Economic Geology
Nima Rahimi; Shojaeddin Niroomand; Mohammad Lotfi; Mojtaba Rahimi Shahid
Abstract
The Janja Cu-Mo porphyry deposit is located at 70 km south of the Nehbandan, Sistan suture zone, Eastern Iran. The porphyry mineralization in the Janja deposit is temporally and spatially associated with the diorite to quartz diorite and granodiorite granular to porphyry stocks that intruded in the Cretaceous ...
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The Janja Cu-Mo porphyry deposit is located at 70 km south of the Nehbandan, Sistan suture zone, Eastern Iran. The porphyry mineralization in the Janja deposit is temporally and spatially associated with the diorite to quartz diorite and granodiorite granular to porphyry stocks that intruded in the Cretaceous flysch units. The Janja intrusions are represented by a Calc-alkaline and metaluminous geochemical affinity, and belong to the I-type granitoid series and subduction-related magmas in composition. Hydrothermal alterations in the area have been completely influenced by the Janja intrusion and as a result of the activity of these hydrothermal fluids, various types of potassic, propylitic, argillic and rarely phyllic alteration zones have been formed. In this deposit, three mineralization styles have been recognized including disseminated, vein-veinlet and stockwork which mineralization is mainly associated with potassic alteration. Mineralization zones in porphyry systems, including the supergene, enriched and hypogene zone, have been identified in the Janja deposit, which are the result of changes in the water table, weathering and erosion effects. The main sulfide minerals consist of chalcopyrite, pyrite, covellite, chalcocite, molybdenite, bornite, and oxide minerals including magnetite, hematite, goethite and hydro carbonate minerals including malachite and azurite. Fluid inclusion studies showed a homogenization temperature range from 301 to 540 ˚C and a mean salinity of 19 wt%NaCl for two-phase inclusions and a homogenization temperature range between 254 and >550 ˚C and mean salinities of 54 wt % NaCl for multiphase fluid inclusions. The results of these studies show that mixing processes have taken place in the Janja deposit and have caused the deposition of Cu-Mo-(Au) mineralization. Eventually, according to the various characteristics of the Janja deposit, including tectonic environment, host rock, mineralogy, ore-forming fluid, metal ore assemblage, mineralization and alteration patterns, and comparison of these characteristics with other porphyry deposits, it can be concluded that mineralization in Janja deposit is comparable with continental margin-type porphyry Cu-Mo-(Au) deposits.
Petrology
Mostafa Delkhah; Habib Biabangard; Hamedreza Soloki
Abstract
Zardkuh igneous complex is located in 35 km Southeast of Iranshahr and is geologically situated flysh zone and the Sistan-suture zone. Rock units in the area are Ophilitic rocks (upper Cretaceous), Eocene flysh and Oligomiocene intrusive and extrusive rocks (Zardkuh igneous complex). Patterns of minor ...
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Zardkuh igneous complex is located in 35 km Southeast of Iranshahr and is geologically situated flysh zone and the Sistan-suture zone. Rock units in the area are Ophilitic rocks (upper Cretaceous), Eocene flysh and Oligomiocene intrusive and extrusive rocks (Zardkuh igneous complex). Patterns of minor and rare earth elements normalized to Primitive mantle and Chonderit show low enrichment to LREE such as La, Ce and Sm than to HREE such as Ho, Yb, Tb and Lu. The dip of digram is soft to HREE and in the extrusive rocks is low increased. . it is thought that the constituent magma of these rocks from the mantle wedge above the subduction plate, which is usually affected by the fluids released from the subducted plate and its elements (including Silica, potassium and sodium) can produce such magma. So these rocks are related to magmatism and subduction Neo-Tehyan oceanic between Lut and Sistan blocks.
Economic Geology
Mohammad Boomeri; Somayeh Naruyi; Mohammadreza Ghodsi
Abstract
The Chah Sorbi area is located in the Sistan suture zone. The geology in the Chah Sorbi, from old to young, are flysch type rocks, Zahedan granitoid, subvolcanic granodiorite porphyry, dioritic to granodioritic dikes and recent deposits. The Pb mineralization in the study area occurs as thin and short ...
