GEOSCIENCES
Year:2005 | Volume:15 | Issue:57|Papers Count:17

The comparative advantage of minerals from production and export point of view is one of the important key factors in economical activities. This issue is central in the developing countries. In Iran, promoting the non-petroleum export and diverting from the single-product economy to a wide range of exports is a major issue. This is an excellent potential for the mining investment. In this paper, the comparative advantage of operating gold mines in Iran, from the production to the export stages, is evaluated by the implementation of the Domestic Resources Cost (DRC) method. Finally this study recommends a regime for the promoting of the production and export or importing the ore. Accuracy of this method is examined by the comparing the result with the real standard ratio, being used in the other countries.

A powerful and independent test for the validity of a structural interpretation is the restoration of the structure to the shape it had before deformation. Such construction is a key in understanding of regional tectonics and plays a vital role in exploration industry. Exploration for oil and gas, in particular, requires the best possible control on underground structures to locate exploration and production wells. A map or cross section can usually be restored by methods based on more than one kinematic model, however, different methods will produce some what different restored. geometries. It follows that any given restoration methods does not necessarily represent the exact pre-deformational geometry. The internal consistency of the restoration by any relevant technique validates the interpretation. The optimum method can be investigated through qualitative and quantitative testing techniques. The main aim is to select an optimum method for length and area balancing of the two oilfields in the eas of Khuzestan. In this study, three line-length, vertical simple shear, and flexural slip methods are compared quantitatively with 3D seismic data of the two oilfields in the Eastern Khuzestan, and finally the flexural slip method is recommended as the optimum method.

This paper is devoted to explore the relationship between earthquake intensity in the epicenter and its magnitude as well as the intensity attenuation laws of the Iranian earthquakes. For this purpose, available data, reports, seismotectonic and isoseismalmaps, related to 21 destructive earthquakes in a period of 1957 to 1998, were studied.The results show that the intensity-magnitude relationships and the intensity attenuation laws are strongly dependent on the site geology that specifies local effects. Therefore, the sites have been classified, according to site geology, into two groups, hard sites and soft sites. The intensity-magnitude and intensity attenuation versus the distance from the earthquake sources (surface refaulting of the causative fault (s)) were determined and introduced for each of the two site groups. Finally, the obtained laws were compared with some other laws offered by other researchers.

In this research the kinetics of copper cementation on iron was investigated by experimental design (Tagochi method). The significant factors in the order of importance were: copper concentration, time, iron surface, agitation intensity, interaction of pHxcopper concentration and pH. The optimum conditions for the selected levels were copper concentration = 7 g/l; time=5 min; iron surface= 62.42 cm2, agitation intensity= 300 s-1 and pH= 1. Estimated performance and confidence interval at this point were 427.557mg and ±6.932 respectively.

Pb-Zn ore deposit in Kuh-e-Surmeh is located at about 33 km, south of Firouzabad. The host rocks of the ore are dolostones of the lower; part of Dalan Formation. The ore body in the dolostones occurs in three ore-bearing horizons. The main facies in the area are as follows: siltstone, sandstone, biomicrite, intrasparite, dolomicrosparite, dolosparite, dolomicrite, gypsum and anhydrite. Dolosparite is the main facies in the main ore horizons. Siliciclastic and carbonate facies are deposited in intertidal to supratidal environment. The mineralogy of the deposit consists of sphalerite, galena, pyrite, cerrusite, anglesite, covellite, azurite, hematite, chalcocite, dolomite, calcite, barite, and gypsum. Mineralization occures as void filling, replacement and dissemination fabrics. In some cases ore deposits fills dissolution breccia and fractures. Stable isotope studies show that dolomite has been altered by fluids with relatively high salinity and temperature of about 100C° . Field observation, texture and structure of ore bodies, type of carbonate facies, paragenetic sequences, fluid inclusions and oxygen and carbon isotopes indicate that Kuh-e-Surmeh Pb-Zn deposits is similar to MVT type deposits.

The Narigan ferro-manganese deposit is located in 30 km NE of Bafq, and 20 km of Chogart mine. The deposit is situated in Central Iran. Dolomitic limestone and rhyolitic tuffs are the main host rocks. Petrological and ore microscopic data indicate that ore and associated host rocks formed in shallow water, on a platform.Furthermore, geochemical studies show that hydrothermal genesis was responsible for the formation of the ore deposit.Field and petrographical studies show that two stages of hydrothermal activities were involved:1-Exhalation of hydrothermal fluids from seafloor, then primitive ore forming process in the form of precipitation of Fe and Mn oxide and hydroxide gels followed by final crystallization.2- Migration of secondary hydrothermal fluids from reducing to oxidizing area, and transportation and precipitation of Fe and Mn in the latter area; therefore, an increase of ore grade in the oxidizing area.Finally, it could be concluded that at the time of ore formation, rifling had probably occurred in the area, and large volumes of felsic magmas formed. In this way and due to hydrothermal activities, Fe and Mn leached from these rocks and precipitated on these a floor.

