Airborne Geophysics Research Articles

Prospectivity mapping for orogenic gold in South-East Greenland

Numerous studies have proven that conceptual targeting based on integration of various geo-datasets can aid exploration companies to identify exploration targets (e.g. Joly et al. 2013). This is particularly true in remote, underexplored areas that are commonly just covered by airborne geophysics and remote sensing and mapped geologically only on a regional scale. Such regions are ‘exploration greenfields’ and may possess undiscovered economic deposits.

سنگ شناسی، سن سنجی، ژئوشیمی و تعیین منشأ توده های گرانیتوئیدی منطقه بجستان، شمال فردوس، استان خراسان رضوی

سنگ شناسی، سن سنجی، ژئوشیمی و تعیین منشأ توده های گرانیتوئیدی منطقه بجستان، شمال فردوس، استان خراسان رضوی

On coincident loop transient electromagnetic induction logging

Coincident loop transient induction wireline logging is examined as the borehole analog of the well-known land and airborne time-domain electromagnetic (EM) method. The concept of whole-space late-time apparent resistivity is modified from the half-space version commonly used in land and airborne geophysics and applied to the coincident loop voltages produced from various formation, borehole, and invasion models. Given typical tool diameters, off-time measurements with such an instrument must be made on the order of nanoseconds to microseconds — much more rapidly than for surface methods. Departure curves of the apparent resistivity for thin beds, calculated using an algorithm developed to model the transient response of a loop in a multilayered earth, indicate that the depth of investigation scales with the bed thickness. Modeled resistivity logs are comparable in accuracy and resolution with standard frequency-domain focused induction logs. However, if measurement times are longer than a few microseconds, the thicknesses of conductors can be overestimated, whereas resistors are underestimated. Thin-bed resolution characteristics are explained by visualizing snapshots of the EM fields in the formation, where a conductor traps the electric field while two current maxima are produced in the shoulder beds surrounding a resistor. Radial profiling is studied using a concentric cylinder earth model. Results found that true formation resistivity can be determined in the presence of either oil- or water-based mud, although in the latter case, measurements must be taken several orders of magnitude later in time. The ability to determine true formation resistivity is governed by the degree that the EM field heals after being distorted by borehole fluid and invasion, a process visualized and particularly evident in the case of conductive water-based mud.

Introduction to the JEEG Special Issue on Airborne Geophysics

Airborne geophysics is indisputably a useful and cost effective approach to geophysical exploration and mapping in the appropriate situations. Depending on the objective, choosing conventional airborne geophysical surveys on projects of a certain size may result in substantial savings. In general, airborne surveys can be carried out over large areas in a matter of days, where the same ground survey might require weeks or months to achieve the same coverage. Certain projects lend themselves to airborne approaches. Objectives of groundwater exploration may necessitate covering an area up to hundreds of square kilometers, something more easily done from the air than on the ground. Wide area ordnance assessment has been done successfully using specialized, low flying aircraft. Certain terrains, such as swamps and marshes, may be more amenable to airborne surveying than to ground approaches. In this issue we present case studies in which airborne geophysics has supplied precise information on water depth, aquifer location, and has also mapped critical geological structures, and a case study in which airborne geophysics is used for more purely geotechnical objectives. The airborne systems described in this volume are all helicopter borne systems, but one of these papers describes an unmanned helicopter geophysical system. In addition, there are more theoretical papers which discuss progress made in forward and inverse modeling of airborne electromagnetic …

Optimizing a Knowledge-driven Prospectivity Model for Gold Deposits Within Peräpohja Belt, Northern Finland

