Editor-in-Chief Lecture
Volume 18, Issue 72 , January 2009, Pages 1-1
Original Research Paper
A. Amiri; I. Rassa; A. Khakzad; M. H. Adabi
Abstract
Stabilization of potentially sliding terraces and natural slopes are of great importance from view point of resident security, environment protection, river engineering and water and soil conversation. Soil reinforcement using tree toots is one of the methods being studied by many researchers. Most of ...
Read More
Stabilization of potentially sliding terraces and natural slopes are of great importance from view point of resident security, environment protection, river engineering and water and soil conversation. Soil reinforcement using tree toots is one of the methods being studied by many researchers. Most of them have worked on the effect of root density and few of them on the root diameter leading to contradicting results. In this paper the combined effect of root diameter and density on the shear resistance of soil is investigated by series of in-situ direct shear tests. Eighteen tests were carried out on soil possessing Willow roots and the results compared with those of non rooted soil as reference. To explain the observations, a new parameter referred to as root diameter-density index (RDDI) was defined. The results reveal that an increase in RDDI causes a significant increase in the apparent cohesion of rooted soil, but a little decrease in the internal friction angle. In both cases the rate of variation decreases with increasing RDDI and tends to a little value; however the extreme values of 212% and -15% are observed respectively. As general conclusion for rooted soils, the dominance of variation of apparent cohesion with respect to that of internal friction angle results the shear resistance ameliorates within a range of RDDI, and for further values it tends to a stabilized value. Moreover, for practical purposes, a relation was developed to be used by designer engineers.
Original Research Paper
Gh. A. Moafpourian; M. Pourmoafi; M. Vosoughi Abedini; M. H. Emami; M. R. Jannessari; S.w. Parman
Abstract
Scattered outcrops of ultramafic – mafic rocks and interbeded sedimentary layers in the North of Fariman – Torbat-e- Jam lineament are exposed mainly at the west of Mashhad, east of Fariman and north of Torbat-e- Jam in Agh- Darband area. Our studies on ultramafic – mafic rocks have ...
Read More
Scattered outcrops of ultramafic – mafic rocks and interbeded sedimentary layers in the North of Fariman – Torbat-e- Jam lineament are exposed mainly at the west of Mashhad, east of Fariman and north of Torbat-e- Jam in Agh- Darband area. Our studies on ultramafic – mafic rocks have revealed several fields and petrographic evidences which demonstrate their volcanic to subvolcanic origin. Moreover, observation of various disequilibrium textures including the presence of glass, elongate and hopper pyroxene and olivine, occurring as pyroxene spinifex and olivine microspinifex textures in mafic and ultramafic rocks, can just be explained on the basis of their volcanic origin. On the basis of geochemical criteria, defined by IUGS for high MgO ultramafic and mafic volcanic rocks, these rocks are classified as komatiitic, picritic and basaltic types. Essential geochemical contrasts, including various ratios of incompatible immobile trace elements and different patterns of REE and spider diagrams, are too high to be explained on the basis of various degrees of partial melting of a uniform mantle source or AFC processes. It is thus possible to consider the role of a heterogeneous mantle source and/or dynamic melting in petrogenesis of these rocks. Furthermore to the cited heterogeneity which can be explained by mantle plume assumption, position of Fariman’s samples in the diagrams of (Nb/Th)N versus (Nb/La)N and Nb/Th versus Zr/Y which mainly plot at the OPB area, and Zr/Y versus Nb/Y which plot on or above ∆Nb line, coincide with the same assumption. Here we have argued that disequilibrium textures had been formed by undercooling of superheated melts, originated from an ascending mantle plume source, and rapid growth of crystals in such a melts. This arguement is favored with regard to high Fo contents of olivines which make necessary equilibrium of these crystals to high MgO contents and hot melts. We have estimated the MgO content and temperature of parent melt as much as 23.74% and 1470-1535ºC respectively based on maximum Fo content of olivine crystal in a komatiitic sample. These values are too high to correspond to a subduction or even a normal MORB related environments; however, similar to a hot spot tectonic setting.