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The Chah Sorbi area is located in the Sistan suture zone. The geology in the Chah Sorbi, from old to young, are flysch type rocks, Zahedan granitoid, subvolcanic granodiorite porphyry, dioritic to granodioritic dikes and recent deposits. The Pb mineralization in the study area occurs as thin and short galena-bearing veins associated with pyrite, quartz, calcite, goethite and limonite. The host rocks are flysch and the subvolcanics that are undergone phyllic and argillic alteration. Propylitic alteration occurs in most dikes in the area and is characterized by chlorite, calcite and epidote. In northeast part of the area, the subvolcanic rocks were intruded by quartz stockworks and was strongly altered. The most intensive and extensive alteration with these rocks is phyllic alteration that is characterized by pyrite, quartz and sericite. Cu mineralization in the stock is characterized by presence of Cu-carbonate and –sulfides. Galena-bearing veins are probably epithermal type in the Chah Sorbi area that is situated in margin of a porphyry Cu system. Major and minor elements were measured in 7 least altered samples from intrusive rocks. The igneous rocks in the study area are metaluminous that are formed from a calc-alkaline magma in a continental margin volcanic arc setting.
Petrology
Marziyeh Abazari; Seyyed Saeid Mohammadi; Malihe Nakhaei
Abstract
Abbas Abad area is located in the northeast of Sarbisheh, in the northern part of Sistan suture zone and southern Khorasan province. In this area, Tertiary volcanic rocks with the composition of intermediate to acid, including basaltic andesite, andesite, and dacite are exposed. Constructive minerals ...
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Abbas Abad area is located in the northeast of Sarbisheh, in the northern part of Sistan suture zone and southern Khorasan province. In this area, Tertiary volcanic rocks with the composition of intermediate to acid, including basaltic andesite, andesite, and dacite are exposed. Constructive minerals of basaltic andesite include of plagioclase, pyroxene and olivine and in andesite consist of plagioclase, hornblende and pyroxene, and in dacite are plagioclase, quartz, biotite and hornblende. The studied rocks have medium to high-K calc-alkaline nature. Most samples show enrichment in LILEs (K, Rb, Sr, Cs) (except Ba) relative to HFSEs (Y, P, Ti, Ta, Nb), which indicates the relation of these rocks to subduction zone and active continental margin. The relatively low (La/Yb)N (7.67 to 13.48) and Dy/Yb (<2) in Abbas Abad lavas indicate that partial melting of mantle occurred in transitional zone of spinel-garnet lherzolite. Based on the concentration of trace elements such as Ce, Yb and Sm, magma originated from a depth of about 95 to 105 kilometers.
Economic Geology
shahriar keshtgar; Sasan Bagheri; shahriar keshtgar
Abstract
Abstract The Mahirud volcano-plutonic Complex (MVPC), known as Cheshmeh Ostad Group, an rock assemblage including several plutons and volcano-sedimentary successions, crops out at the northeastern part of the Sistan Suture Zone. Igneous rocks of the MVPC, consist of volcanic lavas and pyrclastic rocks, ...
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Abstract The Mahirud volcano-plutonic Complex (MVPC), known as Cheshmeh Ostad Group, an rock assemblage including several plutons and volcano-sedimentary successions, crops out at the northeastern part of the Sistan Suture Zone. Igneous rocks of the MVPC, consist of volcanic lavas and pyrclastic rocks, are andesitic basalt, diabase, microgabbro and dacite that were intruded by the late cretaceous granitoids. The volcanic rocks have characteristics of the calc-alkaline to tholeiitic magmatic series. The spider patterns normalized to N-MORB and Chondrite is similar to the ones belong to the supra-subduction zone (SSZ) and Islanc arcs ( IAT). The EPMA studies on the key minerals in volcanic rocks such as clinopyroxene , brought the same results. The pribable presence of an island-arc chain in the Sistan Suture Zone, which some of its parts are considered here as the MVPC, is comparable to continuation of the pakistanian Chagai-Raskoh and Kuhistan Cretaceous-Eocene island-arc/s in east. Considering this reality, we must expect to have a larger ocean much wider than what was already proposed for the Sistan Ocean as a narrow oceanic seaway in Continental rifting setting.
