Economic Geology
Maryam Javidi Moghaddam; M.H Karimpour; Azadeh Malekzadeh Shafaroudi
Abstract
The Rashidi area, which comprises a part of the north Khur in eastern Iran is located at 120 km northwest of Birjand city. Preliminary prospecting in the area using the image processing of ASTER data by Spectral Angle Mapper (SAM) algorithm resulted in the identification of propylitic and argillic alteration ...
Read More
The Rashidi area, which comprises a part of the north Khur in eastern Iran is located at 120 km northwest of Birjand city. Preliminary prospecting in the area using the image processing of ASTER data by Spectral Angle Mapper (SAM) algorithm resulted in the identification of propylitic and argillic alteration zones together with iron oxy-hydroxide minerals. The area consist of outcrops of Eocene pyroclastic rocks ranging from andesitic to rhyolitic in composition, intruded by diorite porphyry dikes. Vein mineralization in the area was mainly occurred along a fracture system hosted by andesitic tuff breccia unit. Vein copper mineralization was formed during two stages including the: (1) quartz-pyrite-chalcocite-tennantite assemblage, and (2) quartz-chalcocite-pyrite-sphalerite assemblage. The values of δ18O for quartz in the first and second stages of vein mineralization was 19.26 and 14.94 and the amount of δ18O water in equilibrium with quartz was 10.96 and 4.94 respectively that shows a magmatic origin and mixing with meteoric water in the second stage. Based on geology, vein geometry, fluid inclusion, and stable isotope geochemistry, the Rashidi Cu deposit can be classified as vein-type copper deposits, which has been formed along fault zones.
Economic Geology
Hossein Abasnia; M. H. Karimpour; Azadeh Malekzadeh Shafaroudi
Abstract
Damanghor area is located northern Bardaskan, Khorasan Razavi province, and structurally, it is a part of Taknar zone. Geology of the area includes of Taknar metamorphosed sedimentary rocks and metarhyolite, which is intruded by diabasic rocks as stoke and dyke. The texture of metarhyolies is porphyry ...
Read More
Damanghor area is located northern Bardaskan, Khorasan Razavi province, and structurally, it is a part of Taknar zone. Geology of the area includes of Taknar metamorphosed sedimentary rocks and metarhyolite, which is intruded by diabasic rocks as stoke and dyke. The texture of metarhyolies is porphyry and contains of quartz and feldspar, whereas diabas has ophitic texture and contain plagioclas, pyroxene, and hornblend. Age of metarhyolite and diabas determined 550 Ma (Neoprotrozoic) and 8.8 Ma (Miocene), respectively, using zircon U-Pb method. Metarhyolites have peraluminous nature and were formed at intracontinental rift. Low enrichment in LREE relative to HREE and Eu negative anomaly indicates the magma is formed at plagioclase stability depth. (87Sr/86Sr)i (0.700712), (143Nd/144Nd)i (0.511852), and εNdi (–1.51) values show source of magma was mantel or lower crust. Diabases have toleitic to metaaluminous nature and were formed at subduction zone. (87Sr/86Sr)i (0.710527), (143Nd/144Nd)i (0.512716), and εNdi (+1.7) values indicate magma is drived from partial melting of metasomatized mantle wedge by released fluid of subducted slab, which is assimilated with continental crust. Taknar formation acidic Neoprotrozoic magmatism, which is formed at rift setting, associated with Miocene basic magmatism, which is formed at subduction zone, reveals an insight of tectonomagmatic conditions of Taknar zone in different times.
Pooneh Eshbak; Azadeh Malekzadeh Shafaroudi; Mohammad Hassan Karimpour
Abstract
Jalambadan area is located northwestern Sabzevar, Khorasan Razavi province, and southwestern Quchan-Sabzevar magmatic belt. Geology of the area includes of andesitic-trachyanesitic volcanic rocks, which is intruded by monzodioritic to dioritic subvolcanic intrusive rocks. The texture of igneous rocks ...