Original Research Paper
A. Maleki
Abstract
The Large numbers of provinces in country use Karst's water Sources as a main Source of securing water for using in different ground of drinking-agriculture and industry. Kermanshah province with an area about 24953,286 square kilometers is located in the middle of western side of the country which its ...
Read More
The Large numbers of provinces in country use Karst's water Sources as a main Source of securing water for using in different ground of drinking-agriculture and industry. Kermanshah province with an area about 24953,286 square kilometers is located in the middle of western side of the country which its main part is in the zones of nappe and foliated Zagross and its heights are often formed of the hard carbonated formations. The Karsti zonations of Kermanshah province play an important role in the providing and feeding of aquiferouses; for this reason to recognize these zonations and the rate of their modification , the zonation of the modification of the karst is done in this research and its map has been drawn too . For the purpose of acquiring of the aims of the research , first the closed superficial holes as the index of the modification of the karst were recognized by using the topographic maps 1 / 50000 and the recognizing pictures 5 meters irs (BW) , their maps were drawn and after examining statistically and confirm the relationship the maps with the subject , with the help of the Kay square and the rotary operation , seven factors of height , lithologic , geomorphology , temperature , rainfall , vaporization and slope as the effective factors in the modification of the karst have been selected . After digitalization of all of the respective data for evaluation ( giving weight ) the classes of the maps of aquired from the statistics ways , analysis of the hierarchic ( expertizing judgement ) , condensation of the surface , the informational value , the variables weight and the experimental way were used . Then in the environment of gis the maps of the factor of overlapping and the maps of the zonation the modification of the karast has been aquired with the 5 ways mentioned .Among the ways used for zonation , the way of the informational value has the most adaption with the selected index (the closed holes) in the zone being studied .The aquired maps of zanation, beside the determinination of the zones with different degrees of modification of the karst's from in the province, It also has detemined the feeding Limitations of underground waters (Karst) and the favourable areas for Pollution of these Sources in the surface of earth.Which should use Suitable Policy for protecting these areas, Other wise many gangers will threat the feeding places.
Original Research Paper
A. R. Ghiasvand; M. Ghaderi; N. Rashidnejad-Omran
Abstract
The iron deposits in north of Semnan are located in the south of Central Alborz structural zone. Stratigraphically, the area consists of Paleozoic to Quaternary rock series exposures. The area has been affected by Semnan, Darjazin, Attari and Diktash faults. An intermediate to acidic granitoid body of ...
Read More
The iron deposits in north of Semnan are located in the south of Central Alborz structural zone. Stratigraphically, the area consists of Paleozoic to Quaternary rock series exposures. The area has been affected by Semnan, Darjazin, Attari and Diktash faults. An intermediate to acidic granitoid body of calc-alkaline and metaluminous composition, representing I-type granite characteristics, has intruded the Eocene volcanopyroclastic rocks in the north of Semnan. Skarn development and iron mineralization have occurred at the contact of the intrusive body and the volcanopyroclastic rocks. Mineral Paragenesis consists of magnetite accompanied by hematite, oligist, pyrite, chalcopyrite, garnet, pyroxene and epidote. Geometry of the ore bodies is massive, lenticular and vein type and their texture is disseminated, brecciated, vein-veinlet and massive. Dominant alterations in the area are propylitic, argillic, silicic, sericitic, chloritic and pyritic, respectively. The intrusive body has many similarities with intrusive bodies which form Fe-skarn deposits. Variations in the calculated parameters for REE indicate contribution of magmatic origin hydrothermal fluids to mineralization and that the intrusive body has had the dominant role as source of the skarn ore materials. Along with the intrusion, emplacement and crystallization of intrusive body, Fe-bearing fluids have intruded the volcanopyroclastic rocks, forming sodic metasomatism and deposited iron ores in the north of Semnan which have many similarities with calcic Fe-skarn deposits.
Original Research Paper
N. Taghipour; A. Aftabi; M.R. Ramezani
Abstract
The Miduk porphyry copper deposit is located in 85 Km northwest of Sarcheshmeh porphyry copper deposit, Kerman province. The deposit is hosted by Eocene volcanic rocks of andesite-basalt composition. The porphyry-type mineralization is associated with two calc-alkaline intrusive phases (P1 and Miduk ...
