مجله یافته های نوین زمین شناسی کاربردی
پیاپی 26 (پاییز و زمستان 1398)

The study of weathering is important in terms of predicting rock behavior against weathering factors and its suitability for borrow material. The first step to surveying weathering is, to provide a appropriate method for classification. In this study, the changes caused by weathering calcareous slate in laboratory condition(salt crystallization, freezing-melting, wetting-drying, cooling-heating(, and also atmospheric conditions (for one year) were analyzed (about 1000 samples). These traces are mostly exfoliate,decoloration of pyrite-magnetite, the effects of iron rust, and edges corrosion. The intensity of these changes in the weathering test has resulted in more tolerance than other tests. In addition to the effect on the engineering behavior of stones, pyrite oxidation also has an adverse effect on the appearance of stone materials. Hence, pyrite-magnetite in calcareous slate, particularly in terms of shape and appearance changes caused by weathering were evaluated and classified. These crystals are categorized mainly into three gravel-cubic, mass and dendritic types, and classified according to the weathering grade to P1 to P5 (without weathering to fully weathered). Finally, we have reviewed geotechnical problems caused by weathering of pyrites.

There are several important deposits such as Kader, Iju, Godekolvari, Serenu and chahfiroozeh that are occurs in the Kerman Cenozoic Magmatic Belt (KCMB). The hydrothermal alterations usually are detected using remote sensing techniques to map porphyry copper deposits. This research used three ASTER images and applied band ratio, principal component analysis, crosta and composite images techniques to discriminate phylic, argillic and propylitic alteration zones. The present study investigated recent researches and introduced the best spectral bands for determining the alteration zones. The results showed that the spectral signature of kaolinite and sericite is the same and it is not easy to differentiate between phylic and argilic zones. But the used methods has an ability to discriminate partially propylitic alteration zone. Finally, crosta technique using bands 5, 6 and 7 presented the best classification for phylic and argilic alteration zones and composite image with RGB = (PC2, PC3, -PC4) detected the propylitic alteration zone.

For improvement and stabilization of problematic soils in terms of geotechnical properties, it should be required to use proper materials. Therefore, tire chips is as new option can be suggested. On the other side, disposing of waste tire is one of the environmental problems. In present study, improving bearing capacity of kaolinite clay soil with using granule particle of tire waste (with aim of reducing environmental pollutants) based on laboratory tests have been investigated. Waste tire Granule particles in 1, 3 and 5 mm diameters and 2.5, 5, 7.5 and 10 percentage were mixed with clay. For evaluating geotechnical properties of stabilized clayey soil, compaction, uniaxial, direct shear and permeability tests were performed. Results of this study showed that, optimum of particle size and waste tire particle content are respectively 1 mm and 2.5 percentage (by weight). So that, in this values minimum void ratio significantly decreased in improved specimens. Consequently, bearing capacity and compressibility were growth. Also, with adding waste tire granule particle by a size larger than 1 mm and more 2.5 % content in improved soil, permeability went up.

Accurate determination of geo-mechanical properties of rocks such as uniaxial compressive strength (UCS) and modulus of elasticity (E) using standard laboratory tests is a difficult, expensive and time consuming task. This is particularly true for anisotropic, thinly bedded, highly fractured, porous and weak rocks. In order to overcome these difficulties, the development of predictive models for the estimation of these properties seems to be essential in rock engineering projects. The main purpose of this study is prediction of UCS and E of sandstones using artificial neural network (ANN) and multiple regression analysis (MLR). For this, a database of laboratory tests (including 130 sandstone samples) was prepared, which includes porosity, P-wave velocity, dry density, slake durability index, and water absorption as input parameters and UCS and E as output parameter. The performance of the MLR and ANN models are evaluated by comparing statistic parameters, including correlation coefficient (r), root mean square error (RMSE), and variance account for (VAF). Comparison of the multiple linear regressions and ANNs results indicated that respective ANN models were more acceptable for predicting UCS and E than the other.

