Iranian Journal of Earth Sciences
Volume:6 Issue: 1, Apr 2014

The aim of this study is prospecting of iron and manganese in the Balvard 1:100000 sheet which is situated in Sanandaj - Sirjan structural zone utilizing Index Overlay and Fuzzy Logic methods in the GIS. In this study, the layers for integration, alterations, geological, geophysical, geochemical and structural data based on stream sediments, airborne magnetometeric and remote sensing studies. Based on results obtained by both of methods, Fe and Mn prospects exist in the NE and northern parts of the area. The prospect areas derived via the Fuzzy Logic method are larger than those of gained from the Index Overlay method because the method used in the range from 0 to 1 value.

Detailed log facies studies of Miocene succession in the well Rashidpur-04, Rashidpur structure, Surma Basin were carried out by integrating wireline log and limited core sample data in order to reconstruct the paleoenvironments of deposition. Based on the analysis of the log motifs, grain size, sand/shale ratio and major change in gamma ray log motifs, two major depositional sequences were identified in the well Rashidpur-04 which consists of 17 para-sequences sets and 22 para-sequences. Serrated bell, funnel, cylindrical, egg/bow and linear log facies were recognized in the study well. Lithology indicates that the whole well interval consist of alteration of sandstone, siltstone, shale and prodelta facies. The Rashidpur sequence-2 inferred to be deposited in tidal flat to shallow marine conditions in prograding and retrograding delta front condition whereas the Rashidpur sequence-1 assumed to be deposited under tidal channel, distributary channel, tidal flat, mudflat, marine inter-distributary bay to shallow and deep marine conditions. The Rashidpur sequence-2 was deposited in comparatively deep water condition while the Rashidpur sequence-1 was deposited in relatively shallow water condition. The present study can be concluded that Miocene succession was coarsening upward in nature and might have deposited under prograding deltaic system.

Estimation of gold reserves and resources has been of interest to mining engineers and geologists for ages. The existence of outlier values shows the economic part of the deposits subject to the fact that don’t depend on the human or technical errors. The presence of these high values causes a pseudo dramatically increment in variance estimation of economical blocks when applying conventional methods as such as kriging. Conventional approach such as replacing the upper limit (capping), log-normal and Median-indicator kriging have been somehow resolved the problem of estimations but they still have numerous drawbacks. The Zarshuran gold deposit is one of the nominated gold deposits in Iran that choosing the appropriate method is a great chance in the estimation procedure. Robust kriging is a method that is able to reduce the allocated pseudo kriging weights to the blocks surrounding with high value data, and correct them in a manner that not only enhance the accuracy of the estimation but also reduce the estimation variance to the reasonable level. In this method, the estimation can be implemented in the presence of outlier and do not need to eliminate, reduce or transfer the data to another space (normalization). In this paper an attempt has been made for estimating the gold in the ore used to be compared with capping high value method. Results showed that this method has a high efficiency and is able to run estimation properly and produces high precision due to the high value reduction.

Chaldoran area in NW of Iran has Mesozoic oceanic crust basement. The studied rocks of this region can be divided into three groups: ophiolitic gabbros and pillow lavas, ophiolitic volcanoclastics and Eocene lava flows. Ophiolitic mafic rocks show continental volcanic arc natures and Eocene lava flow shows OIB-like nature. During the Mesozoic,the Chaldoran region was situated in the active continental margin of the Iranian plate due to Neotetyhan subduction beneath the SSZ (Sanandaj-Sirjan Zone). As the Neo-Tethyan subduction regime changed, a rift in the Chaldoranareagenerated, which caused a continental back arc basin during the Upper Cretaceous. Along with spreading basin in the oceanic ridge, in the surface of new formed oceanic crust, some oceanic island were active and formed volcanoclastic rocks in the Chaldoran Oceanic crust. They were result of ascending continental arc nature plumes that formed in the sub-oceanic crust and up on Neo-Tethys subducted slab in the mantle wedge. After of finishing of spreading this basin in early time of Paleocene, sedimentation followed up to the Middle Eocene. In the Upper Eocene, alkaline and OIB-like volcanism was active in the Chaldoranareadue to breaking off the Neo-Tethyan subducted slab in the sub-oceanic crust of Chaldoran area and developed an asthenosphric window.