Read More
The Miduk porphyry copper deposit is located in 85 Km northwest of Sarcheshmeh porphyry copper deposit, Kerman province. The deposit is hosted by Eocene volcanic rocks of andesite-basalt composition. The porphyry-type mineralization is associated with two calc-alkaline intrusive phases (P1 and Miduk porphyry) of Miocene age. Five hypogene alteration zones are distinguished in the Miduk deposit, magnetite-rich potassic, potassic, potassic-phyllic, phyllic and propylitic. The main stage of mineralization consists of chalcopyrite, magnetite and anhydrite in potassic alteration zone. The mineralization is mostly associated with Miduk porphyry intrusive phase. Three different types of biotite including magmatic, magmatic affected by hydrothermal fluids and secondary are distinguished at the Miduk deposit. Magmatic type biotites affected by hydrothermal fluids and secondary biotites contain higher XMg values than the magmatic biotites. The XMg are positively correlated with Si, Al, Mg, K, Mg/Ti, but negatively correlated with Al×Ti, Fe, Na, Fe/Ti contents. The variations of Cu, Mo, Au and Ag are controlled by vein - type alteration and mineralization zones. The tonnage of deposit is about 170 Mt with average grade of 0.82 % Cu, 0.007% Mo, 82 ppb Au and 1.8 ppm Ag, respectively. Highest values of Mo and Au occur in leached and oxide, supergene sulfide mineralization, phyllic and potassic-phyllic alteration zones, respectively. Gold displays positive correlation with Cu in magnetite-rich potassic and potassic alteration zones. Based on petrography, mineralogy, alteration halos and patterns of Cu, Au, Ag and Mo, the Miduk porphyry copper deposit is similar to those of continental arc setting porphyry copper deposits.
Original Research Paper
N. KhajehMohammadlo; E. Rasa; A. Emamalipur
Abstract
Alibaltalo bauxite deposit is situated in east Shahindezh, south west of west- Azarbaijan. This ore horizon lies along the boundary between Jurassic sandstone and Triassic dolomtite. In this study for understanding the chemical process involved in the formation of the bauxite deposite and in order ...
Read More
Alibaltalo bauxite deposit is situated in east Shahindezh, south west of west- Azarbaijan. This ore horizon lies along the boundary between Jurassic sandstone and Triassic dolomtite. In this study for understanding the chemical process involved in the formation of the bauxite deposite and in order to determine the role and behavior of elements on weathering process, the gain and loss and mass transfer methods, enrichment -depletion diagrams were used. the result of this study diabase sills of Doroud Formation in the area is proposed as the principal source of this bauxitic horizon.. Mass change calculations for different elements compared to an immobile element (Titanium)- with. chemical stability in weathering processes. Results showed Si, Na, K, Mg, Ca depletion while Fe, Al, Ti showed secondary enrichment.The ore body shows decreasing in total mass of -21.02 for brown horizon,-21.02 for gray kaolinite layer,-22.91 for green to gray part and -23.55 for green to gray color horizon.
Original Research Paper
E. Moghimi; M. Badri Far; M. Zarei Nejad
Abstract
Morphodynamic characteristics of Damavand volcanic cone have been affected by two factors including internal and external morphodynamics. Major goal of this research is based on external morphodynamics. The morphodynamical landforms of this area are divided in two main groups, the first one is climatic ...
Read More
Morphodynamic characteristics of Damavand volcanic cone have been affected by two factors including internal and external morphodynamics. Major goal of this research is based on external morphodynamics. The morphodynamical landforms of this area are divided in two main groups, the first one is climatic processes and the second one is anthropogenic processes. Climatic processes, including glacial erosion, pre-glacial erosion and alluvial erosion, have changed morphology of slopes and spatial landforms. For the special geographic condition of Damavand volcanic cone, few data is available. Therefore by using satellite images ETM+, ASTER, SPOT, several new data layer have been prepared based on base maps and field checking in GIS environment.
