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1.
Sheikh  Vahedberdi  Kornejady  Aiding  Ownegh  Majid 《Natural Hazards》2019,96(3):1335-1365
Natural Hazards - This study is aimed at producing an improved ranking method by coupling the technique for the order of preference by similarity to ideal solution (TOPSIS) and Mahalanobis distance...  相似文献   

2.
The metasedimentary and granitoid rocks of the Soresat Metamorphic Complex occur along the northern margin of the Sanandaj–Sirjan Zone in northwest Iran. Four different deformational events (D1–D4) are recorded in the Soresat Metamorphic Complex. The D1 and D2 progressive deformation events resulted from north-northeast–south-southwest regional horizontal shortening due to the subduction of Neo-Tethys oceanic lithosphere beneath the Sanandaj–Sirjan Zone. Post-suturing convergence between Arabia and Iran, which resulted in a right lateral-reverse displacement along the suture caused the north-northwest–south-southeast horizontal shortening of D3. D4 is recorded by normal faulting. Andalusite, cordierite and sillimanite (fibrolite) record the thermal peak (with a geothermal gradient >30°C/km). Field and microscopic studies of intruded granitoid rocks in the Soresat Metamorphic Complex divide them into three major groups: (i) syn-deformation (syn-D2) granitic gneiss; (ii) late- to post-deformation (late- to post-D2) granites and granodiorites; and (iii) post-deformation (post-D2) alkali granites.  相似文献   

3.
The Khoshk River passes through Shiraz City, southwest Iran. It passes through the populated urban area of Shiraz and receives and carries different kinds of industrial and urban solid and liquid wastes produced by industries and domestic sewage. The obje…  相似文献   

4.
Two native ionizing radiation-resistant bacteria were isolated and identified from a soil sample collected from extreme conditions of the Lout desert in Iran. The hottest land surface temperature has been recorded in the Lout desert from 2004 to 2009. Also, it is categorized as a hyper arid place. Both ionizing radiation and desiccation may cause damage on genome. Soil sample was irradiated in order to eliminate sensitive bacteria then cultured in one-tenth-strength tryptic soy broth medium. Bacterial suspension used for radiation treatment. Morphological and physiological characterization and phylogenetic studies based on 16S rRNA gene sequence were used for identification. The cells were rod shape, non-motile, non-spore forming and gram positive. The 16S rRNA gene sequence showed 99.5 % of similarity to Deinococcus ficus. Phylogenetic dendrogram demonstrated that the isolates branched with D. xibeiensis, D. ficus and D. mumbaiensis. Both isolates were resistant to >15 kGy of gamma radiation and >600 J m2 of UV radiation. This is the first report on radiation resistant bacteria belonging to genus Deinococcus isolated from the Lout desert of Iran.  相似文献   

5.
Cherty marbles of Hasan-Robat area, northwest of Isfahan, in the Sanandaj–Sirjan Zone of Iran preserves evidences of multiple deformational events. The Sanandaj–Sirjan Zone is the inner crystalline zone of the Zagros Orogen, which has been highly deformed and exhumed during continental collision between the Arabian Plate and Central Iran. The Hasan-Robat area is an example of the exposed Precambrian–Paleozoic basement rocks that stretched along two NW–SE-trending faults and located in the inner part of the HasanRobat positive flower strcuture. The Hasan-Robat marbles record a complex shortening and shearing history. This lead to the development of disharmonic ptygmatic folds with vertical to sub-vertical axes and some interference patterns of folding that may have been created from deformations during the Pan-African Orogeny and later phases. Based on this research, tectonic evolution of the Hasan-Robat area is interpreted as the product of three major geotectonic events that have been started after Precambrian to Quaternary: (1) old deformation phases (2) contractional movements and (3) strike-slip movements. Different sets and distributions of joints, faults and folds are confirmed with effect of several deformational stages of the area and formation of the flower structure.  相似文献   