This paper combines knowledge- and data-driven prospectivity mapping approaches by using the receiver operating characteristics (ROC) spatial statistical technique to optimize the process of rescaling input datasets and the process of data integration when using a fuzzy logic prospectivity mapping method. The methodology is tested in an active mineral exploration terrain within the Paleoproterozoic Perapohja Belt (PB) in the Northern Fennoscandian Shield, Finland. The PB comprises a greenschist to amphibolite facies, complexly deformed supracrustal sequence of variable quartzites, mafic volcanic rocks and volcaniclastic rocks, carbonate rocks, black shales, mica schists and graywackes. These formations were deposited on Archean basement and 2.44 Ga layered intrusions, during the multiple rifting of the Archean basement (2.44–1.92 Ga). Younger intrusive units in the PB comprise 2.20–2.13 Ga gabbroic sills or dikes and 1.98 Ga A-type granites. Metamorphism and complex deformation of the PB took place during the Svecofennian orogeny (1.9–1.8 Ga) and were followed by intrusions of post-orogenic granitoids (1.81–1.77 Ga). The recent mineral exploration activities have indicated several gold-bearing mineral occurrences within the PB. The Rompas Au-U mineralization is hosted within deformed and metamorphosed calc-silicate veins enclosed within mafic volcanic rocks and contains uranium-bearing zones without gold and very high-grade (>10,000 g/t Au) gold pockets with uraninite and uraninite-pyrobitumen nodules. In the vicinity of the Rompas, a magnesium skarn hosted disseminated-stockwork gold mineralization was also recognized at the Palokas-Rajapalot prospect. The exploration criteria translated into a fuzzy logic prospectivity model included data derived from regional till geochemistry (Fe, Cu, Co, Ni, Au, Te, K), high-resolution airborne geophysics (magnetic field total intensity, electromagnetic, gamma radiation), ground gravity and regional bedrock map (structures). The current exploration licenses and exploration drilling sites for gold were used to validate the knowledge-driven mineral prospectivity model.

日本の地熱資源ポテンシャル調査への空中物理探査の適用性

日本国内の地熱資源ポテンシャルの調査に，空中重力偏差法探査，時間領域空中電磁探査および空中磁気探査を適用した。空中重力偏差法探査により詳細な探査結果が得られ，熱源となる可能性がある貫入岩を示唆するような高鉛直重力偏差異常の近傍に，地熱貯留層を発達させる断裂系に関連する可能性のある線状あるいは環状の重力偏差リニアメントが示された。空中電磁探査で得られた低比抵抗異常と空中磁気探査で得られた低磁気異常が地熱兆候の指標である帽岩や熱水変質帯の分布を示唆しているケースがあることも示された。これらの空中物理探査で得られた個々の物性指標は必ずしも地熱兆候を示唆するものとは限らないが，物性指標が重複する場所は地熱資源ポテンシャルが高いと考えられる。これらの結果に坑井での温度情報を利用した温度構造を組み合わせることで地熱資源ポテンシャルの評価が可能になる。

Application of support vector machines for copper potential mapping in Kerman region, Iran

The first step in systematic exploration studies is mineral potential mapping, which involves classification of the study area to favorable and unfavorable parts. Support vector machines (SVM) are designed for supervised classification based on statistical learning theory. This method named support vector classification (SVC). This paper describes SVC model, which combine exploration data in the regional-scale for copper potential mapping in Kerman copper bearing belt in south of Iran. Data layers or evidential maps were in six datasets namely lithology, tectonic, airborne geophysics, ferric alteration, hydroxide alteration and geochemistry. The SVC modeling result selected 2220 pixels as favorable zones, approximately 25 percent of the study area. Besides, 66 out of 86 copper indices, approximately 78.6% of all, were located in favorable zones. Other main goal of this study was to determine how each input affects favorable output. For this purpose, the histogram of each normalized input data to its favorable output was drawn. The histograms of each input dataset for favorable output showed that each information layer had a certain pattern. These patterns of SVC results could be considered as regional copper exploration characteristics.