Original Research Paper
H. Biabangard; A. Moradian
Abstract
Taftan Volcano in southeast of Iran, Sistan and Baluchestan Province, is located in 45 km north of Khash city and about 100 km south to southeast of Zahedan at the terminal of Nehbandan-Khash flysch and north Makran zones. No Volcano-stratygraphic studies have been carried out around Taftan volcano. ...
Read More
Taftan Volcano in southeast of Iran, Sistan and Baluchestan Province, is located in 45 km north of Khash city and about 100 km south to southeast of Zahedan at the terminal of Nehbandan-Khash flysch and north Makran zones. No Volcano-stratygraphic studies have been carried out around Taftan volcano. Taftan volcano can be classified into three groups from stratigraphic point of view: pre, syn and post volcanic deposits. The first group has formed the basement of Taftan and consists mostly of sandstones, shale, limestones and marl (flysch facies), colored melange complex, ultramafic rocks (preidotites), mafic rocks (gabbros and basalts), pelagic limestones, radiolarites and low metamorphic rocks, (metagreywackes, slates, phylites and schists). Second group has volcanoclastic and lava flows that form the main body of the volcano and third group includes alterations along with reworked product of Taftan. Our studies revealed that Taftan volcano has more than five eruptions stages including olivine basalte lava flows, Anjerk crater, Jamchen crater, Anar mount, principal peaks, eruption related to before and final stages of eruptions.
Original Research Paper
Mehran Arian; S. Keshavarzi Dana
Abstract
The Buneh Kuh anticline (with 25 km length and 7 to 17 km width) is a NW-SE trending anticline in the Coastal Fars Sub-basin (Zagros simple folded belt). Gachsaran formation is cropping out in the core of this anticline. In this paper the elements of fold style and folding mechanism have been investigated ...
Read More
The Buneh Kuh anticline (with 25 km length and 7 to 17 km width) is a NW-SE trending anticline in the Coastal Fars Sub-basin (Zagros simple folded belt). Gachsaran formation is cropping out in the core of this anticline. In this paper the elements of fold style and folding mechanism have been investigated in the Buneh Kuh anticline. It is an asymmetric detachment fold on the Hormoz Formation. Herang anticline is a NW continuation of the Buneh Kuh anticline. Sub-surface contour map on the top of the Dehram group (gas reservoir) was prepared and its western culmination (near to the DD’ cross section) could be recommended for drilling.
Original Research Paper
G. Ghorbani; H. Ghasemi
Abstract
Bagho granitoid is located in the southeast of Damghan and has been cut by many quartz-tourmaline veins with about 1 mm to 30 cm thickness. Based on petrography and electron microprobe analyses, these tourmalines show schorl– dravite– foitite composition with a tendency toward schorl end ...
Read More
Bagho granitoid is located in the southeast of Damghan and has been cut by many quartz-tourmaline veins with about 1 mm to 30 cm thickness. Based on petrography and electron microprobe analyses, these tourmalines show schorl– dravite– foitite composition with a tendency toward schorl end member, and located in alkali and vacancy groups. Compared with the ideal composition of schorl– dravite, many of tourmaline samples have high Al contents and alkali – site vacancies. The increase in octahedral aluminum reflects a combination of substitutions in tourmaline involving deprotonation (O–OH exchange) and vacancies in the alkali-site and then they have magmatic origin. In contrast, the presence of zoning, its occurrence as vein form, having high Mg compared with Fe in some samples and tendency away from alkali- deficient and proton– deficient tourmaline vectors, show that these tourmalines have hydrothermal origin. Then, based on these results, it appears that tourmaline veins form by interaction of boron-rich magmatic-hydrothermal fluids of granitic-dacitic provenance with various quartz-tourmaline and metapelitic-metapsammitic host rocks.
Original Research Paper
REZA KHOSHRAFTAR
Abstract
Zanjan province with 22164 square kilometer is situated in North West of Iran. From geological point of view is a part of Central Iran and in geomorphologic classification it is identified as North West geomorphologic unit. Volcanic formations, intrusive granite rocks, major faults, Miocene ...