6.
The Chah-Bazargan gabbroic intrusions are located in the south of Sanandaj–Sirjan zone. Precise U–Pb zircon SHRIMP ages of the intrusions show magmatic ages of 170.5 ± 1.9 Ma. These intrusions consist primarily of gabbros, interspersed with lenticular bodies of anorthosite, troctolite, clinopyroxenite, and wehrlite. The lenticular bodies show gradational or sharp boundaries with the gabbros. In the gradational boundaries, gabbros are mineralogically transformed into anorthosites, wehrlites, and/or clinopyroxenites. On the other hand, where the boundaries are sharp, the mineral assemblages change abruptly. There is no obvious deformation in the intrusions. Hence, the changes in mineral compositions are interpreted as the result of crystallization processes, such as fractionation in the magma chamber. Rock types with sharp boundaries show abrupt chemical changes, but the changes exhibit the same patterns of increasing and decreasing elements, especially of rare earth elements, as the gradational boundaries. Therefore, it is possible that all parts of the intrusions were formed from the same parental magma. Parts showing signs of nonequilibrium crystallization, such as cumulate features and sub-solidification, underwent fracturing and were interspersed throughout the magma chamber by late injection pulses or mechanical movements under mush conditions. The geological and age data show that the intrusions were formed from an Al-, Sr-, Fe-enriched and K-, Nb-depleted tholeiitic magma. The magma resulted from the partial melting of a metasomatized spinel demonstrated by negative Nb, P, Hf, and Ti, and positive Ba, Sr, and U anomalies typical of subduction-related magmas.  相似文献   

7.
Abundant and well-preserved assemblages of plant macrofossils occur from the Hojedk Formation at Babhutk, Kerman, Iran. This new locality is the first in the Jurassic of Kerman where the plant material is shown preserved. Eight species of seven genera were identified representing five different gymnosperm groups: Nilssonia cf. undulata, Nilssonia cf. orientalis, Elatides sp., Podozamites sp., and Williamsonia asseretoii and two pteridophyt groups: Equisetites laterale and Coniopteris sp. The collected flora suggests subtropical conditions at the time of deposition of the Hojedk Formation. Based on stratigraphical distributions of the encountered macrofossils, Bajocian–Bathonian age is suggested for the lower and middle unit of the Hojedk Formation. These plant fossils help confirm conclusions from recent geological studies that place the Kerman Basin of Iran during the Jurassic.  相似文献   

8.
Wavelet-based analyses were used in this study to interpret the near-source ground-motion characteristics of records obtained during the 2012 Varzaghan–Ahar double earthquakes in the East-Azerbaijan province of Iran. For this purpose, the large pulse of ground motions was extracted by applying continuous wavelet transforms, and then, the residual motions were achieved by subtraction of extracted pulse from the original motions. Analysis of ground motions illustrated that the records obtained at Varzaghan station could be classified as pulse-like motions with pulse index around 0.9. As well, the acceleration response spectra for horizontal directions were compared with the design response spectrum of Iranian seismic design code (Standard No. 2800). The comparisons showed a relatively large amplification in spectral values due to near-source pulse effects.  相似文献   

9.
Iron oxide–apatite (IOA) deposits, often referred to as Kiruna-type iron ore deposits, are known to have formed from the Proterozoic to the Tertiary. They are commonly associated with calc–alkaline volcanic rocks and regional- to deposit-scale metasomatic alteration. In the Bafq District in east Central Iran, economic iron oxide–apatite deposits occur within felsic volcanic tuffs and volcanosedimentary sequences of Early Cambrian age. In order to constrain the age of formation of these ores and their relationship with the Early Cambrian magmatic event, we have determined the U–Pb apatite age for five occurrences in the Bafq District. In a 206Pb/238U vs. 207Pb/235U diagram, apatite free of or poor in inclusions of other minerals plots along the Concordia between 539 and 527 Ma with four out of five samples from one deposit clustering at the upper end of this range. For this deposit, we interpret this cluster to represent the age of apatite formation, whereas the spread towards younger ages may reflect either minor Pb loss or several events of IOA formation. Apatite with inclusions of monazite (±xenotime) yields disturbed systems with inclusions having developed after formation of the iron ore–apatite deposits, possibly as late as 130–140 Ma ago. Obtained apatite ages confirms that (IOA) and the apatite-rich rocks (apatites) of the Bafq district formed coevally with the Early Cambrian magmatic (-metasomatic) events.  相似文献   

10.
Doklady Earth Sciences - A residual tilt after a teleseismic earthquake is described in this work. The results of static and dynamic modeling of this event fit the measured values. The conditions...  相似文献   

11.
The aims of present study are investigation of endemic plants at Masjed–Daghi area introducing hyperaccumulator and indicator plants for Au, Ag, As, Cu, Mo, Hg, Re, Sb, and Te mineralization and also describe the biogeochemical response pattern over a known Au–Cu mineralized site. The Masjed–Daghi prospecting area is covered by Eocene flysch, andesite, trachyandesite, dacite, rhyodacite, Oligocene agglomerate, and Quaternary deposits. Previous researches reported copper porphyry mineralization and related epithermal gold veins in this area. This study presents that plants with high metal intake enabled us to obtain invaluable information about natural concentrations of chemical elements in the substrate and to recognize new potential areas for mineral prospecting. Stachys inflata has biological absorption coefficient mean exceeding or near hyperaccumulating criterion >1 for most of the elements investigated then could be as a hyperaccumulator. The indicator values belong to S. inflata, Artemisia sp., Salvia sp., Astragalus sp., Peganum harmala, Moltkia coerulea, and Cousinia sp.  相似文献   