Identifying potential mineralisation targets through airborne geophysics - The Western Papua New Guinea Case study

Over the last few years exploration activity in Papua New Guinea (PNG) has declined to alarming lows that the Mineral Resources Authority (MRA) has introduced initiatives to acquire new geo-scientific datasets to enhance exploration in the country. One such initiative has been the 30,000 plus line kilometre airborne magnetic and radiometric survey over the western part of the country. The airborne survey was strategically located between the large Ok Tedi porphyry copper-gold mine and the advanced Frieda River porphyry copper-molybdenum prospect. The airborne datasets were acquired at a north-south line spacing of 500m with a Tie-line spacing of 5km and at nominal terrain clearance of 100m. The main aim of the airborne geophysical survey was to identify magnetic and radiometric anomalies that may be further investigated for their mineral potential. Preliminary results of the airborne survey show large deep-seated NW-trending fault systems cross-cut by north-east trending transfer structures that may have contributed to mineral deposition in the region. Several magnetic and radiometric anomalies located within the periphery of existing prospects also have the potential to substantially increase resource values, while isolated anomalies may indicate new targets for further exploration. While this paper highlights some of the interesting magnetic and radiometric features defined from the WPAGS, the release of the datasets now ensures investors have an extra layer of information to build on the mineral potential of the surveyed area. It is anticipated that the results from the survey will not only boost interest to explore in the area, but also drive exploration activities in the area to new heights, hopefully resulting in the identification of new mineral prospects.

Locating hidden channels for placer gold exploration in the Cariboo District, British Columbia, Canada: A case study

During the past 150years, most of the modern day creeks were the target of miners roaming the Cariboo Mountains, British Columbia, in the search for placer gold. In these days, the probability to locate new placer gold occurrence in recent river beds is therefore substantially reduced. New, promising exploration targets appear to be channels mostly buried under alluvial cover sediments. It is airborne geophysical methods that can reveal hidden channels fast and cost-effectively as these penetrate the sub-surface contactless and reflect physical properties of the sub-surface, such as electric conductivity and magnetic susceptibility or magnetization, respectively.We applied the airborne geophysical exploration approach on four exploration areas in the Cariboo gold district. Helicopter-borne transient electromagnetic (TEM) and magnetic data were flown using the SkyTEM system. To our knowledge, it has been innovatory to apply high resolution, high density airborne geophysics in the search for placer gold deposited in pre-Holocene sedimentary channel fills of the Cariboo Mountains. A particular effort of our studies aimed at the Mary creek claims which straddle the boundary of the Quesnel and Kootenay terranes of the Canadian Cordillera and include the dormant Toop mine situated in the Mary creek area known for many finds of coarse nugget from the pre-glacial buried Toop channel. Our objective was to locate the southbound extension of the channel buried in Pleistocene sediments of the Toop plateau. Careful analysis of the airborne geophysical data sets provided indications from both the TEM and magnetic data sets favouring the existence of a hidden channel beneath the plateau.The evaluation of seven reverse circulation (RC) drill holes sunk into a promising elongated narrow conductor beneath the plateau was not conclusive as not clearly showing the sedimentary pattern of a channel with gravels typically at its bottom. Only electric conductivity-depth sections compiled from the airborne TEM and 2D direct current (DC) multi-electrode resistivity ground survey data enabled the interpretation of the airborne TEM and magnetic responses recorded over the Toop plateau. The sections suggest that the electric conductor is generated by an upwarp of a conductive layer extending at the bottom of the Pleistocene sediments. Another feature separated by ≤100m from the conductor line is reflected by low electric conductivity, but is rarely prominent through its neat magnetic signature. Fine accumulations of black minerals, i.e. magnetite grains, in sediments of the area are frequently met when panning material from the creeks. We therefore interpret this low conductivity, magnetic feature as expression of a gravel lense hosting accumulations of magnetite grains and possibly indicating the southbound extension of the Toop channel beneath the plateau.Careful analysis of the airborne magnetic data set led to the result in that magnetite is not only wide-spread in present day rivers and creeks, but also in buried channels and palaeo precipitation run-off paths. Magnetic data proved to be very helpful in this project with regard of pursuing not only present day, but buried valleys and channels, in particular.Our experience made on the Mary creek claims is summarized in a straightforward exploration concept for hidden, possibly gold-bearing channels in the Cariboo gold district.

