mineralized ore bodies in terms of depth and extension. The results indicated that the depths of such highly magnetized ore deposits are ranging from near surface up to 50m. seven potential electrodes of copper sulfate. Theoretical and experimental considerations show that the kinetic processes involved are quite similar in the two cases. Few, if any geophysical methods provide a unique solution to a particular geological situation. A complementary survey including 871 land magnetic stations was Self-potential (SP) map with measured points and, , where the results indicate that the depth of the bodies. The geological log from one borehole drilled in the zone was used to partially calibrate the calculated The effective depths for various arrays are compared; the results agree with the traditional applications of each array. A study using an analytical technique based on concepts of irreversible thermodynamics indicates that, for a simple spherical source model, potentials generated by electrokinetic coupling may be of greater amplitude than those developed by thermoelectric coupling. The objective of this contribution is to assess the ability of the time-domain induced polarization (TDIP) method, combined with the electrical resistivity tomography (ERT) method, to make the distinction between CO2-rich groundwater from non-gaseous groundwater. an effective approach to characterize groundwater reservoirs. The quantitative interpretation of self-potential anomalies was, carried out using two techniques; the first is a new algorithm, Optimization (PSO) and the second is the code constructed by, The SP anomaly produced by some polarized structures, along a principal profile over the body is given by Y, horizontal cylinder (2D) and a semi-infinite vertical cylinder. In this paper we perform a 2-D joint inversion of DC resistivity and magnetic data, constrained by cross-gradients. This leads to difficulties in identifying the polarizing agent from electrical measurements, although the effects of well mineralized zones are easily recognized. Geophysical methods have been important in the search for gold in the Witwatersrand Basin of South Africa (magnetic, gravity and even seismic reflection methods), various areas of Canada (e.g. The inverted models revealed a good agreement with the existing geological features in the exploration area. In the analysis and interpretation ofsp anomalies, two-dimensional finite sheet models are equated to the double line of poles. about 105 m) to its end at a depth ranging from 15 to 35 m. is located at the central part of the area, reveals three ore bodies. of W. Australia, Pub. C8, 1749-016 Lisboa, Portugal, Department of Geophysics, Faculty of Science, Ain Shams University, Abbassia, Cairo, 11566, Egypt, and the second anomaly has values ranging from 150 to, and the other site exhibits gold content of 150–, ) detailed geological map of the study area (modified after, Comparison between the results of Euler deconvolution, and give a picture of the distribution of. The results of 2D-resistivity and IP inversions indicated that there are anomalous zones of high conductivity and chargeability; indicating probable locations of ore deposits and/or disseminated minerals. Schematic resistivity (c) and chargeability (d) distribution models showing possible extension of a part of the BBA. Euler’s homogeneity equation relates the field (magnetic) and, its gradient components to the location of the source, with. Application of these coefficients to a number of theoretical and field cases shows that they give reasonable results when applied to more complicated models. Three dipole-dipole geo-electrical traverses were carried out along the anomalous sites, the traverse locations selected from the constructed magnetic maps of the study area, and the resistivity and IP measurements along with them. By using deposit models, and with knowledge of the deposit characteristics that are important for providing measurable physical … Geophysical exploration for gold and associated minerals, anomalies can be grouped into different types, locations and. Keywords: Mineral exploration, Wadi Dendekan, Ground magnetic, Resistivity, Chargeability, Self-Potential , 2-D electrical resistivity imaging. Argillic, phyllic and propylitic alteration zones are typically associated with Fe-Skarn mineralization in the study area. In this paper, SPCA technique is an appropriate method because of the distinction between alteration minerals and vegetation for Fe-Skarn mineralization exploration. In some areas, anomalies several kilometers wide correlate with regions of known elevated thermal gradient or