Read More
Jalambadan area is located northwestern Sabzevar, Khorasan Razavi province, and southwestern Quchan-Sabzevar magmatic belt. Geology of the area includes of andesitic-trachyanesitic volcanic rocks, which is intruded by monzodioritic to dioritic subvolcanic intrusive rocks. The texture of igneous rocks is porphyry and the main minerals are plagioclase, alkali fldespar, pyroxene, hornblende, and magnetite. Age of intrusive rocks determined 44.7 to 45.2 Ma (Middle Eocene-Lutetian), using zircon U-Pb method. Geochemically, igneous rocks of the area are calc-alkaline and were formed at subduction zone. Relativelly, enrichment in LREE relative to HREE and enrichment of K, Rb, Cs, and Sr relative to Ti and Nb elements are observed in all of samples. Eu anomaly and Sr/Y ratios can be attributed to the presence of residual plagioclase and a few garnet in a source. (87Sr/86Sr)i (0.703708 to 0.704444), (143Nd/144Nd)i (0.512858 to 0..512933), and εNd I (5.42 to 6.88) values of intrusions and geochemical signatures of volcanic rocks indicate magma is drived from partial melting (7-5% for intrusions and 15-25% for volcanic rocks) of spinel lherzolite mantle wedge above subducted slab, which is assimilated slightly with upper continental crust very little.
Remote Sensing
R. Ahmadi Rohany; M. H. Karimpour; B. Rahimi; A. Malakzadeh Shafaroudi; S. Najafi Afshar
Abstract
The studied area is located at the east of Bajestan city and south west of Khorasan Razavi province. This region is at the north of the Lut Block, the largest structural block in east of Iran. Structure of this area is affected by activity of deep strike-slip faults in the boundary of the blocks. Lineaments ...
Read More
The studied area is located at the east of Bajestan city and south west of Khorasan Razavi province. This region is at the north of the Lut Block, the largest structural block in east of Iran. Structure of this area is affected by activity of deep strike-slip faults in the boundary of the blocks. Lineaments are mapped by the means of SPOT-5 and Landsat satellite data and DEM data. Structural studies were carried out in two stages: at first, main faults were indicated, mapped and analyzed and then for more detail research, total lineaments (faults and joints) were mapped and analyzed. Verification studies were conducted with field surveys. Remote sensing studies indicate importance of applying enhancement filters like standard kernels on stereoscopic data like SPOT as an efficient tool for structural studies, especially for lineament extracting. Fractal studies and using fractures statistical parameters (based on fracture map obtained by remote sensing data (in the area in addition to determining fractal dimension, were used as complementary methods for recognition structural evolution and specifying the most probability of mineralization occurrence. Fractal, structural- statistical analyzes, field and remote sensing studies on fracture systems in the area indicate that structural elements in the studied area, most probably are related to the main strike-slip faults activities and can be considered as Riedel shear fractures in its wall of damage zone. Also the results indicate that most of the lineaments in this area are extensional fractures corresponding to both dykes emplacement and alteration zones associated with mineralization. Combining the mentioned information can play important role in identifying structural evolution processes and specifying areas with more mineralization potential.
A Hosseinkhani; M.H Karimpour; A Malekzadeh Shafaroudi
Abstract
The SW Sorkh-Kuh area makes part of the Tertiary volcanic-plutonic rocks in the west of the Lut Block, SW of Birjand city. Geology of this area consists of andesitic and basaltic volcanic rocks intruded by hornblende diorite, hornblende microdiorite, hornblende diorite porphyry, hornblende quartz diorite ...