Misho-Dagh Mountain range is part of Azerbaijan plateau in Northwest Iran. This E-W range is located between Marand and Shabestar plains. Northern Misho fault, the main fault in study area, and other parallel faults have separated the topographic units and geological structures. Rivers on the northern slope of Misho- Dagh, flowing from the south to the north, cut across geological structures and topographical units in their distal reaches, prior to joining in the Marand plain. The long-term drainage evolution and its creation, as transverse fluvial systems, have been examined by reconstruction of drainage network using a combination of geological and geomorphological records. This reconstruction is based on analysis of topographic and geologic maps and area photos and repeated field studies on fluvial remnants. Results show that drainage evolution in the study area has occurred in three stages: a) sedimentation of the Plio-Pleistocene non-compacted conglomerates (relict alluvial fans), b) uplift of the Plio- Pleistocene sediments in mid-? Late Pleistocene, separation of this sediments from main mountainous body of M isho-Dagh due to a E-W synclinal valley, formation of new block of mountains (anticline) in the north of the valley and eastward diversion of rivers in their distal reaches, and c) faulting of new relief block by S-N faults crossing the relief axis, verification of rivers to fault lines and formation of new alluvial fans. Neotectonic indices such as inclination of the Plio- Pleistocene sediments, separation of this sediments from main mountainous body of Misho-Dagh, verification and non-verification of rivers by tectonic and geologic structures, catchments morphometric properties, and situation and morphology of alluvial fans indicate that fluvial systems in the study area are influenced by the Pleistocene and Holocene tectonic activities, and tectonics is the main factor in the fluvial system replacement and their situation.

The sedimentary pattern of the northern Tabas Block during the Jurassic period, apart from global sea-level fluctuations, was mainly governed by tectonic events of varying intensity and extent. These events took place during the Late Triassic (Early Cimmerian phase), Middle Bajocian (Mid-Cimmerian phase), Early Callovian, Late Oxfordian and Late Kimmeridgian/ Tithonian (Late Cimmerian phase). The importance and extent of these events and their influence on the facies pattern of the northern Tabas block are discussed. In this context the lithostratigraphy of the Jurassic strata in the northern Tabas Block is revised.The stratigraphic position of the Badamu and Parvadeh formations is briefly discussed and three facies types of the Hojedk Formation, belonging to different sedimentary environments, are reported. The Middle and Upper Jurassic Magu Group is subdivided into three new and genetically related subgroups, Le. the Upper Bajocian to Middle Callovian Baghamshah Sub group, the Lower Callovian to Middle Kimmeridgian Esfandiar Subgroup and the Upper Kimmeridgian to Tithonian Garedu Sub group (Fig. 3). Furthermore the Qal' eh Dokhtar Formation is revised and three new formations, Le. the Sikhor Formation(Lower/Middle Callovian), Kamar-e-Mehdi Formation (Callovian to Lower Kimmetidgian) and the Korond Formation (Upper Oxfordian to Middle Kimmeridgian) are established. This new subdivision will considerably facilitate the applicabilityof the lithostratigraphic scheme to future work.

The widespread listweanites (carbonatized serpentinites) outcrop in Birjand-Nehbandan axis in the east of Iran and south of Khorasan province. listweanites cover an area extending more than 25000 km2 , and occur along the major faults and between flysch-colored melange-ophiolite complex. The most extensive outcrop is in the south of Mokhtaran map (scale 1:100000). On the basis of lithology, listweanites, occurring mostly close to ultrabasic rocks, are divided into four categories: breccia cryptocrystalline silicic listweanite bearing sulfide minerals, silicic list weanite, and silicic-carbonatic listweanite. Among these, breccia silicic listweanite bearing sulfide can be a suitable case for gold exploration. Sulfide minerals such as pyrite, chalcopyrite, bornite, arsenopyrite and covelite occur in this listweanite. With respect to mineralogy, listweaniterocks consist of major minerals such as cryptocrystalline quartz (opal, jasper), calcite, dolomite, magnesite, siderite, serpentine, chlorite, and minor minerals such as pyroxene, chromite, magnetite, cinnabar, chalcopyrite, bornite, arsenopyrite and Fe-oxide-hydroxide. Some of the sulfide minerals have altered to Fe-oxide and hydroxides. Heavy mineral studies, on the samples taken from river sediment, show that the particles of gold (30-150 microns) are associated with pyrite, chalcopyrite, cinnabar and native copper.Significant alterations in the listweanitic complex are silicification, hematitization, and slight argillitization. The origin of gold, silver, arsenic and other associated elements are from serpentinized ultrabasic rocks. With development of regional metamorphism, fluid bearing anions like (CO3)2- and (SO4)2- form complexes with metallic elements such as Au, Ag, Sb, As, Hg, Cu, Ni, Cr, and Co. This fluid ascends to the upper parts, forming gold-bearing sulfide-silicic vein deposit in breccia zones and in the geochemical bars of carbonatic parts (carbonatic listweanite with silica deposition).

