Search Result

145

Results Found

Relevance

Filter

Newest

Filter

Most Viewed

Filter

Most Downloaded

Filter

Most Cited

Filter

Pages Count

15

Go To Page

Search Results/Filters    

Filters

Year

Banks


Expert Group






Full-Text


مرکز اطلاعات علمی SID1
اسکوپوس
مرکز اطلاعات علمی SID
ریسرچگیت
strs
Author(s): 

NOUHEGAR A. | HSSAINZADE M.M.

Journal: 

DESERT (BIABAN)

Issue Info: 
  • Year: 

    2004
  • Volume: 

    9
  • Issue: 

    2
  • Pages: 

    155-168
Measures: 
  • Citations: 

    0
  • Views: 

    1581
  • Downloads: 

    327
Abstract: 

In this present essay, exploitation study of underground water in Minab Deltan has been taken into consideration in physical, geotechnic and GEOPHYSICS studies format. Under study area is drainage basis of Minab Dam with an area of 800 square meters. Type of aquifers are selected in accordance with their type of electrical resistance and determination for quality and quantity of underground water tables in Minab.It should be mentioned that, penetration velocity of water is high in entrance area of Minab river to delta due to physical features and grading position of sediment inside water and then with regard to fine aggregate of sediment in lower area of delta, such a rate little by little decrease and fixed in a gravity force.As a result" with regard to this point that water flow in soil is due to change in soil and structure of land texture, then should bear in mind that method of use from utilization of underground water throughout delta is not equal from view point of quantity and quality in such a way that the best water with regard to measurement of EC (Electric conductivity) and TDS (total disolvs solids) is in river inlet to Minab delta and the most hardness is relating to end area of delta.We faced with some limitation regarding utilization of underground water in accordance with performed GEOPHYSICS and geotechnics studies performed in northeast area.In southwest of the City of Minab, west direction of Minab city to Hormoz -Strait coast and southwest of the said mentioned delta, we have fine aggregate alluvium basis in such a way that, we faced with limit in possibilities of providing underground waters table.The top quality of Minab Delta underground waters is in distance between Minab bridge to Gourzang village due to having coarse aggregate and highest underground quality have considerable importance for taking into consideration.

Yearly Impact:

View 1581

Download 327 Citation 0 Refrence 3
Issue Info: 
  • Year: 

    2006
  • Volume: 

    32
  • Issue: 

    2
  • Pages: 

    23-30
Measures: 
  • Citations: 

    0
  • Views: 

    734
  • Downloads: 

    118
Abstract: 

Trend surface analysis is a type of multiple regressions where point coordinates are independent variables and grade or thickness and ... can be dependent variables. In this method, we fit a suitable surface to major values. In this paper, we applied trend surface analysis to airborne geophysical data sets including the magnetic field intensity, resistivity (frequency=4600 Hz) and radioactivity (potassium counting). Results show the trend of these factors and their relations. Magnetic field intensity and resistivity have a similar trend despite the trend of Potassium counting. Finally, the ability of this method in interpreting the same data has been acknowledged.

Yearly Impact:

View 734

Download 118 Citation 0 Refrence 0
Author(s): 

ASADI M. | GHADERI SOHI A.

Issue Info: 
  • Year: 

    2015
  • Volume: 

    41
  • Issue: 

    1
  • Pages: 

    147-166
Measures: 
  • Citations: 

    1
  • Views: 

    778
  • Downloads: 

