M.J Mohammadzadeh; A Nasseri; S Ansari
Abstract
Sahebdivan area is located at 20.km of Meshkinshahr in Ardebil province. The study area is comprises of volcanic rocks and intrusive masses consisting of quartz monzonite and granite along with several vast epithermal alterations. The main objective of this paper is to recognize the present ...
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Sahebdivan area is located at 20.km of Meshkinshahr in Ardebil province. The study area is comprises of volcanic rocks and intrusive masses consisting of quartz monzonite and granite along with several vast epithermal alterations. The main objective of this paper is to recognize the present alteration zones indicating metal promising areas using geophysical methods such as induced polarization (IP) surveying and resistivity (RS) in order to assess the presence of minerals and delineate the subsurface masses at depth. Therefore, IP/resistivity survey was carried out based on rectangular array in the area and their corresponding maps were prepared. Accordingly, their promising anomalous zones for mineralization were initially detected. Furthermore, a new IP survey was attempted based on a dipole-dipole electrode array for detailed potential mapping.
Considering IP/RS pseudo-sections, the position, depth, intensity and extent of mineralization was defined. Correlating the anomalous zones obtained from geophysical results with Lithology and alteration zones in the area indicate Cu mineralization along E-W trend in Sahebdivan which is associated with increase in chargeability and reduction in resistivity. Furthermore topographic corrections were attempted resulting in anomalous halos enhancement. Discriminating the important alteration zones in the area were carried out based on chargeability variations where higher chargeability indicate phyllic alteration with pyrite and in contrast the Potassic alteration with low chargeability that coincide with igneous intrusive.
It can be deduced from this study that the porphyry micro quartz monzonite - micro quartz diorite generator fluids was recognized as source of mineralization along with surrounding andesite–dacite andesite as source of the anomalous zones in Sahebdivan area. Summing all the evidences from field studies and their compliance with geophysical results, Lithology, alterations and ultimately considering the susceptible mineralization zones, the optimal drilling points was proposed with priority of SABH-1 according to the Potassic zone in terms of potential copper mineralization.
A Naseri; M.J Mohammadzadeh; P Mohebbi; P Javani
Abstract
Gharahchaman is located inthe Urumieh Dokhtar zone in east Azerbaijan. The area is mostly comprises of intermediate to acidic intrusive and extrusive, Oligocene igneous rocks along with younger sedimentary units. The regional geochemical exploration program with the aim of delineating potential zones ...
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Gharahchaman is located inthe Urumieh Dokhtar zone in east Azerbaijan. The area is mostly comprises of intermediate to acidic intrusive and extrusive, Oligocene igneous rocks along with younger sedimentary units. The regional geochemical exploration program with the aim of delineating potential zones in the area were attempted by collecting 394 stream sediment samples, which analyzed for 44 elements. Most of the exploration programs are routinely based on the positive anomalies (+ve) detection and the negative halos (-ve) are rarely considered. The depletion of some pathfinder elements may be related to ore mineralization in the area. Therefore (-ve) halos also can be significant in regional exploration. Conventionally, negative anomalous threshold values have been calculated in the same way as positive one, which causes drawbacks and hinder their application. In this paper an attempt were made to construct integrated models of (-ve) and (+ve) potential maps for detecting optimized geochemical pattern. It can be deduced from this study that the detected significant (-ve) halos, mostly are influenced by syngenetic processes and some are also related to ore bearing solutions. Detecting (-ve) halos of elements such as Sc, Sr, and Na in a particular pattern and in vicinity of (+ve) halos like Au, Cu, Pb, U, Zn are related to base metal mineralization and other important elements in the region. On the basis of combined distribution pattern of elements three models of geochemical anomalies are accompanied each other;1) Overlapping of multi-element (-ve) and (+ve) anomalies like (Rb, Sr); 2) Peripheral regional multi-element (-ve) anomalies that surround (+ve) anomalies like (-ve) halo of Sc around (+ve) halos of Ce, Rb/K and (–ve) halo of Sr with Ba/Sr ratio, felsic and chloritic zones in the area; 3) Discriminated Indices model of (-ve) and (+ve) halos of (Mo-Sr), (U-Sr), (Cu-Sr).This indicates that the combined study of (+ve) and (-ve) halos in regional geochemical exploration studies can be more significant in detecting hidden ore deposits. The distribution pattern of felsic and chloritic additive composite alteration zones match with Model2, which mutually correspond to (+ve) and (-ve) anomalies of Au and Sr respectively. Ultimately the results revealed deficiency in study of only positively concentration of elements along with faulted zones, whereas the present study emphasis that modeling corresponding of (-ve) and (+ve) halos along with results obtained from composite additive indices confirms NW-SE concentration of ore mineralization in the area.