The study area is situated in the southern part of the Central Iranian Volcano-Sedimentary belt. The Eocene volcano-sedimentary rocks are the main geological features in the area. These rocks are intruded by the Oligo-Miocene intrusive bodies where they caused an intensive alteration and formation of copper mineralization. Different image processing techniques such as band ratios, Costa technique, supervised fuzzy classification, and lineament factor analysis are used for identification of the alteration zones associated with copper mineralization. The supervised fuzzy classification of the images obtained through Costa technique was found to be the best image processing technique for delineation of the hydrothermally altered rocks associated with porphyry copper deposits. Analysis of the lineaments interpreted out of ETM+ (band 8) data is recognized as another method for locating porphyry and vein type copper mineralizations. There is a close correlation between photo lineament factor values and the known copper mineralization in the area. After analyzing and interpreting the processed images, a few selected sites were sampled. The thin sections and XRD data from the samples showed that ETM+ data was capable of mapping hydrothermal alteration.

To study and introduce plant macrofossils of Late Triassic- Middle Jurassic (Shemshak Formation), Ramsar- Javaherdeh (Northern Alborz) and Eshkevarat-e-olia (Central Alborz) areas were studied. The performed investigation led us to the presentationof four species of Gymnosperms group for the first time in Iran. The two, Ctenis kaneharai and Pseudoctenis herriesispecies belong to division Cycadophyta (order Cycadales) and the two, Ginkgoytes longifolius and Baiera furcata speciesare the members of division Ginkgophyta (order Ginkgoales). With respect to Schweitzer et al (1995, 1998, 2000), the species: Ctenis sp. A and Ctenis sp. B, introduced by Fakhr (1975) from Gajereh and Ferizi and Ctenis afghanensis, introduced by Jacob & Shukla (1955) from Afghanistan, are not synonymous with Ctenis kaneharai. Likewise, Pseudoctenis herriesi is not synonymous with Nilssonia herriesi species.

The main purpose of this paper is to apply statistical data analysis to find an acceptable geochemical pattern for Qanat Marvan area. Geological and geochemical information of Pb-Zn mineralization of Qanat Marvan district is first introduced and then data input to the Surfer software, contour map, drawing and principal component analyses are carried out. Pb-Zn thresholds are determined with fractal method and subsequently the sericitization index (K2O/K2O+Na2o) and its contour map are prepared.Finally, with respect to correlation coefficient matrices, principal component analyses, hierarchical clustering and the produced maps, it can be concluded that Pb-Zn elements in the PC2 and PC3 have high values. Therefore, principal component score map PC4 is equal to the Pb-Zn contour maps, suggesting component mineralization of Pb-Zn in the study area. These areas have undergone phyllic (sericitic) alteration due to Pb-Zn mineralization.

Posah cave is located near Skel-Abad village, beside the Zahedan-Khash road, about 114 km south of Zahedan city and about 22 km in the west of Taftan Mountain in the north of Baluchistan. This cave has been developed in a flysch unit consisting mainly of thin-bedded sandstone and shale layers. The roof of the cave is composed of Taftan lahar, a mudflow poorlysorted and consists mostly of volcanic ash with pyroclastic materials produced by Taftan volcano. The Posah cave is a unique pseudokarst cave in both the region and the whole country. The results of XRD and XRF analyses on two specimens of rocks from the cave have shown that rock units in the area are insoluble. Moreover, there is no significant difference between Ca2+ concentration values in the surface and ground waters. Therefore, it can be concluded that the cave has been developed in insoluble rocks. This paper deals with the development of the cave from a geological point of view.

Accessibility to industrial minerals and ores is one of the necessities to facilitate the development. Meanwhile, it is clear that the shallow mineral resources are near to exhaust, therefore, using modern exploration methods to attain deeper mineral deposits is inevitable. An attempt has been made in this paper to apply and accomplish the results of geological and surface geochemical studies for determination of spatial mineralized zones in western area of Tappeh Sorkh lead - zinc mine (which is one of Bama mining complex mines).IP and Resistively techniques are the most popular geophysical methods for exploration of Pb and Zn sulfide deposits. There are some advantages in applying SIP method, such as identification of mineralization texture, grain structure, type of material, ore phase and parasitical data. In this study, a relatively new method of time domain SIP was used and apparent time constant, apparent frequency -dependent and true chargeability parameters were extracted. By using the results of time constant parameter, the average of metal grain size was determined, also the amount of metal grain dispersion (mineralization texture) was determinedly applying the results of frequency dependent parameter. Probable mineralization places were determined by using SIP sections. Since the results of raw data do not indicate accurate information about the depth and geometry of mineralization, smooth and parametric inverse modeling were applied to determine probable zones and vertical and horizontal extent of mineralization.

In this research, Kope-Dagh area (Khangiran formation.), some 25 km of Shorlogh village, north-east of Iran was Investigated. Many researchers have paid their attention to the area that is economically important due to gas reservoirs. To explore the area, characteristic light microscope (LM) and scanning electron microscope (SEM) were employed to study the calcareous nanofossils. Based on the first occurrence and fossil assemblages, nine biozones were recognized. These assemblages, from the base to the top, are NPI3-NP24 (Martini 1971) and CPII-CPI9a (Okada & bukry 1980). The age of Late Early Eocene to Late Oligocene is suggested for Khangiran section.