assumption of Hf as low-mobile index element) show that progression of bentonitization process at Chahreeseh was accompanied by depletion of elements like Al, Fe, K, Ti, Mn, P, Ba, Co, Zn, Cs, Rb, Y, Zr, Ni, Sr, and Cu, enrichment of U, and leaching-fixation of elements such as Na, Mg, Ca, and Si. The geochemical interpretations revealed that variations of Eu negative anomaly (0.27-0.90) and weak negative to weak positive anomalies of Ce (0.97-1.22) at Chahreeseh have been controlled by the degree of feldspar alteration and changes in the rate of oxidation potential of the environment, respectively. By considering the results obtained from field relations, mineralogy and geochemistry, it seems factors such as physico-chemical conditions of alteration environment, absorption mechanism, difference in degree of alteration intensity of parent materials, the degree of access to fluoride, chloride, and sulfate ligands, incorporation in crystal structure, ionic exchange, physical concentration, and the presence in resistant mineral phases played significant roles in distribution and concentration of elements in this deposit, respectively.
F Kangarani Farahani; A.A Calagari; A Abedini
Abstract
Kambelu lateritic deposit is located in ~80 km west of Damghan, Semnan province. This deposit was developed as stratiform lenses along the contact of carbonates of Elika Formation (Triassic) and shale-sandstone of Shemshak Formation (Jurassic). Petrographical studies testify to the presence of collomorphic, ...
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Kambelu lateritic deposit is located in ~80 km west of Damghan, Semnan province. This deposit was developed as stratiform lenses along the contact of carbonates of Elika Formation (Triassic) and shale-sandstone of Shemshak Formation (Jurassic). Petrographical studies testify to the presence of collomorphic, colloformic, pseudo-porphyritic, and nodular textures within the ores of this deposit. Mineralogical data show that the ores contain diaspore, goethite, anatase, kaolinite, hematite, boehmite, and zircon. Considering the mineralogical composition and textural characteristics, this deposit was formed in an almost reduced near-surface environment. Geochemical indices like Eu/Eu* along with ratios such as Ti/Zr, Nb/Y, and Al/Ti suggest that Kambelu deposit is a product of alteration and weathering of rocks of trachy-andesitic to basaltic composition. Comparison of the variation trend of elements like Si, Al, and Fe within a selective profile reveals that the variation in chemistry (i.e., pH) of solutions responsible for lateritization and drainage intensity are the two principal factors for formation of the ores. Geochemical considerations show that distribution of trace elements in this deposit is a function of factors such as adsorption, scavenging by metallic oxides and hydroxides, fixation in neomorphic phases, and presence in resistant mineral phases. Inharmonic distribution of REEs in the studied profile indicates an allogenic origin for this deposit. The obtained data indicate that clays, anatase, zircon, xenotime, gorceixite, and churchite are the potential hosts for REEs in this deposit.
H. Khalilzadeh; A. A. Calagari; A. Abedini; H. Rahimpour-Bonab
Abstract
Boket residual horizon is located in ~15 km northeast of Ajabshir, East-Azarbaijan province. This horizon was developed as stratiform lenses along the contact of Ruteh (middle-upper Permian) and Elika (Triassic) carbonate formations. The ores within this horizon display pelitomorphic, micro-granular, ...
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Boket residual horizon is located in ~15 km northeast of Ajabshir, East-Azarbaijan province. This horizon was developed as stratiform lenses along the contact of Ruteh (middle-upper Permian) and Elika (Triassic) carbonate formations. The ores within this horizon display pelitomorphic, micro-granular, micro-ooidic, pseudo-porphyritic, ooidic, pisoidic, pseudo-breccia, and nodular textures. Based on geochemical data, the ores within this horizon are divided into five types, (1) ferritic laterite, (2) bauxitic laterite, (3) kaolinitic laterite, (4) ferritic kaolinite, and (5) laterite. Comparison of distribution patterns of elements across a selected profile indicates the effective role of Al and Ti in distributing and concentrating of Zr, Ga, Nb, Th, V, and HREEs within the ores. Incorporation of data obtained from petrographical and geochemical studies shows that the ores have authigenic origin. Furthermore, factors such as chemical variations of weathering solutions, fixation in neomorphic phases, existing in resistant minerals, heterogeneity of protolith, differences in the degree of weathering intensity, and adsorption processes coupled with weak drainage, diagenesis, dynamic pressures, and fluctuation of underground water table played crucial roles in distribution and development of ores within this horizon. The most notable geochemical characteristics of the ores (except in kaolinitic laterite) is the greater mobility of LREEs relative to HREEs during weathering processes. This abnormal behavior within the horizon could be related to factors such as differences in stability of primary minerals containing REEs, the pH variation (from 6.7 to 7.8) of weathering solutions, and moderate degree of evolution of the profile.