Read More
Zanjan province with 22164 square kilometer is situated in North West of Iran. From geological point of view is a part of Central Iran and in geomorphologic classification it is identified as North West geomorphologic unit. Volcanic formations, intrusive granite rocks, major faults, Miocene evaporative basins and karst topography resulted in a variety of geosites in this province. Mountains and interval plains are stretching from north west to south east direction and drained by Ghezel Ozan, its tributaries, Abharrud and Khrarud Rivers. Ghezel Ozan pours into Caspian Sea and others goes to Hoz-e-Soultan Lake in Central Iran. The highest point in province is 3332 m above sea level in Belghaise Mountain and the lowest (250 m) located near to Sefidrood reservoir. Karstic caves such as Katalekhor, Zarin and Kharmanesar caves in south east and north east of the province, Chehr-Abad historical salt mine (where six salt men were discovered in north west of the province), tens of fingers of god and butte in conglomerate formations in Mahneshan and Angoran districts, badlands in Tarom area and west of zanjan city, tens of diapir domes in Ghezel Ozan watershed, mushrooms in granite rocks, and several hot springs are examples of this geosites. For inventory and analyses of these geosites in field work, topographical and geological maps of different scales and Global Positioning System (GPS) were used. Some of these geosites can have national and international importance. The Province is thus having very favorable conditions for geotourism development.
Original Research Paper
Morteza Hashemi; M.R. Nikudel; N. Hafezi Moghaddas
Abstract
Engineering geology mapping has been central to engineering geology research since it is objectives that the project continues to develop and investigate methods for obtaining data and “mapping’ this data to be suitable for the needs of civil engineering and environmental assessments. Engineering ...
Read More
Engineering geology mapping has been central to engineering geology research since it is objectives that the project continues to develop and investigate methods for obtaining data and “mapping’ this data to be suitable for the needs of civil engineering and environmental assessments. Engineering geological maps of Chabahar area (at a scale of 1:25,000) was prepared to provide engineering geological information as an aid in land use planning. Study area consists of tertiary deposits and studied for assessment of some parameters such as foundation condition, excavation condition, waste disposal condition, engineering geological problems and environmental problems. Data collection was done through field investigations, inclusive borehole boring, systematic sampling and field and laboratory tests. Finally, results are shown in applied geological maps.
Original Research Paper
M. Hosseini-Barzi; M. Houshyar; H. Ghalavand
Abstract
Field study, calcimetery and petrography of thin sections from Gurpi type section and petrography of cuttings from Ziloee oil field (well No. 5 and well No. 8) represent two carbonate members and two hybrid (mostly marl and in a few samples clay marl) members in these deposits. Microfacies analysis of ...
Read More
Field study, calcimetery and petrography of thin sections from Gurpi type section and petrography of cuttings from Ziloee oil field (well No. 5 and well No. 8) represent two carbonate members and two hybrid (mostly marl and in a few samples clay marl) members in these deposits. Microfacies analysis of the carbonate members implies 2 microfacies belong to open sea of a carbonate ramp model. Moreover, authigenic glauconite and phosphate and framboidal pyrite propose deposition of these sediments in an anoxic condition. XRD and SEM analysis of marl members provide existence of illite and chlorite as clay minerals by certain detrital source and smectite by digenetic and probability detrial source in the upper marl member and existence of quartz in lower member. Coexistence of these minerals proposes a temperate climate during deposition of the upper marl member. Semi-quantitative analysis of XRD data represents descending trend for relative amounts of illite and ascending trend for smectite during deposition of upper marl member of Gurpi Formation which implies deepening of the sedimentary basin and relative climate warming. The digenetic processes in these deep marine deposits are limited to cementation, illitization, hematization and fracturing. Moreover, studying SEM images evident autogenetic origin of smectite in two samples from upper cretaceous (under K/T boundary) which can form during fluid exchange with mafic minerals and/or detrial clay minerals such as detrial smectite, illite. The absence of digenetic smectite in two samples from Paleocene (over K/T boundary) can be related to change in basin condition in Zagros basin, this period of time. Also, studying relative abundance of K and Th in NGS logs of well number 8 in Ziloee oil field shows that clay minerals in this formation are illite and montmorillonite.
Original Research Paper
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 ...
Read More
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.