    335
Abstract: 

Identifying and measuring the impact and value of scientific output plays an important role in today’s world of information overload. On one side, governments are trying to distribute research funds in ways that support research in strategically important fields, on the other side, researchers and scientists are seeking to access only relevant and quality information that have mainly worthy of their attention. Nowadays, countries are evaluated not only by their national products, military power, geographical area, etc., but also by such factors as the production and consumption of scientific information. Scientometric approaches are used to provide appropriate tools for evaluating scientific products at local, national, and international levels. These tools have a number of advantages, including identifying core and significant journals, authors, institutions, universities, and papers; navigating thoughts and developing literature and resources; anticipating scientific products trend; visualizing different subject fields and determining the most important subjects; identifying collaboration and co-authorship patterns; comparing courtiers based on scholarly publications etc. Regarding to the above-mentioned tools it seems that citation indexes and databases such as Scopus database are suitable tools, which can measure scientific products in all the fields. Scientific products of GEOPHYSICS, the same as other fields constitute a part of the Iran's scientific output. The purpose of this study is better to understand the scientific production of GEOPHYSICS and to present a scientific map. This study is a descriptive approach using scientometric methods. The population of this research comprises of 1996 documents indexed in Scopus database. Network workbench tool (NWB) software was used for mapping and other data were extracted manually. The results showed that the published papers of Iranian researchers in the field of GEOPHYSICS showed a good trend in period of 1975-2013. The contributaion of Iran in the GEOPHYSICS outputs constituted 0.65% of total publications and ranked 30 in the world during 39 years. Riahi from Tehran University and Ataei from Shahrood University were the most productive authors in the field of GEOPHYSICS. Tehran University and Islamic Azad University accounted for most products in GEOPHYSICS. Most of articles were published in the Journal of the Earth and Space Physics released by the Institute of GEOPHYSICS, University of Tehran, Journal of GEOPHYSICS and Engineering, Geophysical Journal International, and Journal of Asian Earth Sciences. A writing pattern of three and more authors had the highest frequency. Results indicated that the level of productivity for single author or one-author products is stagnating and the number of publications with two and three or more authors is increasing sharply. Fifty-nine countries had the most academic collaboration with Iranian researchers in GEOPHYSICS field. Iran has collaborated more often with USA, England, and France. The international cooperation is much lower than the national cooperation. From 1996 articles were extracted 5304 subjects and Iran, Zagros, Artificial Neural Network, Fuzzy logic, Tehran, Inversion, Seismic attributes, Simulation, Resistivity, and Earthquake were the most important topics in the field of GEOPHYSICS. In addition, it was found that most papers in the field of GEOPHYSICS were in geophysical observation, instrumentation, and techniques.

Yearly Impact:

View 778

Download 335 Citation 1 Refrence 0
گارگاه ها آموزشی
Author(s): 

LOTFI M. | Arefi H. | BAHROUDI A.

Issue Info: 
  • Year: 

    2020
  • Volume: 

    11
  • Issue: 

    2
  • Pages: 

    405-417
Measures: 
  • Citations: 

    0
  • Views: 

    14144
  • Downloads: 

    12434
Abstract: 

Hyperspectral remote sensing records reflectance or emittance data in a large sum of contiguous and narrow spectral bands, and thus has many information in detecting and mapping the mineral zones. On the other hand, the geological and geophysical data gives us some other fruitful information about the physical characteristics of soil and minerals that have been recorded from the surface. The Sarcheshmeh mining area located in the NW-trending Uromieh-Dokhtar magmatic belt within Central Iran is mainly of porphyry type, and is associated with extensive hydrothermal alterations. Due to the semi-arid type of climate with abundant rock exposure, this area is suitable for application of remote sensing techniques. In this work, we focus on generating the alteration maps around Cu porphyry copper deposits using the spectral angle mapper algorithm on Hyperion data by applying two filters named reduction to pole and analytical signal on a total magnetic intensity map and generating the Kd map from radiometry data. What is clear is the high importance of applying the adequate pre-processing on Hyperion data because of low signal-to-noise ratio. By comparing the known deposits in the region with the results obtained by applying the mentioned methods, it is revealed that not all the higher K radiometric values are entirely associated with the hydrothermal alteration zones, and in contrast, the potassic alteration map extracted from Hyperion imagery successfully corresponds to the alteration zones around the Sarcheshmeh mining area. Finally, the results particularly obtained from processing the Hyperion data are confirmed by indices of Cu porphyry deposits in the region.

