Rock types of the Kangan Formation and the effects of pore-filling minerals on reservoir quality in a gas field,Persian Gulf,Iran     

Ali-Akbar Irajian  Kamaladdin Bazargani-Guilani  Rahim Mahari  Ali Solgi  Alireza Moshrefizadeh  Hossein Alnaghian 《Arabian Journal of Geosciences》2017,10(12):272

  相似文献   

Biological assessment of the Zayandeh Rud River, Iran, using benthic macroinvertebrates   总被引：1，自引：0，他引：1  

Mohammad Nemati Varnosfaderany  Esa Ebrahimi  Noorolla Mirghaffary  Alireza Safyanian 《Limnologica》2010,40(3):226-232

Benthic macroinvertebrate communities from the middle of Zayandeh Rud River were analyzed monthly during 1 year at 8 stations, in order to assess changes in their diversity and richness in relation to water quality. Two major groups of sites based on similarity between macroinvertebrate communities were identified by cluster analysis. The performances of the original and revised BMWP score systems were assessed by comparing the community structure indices of benthic macroinvertebrates along with physico-chemical parameters of the water. The biotic indices (BMWP, ASPT, revised BMWP and ASPT) showed better correlation with water quality parameters than that of the richness and diversity indices. The revised ASPT had the highest correlation with water quality parameters. It seems that the application of the revised BMWP score system could be useful for assessment of the water quality in Zayandeh Rud River.  相似文献   

Hydrothermal Alteration, Fluid Inclusion and Stable Isotope Studies of the North Roby Zone, Lac des Iles PGE Mine, Ontario, Canada     

Alireza Karimzadeh Somarin  Stephen A. Kissin    Donald D. Heerema    Daniel J. Bihari 《Resource Geology》2009,59(2):107-120

The Archean mafic–ultramafic complex of Lac des Iles, Ontario, Canada, hosts economic platinum group elements (PGE)-Au-Cu-Ni mineralization in the Roby Zone. All lithologies in the North Roby Zone have been affected by hydrothermal alteration. The alteration products include talc (the most dominant mineral), anthophyllite, serpentine, actinolite, tremolite, chlorite, hornblende, zoisite, clinozoisite, epidote and sericite. In the altered rocks, light rare earth elements (La, Ce, Nd, Sm), Pb, Rb, Ba, Cs, S and possibly Y have been added by hydrothermal solution whereas Eu and heavy rare earth elements (Yb, Gd, Dy, Er) remained immobile. There are five types of fluid inclusions in the pegmatitic plagioclase with homogenization temperature and salinity ranging from 240°C to 445°C and 15.37 to 48.52 wt% equivalent NaCl, respectively. The δ¹⁸O and δD of talc range form 6.2‰ to 6.9‰ and −28‰ to −48‰, respectively. δ¹⁸O and δD water in equilibrium with talc during the hydrothermal alteration suggest a modified source for the hydrothermal solution. Microthermometry and stable isotope studies suggest that high temperature–high salinity fluid was diluted by, and mixed with, low temperature–low salinity meteoric solution. This mechanism precipitated the hydrothermal assemblage and redistributed trace elements during and after pegmatite formation in the North Ruby Zone.  相似文献   

Surface-wave analysis for static corrections in mineral exploration: A case study from central Sweden     

Myrto Papadopoulou  Federico Da Col  Binbin Mi  Emma Bäckström  Paul Marsden  Bojan Brodic  Alireza Malehmir  Laura Valentina Socco 《Geophysical Prospecting》2020,68(1):214-231

In mineral exploration, increased interest towards deeper mineralizations makes seismic methods attractive. One of the critical steps in seismic processing workflows is the static correction, which is applied to correct the effect of the shallow, highly heterogeneous subsurface layers, and improve the imaging of deeper targets. We showed an effective approach to estimate the statics, based on the analysis of surface waves (groundroll) contained in the seismic reflection data, and we applied it to a legacy seismic line acquired at the iron-oxide mining site of Ludvika in Sweden. We applied surface-wave methods that were originally developed for hydrocarbon exploration, modified as a step-by-step workflow to suit the different geologic context of hard-rock sites. The workflow starts with the detection of sharp lateral variations in the subsurface, the existence of which is common at hard-rock sites. Their location is subsequently used, to ensure that the dispersion curves extracted from the data are not affected by strong lateral variations of the subsurface properties. The dispersion curves are picked automatically, windowing the data and applying a wavefield transform. A pseudo-2D time-average S-wave velocity and time-average P-wave velocity profile are obtained directly from the dispersion curves, after inverting only a reference curve. The time-average P-wave velocity profile is then used for the direct estimation of the one-way traveltime, which provides the static corrections. The resulting P-wave statics from the field data were compared with statics computed through conventional P-wave tomography. Their difference was mostly negligible with more than 91% of the estimations being in agreement with the conventional statics, proving the effectiveness of the proposed workflow. The application of the statics obtained from surface waves provided a stacked section comparable with that obtained by applying tomostatics.  相似文献   

Deep reflection seismic imaging of iron-oxide deposits in the Ludvika mining area of central Sweden     

Magdalena Markovic  Georgiana Maries  Alireza Malehmir  Julius von Ketelhodt  Emma Bäckström  Monica Schön  Paul Marsden 《Geophysical Prospecting》2020,68(1):7-23