Mapping and discriminating the Pan-African granitoids in the Hoggar (southern Algeria) using Landsat 7 ETM+ data and airborne geophysics

This study presents a multidisciplinary approach to discriminate and map different types and generations of Pan-African granitoids in the Hoggar, southern Algeria, using remote sensing and airborne geophysics in close correlation with previous works and established geological maps. RGB (Red, Green, Blue) combinations of band ratios; principal component analysis (PCA) and image classification for Landsat 7 ETM+ (Enhanced Thematic Mapper Plus), allow spatial discrimination and mapping of granitoid rocks of the studied area (200*350 km). This area extend over four contrasted Pan-African terranes (In Tedeini, Iskel, Tefedest and Laouni terranes, the two latter belong to the LATEA (Laouni-Azrou-n-Fad-Tefedest-Egéré-Aleksod-Assodé-Issalane) metacraton. The airborne magnetic intensity provides a wide range of responses from high values (youngest granitoids) to low values (volcano-sedimentary and gneissic country-rocks). Radiometric data, displaying radioelements concentration, discriminate efficiently the late alkaline granitoids (high values), the calk-alkaline granitoids (intermediate values) and the Tonalite-Trondhjemite-Granodiorite series (low values). This study led to the establishment of a more accurate geological map where the geochemical characteristics of the Pan-African granitoids are determined, including plutons not yet studied, especially in the poorly known In Tedeini terrane, and brings new constraints for the geodynamic development of the Tuareg Shield, which includes the Hoggar.

Remote Sensing of Landscape Change in Permafrost Regions

AbstractAmplification of global warming in Arctic and boreal regions is causing significant changes to permafrost‐affected landscapes. The nature and extent of the change is complicated by ecological responses that take place across strong gradients in environmental conditions and disturbance regimes. Emerging remote sensing techniques based on a growing array of satellite and airborne platforms that cover a wide range of spatial and temporal scales increasingly allow robust detection of changes in permafrost landscapes. In this review, we summarise recent developments (2010 − 15) in remote sensing applications to detect and monitor landscape changes involving surface temperatures, snow cover, topography, surface water, vegetation cover and structure, and disturbances from fire and human activities. We then focus on indicators of degrading permafrost, including thermokarst lakes and drained lake basins, thermokarst bogs and fens, thaw slumps and active‐layer detachment slides, thermal erosion gullies, thermokarst pits and troughs, and coastal erosion and flooding. Our review highlights the expanding sensor capabilities, new image processing and multivariate analysis techniques, enhanced public access to data and increasingly long image archives that are facilitating novel insights into the multi‐decadal dynamics of permafrost landscapes. Remote sensing methods that appear especially promising for change detection include: repeat light detection and ranging, interferometric synthetic aperture radar and airborne geophysics for detecting topographic and subsurface changes; temporally dense analyses at high spatial resolution; and multi‐sensor data fusion. Remotely sensed data are also becoming used more frequently as driving parameters in permafrost model and mapping schemes. Copyright © 2016 John Wiley & Sons, Ltd.

Helicopter AFMAG (ZTEM) EM and magnetic results over sedimentary exhalative (SEDEX) lead-zinc deposits at Howard’s Pass in Selwyn Basin, Yukon