Read More
The SW Sorkh-Kuh area makes part of the Tertiary volcanic-plutonic rocks in the west of the Lut Block, SW of Birjand city. Geology of this area consists of andesitic and basaltic volcanic rocks intruded by hornblende diorite, hornblende microdiorite, hornblende diorite porphyry, hornblende quartz diorite porphyry and biotite quartz monzonite, which caused extensive alteration and mineralization. The vein mineralization with a NW-SE trend have been observed in the NW portion of the area which is composed of quartz, chalcopyrite, pyrite and Fe-Cu secondary minerals. This vein is the youngest occurrence of mineralization, related to intrusive rocks, in the Lut Block (after Miocene). Primary fluid inclusions of quartz in paragnesis with mineralization, revealed three types of two phases inclusions with difference in density, which liquid rich phases have an average 270 and 330°C of homogenization temperature. Based on freezing studies, calculated temperature of last melting point of these fluids equals to 12-15 and 16-19% wt eq. NaCl, respectively. Some fluids, which homogenized to gas, have more homogenization temperature and salinity. In evaluation of depth, using homogenization temperature, salinity, density and pressure of fluid inclusion, 700 m depth was calculated for mineralization, corresponding to the present erosion surface. δ18O values of quartz in mineralized vein and fluid in equilibrium with quartz have a range between +8.66 – +13.09‰ and +3.06 – +7.59, respectively. It could be inferred that the source of ore-forming fluids was magmatic in the mineralized vein. In general, stable isotope and fluid inclusion studies show similarity of mineralization of the SW Sorkh-Kuh with epithermal deposits in which mineralization is related to the dioritic intrusive rocks. The changes in fluid composition and boiling resulted in mineraliztion along a fault as vein.
A Askari; M.H Karimpour; S.A Mazaheri; A Malekzadeh
Abstract
The Hired gold prospect area is located in the Southern Khorasan province and 140 Km south of the Birjand city. The Acidic to mafic intrusive bodies with gabbro to granite composition have intruded into the Tertiary volcano-sedimentary sequences. Based on magnetic susceptibility, the intrusives are divided ...
Read More
The Hired gold prospect area is located in the Southern Khorasan province and 140 Km south of the Birjand city. The Acidic to mafic intrusive bodies with gabbro to granite composition have intruded into the Tertiary volcano-sedimentary sequences. Based on magnetic susceptibility, the intrusives are divided into two categories: magnetite (oxidized) and ilmenite (reduced) series. The important alterations recognized on land surface and bore holes consist of: 1) quartz-tourmaline-sericite alteration, 2) carbonation alteration, 3) skarnization, and 4) propylitic alteration. Au and accompany elements mineralization (W, Sn, Bi, As, Sb, Pb, Zn, Ag) have formed as replacement, disseminate, vein-veinlet, massive, breccias, and skarn related to reduced granitic-granodioritic intrusive bodies and with different distance as compared with the bodies. Geological, mineralization, petrographical, mineralogical and alteration studies of the Hired gold deposit and comparison with the characteristics of different types of gold mineralization in the world indicate that this deposit has the most similarity with reduced intrusion-related gold systems (RIRGS). Since In this system, the most of gold reserve is accompanied with sulfide minerals and they form in roof of the reduced granitoid stocks and adjacent hornfels rocks, The IP- RS geophysical methods on reduced granitoid intrusive body and near regions was executed with the aim of recognition of hidden parts. Combination of geophysics data (IP, RS) with geological, alteration, and mineralization studies shows well development mineralization in the east of intrusive body and the country rocks. In this relation, 6 anomalous regions has been defined with Chargeability up to 30 mv/v that on the whole, they can be divided into two groups: 1) anomaly with high induced polarization and low specific resistivity resulting from presence of much metallic sulfurs as disseminate, veinlet, and massive accompanied with high sericitic alteration, 2) anomaly with high induced polarization and medium-high specific resistivity resulting from presence of much metallic sulfurs as disseminate and very high carbonation-silicic alteration.
R Ahmadi Rohany; M.H Karimpour; B Rahimi; A Malakzadeh Shafaroudi
Abstract
The studied area is located in east of BajestanTownship, KhorasanRazaviProvince and this region is a part of the Lut Block. Granite is the most important rock in this area with covering approximately 70km2. Processing of satellite data in this area was done by using of SPOT, ASTER and Landsat ETM+ data. ...