Yearly Impact:

View 14144

Download 12434 Citation 0 Refrence 0
Issue Info: 
  • Year: 

    2007
  • Volume: 

    33
  • Issue: 

    42
  • Pages: 

    63-74
Measures: 
  • Citations: 

    0
  • Views: 

    963
  • Downloads: 

    333
Abstract: 

In this survey, the surface ozone measurements and meteorological parameters in the vicinity of synoptic station of GEOPHYSICS Institute (Tehran University) have been analyzed for a period from Jan to Nov 2002. The hourly averaged pattern of surface ozone shows that the ozone concentration is high in the afternoon as expected as a result of photochemical processes in urban environment and it also varies by local advection due to the local orography. Comparison between wind intensity and the surface ozone shows that, during the day, the advection of polluted air by anabatic wind which blows towards the station increases its intensity. Also a smaller secondary peak in the summer afternoons is due to change in wind regime, from anabatic to Katabatic. This is particularly in summer months especially for June. The main peak in daily ozone concentration also becomes weaker in other seasons due to slowing down of the photochemical processes. The monthly averaged ozone shows that, the main ozone peak has occurred in March (typically 64.4 ppbv) and the second peak in August (typically 49.5 ppbv). The comparison of the monthly averaged of total ozone (measured by Dobson photo-spectrometer) with the surface ozone shows that the main cause of the large peak in March, is due to the increasing of the total ozone and the transport of ozone from stratosphere to troposphere while the main cause of second peak in August is photochemical processes.

Yearly Impact:

View 963

Download 333 Citation 0 Refrence 0
Issue Info: 
  • Year: 

    2013
  • Volume: 

    7
  • Issue: 

    2
  • Pages: 

    128-141
Measures: 
  • Citations: 

    0
  • Views: 

    521
  • Downloads: 

    201
Abstract: 

Atmospheric visibility is an important parameter that can affect human activities as well as being a good indicator of the air pollution condition in urban areas. Hence its monitoring is important for urban such areas as Tehran which often suffer from acute air pollution episodes. Atmospheric visibility is closely related to the meteorological conditions determined by local and regional factors such as topography, latitude, closeness to water body, etc.In this study, the atmospheric visibility for the years 2001-2011 at the Institute of GEOPHYSICS, Tehran, including the effects of meteorological conditions such as rain, fog and suspended dust on its variations were considered. The visibility and meteorological data were obtained from Meteorology Organization of Iran and the air pollution data are acquired from the air quality company of the municipalily of Tehran. In this ten-year period, the mean annual visibility of this city was about 8.7 km while the seasonal visibilities for spring, summer, autumn, and winter were 9.2, 9.7, 9.1, and 6.7 km, respectively. The largest visibility occured in August (9.9 km) while the least one occured in December (5.7 km). On the whole, the visibility was affected by rain, fog and dust from which dust was more effective in reducing the visibility especially in winters in which its frequent value was less than 3 km, and is less than the other periods. Also in the cold season, the average visibility for relative humidities less than 60 percent increased from 1 to 2 km. The average annual PM10 concentration for the years 2007-2009, for which the whole data were available, was 68.9 mg/m3, with its maximum for August and December.The relationship between the visibilities and some other air pollution and meteorological factors were also considered. The largest negative correlation between the PM10 concentration and the visibility occured in spring and summer. This was due to the fact that the moisture content of air in this period was more than that of the rest of the year in this area. Moisture usually contributes to the formation of very fine urban aerosols and also makes larger aerosols known as haze.City of Tehran is in the vicinity of a high mountain range that induces a very marked local circulation. This circulation is particularly marked in this area which is often away from active mid-latitude storm tracks leading to calm conditions. This study showed that as the daily wind turns from northerly katabatic to southerly anabatic during the morning transition, the visibility deteriorates due to the movement of the more polluted air over the station.This study also showed that poor visibilities less than 3 km often occured with high concentrations of PM10 in calm conditions over the city in which urban aerosols dominate especially in winter, or when strong dusty winds prevail.

Yearly Impact:

View 521

Download 201 Citation 0 Refrence 0
strs
Author(s): 

ABDI M. | KARIMPOUR M.H.

Issue Info: 
  • Year: 

    2012
  • Volume: 

    4
  • Issue: 

    1
  • Pages: 

    77-107
Measures: 
  • Citations: 

    0
  • Views: 

    942
  • Downloads: 