Original Research Paper
S. Madanipour; A. Yassaghi
Abstract
Taleqan Mountains located in South-Central Alborz range accommodate one of the best stratigraphic sequences of the range. The area bounded by the Taleqan fault in the north and the Mosha fault in the south. These faults separate Paleozoic-Mesozoic rocks from southern and northern Tertiary rocks. In this ...
Read More
Taleqan Mountains located in South-Central Alborz range accommodate one of the best stratigraphic sequences of the range. The area bounded by the Taleqan fault in the north and the Mosha fault in the south. These faults separate Paleozoic-Mesozoic rocks from southern and northern Tertiary rocks. In this paper structural geometry of these faults is analyzed to unravel structural evolution of the range which interpreted to be initiated as inversion tectonics then followed by transpression tectonics. The Mosha fault in the eastern part of the Mountains has high angle and thrusts Precambrian rocks, cored a large Hangingwall anticline, over the Tertiary rocks accommodate footwall synclines. This geometry constrains the fault as a deep-seated basement fault which has been developed through inversion of an initial normal fault. The Taleqan fault consequently is analyzed as a back thrust to the Mosha fault and the mountain as a pop up zone between them. Detail kinematic analysis of the Taleqan fault show two different reverse movement with right and left lateral components. Given that the fault located on the Mosha fault hangingwall, it has been analyzed that the former movement direction to be related to the Mosha fault inversion from Late Cretaceous while the latter movement direction is the consequence of left lateral transpression tectonics in the range since late Pliocene.
Original Research Paper
A.H. Kokabi Nezhad; Z. Purabrishami; Kh. Tehrani
Abstract
One of Hipparion species which has complete characters of cranium and maxillary with teeth found during excavation is H.primignium. Since this sample is the only complete one in the world, (of course without mandible) with special species characters we can call it Homeotype. Because of finding this species, ...
Read More
One of Hipparion species which has complete characters of cranium and maxillary with teeth found during excavation is H.primignium. Since this sample is the only complete one in the world, (of course without mandible) with special species characters we can call it Homeotype. Because of finding this species, pyroclastic sediments of Maragheh would be dated upper Astracian, so Maragheh informal formation which in the past was thought to be as old as vallencian- Trulain, seems a bit older. Because the mentioned samples were also found in Samus and Pikermi in Greece, so we can say these two regions have vertebrate familiarities in fossils fauna and other characters like paleogeography, biochronology and biogeography in late Miocene- early Pliocene.
Original Research Paper
R. Hajialioghli; A. Jahangiri; M. Moazzen; G.T.R. Droop; R. Bousquet
Abstract
The igneous rocks of Takht-e-Soleyman area in the north western Iran crop out in association with the amphibolites. The contact between igneous rocks and amphibolites is sharp. Igneous rocks in the study area are mainly granodiorite, quartz-monzodiorite and quartz-diorite. Plagioclase and hornblende ...
Read More
The igneous rocks of Takht-e-Soleyman area in the north western Iran crop out in association with the amphibolites. The contact between igneous rocks and amphibolites is sharp. Igneous rocks in the study area are mainly granodiorite, quartz-monzodiorite and quartz-diorite. Plagioclase and hornblende form dominant minerals of the igneous rocks. Titanite and epidote occur in rare amounts. Chemical compositions of the clinopyroxene, plagioclase, hornblende and titanite in quartz-diorites were analysed using EPMA.
High Mg and Si contents accompanied by low Ti at the rim composition of the analysed amphiboles can be attributed to subsolidus cooling event. Magmatic crystallisation temperature for quartz-diorites is determined based on compositions of hornblende and coexisting plagioclase. Clinopyroxene composition was used to estimate crystallization pressure of the investigated rocks in the Takab area. Estimated temperature and pressure are consistent with 820±75oC and 8 kbar, respectively. Thermometry based on Ti content of the analysed hornblende gives temperature of 760oC. On the basis of chemical compositions of the analysed clinopyroxenes, sub-alkaline and I-type natures of the quartz-diorites in the study area can be concluded.