Read More
The studied area is located in east of BajestanTownship, KhorasanRazaviProvince and this region is a part of the Lut Block. Granite is the most important rock in this area with covering approximately 70km2. Processing of satellite data in this area was done by using of SPOT, ASTER and Landsat ETM+ data. SPOT images processing and using PCA methods (standard and selective) on the ETM+ data show this intrusive body doesn't have an equal chemical composition. The central part of the intrusive body has distinctive from margin and it seems that the central part have more mafic mineral. For enhancing linear structure, high pass, directional, threshold and sobel filters were applied separately and compositional on the SPOT data. By using these filters linear structures became completely obvious and were vectorized digitally. The most of them show northwestern-southeastern trend. ASTER data processing by spectral angle mapper (SAM), band ratio and band composition methods enhanced epidote, sericite, hematite, argilic and silicified alterations. Processing and Interpretation of airborne geophysical data (potassium, thorium, uranium and total magnetic intensity), which collected by airplane show the amounts of these triple elements (K,U,Th) are high and in vice versa Total Magnetic Intensity data (TMI) is low in this granite. Separating geological boundaries and enhancing major faults are other results from processing of geophysics data. Merging all of the data consist of: satellite and geophysics data processing and field research indicate alteration zones have relation to linear structures in this area. This research specifies the most probability of mineralization presence in this area so that Fe and Cu mineralization conform to epidotic-chloritic and argilic alterations. Introducing favorable area can help us to concentrate exploration activities and next researches in this area and prevent wasting money and time.
M Abdi; M.H Karimpour; M.H Zarinkoob
Abstract
The main purpose of this study is processing of raw data by factor analysis method and having interpretation and integration them by geological, alteration and mineralization data. The distinctiveness of third factor of factor analysis for Au, Mo and W and the coincidence of third factor anomalies by ...
Read More
The main purpose of this study is processing of raw data by factor analysis method and having interpretation and integration them by geological, alteration and mineralization data. The distinctiveness of third factor of factor analysis for Au, Mo and W and the coincidence of third factor anomalies by gold, high primary sulfide bearing area, secondary iron oxide and sericitic and silicic alterationrevealed that the third factor of factor analysis is the agent of mineralization in the study area. The suitable tectonic setting, shallow depth intrusiveswithintermediate composition, calc-alkalineand oxidant magmatism, anomaly of gold and disseminated mineralization in thehost rock and sulfide veinlet accompanied byabundant secondary iron oxide providedproperconditions for porphyry and epithermal type gold mineralization in the study area.
R Arjmandzadeh; M.H Karimpour; S.A Mazaheri; J F.Santos; M Medina
Abstract
The dehsalm porphyritic granitoids belong to the Lut Block volcanic-plutonic belt in East - Central Iran. The intrusive rocks range in composition from gabbro - diorite to granite and can be classified as high-K calc alkaline to shoshonitic volcanic arc granites. Elevated contents of Mo, Cu, Au, Pb, ...
Read More
The dehsalm porphyritic granitoids belong to the Lut Block volcanic-plutonic belt in East - Central Iran. The intrusive rocks range in composition from gabbro - diorite to granite and can be classified as high-K calc alkaline to shoshonitic volcanic arc granites. Elevated contents of Mo, Cu, Au, Pb, Zn occur in silica veins within Bt - Px - Quartz monzonite and Hbl - monzonite. The trend of major oxides on Harker diagrams point to the crystal fractionation of Ca - plagioclase and mafic minerals. Primitive mantle - normalized trace element spider diagram display strong enrichments in LILE such as Rb, Sr, Ba, Zr, Cs and depletions in some high field strength elements (HFSE) e.g. Nb, P and Y. On chondrite - normalized plots, display significant LREE enrichments, high La/Yb = 21.5-31 and the lack of Eu. On the basis of Sr/Y and La/Yb ratios, Dehsalm intrusives cover characteristic features of adakites and (87Sr/86Sr)i and εNdi isotope ratios range from 0.70469 to 0.70505 and from +1.5 to +2.5 respectively, and show that the source is related to the mantle melts contaminated slightly by the crustal materials. They are classified into the magnetite series granitoids and have high mineralization potential for Cu-Mo-Au porphyry type deposits. Two-sided asymmetric subduction explains all the tectonic and magmatic occurrences and the mineralization of porphyry type deposits within the Lut Block during the Tertiary.
A. Najafi; M.H. Karimpour; M. Ghaderi
Abstract
Based on data processing for 51 stream sediment, 115 rock and 22 heavy mineral samples, together with field evidence for mineralization and alteration, mineralization pattern for Rahimi copper-gold prospecting area was analyzed. Twelve primary and secondary geochemical halo maps for Au-Ag-As-Ba-Cu-Co-Hg-Mo-Pb-Sb-W-Zn ...