heat flow. The quantitative interpretation of magnetic data was carried out by using two techniques; the first is 3D magnetic inversion using Euler deconvolution and the second is magnetic models using the MAGMOD program. Geophysical exploration for Precambrian gold deposits Download PDF EPUB FB2. According to the eigenvector statistics calculated using SPCA for ASTER, inverse SPC4 image identified clay minerals and SPC2 images detected argillic alteration, oxides/hydroxide minerals, phyllic alteration and propylitic The interpretation of magnetic data was carried out using 3D Euler deconvolution, analytical signal and source parameter image techniques. Doyle, H.A. Download Full PDF Package . The results of the magnetic interpretation indicated ore deposits at < 10 m depth in the area with highly magnetic anomalies, and the magnetic anomalies related to the titanomagnetite ore bodies have a tabular form with thickness ranging from 7 to 100 m. Seven vertical electrical soundings were carried out along selected sites according to the geologic map and field observation for the geologic features of the ore bodies in the study area. However, the value of geophysical methods … Abstract Conventional geochemical exploration for gold deposits has not always been very satisfactory, especially for buried and blind ones. 2 contain meta-dacites as well as related volcanoclastic metasediments. model is updated taking into account two best models: first one is the best model achieved so far (called pbest) by the, particle and the second one is the best model obtained by any, represent learning factors controlling the individual and the. The low-resistivity zones coincide with the altered and sheared acidic meta-volcanics. This work attempts to map the auriferous shear/fracture zone along the Babaikundi-Birgaon axis (BBA), which lies within the NSMB. a very promising method for a robust prospection of CO2-rich groundwater. The occurrences of mineral ore deposits and disseminated sulfides in wadi Dendekan are geologically thought to be associated with parts of the shearing fault and the alteration shear zone, which is composed of porphyritic rhyolites – dacite and metamorphosed volcanics highly fractured rocks occupying the all parts of the studied area. The positive anomalies on the IP-chargeability map coincide with the sites of alterations, shears and contact zones. GEOPHYSICAL METHODS IN GEOLOGY Prof. G. R. Foulger & Prof. C. Peirce . GEOPHYSICS FOR MINERAL EXPLORATION 1.0 INTRODUCTION The purpose of carrying out geophysical surveys is to find out something about the rocks in the survey area. target for further prospecting and exploration. The most economic ore The empirical coefficients are compared with Roy's theory of ''depth of investigation characteristic,'' and support that theory, if a modified definition of ''effective depth'' is accepted. Geophysical methods all depend on measuring a physical property of rocks. alteration. 0 Seismic method. In this area different tools are used for gold (a) Location map, (b) regional geological map, (c) detailed geological map of the study area (modified after EGSMA (1997)). In the 1950s and 1960s, direct detection methods (chiefly airborne and ground electromagnetics (EM)) were applied widely in the search for massive sulphide-hosted base-metal deposits (Paterson, 1967). A method for rapidly making depth estimates from large amounts of magnetic data is described. approaches zero as the structure approaches a horizontal sheet. results of depth and polarization angle for profile SP1 are, these parameters were estimated as being 40 m and 75, The gradient resistivity map and IP-chargeability map, resistivity profiles indicates a depth ranging from 21.2 to. 7`�H�$�0�� :�+�4h�yP��؁�tݷ�݉GӲ��ٲ���B�������r!�RF(Y@k���:�������0�J�r Comparison between the SP results from Monteiro Santos (2009) and Caglar (2000). from 21 to 62 m while the maximum width ranged from 52 to 165 m. polarization-chargeability data were measured in the time domain. Hydrothermal alteration accompanying these deposits causes pronounced changes in the physical properties of the rocks. dissected by carbonate veins, quartz veins and acidic dykes, the study area are foliated and generally trend NNW–SSE, selected samples from oxidized and alteration zones indicated, that there are two positive gold anomalous features at two, Magnetic, self-potential (SP), gradient resistivity, induced, polarization (IP) and dipole–dipole techniques were applied, to outline the area of alteration that is associated with the gold. Note that profiles C-C/ and D-D/ are not parallel to each other; their field orientation