Reflection seismic data were acquired within two field campaigns in the Blötberget, Ludvika mining area of central Sweden, for deep imaging of iron-oxide mineralization that were known to extend down to 800–850 m depth. The two surveys conducted in years 2015 and 2016, one employing a seismic landstreamer and geophones connected to wireless recorders, and another one using cabled geophones and wireless recorders, aimed to delineate the geometry and depth extent of the iron-oxide mineralization for when mining commences in the area. Even with minimal and conventional processing approaches, the merged datasets provide encouraging information about the depth continuation of the mineralized horizons and the geological setting of the study area. Multiple sets of strong reflections represent a possible continuation of the known deposits that extend approximately 300 m further down-dip than the known 850 m depth obtained from historical drilling. They show excellent correlation in shape and strength with those of the Blötberget deposits. Furthermore, several reflections in the footwall of the known mineralization can potentially be additional resources underlying the known ones. The results from these seismic surveys are encouraging for mineral exploration purposes given the good quality of the final section and fast seismic surveys employing a simple cost-effective and easily available impact-type seismic source.  相似文献   

Intensity measures for the seismic response evaluation of buried steel pipelines under near-field pulse-like ground motions     

Kiani  Alireza  Torabi  Mehdi  Mirhosseini  S. Mohammad 《地震工程与工程振动(英文版)》2019,18(4):917-931

Ground-motion Intensity Measures (IMs) are used to quantify the strength of ground motions and evaluate the response of structures. IMs act as a link between seismic demand and seismic hazard analysis and therefore, have a key role in performance-based earthquake engineering. Many studies have been carried out on the determination of suitable IMs in terms of efficiency, sufficiency and scaling robustness. The majority of these investigations focused on ordinary structures such as buildings and bridges, and only a few were about buried pipelines. In the current study, the optimal IMs for predicting the seismic demand of continuous buried steel pipelines under near-field pulse-like ground motion records is investigated. Incremental dynamic analysis is performed using twenty ground motion records. Using the results of the regression analysis, the optimality of 23 potential IMs are studied. It is concluded that specific energy density (SED) followed by \(\sqrt {VSI[{\omega _1}(PGD + RM{S_d})]} \) are the optimal IMs based on efficiency, sufficiency and scaling robustness for seismic response evaluation of buried pipelines under near-field ground motions.

  相似文献   

b-value and fractal dimension variations in Iran     

Alireza Firoozfar  Bahman Ansari 《地震科学（英文版）》2019,32(2):57-63

Iran sits on a region with a high intrinsic level of seismic activity due to its tectonic setting. Through statistical examination of the earthquakes listed in the catalogue from International Institute of Earthquake Engineering and Seismology (IIEES), this research attempted to calculate some seismicity factors and find correlation between them. A preliminary analysis indicated changes in the b-value of the Gutenberg-Richter relationship over the study region. Thus, the study area was divided into five zones (Alborz, Zagros, Azerbaijan, Central and East) and b-value was computed for each zone. Considering faulting mechanism styles and the b-values in the region, it was found that the lowest b-values belong to the thrust events and strike-slip faulting earthquakes have intermediate values. These findings support previous studies. Furthermore, results of b-value calculation were used for the estimation of accumulated differential stresses (σ₁–σ₂) over each zone. Overall, the b-value for Iran is averagely low which signifies the high stress tectonic regime in this region. Also, by having calculated fractal dimension (D) in each zone, a correlation obtained showing that in Iran region, the b-value correlates to fractal dimension by D = 4.2b–2 relation which does not support Aki's (1981) speculation of D = 3b/c.  相似文献   

Delineation of riparian vegetation from Landsat multi‐temporal imagery using PCA          下载免费PDF全文

Masoomeh Alaibakhsh  Irina Emelyanova  Olga Barron  Neil Sims  Mehdi Khiadani  Alireza Mohyeddin 《水文研究》2017,31(4):800-810

A deficiency in crucial digital data, such as vegetation cover, in remote regions is a challenging issue for water management and planning, especially for areas undergoing rapid development, such as mining in the Pilbara, Western Australia. This is particularly relevant to riparian vegetation, which provides important ecological services and, as such, requires regional protection. The objective of this research was to develop an approach to riparian vegetation mapping at a regional scale using remotely sensed data. The proposed method was based on principal component analysis applied to multi‐temporal Normalized Difference Vegetation Index datasets derived from Landsat TM 5 imagery. To delimit the spatial extent of riparian vegetation, a thresholding method was required and various thresholding algorithms were tested. The accuracy of results was estimated for various Normalized Difference Vegetation Index multi‐temporal datasets using available ground‐truth data. The combination of a 14‐dry‐date dataset and Kittler's thresholding method provided the most accurate delineation of riparian vegetation.  相似文献   

Introduction to the special issue on “Cost-effective and innovative mineral exploration solutions”     

Alireza Malehmir  Musa Manzi  Deyan Draganov  Ute Weckmann  Esben Auken 《Geophysical Prospecting》2020,68(1):3-6

  相似文献   

Geochemical analysis of evaporite sedimentation in the Gachsaran Formation,Zeloi oil field,southwest Iran     

Alireza Bahadori  Emmanuel John M. Carranza  Bahman Soleimani 《Journal of Geochemical Exploration》2011,111(3):97-112

In this study, the paleo-sedimentary depositional environment of the Gachsaran Formation and the Asmari reservoir cap rock (i.e., the stratigraphically lowest member of the Gachsaran Formation) was investigated from elemental geochemical data and mineralogical data obtained XRF and SEM analyses, respectively, of anhydrite samples collected from two oil wells in the Zeloi oil field in southwestern Iran. The present data reveal that arid conditions and cycles of transgression–regression of the sea contributed to the formation of evaporite sequences of the Gachsaran Formation in a coastal sabkha-lagoon basin that was partly closed to the sea. This interpretation was based on synthesis of statistical correlation analysis the geochemical data, chemostratigraphic correlation of geochemical ratios, and textural analysis of salts observed in SEM images.  相似文献