Read More
Based on data processing for 51 stream sediment, 115 rock and 22 heavy mineral samples, together with field evidence for mineralization and alteration, mineralization pattern for Rahimi copper-gold prospecting area was analyzed. Twelve primary and secondary geochemical halo maps for Au-Ag-As-Ba-Cu-Co-Hg-Mo-Pb-Sb-W-Zn as well as maps showing iron-oxide minerals in heavy mineral samples were analyzed using new geological and mineralization field evidence for the area. Therefore, two distinct promising areas, with IOGC and porphyry copper mineralization patterns were proposed for semi-detailed studies.
R. Monazzami bagherzadeh; H. Mirnejad; P. Eshback; M. H. Karimpour
Abstract
Listvenites or ophiocarbonates are considered important for exploration of precious and base metlas particularly Au, Ag, Cu, As and Hg. These rocks, which crop-out dominantly in ophiolite-mélange zones and in the vicinity of main faults and shear zones, have formed as the result of hydrous ...
Read More
Listvenites or ophiocarbonates are considered important for exploration of precious and base metlas particularly Au, Ag, Cu, As and Hg. These rocks, which crop-out dominantly in ophiolite-mélange zones and in the vicinity of main faults and shear zones, have formed as the result of hydrous and carbonic alteration of ultramafic rocks. Listvenites occur extensively in eastern Iran. Based on petrography, Hangaran listvenites are grouped into three major types: 1. Carbonatic listvenite (type I), 2. Silicic listvenite (type II), and 3. Sulfie-bearing silicic listvenite with brecciated texture (type III). Gold contents of listvenites is generally low and the highest concentration (290 ppb) has been found in type III. Studies of mineral concentrates from stream sediments reveal the presence of gold, pyrite, chalcopyrite, cinnabar and native copper. Gold grains reach to a maximum sizes of 80 microns, and they are often associated with pyrite. Electron microprobe analyses on several sulfides and carbonates in Hangaran listvenites show that sulfide minerals are mainly pyrite, marcasite, bravoite and to a lesser amount chalcopyrite, and that many pyrite grains have been altered to marcasite. Important carbonated minerals are magnesite and dolomite. The presence of obiquitous bravoite zonation that results from alternations in Ni content indicates periodic changes in the physicochemical conditions of the hyrdorthemal solution. Petrographic studies and paragenetic sequence of minerals show that magnesite and dolomite formed prior to the mineralization stage, which was then followed by the formation of sulfides (mainly pyrite). Studies on the oxygen and carbone isotopes in 3 dolomite samples (δ18OSMOW = 9.353- 9.982 ‰, δ13CPDB =1.57- 1.67 ‰ ) show that oxygen and carbone can originate from oceanic waters, and that dolomite has formed due to the circulation of this water in ultramafic rocks and their subsequent alteration. Considering the variation in marcasite-pyrite paris from Hangaran silicic listvenite (δ34SCDT value 5.7-7.9 ‰ ), it seems that sulfur has originated from granitic rocks in south of the study area. Taking into accout the extentive outcrops of serpentinized ultramafic rocks and granite in the region can considered the source of Au, Ag and base elements such as Cu, Pb, Zn, Hg, As, Sb in related to granite masses, and Cr, Ni, Ti and Fe in related to serpentinized ultramafic rocks. Fluid inclusion studies on mineralized quartz in Hangaran listvenites show that the hydrothermal fluid affecting the host rocks was low salinity and had a maximum temperature of 280ºC.
M. H. Karimpour; G. L. Farmer; C. R. Stern
Abstract
Biotite-muscovite leucogranite and associated pegmatite intruded meta-ophiolite and meta-flysch (the remnants of Paleo-Tethys) during collision of Turan plate with Iran plate. Four types of pegmatite dykes, crosscutting biotite muscovite leucogranite, are identified. The results of U-Pb zircon ...