    416
Abstract: 

The Kuh Shah prospecting area is located in Tertiary volcano-plutonic belt of the Lut Block. More than seventeen sub volcanic intermediate to acidic intrusive rocks, diorite to syenite in composition, were identified in the study area. The intrusions are related to hydrothermal alteration zones and contain argillic, propylitic, advanced argillic, silicified, quartz-sericite-pyrite, gossan and hydrothermal breccia which overprinted to each other and are accompanied by weathering which made it complicated to distinguish zoning. Mineralization is observed as sulfide (pyrite and rare chalcopyrite), disseminated Fe-oxides and quartz-Fe-oxide stock work veinlets. Intrusive rocks are met aluminous, calc-alkaline with shoshonitic affinity with high values of magnetic susceptibility. The Kuh Shah intrusive rocks are classified as magnetite-series of oxidant I-type granitoids. Based on zircon U–Pb age dating, the age of these granitoid rocks is 39.7±0.7 Ma (Middle Eocene). The radioisotope data (initial 87Sr/86Sr and 143Nd/144Nd ratios as well as eNd) and geochemical data suggest that the Kuh Shah granitoid rocks formed from depleted mantle in a subductionrelated magmatic arc setting. Geochemical anomalies of elements such as Cu, Au, Fe, Pb, Zn, As, Sb, Mo, Bi, Hg and also Mn, Ba, Te and Se, correlated with quartz-sericite-pyrite, gossan-stock work-hydrothermal breccias, irregular silicified bodies and advanced argillic hydrothermal alteration zones. Geophysical anomalies correlated with hydrothermal alteration and mineralization zones. The interpretation of the results represents complex patterns of sub-circular to ellipsoid shape with north-east to south-west direction. These evidences are similar to the other for known Cu-Au porphyry and Au-epithermal systems in Iran and worldwide.

Yearly Impact:

View 942

Download 416 Citation 0 Refrence 1
Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2015
  • Volume: 

    24
  • Issue: 

    94 (PETROLOGY & MINERALOGY)
  • Pages: 

    253-262
Measures: 
  • Citations: 

    0
  • Views: 

    834
  • Downloads: 

    242
Abstract: 

The studied area is located in east of Bajestan Township, Khorasan Razavi Province 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.

Yearly Impact:

View 834

Download 242 Citation 0 Refrence 0
Issue Info: 
  • Year: 

    2019
  • Volume: 

    8
  • Issue: 

    4 (30)
  • Pages: 

    66-76
Measures: 
  • Citations: 

    0
  • Views: 

    274
  • Downloads: 