The content of sulfur in iron ore concentrate is the major problem of steel making industries. In this regard, the reverse flotation operation is used to reduce the amount of sulfur of the final concnetrate. Recently, the substitution of mechanical flotation cells with flotation columns for the sake of impurities removal has been highly taken into consideration. The purpose of this study is comparing the performance of mechanical and column cells in desulphurization of Gole Gohar iron ore complex magnetic separators concentrate. Using column flotation in an optimal condition led to the remarkable reduction of sulfur so that the final concentrate with the sulfur grade lower than 0.1 % and iron recovery over 98% was obtained. The results comparison of column and mechanical flotation have showed that the column cell outperformed the metallurgical performance for producing iron concentrate consisting of low sulfur content. Sulfur separation efficiency in column flotation was almost 7% higher than that of the mechanical cells, meanwile, the wasting rate of non- pyrit iron in column flotation is less than that of the mechanical cells.

The study of petrological findings and geochemical data of mafic and ultramafic rocks and related petrographic units in the ophiolites can be an introduction to environmental geology studies, agriculture and natural resources. Regarding the urban and rural areas of Nain to Ashin in the vicinity of ophiolitic zone (Central Iran), geochemical investigations of mafic and ultramafic rocks of these ophiolites have very important applications in the field of environmental geology of these areas. Therefore, available geochemical data of basic rocks (pillow lavas and basalts), metabasic rocks (amphibolites) and metamorphosed and altered peridotites are considered based on environmental factors. For examples, in the peridotites which are one of the most abundant rock units in these ophiolites, the enrichment factor (Ef) for Ni is extremely high, for Cr is very high, and for Co is high. In addition, the geo-accumulation index or Igeo for Ni (~4) and Ni (>5) in peridotites is heavily to extremely high. therefore, high Ef and Igeo factors of the studied heavy metals (e.g., chrome, nickel, cobalt, arsenic, vanadium) and asbestose minerals (hornblende, tremolite, talc and chrysotile) in the mafic and ultramafic rocks of Ophiolites can be known as some dangerous environmental pollutants. Thus, investigatation of the volume of such elements penetrated into the surface and underground waters and soils in the villages and cities at the foot of these ophiolites could be a theme for ongoing studies in environmental geology of these areas.

At the structural of Sanandaj - Sirjan, Zone of Iran (Kurdistan providence) Kuh-Siyah and Tahmoures young volcanic rocks are exposed. The main phenocrystals of these rocks consist of olivine and clinopyroxene. These metaluminous rocks are combinations of trachy basalt, basalt to havaiite have shoshonitic to alkaline affinities. Based on geochemical studies, the partial melting of a garnet - spinel Lherzolitic source was responsible for the magma generation. The basic rocks, have LILE enrichment and low content of HFSE. Enrichment of LREE can influence magmatic evolution (High depth and low partial melting degree) and tectonic setting of the formation of rocks, attributed. Significant depletion of HREE could be as a result of residue of the mineral garnet phase in the liquid production process. The studied alkali-basalts have all the high Nb basalts signatures such as Nb>18 ppm, Sr/Y>25, La/Yb>14, low Rb/Sr and Yb. Hence these are high Nb basalts, but isotopic investigations are required to confirm it.

Land subsidence is one of natural hazards which is involved with most of plains in Iran and leads to damages of urban area, roads, bridges, power transmission lines, agriculture lands, wells and piezometers. Generally, regional subsidence is depended to human activities such as overexploitation of groundwater and geological conditions which can induce considerable damages to economical basis of the area if it be occurred. In the last few decades, the rapid development of agriculture and the increase in the need for water has led to overexploitation of groundwater in the Semnan plain. In this paper, the occurrences pattern of regional subsidence phenomenon in the south and south-east of the Semnan plain and also the zoning of this region in terms of the susceptibly of land subsidence have been discussed. In this research at the first step data of 18 piezometers for 24 years period (May 1993-2017) were used to provide iso-potential lines of drawdown groundwater level and unite hydrograph of the plain. Furthermore, for the determination of type and thickness of the subsurface layers some data including piezoelectric log, geoelectric studies and geological map with a scale of 1: 250,000 were used. Then, using the drawdown groundwater level map and the subsurface layers conditions map, a subsidence susceptibility map of the Semnan plain was prepared. The results showed that during the period of 1993-2018 continuous overexploitation of groundwater caused a drop of 18.9 meters of groundwater level and provided conditions for consolidation of clayey layers and land subsidence. The subsidence hazard zonation map indicates that the region with a high potential of subsidence in this plain is located in the northeastern part of the plain and in the south-southwest of the Semnan industrial park.