Read More
Biotite-muscovite leucogranite and associated pegmatite intruded meta-ophiolite and meta-flysch (the remnants of Paleo-Tethys) during collision of Turan plate with Iran plate. Four types of pegmatite dykes, crosscutting biotite muscovite leucogranite, are identified. The results of U-Pb zircon age of Khajeh Mourad biotite muscovite leucogranite is 205.9 ± 4.1 Ma (Late Triassic, Rhaetian). Chemically, biotite muscovite leucogranite and aplite granite are peraluminous S-type pluton. Magnetic susceptibility of biotite muscovite leucogranite and aplite granite are between than 0-5 × 10-5 and the ratio of ferric to ferrous ratio (< 0.35),therefore they are classified as belonging to the ilmenite-series (reduced type). The total REE content of biotite muscovite leucogranite is between TREE = 130-176 and aplite is very low Total REE = 50.79. They have small negative Eu anomalies (Eu/Eu*= 0.52 to 0.76). The initial 87Sr/86Sr and (143Nd/144Nd)i was recalculated to an age of 205 Ma. Initial 87Sr/86Sr ratios for B-M leucogranite and aplite are 0.708161-0.709853. The (143Nd/144Nd)i isotope composition for B-M leucogranite 0.512214, aplite dykes 0.512024. Initial ε Nd isotope values for B-M leucogranite -6.48 and aplite dykes is -6.83. These values could beconsidered as representative of continental crust-derived magmas. The ratios of Rb/Sr = 1-1.3 and CaO/Na2O » 0.3 of biotite-muscovite leucogranite indicate that the source rock had a composition between meta-pelite and meta-psammite.
M. H. Karimpour; A. Malekzadeh Shafaroudi
Abstract
Sangan Iron ore deposit is located 300 km southeast of Mashhad (Eastern Iran). Based on the high grade, low P- content and big ore reserve, Sangan is an important Iron mine in Iran. It is a magnetite skarn and can be classified as iron-oxide type deposit. Based on the surface exposure, the western magnetite ...
Read More
Sangan Iron ore deposit is located 300 km southeast of Mashhad (Eastern Iran). Based on the high grade, low P- content and big ore reserve, Sangan is an important Iron mine in Iran. It is a magnetite skarn and can be classified as iron-oxide type deposit. Based on the surface exposure, the western magnetite skarn (A´), a Ca-rich type skarn, was formed at the contact of intrusive. Eastward, the skarn gradually becomes distal and Mg-type. The A´ magnetite skarn contains andradite, magnetite, K-rich amphibole, hedenbergite and calcite. Magnetite skarn in A, B, and C- south contain magnetite, repidolite, ferro-actinolite, siderite and minor pyrite. Baghak and C- north magnetite skarn comprise Mg-rich- magnetite, phlogopite, chinochlore, talc, dolomite, forsterite, dolomite, pyrite ± chalcopyrite ± arsenopyrite ± pyrrhotite. High S-content is found mainly in Baghak and C-north deposits. In this research, the igneous source rock is found in A´ deposit and identified as ultra-potassic type (K2O> %9). Sarnowsar granite which used to be the source rock for Iron, contains less than %5 K2O, therefore it cannot be the source. The K2O content of Sarnowsar granite increases near the magnetite skarn due to alteration. The Fe-ore bearing solution moved along the contact between Sarnowsar granite and the limestone. Sarnowsar granite was altered and skarn formed in the limestone.
The source rock is quartz biotite-hornblende alkali syenite to quartz hornblende syenite porphyry. The younger intrusive rocks are biotite granite, biotite-hornblende quartz monzonite porphyry and quartz syenite porphyry. Potassium within the ore bearing solution controlled the mineralogy of skarn. Contact skarn in A´ magnetite deposit comprises K-rich amphibole and distal skarn (Baghak and C-north) contains phlogopite.
Comparison of trace elements from source rocks with Sarnowsar granite indicates that the Nb, Zr, Zn and Rb contents are high in the former rocks and Cu and Sr ones are higher in the latter rock. Furthermore, comparison of some trace elements from source rocks with younger intrusive rocks indicate that Cr, Ni, Zr, Ce, Cu, Sr, and La contents are higher in younger intrusive and Rb content is higher in source rocks.