Tsunamis are caused by the displacement of a large volume of water, generally in an ocean or a sea. Earthquakes, volcanic eruptions and other underwater explosions, landslides, glacier calvings, meteorite impacts and other disturbances above or below water have the potential to generate a tsunami. The coastal areas of Kollam district, the present study area was seriously affected by the catastrophic Indian Ocean Tsunami of 26 December 2004. The present study aims to demarcate tsunami vulnerable areas in Kollam district using Remote Sensingand GIS techniques. A multi criteria decision analysis was carried out using GIS techniques. The factors selected for this study were Land use/land cover, Slope, Elevation, Geomorphology and Distance from shore line. The thematic maps were prepared by using ArcGIS and ERDAS Imagine software tools. Knowledge based weight assessment method was used to prepare the weightage maps. After weighting and ranking, the vulnerability map was prepared by combining these thematic layers by ArcGIS weighted overlay analysis. The prepared vulnerability map was classified into five zones, viz; safe, rather safe, moderate, rather vulnerable and vulnerable. The village boundary was overlaid on the vulnerability map in order to highlight the vulnerable villages. This study provides an interactive method to identify the tsunami affected areas after the disaster and mapping the tsunami vulnerable areas before the disaster, which will be helpful in managing future disasters.

The Qom Formation, a series of shales, sandstones and carbonate deposits, is the last transgression of the sea in Central Iran sedimentary basin. Foraminifera are one of the most important and numerous fossil groups present in the Qom Formation. In this study, the micropaleontology of the Qom Formation in three measured stratigraphic sections in south and west of Tafresh (Rakin, Band-e-Ali Naghi Beig and Hezar Abad) are discussed. Except of the Rakin stratigraphic section, the lower and upper boundaries of the Qom Formation with Lower and Upper Red formations are conformable from the stratigraphy point of view. But, there is no outcrop in the upper boundary of the Rakin stratigraphic section. The study of 78 samples which were taken from the studied sections led to the identification of 34 genera and 39 species of benthonic foraminifera, 2 genera and 2 species of planktonic foraminifera, 4 genera of red algae and 3 genera of bryozoan. Based on the recognized foraminifera such as Lepidocyclina (Nephrolepidina), Miogypsioides sp., Meandropsina anahensis, Ammonia beccarii the age of the Qom Formation in the Rakin stratigraphic section is determined as Chatian-Aquitanian and in the Band-e-Ali Naghi Beig stratigraphic section as well as the Hezar Abad stratigraphic section is determined as Aquitanian.

The area of study is located 120 Km north-east of Shahrood city. In terms of structure and geological classification, this area is located in the northern part of central Iran zone. Granitoids of Troud ranging from monzonite to granite. The main minerals of granitoids are quartz, plagioclase, and orthose. The accessory minerals are biotite, hornblende, sphene, and opaque minerals. Various textures of granular, graphic and prethite are observed in these rocks. Based on various diagrams of major and trace elements, this rock is I-type arc calk-alkaline, Meta to para-aluminous with continental origin form at subduction zone. All these characteristics, combined with low Al2O3/(FeO + MgO + TiO2) and (Na2O +K2O)/(FeO + MgO + TiO2) ratios and high Mg# values, suggest an origin through dehydration melting of alkaline mafic of lower crustal source rocks.

The purpose of this study is to identify the effect of Ordinary Kriging (OK) and Inverse Distance Weighted (IDW) estimation methods for the delineation of mineralized zones based on subsurface data using concentration–volume (C–V) multifractal modeling in the Dardevey iron ore deposit, NE Iran. Variograms and anisotropic ellipsoid were generated for the Fe distribution by the above estimation methods. Continuity of ore and waste, the number of points involved, discretization factor for ore and waste boundaries and block model were generated for reserve estimation purposes. In addition, the C-V log–log plots based on the estimation methods represent the various mineralized zones fromexisting thresholds, and error estimations in both methods were compared. The comparison and interpretation of themineralized zones based on the C–V fractal modeling show that the error is less in the OK method, although the volume of extremely, highly and moderate zones resulting from the OK method is greater than the IDW method. The thresholds considering C-V fractal modeling for extremely, highly, moderately and weakly mineralized zones are 60.37%, 55.27% and 45.66%respectively for the OKmethod and 55.14%, 50.12% and 41.48%respectively for the IDW method. According to the threshold values, the error in the OK methodis less than 20% while the error estimation resulted from the IDW method increases to 60%.