Mining Department

ABSTRACT: In this study, the crustal velocity structure and depth of Moho is determined under the eastern part of Iranian Kopeh Dagh, North-East Iran that is named Hezar-Masjed mountains. The teleseismic waveform receiver functions technique is used to determine ...

ABSTRACT: In this study, the crustal velocity structure and depth of Moho is determined under the eastern part of Iranian Kopeh Dagh, North-East Iran that is named Hezar-Masjed mountains. The teleseismic waveform receiver functions technique is used to determine crustal thicknesses in this study. 41 teleseismic earthquakes from three broadband seismometers installed in the Iranian Kopeh-Dagh, are used to calculate P-wave receiver functions. Receiver functions for each station are generated from events for a wide range of backazimuths. From analysis of receiver functions at KAR, ZOW and HAM stations, the crustal structure is suggested for the Hezar-Masjed area with a Moho depth of 44-50km. Results indicate three main layers; the upper crust has an S-wave velocity between 2.1-3.2km/s and a 10 to 12km thickness, a middle crust with S-wave velocity between 3.2-3.7km/s and a 22 to 25km thickness and the lower crust with S-wave velocity between 3.7-4.4km/s and a 12 to 15km thickness. An S...

In this paper trend surface, tilt angle, analytical signal and total horizontal of tilt derivative methods have been used for study of tectonic lineaments in Poshtbadam area. Studied area is located in north eastern of Yazd province. The surveyed magnetic data of studied area are processed and related maps are produced by using of mentioned methods. All the maps are interpreted. The results obtained that the processing and interpretation methods have an acceptable degree of reliability. The specified faults by using of this methods that are offspring of mineralization have good compatibility with geological information.

Magnetic method is an important passive surface geophysical method which uses the
Earth’s natural magnetic fields to investigate the susceptibility structure of the subsurface
material. The geomagnetic field measurements can be used to determine the structure of
the earth, because the rocks often contain magnetic minerals. The interpretation of data of
this nature, in some cases, will determine geological characteristics that would help
contribute to the success of mining or oil exploration. In this study, for the review of more
details and achieving an idea about accurate location, dip, depth and mineralization
spread, geomagnetic surveys were applied and then data processing method were used.Preparing a suitable map which contains the informative data without interference from
noise is the main purpose of the data processing. To reach this aim, the acquired data
should be corrected for different non-geological effects.
These are: 1. Diurnal correction to remove time varying parts of the magnetic field. 2.
IGRF correction to remove the field of earth core and upper mantle response.
Many interpreting methods, that estimate the depth, location and the shape of a
potential source, are based on using the gradients of potential fields. Derivatives are high
pass filters. They intrinsically amplify any noise and shallow anomalies present in the
data. Therefore, using high order derivatives would be less common. Tilt angle has many
interesting properties. For example, due to the nature of arctan trigonometric function, all
tilt amplitude are restricted to values between -90° and +90° (Salem et al. 2007). Another
property of tilt angle is that the value of tilt angle above the edges of the contacts is 0°,
and it is equal to 45° when h = zc and -45° when h = zc. This suggests that contours of
magnetic tilt angle can identify the locations of contact-like structures.
The studied area is located in Yazd province and it is part of micro continent Iran
central. The intrusive rock in this area is genais and the sedimentary rock is schist and the
host rock of studied area is limestone. Igneous units of the trust are located on limestone.
Also outcrop of hematite has been observed in this area. Designing the field operation
grid were carried out based on geology and primary studies of region and therefore 2400
points were along 60 profiles. After diurnal correction, total magnetic intensity has been
corrected by using IGRF 2000 so that components of Earth's magnetic fields have been
eliminated. Also reduction to pole operation was done. In this paper, first derivative,
second derivative, analytical signal tilt angle and Euler deconvolution methods were used
to study fractured structures. The edges of these faults were detected by using analytical
signal, first derivatives, second derivatives and the tilt angle method .
Then, we use the standard Euler deconvolution method. Reid et al (1990) used this
method as Grade analysis. Simple geometric models for magnetic field source (Balkely,
1995) and determination of structural index with earlier data are disadvantages of the
Euler method. However, Thompson (1982) and Reid et al (1990) determined the optimum
structural index for different structures; nevertheless the Euler method estimated quite
well the location and depth of magnetic sources (Aboud et al., 2005)
The results of the first vertical derivative showed three major faults in this area strikes
of which were east-west in north, northeastern-southwestern in middle and northwesternsoutheastern
in south of the area and the other interpretation methods have an acceptable
degree of reliability. The faults specified by using these methods that are offsprings of
mineralization have good compatibility with geological information. Also, the depths of
the faults in the area were estimated by the Euler method. The estimated depths of the top
of major faults in the area were similar at 5 m and 15 m.

In this paper, groundwater seepage into Amirkabir tunnel has been estimated using analytical and numerical methods for 14 different sections of the tunnel. Site Groundwater Rating (SGR) method also has been performed for qualitative and quantitative classification of the tunnel sections. The obtained results of above mentioned methods were compared together. The study shows reasonable accordance with results of the all methods unless for two sections of tunnel. In these two sections there are some significant discrepancies between numerical and analytical results mainly originated from model geometry and high overburden. SGR and the analytical and numerical calculations, confirm high concentration of seepage inflow in fault zones. Maximum seepage flow into tunnel has been estimated 0.425 lit/sec/m using analytical method and 0.628 lit/sec/m using numerical method occured in crashed zone. Based on SGR method, six sections of 14 sections in Amirkabir tunnel axis are found to be in &qu...

SYNOPSIS Blasting, which is carried out regularly in open-pit mines, causes considerable ground vibration in the vicinity of the blasting site. These vibrations may affect the stability of mine slopes, causing problems in safety and constituting a hazard to life and property. In this study, the effect of the blasting-induced vibrations on slope stability was investigated using finite element (FE) analysis. A pit slope containing a fault was examined under seismic loading caused by successive explosions with varying intensity. Some reference points were selected above/under the fault surface and their motions recorded during the FE analysis. The results show that the points above the fault surface have the greatest displacement, while below the fault surface, only minimal (negligible) motions occur. Also, the intensity of the explosion has the greatest impact on motions at the upper points, but below the fault surface, the effect of the blast intensity was minimal. Usually, each expl...