Original Research Paper
A. Abedini; A. A. Calagari
Abstract
Karstic bauxite horizon at Kanisheeteh is located ~19km east of Bukan, south of West-Azarbaidjan province, NW of Iran. This horizon lies conformably along the boundary of Ruteh (carbonate-shale) formation (middle to upper Permian) and Elika (carbonate) formation (lower Triassic), and consists of five ...
Read More
Karstic bauxite horizon at Kanisheeteh is located ~19km east of Bukan, south of West-Azarbaidjan province, NW of Iran. This horizon lies conformably along the boundary of Ruteh (carbonate-shale) formation (middle to upper Permian) and Elika (carbonate) formation (lower Triassic), and consists of five distinct lithic units. Field evidence, petrographical and mineralogical examinations showed that fluctuations of climatic conditions along with structural stresses had a great influence in the formation of this horizon. Distribution pattern of REE (normalized to chondrite) indicates an intensive fractionation and enrichment of LREE over HREE, and an authigenic formation for the horizon. Calculations of absolute weathering index (AWI) and assumption of Nb as an immobile element and the upper continental crust (UCC) as a source for parent materials show that leaching and fixation processes are the two major regulators in concentrating of trace-elements in this horizon. Geochemical investigations indicate that distribution of Al, Fe, Si had great influence in changes of La/Y ratio, distribution of trace-elements in residual system, and Eu anomaly. Incorporation of the obtained results revealed that textural variations, preferential adsorption by metallic oxides (hematite), buffering of weathering solutions by carbonate bedrock, mineralogical control, and pH changes of the environment are the most important controlling factors in the distribution of LREE, HREE, HFSE, LILE and TTE during lateritization processes at Kanisheeteh.
Original Research Paper
H. Shafaii Moghadam; M. Rahgoshay; H. Whitechurch; I. Monsef; A. Soltan Mohamadi
Abstract
Basalts, gabbros, tuffs, diabasic dikes, agglomerates and breccias and the rock fragments of breccias are the main mafic constituents of the Balvard-Baft ophiolites. Geochemical signatures of these rocks reveal depletion in HFSE and enrichment in LILE and simultaneous occurrence of island-arc tholeiitic ...
Read More
Basalts, gabbros, tuffs, diabasic dikes, agglomerates and breccias and the rock fragments of breccias are the main mafic constituents of the Balvard-Baft ophiolites. Geochemical signatures of these rocks reveal depletion in HFSE and enrichment in LILE and simultaneous occurrence of island-arc tholeiitic and calc-alkalic volcanisms. These geochemical behaviors are the evidences suggesting that these mafic rocks are of supra-subduction zone affinity. These special signatures associated with the position of the Nain-Baft ophiolitic belt behind the Mesozoic magmatic arc of the Sanandaj-Sirjan zone, suggest back-arc spreading (in the active margin of the Central Iranian block), during middle Cretaceous due to the oblique subduction of Neo-Tethys beneath the Central Iranian block.
Original Research Paper
H. Atapour; A. Aftabi
Abstract
Magmatism in Dehaj- Sarduieh volcanic belt has been occurred in three phases. The first magmatic phase consists of Eocene volcanic rocks (tephrite –phonolite, basalt, trachybasalt, tracyandesite, andesite, dacite, rhyolite and pyroclastic rocks) of Bahraseman, Razak and Hezar complex. With increasing ...
Read More
Magmatism in Dehaj- Sarduieh volcanic belt has been occurred in three phases. The first magmatic phase consists of Eocene volcanic rocks (tephrite –phonolite, basalt, trachybasalt, tracyandesite, andesite, dacite, rhyolite and pyroclastic rocks) of Bahraseman, Razak and Hezar complex. With increasing angle of subduction, the acidic (Bahraseman complex), intermediate (Razak complex) and basic volcanism (Hezar complex) occurred in Dehaj – Sarduieh volcanic belt. After ceasing the volcanism, the Oligo-Miocene granitoid rocks (gabbro-diorite, diorite, monzonite, quartz diorite, granodiorite, quartz monzonite and granite) with calcalkaline, potassic calcalkaline and shoshonitic affinity intruded into the volcanic rocks, forming the first phase of porphyry copper mineralization.The second magmatic pulse includes Neogene volcanic rocks (dacite – rhyodacite- rhyolite ) and plutonic bodies ( diorite – quartz diorite ) of flat subduction- related calcalkaline-adakitic affinity, associated with the second phase of porphyry copper and polymetallic vein mineralization. Polymetallic vein type mineralization occurs in volcanic rocks, but genetically is related to porphyry mineralization and tectonomagmatic characteristics of the belt. The occurrence of ignimbrite strongly indicates a continental arc subduction setting. The high values of incompatible elements such as K, Rb and Ba show that porphyry copper and their host igneous rocks were developed by partial melting of metamorphosed oceanic crust and mantle wedge ( phlogopite eclogite and or phlogopite amphibolite ) in a continental arc setting. The third magmatic phase is characterized by the occurrences of postcollisional lamprophyres and basaltic lavas of potassic and alkaline affinity. The final postmagmatic activity was related to the vast occurrences of Quaternary travertine deposits.