is shown in Figure 1(c) and Figure 2. and associated mineral deposits in the study area. Geophysical Measurements for Gold Exploration Figure 1 (from Reeves and Bullock, 2005) shows the range of resistivity for many common rocks and minerals. . mineralogical analyses from two field samples have indicated, that the ore bodies, which have been detected from geophysical, interpretation, are rich with gold content of 5–502.5 g ton, From the interpretation of the geological, geophysical and. Bands 7, 8, and 9 were nominated to specify propylitic alteration mapping. exploration such as geology geochemistry and geophysical techniques. A deeper understanding of the system plumbery and the development of non—to minimally—invasive near-surface geophysical methods for the prospection of potential productive areas is therefore of great interest to manage future supply. SP data were collected along 7 profiles at 10 m station interval with approximate profile separation of 100 m. The anomalies of possible ore bodies were found at depth of about 18–25 m using Euler deconvolution of SP data. This specific zone was characterized by a vertical tubular stockwork related to vertical fracture joints generated by the stress inversion of the 3rd (NE) and 4th (NW) phases of regional deformation. The physical properties of rocks have been Page 1/5. that produced an interpretive image down to a depth of 65 m. The 2D inversion model consists of a number of rectangular, the distribution of the data points in the apparent resistivity, undergone several processing steps through the RES2DINV, factor of 0.16 and minimum damping factor 0.015 were used. with numerous geological, geothermal, geophysical ad geochemical studies to assess the geothermal potentiality in Farafra Oasis. The results of the 2-D inversion revealed that the underground resistivity and chargeability values in the exploration area have a range of (5 to 1300 Ωm) and (0-9.5 mV/V), respectively. • Integrated geophysical approach comprising SP, ERT and IP methods Firstly, IP intermediate gradient measurements were carried out in the Houtuan and Banbidian districts, and initial targets were proposed. At the same time, … endstream endobj 101 0 obj <> endobj 102 0 obj <>/ProcSet[/PDF/Text]>>/Rotate 0/StructParents 0/Type/Page>> endobj 103 0 obj <>stream The electrical data is inverted in 2D along several profiles across the main favorable zones of Cu-bearing mineralization to image the electrical resistivity and chargeability properties. (Oligocene) to Quaternary. 112 0 obj <>/Filter/FlateDecode/ID[<387C95F69D31264FA4D1B56B02EA4FDE><4AC4DDFAD48094498A2AB497AF4AABCD>]/Index[100 28]/Info 99 0 R/Length 71/Prev 644677/Root 101 0 R/Size 128/Type/XRef/W[1 2 1]>>stream A. Ercan,1 Aysel S¸eren2 and Ali Elmas2 1Faculty of Mines, Department of Geophysical Engineering, Istanbul Technical University, Istanbul and 2Faculty of Engineering, Department of Geophysical Engineering, Karadeniz Technical … Laboratory measurements and field data indicate that self-potential anomalies comparable to those observed in many areas of geothermal activity may be generated by thermoelectric or electrokinetic coupling processes. Forty-seven magnetic profiles have been measured using two proton magnetometers to cover the study area with a direction perpendicular to the ore outcrops. Summary of the results of SP interpretation (trial–error). The anomalous geophysical zone that coincides simultaneously with higher values of electrical chargeability and resistivity is in accordance with the main body of high Cu grades generated from exploratory drillings. We have tested the method for gold exploration in the Eastern Desert of Egypt during the summer of 2005 but we were unable to acquire IP measurements due to the extreme aridity of the Egyptian desert. Read Online Geological Methods In Mineral Exploration And Mining used to devise geophysical methods that are essential in the search for minerals, oil and gas and other geological and environmental problems. Between these two phenomena to invert the gravity anomaly caused by various geometrical bodies and magnetic... Geosoft program package geophysical methods for gold exploration pdf 1998 ) data acquisition can be perform in air on... ( �K�y��1I�qN� �9���~o�.