M. R. Bakhshi Mohebbi; A. A. Moridi farimani; R. Moezzi nasab
Abstract
Among the sedimentary units of the east flysch basin in the Nosrat-Abad area, where in the 105km northwest of Zahedan, there is a sandstone-conglomerate unit with an Oligo-Miocene age. The depositional environment of this deposit was fluvial which has been morphologically dissected in several portions; ...
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Among the sedimentary units of the east flysch basin in the Nosrat-Abad area, where in the 105km northwest of Zahedan, there is a sandstone-conglomerate unit with an Oligo-Miocene age. The depositional environment of this deposit was fluvial which has been morphologically dissected in several portions; this unit covers the Eocene sandstone-shale deposits by an angular unconformity about 30 degrees. The measured thickness is about 2650 meters. The composed particles and pebbles are in various grain size. On the other hand, sandstone, siltstone, and mudstone accompany the conglomerate unit. Field observations document the unit was formed in a fluvial depositional environment. Imbrication and cross, smooth, and lens-shaped bedding are the main recognizable sedimentary structures. Moreover, the caved and filled structure are seen. Note that there is difference between the lithology of the pebbles in the conglomerate and the rocks composing the flysch zone, the pebbles could be originated from the west side, where in the Lut block. The recognized fossils from limestone pebbles are belong to the families such as Orbitolina, Alveolina, Nummulite, and Miliolid, consequently, the age of conglomerate-sandstone unit must be younger than Eocene and cover by Conglomarate Quaternary probably could be Oilgo-Miocene.
Stratigraphy and Palaeontology
Reza Moezzi nasab; Mohammad Nabi Gorgij; Mohammad Reza Bakhshi mohebbi
Abstract
Hormak Section consist of alternation of Oligomictic conglomerate with mainly Alveolinids and Nummulitid bearing calcareous pebbles and afew andesits, basalt and rhyolitic tuff pebbles, Pebbly Sandstone and red shale. The Sourse of red continental - clastic Hormak formation conglomerate probably was ...
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Hormak Section consist of alternation of Oligomictic conglomerate with mainly Alveolinids and Nummulitid bearing calcareous pebbles and afew andesits, basalt and rhyolitic tuff pebbles, Pebbly Sandstone and red shale. The Sourse of red continental - clastic Hormak formation conglomerate probably was Debil formation and Equvaleut Late Paleocene – Early Eocene deposits. Approxmalty 80% of Debil formation foraminifer contents very resemble to that are identified in the Hormak Section conglomerate. In the studied area based on identified species such as A.canavarii, A.elliptica nuttalli, A.pasticillata, A.decipiens, A.fornasinii, A.globula, A.solida Early Eocene age are suggested.
M Delavari; S.A Amini; A Saccani
Abstract
Tertiary volcanism in east and northeast of Nehbandan, eastern Iran, includes mostly basic-intermediate associations. They are characterized by sodic (1<Na2O/K2O) compositions and contain both low-k tholeiitic and calk-alkaline series. Based on petrographic, mineral chemistry and whole-rock geochemical ...
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Tertiary volcanism in east and northeast of Nehbandan, eastern Iran, includes mostly basic-intermediate associations. They are characterized by sodic (1<Na2O/K2O) compositions and contain both low-k tholeiitic and calk-alkaline series. Based on petrographic, mineral chemistry and whole-rock geochemical evidences basalts can be classified into two groups; arc-related calc-alkaline basalts (CAB) and low-K tholeiites (LKT). The evolutionary trends of some major and trace elements vs. SiO2 and also chondrite-normalized rare earth element (REE) patterns represent gentic relation between low-K tholeiitic intermediates and LKT but reject calkalkaline intermediate generation by magmatic evolution from CAB. In MORB-normalized multi-element patterns, negative anomally of high field strength elements (HFSE) and enrichment of large-ion lithophile elements (LILE) suggest subduction zone-related tectonomagmatic setting for basic-intermediate associations in which compositional change from LKT to CAB is accompanied by the evolution of arc system. This scenario in Sistan suture zone is interpreted as subduction continuation of Sistan oceanic lithosphere in Tertiary.