12.
The Asmari Formation(a giant hydrocarbon reservoir)is a thick carbonate sequence of the Oligocenee Miocene in the Zagros Basin,southwest of Iran.This formation is exposed at Tang-e-Lendeh in the Fars interior zone with a thickness of 190 m comprising medium and thick to massive bedded carbonates.The age of the Asmari Formation in the study area is the late Oligocene(Chattian)eearly Miocene(Burdigalian).Ten microfacies are defned,characterizing a gradual shallowing upward trend;the related environments are as follows:open marine(MF 8e10),restricted lagoon(MF 6e7),shoal(MF 3e5),lagoon(MF 2),and tidal fat(MF 1).Based on the environmental interpretations,a homoclinal ramp consisting of inner and middle parts prevails.MF 3e7 are characterized by the occurrence of large and small porcelaneous benthic foraminifera representing a shallow-water setting of an inner ramp,infuenced by wave and tidal processes.MF 8e10,with large particles of coral and algae,represent a deeper fair weather wave base of a middle ramp setting.  相似文献   

13.
The OligoceneeMiocene Qom Formation has different depositional models in the Central Iran,SanandajeSirjan and Urumieh-Dokhtar magmatic arc provinces in Iran.The Kahak section of the Qom Formation in the Urumieh-Dokhtar magmatic arc has been studied,in order to determinate its microfacies,depositional model and sequence stratigraphy.The textural analysis and faunal assemblages reveal ten microfacies.These microfacies are indicative of five depositional settings of open marine,patch reef,lagoon,tidal flat and beach of the inner and middle ramp.On the basis of the vertical succession architecture of depositional system tracts,four third-order sequences have been recognized in the OligoceneeMiocene Kahak succession of Qom Formation.Based on the correlation charts,the transgression of the Qom Sea started from the southeast and continued gradually towards the north.This resulted in widespread northward development of the lagoon paleoenvironment in the Aquitanian-Burdigalian stages.Also,the sequence stratigraphic model of the OligoceneeMiocene Qom Formation has an architecture similar to those that have developed from OligoceneeMiocene global sea level changes.  相似文献   

14.
《地质学报》1932,11(2):101-105
In opening the meeting, the chairman made the following address: "It is my agreable duty to announce and make the award of the Grabau Medal to two members of our Society, Drs. J. S. Lee and Davidson Black. "The Grabau Medal was founded in 1925 by Mr. C. Y. Wang. the then President of the Geological Society. It was so named in honor of Dr. Grabau  相似文献   

15.
This study concentrates on the petrological and geochemical investigation of mafic rocks embedded within the voluminous Triassic June Complex of the central Sanandaj–Sirjan zone (Iran), which are crucial to reconstruct the geodynamics of the Neotethyan passive margin. The Triassic mafic rocks are alkaline to sub-alkaline basalts, containing 43.36–49.09 wt% SiO2, 5.19–20.61 wt% MgO and 0.66–4.59 wt% total alkalis. Based on MgO concentrations, the mafic rocks fall into two groups: cumulates (Mg# = 51.61–58.94) and isotropic basaltic liquids (Mg# = 24.54–42.66). In all samples, the chondrite-normalized REE patterns show enrichment of light REEs with variable (La/Yb)N ratios ranging from 2.48 to 9.00, which confirm their amalgamated OIB-like and E-MORB-like signatures. Enrichment in large-ion lithophile elements and depletion in high field strength elements (HFSE) relative to the primitive mantle further support this interpretation. No samples point to crustal contamination, all having undergone fractionation of olivine + clinopyroxene + plagioclase. Nevertheless, elemental data suggest that the substantial variations in (La/Sm)PM and Zr/Nb ratios can be explained by variable degrees of partial melting rather than fractional crystallization from a common parental magma. The high (Nb/Yb)PM ratio in the alkaline mafic rocks points to the mixing of magmas from enriched and depleted mantle sources. Abundant OIB alkaline basalts and rare E-MORB appear to be linked to the drifting stage on the northern passive margin of the Neotethys Ocean.  相似文献   