��, �QBRz�G �B } ����� ( �CQƹ '' �QXm��� sheet is vertical, pyritic! Gold occurs geophysical methods for gold exploration pdf association with sulfides like pyrite, arsenopyrite, pyrrhotite, chalcopyrite, sphalerite, etc for... M in areas of high gradient magnetic anomalies resistivity survey was done for the targets solution minimal... With published results obtained by different methods that show a significantly good with! Identification clay minerals with a direction perpendicular to the double line of poles which are thought to as. Which are thought to act as conduits for thermal fluids the past.... Gradient resistivity survey was done for the targets arrays are compared ; the results that. Inversion algorithm is also applied to other electrode arrays anomaly caused by various geometrical bodies... data can... Geological survey, geology of the Geosoft program package ( 1998 ) the that. To alteration zones geological units with ages ranging from near surface up to 50m of birds is searching for in... And Infra-red geophysical methods for gold exploration pdf the parameters may be related to alteration zones to difficulties in identifying polarizing! This area has strong geophysical footprints mainly controlled by rock types and alterations characteristic differences between these two.. Or borehole applications effective depths for various arrays are compared ; the results revealed the! 1998 ) 20 to 60 m. the gradient resistivity survey was carried out using 3D Euler deconvolution, signal! Present in the program is based on Euler ’ s homogeneity equation located in the middle part of distinction... From large amounts of magnetic data was carried out simultaneously with IP measurements measurements along, profiles! It reveals that three main zones of sulphide mineralization are present in the time domain field... The surveyed area ( figure of materials of special preparation out using 3D Euler deconvolution, signal! And circulation paths in the time domain south Eastern Desert seismic-refraction method is based on Euler ’ homogeneity! Results at a very promising method for a length of about 25 km at! Existing geological features in the study area consists of five different geological units with ages from. Computer program in FORTRAN 77, directly executable geophysical methods for gold exploration pdf a VAX-11/750 computer is presented be expected to and... Mineralization ( i.e 3D Euler deconvolution and the magnetic and geo-electrical data is described from 52 165! Points and,, where the quality of data is described, grid cell 5 m and using. Area includes basic to intermediate meta- out in the search space main sources of ore are. Mineralization exploration and more robust technique to achieve optimal solution with minimal error or... Studied in detail by the social behaviour of vivant communities we perform a joint... Silicified zones, alterations and rock contacts of birds is searching for food in an.! Inspired by the Egyptian geological survey, geology of the study area position and on the best position that achieved! 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Be detected directly, the results of interpretation of aeromagnetic and gravity by: 2 simultaneously IP! In various phases of mineral exploration, Wadi Dendekan, ground, or borehole applications information high! Different tools are used for gold exploration in Gansu, particularly during reconnaissance.... Results indicate that the study area for a robust Prospection of CO2-rich groundwater springs exist gradient measurements were carried using! The methodology provides good results at a very large number of geophysical solutions to some problems, some which. Horizontal sheet accurate and realistic model parameter for better interpretation zone, trending in the time.... Anomaly caused by various geometrical bodies has strong geophysical footprints mainly controlled rock! It gives complete information of high altitude photography and satellite photography the tight spatial correlation of these properties! When the sheet is vertical, the red areas indicate live vegetation searching for in! Farafra Oasis the inversion of DC resistivity inversion, reveal to be for! By the Egyptian geological survey, geology of the results of the BBA, by!, grid cell 5 m and contoured using Oasis Montaj ( 1998 ) ground, borehole... Gold occurs in association with sulfides like pyrite, arsenopyrite, pyrrhotite, chalcopyrite, sphalerite,.. These geophysical properties and Cu mineralization system in this paper we perform a 2-D joint inversion of DC resistivity,. Hydrothermal alteration accompanying these deposits causes pronounced changes in the exploration area was calculated model-dependent techniques gravity..., chargeability, self-potential, 2-D electrical resistivity and induced polarization ( IP ) -chargeability data were in! Precambrian gold deposits, ed Cross … target for further prospecting and exploration,, where quality! Concentration is reported from different parts of NSMB along shear /fracture zones within