M. Alimohammadi; P. Behnia; A. Khakazad; M.A. Ghorbani
Abstract
Hired gold-bearing area is located to the northeast of the Lut zone and in the vicinity of the Sistan suture zone. Several post Eocene plutons have intruded into the Eocene volcanic and pyroclastic units and caused hydrothermal alteration and mineralization of gold, copper, lead and zinc. We have applied ...
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Hired gold-bearing area is located to the northeast of the Lut zone and in the vicinity of the Sistan suture zone. Several post Eocene plutons have intruded into the Eocene volcanic and pyroclastic units and caused hydrothermal alteration and mineralization of gold, copper, lead and zinc. We have applied the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data including three visible and near infrared (VNIR), six shortwave infrared (SWIR) and five thermal infrared (TIR) bands to determine the alteration minerals of Hired gold-bearing area. Spectral analysis of the surface reflectance SWIR manifests absorption in 2.20μm and 2.33μm wavelength regions.Absorption at 2.20μm(band6),due to Al-OH anionic agent is consistent with the presence of clay minerals (illite, kaolinite) and sericite, whereas absorption at 2.33μm (band 8) due to Mg-OH anionic agent and carbonates is consistent with the occurrence of chlorite, epidote and calcite minerals. In this study different image processing techniques such as band combination, band ratios transformation, and Binary Encoding were used to identify and delineate the altered minerals accompanied by gold mineralization. The Binary Encoding method was found to be the best image processing technique for delineation of the hydrothermally formed minerals. Analysis of the spectral emission data in the five TIR bands has provided valuable lithological information. It would not be possible to identify silicified rocks in the nine VNIR+SWIR bands due to the lack of recognizable spectral absorption features in quartz at this wavelength region. We have therefore mapped Quartz-bearing surface deposits as well as hydrothermally silicified rocks in the TIR region by using a band ratio (b11×b11) / (b10×b12) image. The results obtained from ASTER data are compatible with conclusions inferred from petrographic and XRD studies of the surface samples. The ASTER data appear to be useful in mapping hydrothermal alteration and in ore deposit exploration.
M.A. Ghorbani; M. Mohajel; M. Pourkermani; M. Alimohammadi; H. Kheyrollahi
Abstract
Hired area is located in the northeastern border of Lut zone and western vicinity of Sistan suture zone. Northern part of Sistan suture zone trending NW-SE with complicated structure is the locality of several considerable ore deposits. We have employed aeromagnetic data, satellite images and field observations ...
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Hired area is located in the northeastern border of Lut zone and western vicinity of Sistan suture zone. Northern part of Sistan suture zone trending NW-SE with complicated structure is the locality of several considerable ore deposits. We have employed aeromagnetic data, satellite images and field observations to consider the relation of surface and subsurface structures to the significant superficial structural features of Hired mining area. Aeromagnetic data were processed by applying appropriate filters including Reduction to pole and First vertical derivative for proper distinguishing the magnetic features. In addition, highpass filters were used for edge sharpening of the ASTER images.
Aeromagnetic data have shown two main N-S and NW-SE structural directions which follow the northern Sistan suture zone. Presence of mineralized and altered veins and brittle shear zones with the same trend around the fractures is noticeable. Moreover, fractures intersections and conjuncture places are dramatically compatible with mineralization areas. Another result from aeromagnetic data is identification of a circular structure in the east of study area. The gold mineralization has occurred in the west part of mentioned structure which is strongly affected by NNW striking features. Satellite images in addition to confirmation of aforesaid structural trends imply a third structural NE-SW strike. This structure is not vivid on the aeromagnetic map and has only an ambiguous trace on it. Our field measurements verify this new structural trend as well.