Original Research Paper
S. Orandi; A. Yaghubpur; M. Nakhaei; B. Mehrabi; H. Sahraei; M. Behrouz
Abstract
Sarcheshmeh Copper Mine, one of the well known porphyry copper deposits, is located in 55 km south of Rafsanjan, south-eastern Iran. Metalliferrous deposit mining, prepare proper conditions for oxidation of sulphide minerals and acid mine drainage will be produced easily by chemical reactions between ...
Read More
Sarcheshmeh Copper Mine, one of the well known porphyry copper deposits, is located in 55 km south of Rafsanjan, south-eastern Iran. Metalliferrous deposit mining, prepare proper conditions for oxidation of sulphide minerals and acid mine drainage will be produced easily by chemical reactions between metal sulphides and water, with the presence of air. Investigations on impact of waste dumps on producing acid mine drainage at Sarcheshmeh copper mine shows decreased pH up to 3-5.5 in acid drainages with the presence of some dissolved toxic and heavy metals higher than permitted standard limits (WHO). In such degraded water and improper environment for aquatic life, just some of microorganisms are able to survive. At Sarcheshmeh copper mine in some of acidic drainages which maintain high dissolved elements, an acid tolerant alga recognized. The genus of this filamentous green alga is Ulothrix and species is Ulothrix gigas without antimicrobial and antifungal properties. The alga is observed in the drainages with high dissolved solids (TDS≈1800mg/l). It seems pH values, type of dissolved elements and secondary minerals formed on the substrate, are important factors in distribution of Ulothrix. This research shows the most prolific and densely populated communities occur in effluent with the pH 3- 4.5. The colloidal conditions and presence of suspended Iron and Aluminium prevent growth or reproduction of them. Sampling and chemical analysis of algae show elevated absorption of heavy metals. Therefore the presence of this alga is a factor to remove heavy metals from acid mine drainage naturally and improve the water quality.
Original Research Paper
N. Hashemi
Abstract
This paper presents a study of the spatial variation of Gutenberg-Richter seismic b-value over the Iranian region. For this purpose, based on the works carried out by investigators for tectonic and seismotectonic zoning of Iran, the region subdivided into five structural zones, namely, Alborz-Kopet Dagh ...
Read More
This paper presents a study of the spatial variation of Gutenberg-Richter seismic b-value over the Iranian region. For this purpose, based on the works carried out by investigators for tectonic and seismotectonic zoning of Iran, the region subdivided into five structural zones, namely, Alborz-Kopet Dagh zone, Azarbaijan zone, East-Central Iran zone, Makran zone, and Zagros zone. Then, the seismic b-value parameter has been computed for these five zones. The results obtained reveal that among these five mentioned zones, the Zagros zone shows the highest b-value (1.28 ± 0.03), and in contrast, the East-Central Iran zone shows the lowest value (0.84 ± 0.08). In addition, the contour map showing the spatial distribution of b-value over the region is presented. According to this map, some parts of the Iranian region such as the Central Iran and the Eastern Iran clearly act as resistant (rigid) blocks. In summary, the results of this research reveal that the study of the frequency-magnitude distribution of earthquakes can be reliably used as a tool to discover the seismic deformation patterns as well as different tectonic structures of the regions.