    192
Abstract: 

1-Introduction Pb mineralization in Horeh area is located in 25 km northeast of Shahrekord, the middle part of Sanandaj-Sirjan zone in the mineralization belt of Malayer-Isfahan, in the geology map of 1/100000 of Chadgan (Ghasemi et al., 2005). There are nine mineralization belts, and 120 index mineralization of Pb-Zn has been identified based on paragenesis of mineralogy, time and type of mineralization in the Sanandaj-Sirjan zone. The Malayer-Isfahan mineralization belt is in the middle part of the Sanandaj-Sirjan zone, which formed in Mesozoic in carbonate sequences along with deep faults (Shahabpour, 1385). Often, this type mineralization is similar to Mississippi Valley-type (MVT) Pb-Zn deposits that many of these deposits have been created simultaneously with orogeny so that topographic slope is an essential factor in the ore fluids displacement (Leach et al., 2005, 2003, 2001; Appold and Gruven, 1999). The lithostratigraphy units in Horeh area include dolomite and limestone Permian, conglomerate, sandstone and shale Jurassic, limestone cretaceous, low grade metamorphic and young alluvium. The primary trend of the structure of the Hore Pb mineralization is NW-SE as same as the trend of the Sanandaj-Sirjan zone and the Zagros fault. This paper aims to identify the geological, geochemical and petrogenesis of the Pb mineralization on the base of the mineralogy, geochemistry, GEOPHYSICS and fluid inclusion data. 2-Methodology There are taken 35 samples and the number of 10thin section and 5 polished sections were prepared and studied in order to petrography and mineralogy. Major oxides (XRF method) elements were analyzed for 5 samples. 3 samples (calcite) were selected for Fluid inclusion study by linkam THMS-600 in Isfahan University. Data GEOPHYSICS was taken by IPRSw-888 set and was measured Rs, Ip, Sp. 3-Result and discussion Horeh Pb Mineralization occurred as lens and veins with a thickness of several centimeters to several meters in sedimentary rocks, with slopes and stretches of NW-SE and angle of 45° . This deposit is sulfide-type consists of galena, pyrite, and chalcopyrite as the primary ore and malachite, calcite and iron oxides as gangue. There are observed galen as fine-coarse grain, euhedral to xenomorph with triangular cleavage cavities, pyrite, and chalcopyrite as finely-coarse-grain, calcite as open space filling and comb texture, and veins in other rocks. Malachite often is formed by oxidation of the pyrite and chalcopyrite. Also, there are goethite, hematite, magnetite, illite, dolomite, and quartz. The mineralogical paragenesis sequence in Horeh area is two stages: the initial phase of the reduction that caused to deposit the sulfide minerals such as galena, and the second phase of the oxidation, which led to the formation of oxides and hydroxides minerals by initial carbonate and silicate minerals. Based on geochemical data, SiO2 =38. 31% indicates to low maturity of sedimentary rocks compared to the upper crust (Taylor and McLennan, 1985; SiO2 = 64. 8%). The high mean value of CaO = 25. 22% (upper crustal crust = 4. 19%) indicates to high amounts of carbonate cement, which cause to decrease of the relative amounts of SiO2 and Al2O3 in the samples. Al2O3 amounts are due to the clay and mica and Al-rich mineralogy, especially illite (Elsass et al., 1997). Fluid inclusion data of mineral calcite indicate to the two-phase of the fluid include (L + V) with irregular shapes in the size of 4 to 10 μ m, and 136. 6 ° C average homogeneity,-14. 5° to-20° ice melting and 20. 15% average salinity ( weight equivalent to NaCl)( Bodnar, 1993). The result of fluid inclusion indicates to the basinal brines that is similar to the Pb deposits of the Mississippi Valley type. Geophysical investigations identified 4 Pb anomalies in the region, which begins at depths of 10 m and extends along NS and steep slope toward the west to the depth of 50 m by measure chargeability (PI), electrical resistivity (RS) and metal coefficient map (FM). 4-Conclusion The Pb mineralization in the Horeh area is as Galena with chalcopyrite and pyrite. Based on field study and petrography data, Galena is the main mineral and carbonate, and silicate minerals are gangue. Pb Mineralization has occurred as the replacement, bedding and tangential in the Jurassic formations by basin brine fluid. The combinations of field study and mineralogy, geochemical and geophysical data indicated to the similarity Pb deposit of the Horeh to the Mississippi type that was formed during the two-stage reduction and oxidation. Geophysical data were indicated to the, 4 Pb anomalies from 10 m the topography level with 50m thick with the steep slope to the west.

Yearly Impact:

View 274

Download 192 Citation 0 Refrence 0
Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2020
  • Volume: 

    29
  • Issue: 

    114
  • Pages: 

    3-14
Measures: 
  • Citations: 

    0
  • Views: 

    333
  • Downloads: 

    192
Abstract: 

The Kuh-Baba iron ore deposit is located in ~70 km south of Hashtroud, East-Azarbaidjan province, NW Iran. The lithologic units cropped out around this deposit include Oligo-Miocene volcanic-sedimentary rocks, Pliocene intrusive rocks, and Pliocene dacitic domes. The principal host rocks for the Fe mineralization include units of gabbro-norite, pyroxene hornblende gabbro-norite, and monzo-diorite. Remote sensing investigations (using Sentinel satellite images) display the presence of lineaments, NE-SW trending fault structures, and various alteration zones. The dominant hydrothermal alteration in inner parts of the deposit is mainly propylitic (epidote, chlorite, sericite) which gradually changes to argillic outward toward the peripheral parts. Based upon field relations and microscopic examinations, the ores show massive, vein/veinlet, brecciated, and disseminated textures. In the propylitic zone, magnetite is accompanied by epidote and actinolite. The geochemical studies revealed that the FeT content in the diamond drill core samples varies from 3. 85 wt% to 63. 2 wt%. Ground magnetic survey was conducted in the area and also, the maps of total magnetic field, reduced to pole magnetic, analytic signal, first vertical derivative, and upward continuation were prepared in an attempt to identify the potential deep and shallow subsurface mineralized zones. The obtained results show that two anomalies, one in the north and the other in the central parts of the study area, were recognized which almost correspond with the location of the intrusive bodies.

Yearly Impact:

View 333

Download 192 Citation 0 Refrence 0
litScript