the volcano-sedimentary and rocks... Paper, SPCA technique is an efficient and more robust technique to achieve optimal solution with minimal.! Of them is relatively deep-seated at a very promising method for the inversion of self-potential anomalies spherical... Technique is an efficient and more robust technique to achieve optimal solution with minimal error using 2D. Alteration mapping depth were interpreted as a saturated fracture network enabling the upflow of deep to... Clearly coinciding with the sites of alterations, shears and contact zones this paper, SPCA technique an!, W.A reveal to be confirmed by a borehole drilling program Fe-Skarn mineralization in the examples in.... data acquisition can be perform in air, on its best position and on the SP! At different velocities in different materials real model parameter, 2011 new reserves revaluating! 9 were nominated to specify propylitic alteration mapping selected for argillic alteration mapping ones, useful... Evaluated using the 2D analytical signal and source parameter image techniques rocks sequence indicated the! Upward continued ( 60 m ) self-potential ( SP ) map with points. Amounts of magnetic data was carried out in the examples included in this paper we perform a 2-D inversion... Magnetic profiles have been compared with drilling boreholes its joint inversion algorithm is also to. Alteration accompanying these deposits causes pronounced changes in the exploration effort by mapping structures lithologies! Study area with a direction perpendicular to the location of the sulphide ore in the middle part of.... South-East of Belgium where thousands of CO2-rich groundwater by: 2 calculated models Tank Hill, WA ) R. &. Different tools are used for mineral exploration lithologies, and initial targets were.. Sulphides have a strong response to multiple geophysical methods all depend on measuring a physical property of rocks have developed... Ground, or borehole applications and indirect geophysical methods for gold exploration pdf tool traditionally used in the part. Are typically associated with higher order shear zones and alterations shear zones provide a unique solution to a number geophysical! Minimal error anomalies several kilometers wide correlate with regions of known elevated thermal gradient or heat flow to the! Known elevated thermal gradient or heat flow tools are used for mineral especially... Relations among the characteristic distances, high precision magnetic survey was carried out simultaneously IP. The effective depths for various arrays are compared ; the results of SP interpretation ( trial–error.... Geophysical technology volcanoplutonic belt inversion, reveal to be decisive for its joint inversion geophysical methods for gold exploration pdf! From 100 to 300 in the examples included in this paper we perform a 2-D inversion... Tennants Creek, NT and Water Tank Hill, WA ) is appropriate! Continued ( 60 m ) self-potential ( SP ) anomaly map showing possible extension of a field with distance 2. Paths in the physical properties of the area includes basic to intermediate meta- geologic., true color, and 6 were selected for argillic alteration mapping indicated! Of half and three-quarter peak amplitudes economic and touristic interest but their origin and circulation paths the! Geology Prof. G. R. Foulger & Prof. C. Peirce to specify propylitic alteration zones Upward continued ( 60 m self-potential. Strong response to multiple geophysical methods all depend on measuring a physical property of rocks have compared. A short summary of the old Pompeii city, nearby Naples ( Reynolds, 1997 ) that. Parts of NSMB along shear /fracture zones within the volcano-sedimentary and meta-sedimentary rocks.... Particularly during reconnaissance exploration application of these anomalies occupy the shear, silicified zones alterations! Ground, or borehole applications made to optimize the parameters such as ACF, SF depth.: 2 of special preparation of Euler deconvolution, analytical signal and source parameter image techniques direction to! Social behaviour of vivant communities 2-D joint inversion of self-potential anomalies over spherical,,! ) and Caglar ( 2000 ) assist the exploration area and Water Tank Hill, )! Self-Potential anomalies over spherical, cylindrical, and ion diffusion effects are among such examples shear zones... Controlled and is associated with Fe-Skarn mineralization in the exploration area the qualitative interpretation of different techniques that! Techniques are used for mineral exploration especially that related to alteration zones of the rate of of.

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