M. J. Mohammadzadeh; H. Shahinfar; A. Nasseri
Abstract
Optimization of geochemical anomalies needs an orientation survey in which one of its important aspects is selecting an advanced data processing method. The main objective of this study is to recognize the blind and mineralization zones by employment of new processing techniques in order to establish ...
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Optimization of geochemical anomalies needs an orientation survey in which one of its important aspects is selecting an advanced data processing method. The main objective of this study is to recognize the blind and mineralization zones by employment of new processing techniques in order to establish an optimized exploration tool and reliable geochemical pattern for potentially promising areas in Gulan. In this respect 233 stream sediment samples were collected and analyzed for Cu, Pb, Zn, Mo, Co, Ni, Cr, As, and Y. The anomalous zones were detected by using PCA&FCMC methods. The FCMC results revealed Cu, Mo anomalous zones in Garachilar area. It shows secondary halos separation of Cu and Mo probably due to transportation of Mo in the form of molybdates by acidic solution around outcrops, and consequently their adjoined redeposition. Application of Fuzzy logic Based FCMC shows the emplacement of Cu and Mo in the same cluster and overlapping of their anomalies which indicate their paragenetic relation in the ore bearing solution. Comparative study of the methods (FCMC&PCA) revealed some how similar results in detecting Garachilar anomalies. But the PCA results not only indicate Garachilar as promising zones but also could detect western part of Lutkeh and blind anomalies of Namnig in the same trend of NW-SE. This study indicates that geochemical pattern detected by PCA is more effective in enhancement of halos and blind anomalies than FCMC. Moreover, the characterization of geochemical pattern by PCA can be optimized more precisely in eliminating lithological effect and its results can be used successfully as prospecting tool in the area.
M. J. Mohammadzadeh; H. Aghababaei; A. Naseri
Abstract
The amount of total organic carbon (TOC) is one of the most important parameter in evaluating hydrocarbon source rock. This parameter is not only used for hydrocarbon geochemical studies but also plays an important role in evaluating the extension of hydrocarbon source rock. ...
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The amount of total organic carbon (TOC) is one of the most important parameter in evaluating hydrocarbon source rock. This parameter is not only used for hydrocarbon geochemical studies but also plays an important role in evaluating the extension of hydrocarbon source rock. As the increase in TOC may indicate the presence of source rock, the depletion of TOC reveals no extension of source rock in a certain depth. Therefore the need for a powerful tool in this aspect is essential. One of the linear methods for solving such problem is artificial neural network, a biologically inspired computing method which has an ability to learn; self adjusted and are trained, capable of classification, image processing and different problem analysis, with an attempt to estimate. This paper presents the features and framework for application of neural network in estimating TOC for hydrocarbon source rock in Binak oil field, Bushehr province, using well log data. The results of this study reveal that Multi-Layer Perception (MLP) is the optimum network which was used for TOC estimation. MLP topology was a hidden layer with 6 nodes, back propagation momentum learning algorithm and tangent activation function. After training is completed, the estimated error calculated as 0.0013, and then the network performance was tested upon training and testing data. Ultimately the predicted TOC values were compared with the actual one which showed a reliable network performance (R=0.9956). Finally the sensitivity analysis was attempted on effective parameters and based on neutron porosity parameter (NPHI) found to be as the most sensitive, and the sonic travel time (DT), the least sensitive parameters in estimating TOC.