16.
In southern Iran’s Gareh Bygone Plain, water-supply qanats in four mixed farming communities were desiccated by over-pumping of illegal dug wells throughout the area. Emergency situations developed, resulting in city-ward migration. Since 1983, 193 million m3 of water has been supplied to those communities by floodwater spreading (FWS) to facilitate spate irrigation of sandy rangeland (2,034 ha) and artificial recharge of groundwater (ARG), of which 76 % has recharged the aquifer. This resulted in a reverse migration of the population. The irrigated area in the 2010–2011 growing season increased 13.2 fold when compared to the pre-FWS period, and year-round forage for about 700 sheep has been provided since 1991. The ARG is a logical alternative to building large dams in Iran; 420,000 km2 of coarse-grained alluvium provides capacity to store 5,000 km3 of water, representing more than ten times the annual precipitation of the whole country. As the equivalent cost for building dams to accommodate that volume is estimated at US$12.5?×?1012, the potential value of the alluvium may be realized. ARG on the recharge areas of 33,000 of the desiccated qanats eventually could rejuvenate them. As agricultural commodities absorb 19 % of the monetary value of Iran’s imports, and ARG activities could supply the water to produce them, alluvium is even more valuable than oil, which provides foreign exchange. More importantly, ARG on 140,000 km2 of the alluvium could strengthen the capacity to adapt to droughts and reduce the number and impact of water-related emergency situations.  相似文献   

17.
The Ching-dar syncline is located to the west of the city of Birjand, in the east of han. The ca. 500 m thick studied section at the eastern flank of the syncline contains a sequence of almost continuous shallow- marine limestones that exhibit no major sedimentary breaks or evidence for volcanic activity. Skeletal grains consist of large benthic foraminifera and green algae whereas non-skeletal grains are mostly peloids and intraclasts. They were deposited on a shallow-marine carbonate ramp. The limestones have undergone extensive diagenetic processes with varying intensities, the most important of which are micritization, cementation, compaction （chemical and mechanical）, internal filling and stylolitization. Chemical analysis of the limestone samples revealed high calcium and low magnesium content. Major and minor element values were used to determine the original carbonate mineralogy of these lime- stones. Petrographic evidence and elemental values indicate that calcite was the original carbonate mineral in the limestones of the Ching-dar syncline. The elemental composition of the Ching-dar car- bonates also demonstrates that they have stabilized in a meteoric phreatic environment. Variation of Sr/ Ca vs. Mn values suggests that diagenetic alteration occurred in an open geochemical system.  相似文献   

18.
Basic volcanic rocks from Tafresh, west Kashan, and west Nain volcanic successions in the central part of Urumieh-Dokhtar Magmatic Assemblage (UDMA) of Iran yield K–Ar ages ranging from 26.8 to 18.2 Ma. These ages indicate significant Late Oligocene–Early Miocene basic volcanism in the UDMA. These ages, combined with K–Ar ages of 26.0 and 14.1 Ma, respectively, for associated low-silica and high-silica adakites, help constrain reconstructions of the UDMA geodynamic evolution. Late Oligocene–Early Miocene slab roll-back associated with an asthenospheric mantle influx are suggested as the major processes responsible for concurrent volcanism showing Nb–Ta-depleted, Nb–Ta-enriched and low-silica adakite signatures. Slab roll-back, the likely consequence of a decrease in subduction velocity, led to partial melting of the subducted slab and produced Early–Middle Miocene high-silica (dacitic) adakites. Oligocene to Miocene volcanic rocks do not conform to the Oligocene continental collisional model for the UDMA, rather they suggest a decrease in the subduction rate that prompted the asthenospheric mantle influx.  相似文献   

19.
Following the recommendation of the International Commission on Stratigraphy (16 votes Yes [94%], 1 abstention, 2 votes not received), the Global boundary Stratotype Section and Point (GSSP) for the base of the Turonian Stage of the Cretaceous System is defined as the base of bed 86 of the Bridge Creek Limestone Member of the Greenhorn Limestone Formation at the western end of the Denver and Rio Grande Railroad cut near the north boundary of the Pueblo Reservoir State Park Recreation Area, west of Pueblo, Colorado, USA. This GSSP horizon is also exposed and protected in the adjacent state recreation area. It coincides with the first occurrence of the ammonite Watinoceras devonense, is in the middle of a global positive excursion in Carbon-13 isotopes, and is bracketed by widespread bentonites that have yield edages of 93 to 93.5 Ma.  相似文献   

20.
International Journal of Earth Sciences - The presence of the Bashkirian–Moscovian (lower Pennsylvanian) sequence with mixed siliciclastics and fossil-rich carbonates has long been known from...  相似文献   

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