In many construction projects, cement mortar is affected by wetting-drying cycles, often due to factors such as varying rainfall, evaporation, changes in level of water in reservoirs. Alternative interactions between water and mortar affects the physical and mechanical properties of cement mortar and accelerates its erosion. Therefore, evaluating the effect of wetting-drying cycles on the physical and mechanical properties of cement mortar seems to be essential. For this purpose, a number of cylindrical and disc shaped samples were prepared. Samples were prepared for Uniaxial Compression Test, Brazilian Test, Effective porosity Test, and also determining longitudinal wave velocity. Samples were examined in cycles 0, 1, 5, 10, 15, 20 and 25. In each cycle, the samples were saturated in water for 24 hours and then dried at 105 ° C for 24 hours; then the samples were cooled at room temperature and finally examined. After cycle 25, uniaxial compressive strength, Brazilian tensile strength, modulus of elasticity and longitudinal wave velocity decreased by 37.96, 36.72, 35.44 and 8.1 percent, respectively; while porosity increased by 7.6 percent.

The principal rock units are a gabbro sequence, late intrusive rocks that consist largely of the plagiogranite and volcanic rocks, which are largely pillow basalts interbedded with pelagic sedimentary rocks, including radiolarian cherts. Chondrite- and primitive mantle-normalized incompatible trace element data indicate that the Lahroud ophiolite was derived from a within plate basalt-like mantle source. All rocks are cogenetic geochemically and were derived by fractionation from melts with a composition similar to average E-MORB with calc-alkaline signatures. Plate reconstructions suggest that the rocks appear to be approximately contemporaneous with the Mashhad ophiolites and Rasht ophiolite, which has a crystallization age of ~380 Ma. Rocks from the Lahroud ophiolite complex represent northern Paleo-Tethyan ocean crust that was formed distinctly earlier than crust preserved in the Ma Paleo-Tethys suture zone ophiolite from upper Paleozoic to Later Teriassic. The results from microfossil studies show the presence of Paleozoic biostratigraphy (e.g., Paleotextularia, Nodosinella cf. concinna, Pseudokahlerina, Cylindrica, Earlandia, Endothyra baileyi, pachyphloia, Fusulinella Stafella and Bivalve, Paratikhine). The data suggest that although the initial rifting and crystallization of the oceanic crust of the Lahroud ophiolite began in the Carboniferous, with volcanic activities continuing through to the late Triassic.

Over the past several years, geoheritage and conservation of valuable earth science features have become important issues for several developed countries. In our country, the geologists and other related specialists such as geoarcheologists are not well familiar with the concept of geoheritage. So, in this paper, we tried to define the geoheritage and related terms including geoconservation and geodiversity. In order to explore the value of the geological features in different fields, this paper can help the geologists and other related specialists like geoarcheologists to evaluate the geological features during their routine research activities. Different types of classification of geoheritage resources are represented in this paper. They can be classified on the basis of the scale of occurrence of the geodiversity, in-situ or ex-situ occurrence of geodiversity, levels of significance for sites of geoheritage significance and the uses of geoheritage. The uses of the geoheritage site are so important and critical for characterization of a geodiversity as a geoheritage site. The main uses proposed for the geoheritage are scientific, educational or geotourism/recreational. In this paper, it is shown that how geodiversity elements can be classified qualitatively and quantitatively. Geodiversity assessment can lead to the characterization of a geodiversity element as a geoheritage with scientific, educational or geotourism/recreational value. Here mentioned some examples from Iran.

Divination and determination of catchment surface runoff are the most important contestable process of hydrology. Soil Conservation Service - Curve Number (SCS – CN) method is employed to estimate the runoff. It is one of the physical based and spatially distributed hydrological models. In this model, the curve number is a primary factor used for runoff calculation. The selection of curve number is based on the land use pattern and HSG (Hydrological Soil Group) present in the study area. Since the spatial distribution of CN estimation by the conventional way is very difficult and time consuming, the GIS (Geographic Information System) based CN method is generated for Shirvan, Bojnoord, Farooj, Safi ababd and Meshkan watershed. With the combination of land use and HSG the estimated composite CN for the entire watershed was about 48, 68 and 83 respectively.The average annual runoff depth estimated by SCS-CN method for the average annual rainfall of 173.5 mm was found to be 72.5 mm.The obtained results were comparable to measured runoff in the watershed.