In 2008, a regional scale 24,675 line-km survey covering a 25,000 km2 area (1 km line spacing) was flown in the Selwyn Basin. The survey footprint straddles east-central Yukon and overlaps into the western North-west Territories. In March 2013, Yukon Geological Survey purchased the survey data and, in November 2013, released the data publicly. The Selwyn Basin area is prospective for sedimentary exhalative (SEDEX)-style Pb–Zn–Ag mineralisation and the z-axis tipper electromagnetic (ZTEM) survey data provide insights into regional structures and plutons in the region. The survey overflew the Howard’s Pass SEDEX deposits at the south-eastern edge of the Selwyn Basin survey area that hosts a ~250 million tonne resource with ~4.5% Zn and ~1.5% Pb. Airborne geophysics has not been extensively used in SEDEX exploration of the Selwyn Basin and the ZTEM survey is one of the few publicly available airborne audio-frequency magnetic (AFMAG) EM-magnetic datasets that offer the opportunity to study the deposit response at Howard’s Pass in close detail.Rock physical properties indicate that the lowest resistivities are associated with the Road River Group that contains the Pb–Zn mineralised horizon at Howard’s Pass, but also include graphitic shales in the same formation. Major NW–SE to ESE and minor NNW–SSE linear conductive trends correlate with known regional geologic, structural and inferred mineral trends that were previously not visible in magnetic results. At the deposit scale, a thin NW–SE trending conductive lineament extends along the > 37-km-long ‘Zinc Corridor’ horizon at Howard’s Pass, but must include both the Pb–Zn sulphide mineralisation deposit horizon as well as the surrounding graphitic black shales. 2D and 3D ZTEM inversions reveal zones of enhanced conductivity along strike and at depth that appear to correlate with the clustering of Pb–Zn deposits, which had not been previously noticed.

3D aquifer mapping employing airborne geophysics to meet India's water future

With the growing dependence on groundwater, escalating demand, and increasing depletion of aquifers, the Government of India has accorded special emphasis to management of groundwater resources through precise aquifer mapping. We have carried out hydrogeophysical surveys, including airborne electromagnetic (AEM), in six hydrogeologically divergent areas comprising sedimentary basins, basalts, weathered and fractured granite gneisses and schists, desert, and costal alluvium with the objective to establish suitability of AEM for a countrywide aquifer mapping in India. Efficacy of the dual-moment AEM surveys in mapping the shallow and deep aquifers is evaluated in conjunction with geologic, geophysical, and borehole data. It is found that the AEM surveys provide reliable images of the subsurface resistivity distribution defining the 3D geometrical and electrical attributes of aquifers in different areas. The surveys helped identify the suitable zones for managed artificial recharge (MAR), subsurface structures controlling the groundwater conditions, regional continuity of principal aquifers, palaeoriver channels, variations in lithologic character of aquifers, and the quality of water in terms of salinity, etc. In this paper, we present the efficacy of the aquifer-mapping approach illustrated by an example from an alluvium-covered hard-rock terrain (Dausa, Rajasthan), where a weathered-fractured aquifer system with compartmentalization under alluvium cover is mapped. The integrated data set, comprising AEM, aeromagnetic, ground geophysical, and borehole measurements, was utilized to derive lithologic and hydrogeologic maps useful in developing an aquifer-based groundwater-management plan.

Copper potential mapping in Kerman copper bearing belt by using ANFIS method and the input evidential layer analysis

Earth science information used in mineral potential mapping has an empirical component comprising an exploration database and a conceptual component comprising an expert knowledge base. The hybrid neuro-fuzzy model combines conceptual and empirical components of available earth science information for predictive mineral potential mapping effectively. This paper describes a neuro-fuzzy model, which combines exploration data in the regional scale for copper potential mapping in Kerman copper bearing belt in south of Iran. Data layers or evidential maps are in six datasets namely lithology, tectonic, airborne geophysics, ferric alteration, hydroxide alteration, and geochemistry. The modeling result was 1044 pixels selected as favorable in order to continue the copper exploration in the study area; in other words, approximately 11.7 % of the area was selected. Fifty six known deposits out of 86 ones, equal to 65 % of all, were located in favorable zone. Other main goals of this study were to determine how each input affects favorable output. For this purpose, the histogram of each normalized input data with its favorable output was drawn. The histograms of each input dataset for favorable output showed that each information layer has a certain behavioral pattern. These behavioral patterns can be considered as regional copper exploration criteria.

Satellite imagery and airborne geophysics for geologic mapping of the Edembo area, Eastern Hoggar (Algerian Sahara)

Satellite imagery combined with airborne geophysical data and field observations were employed for new geologic mapping of the Edembo area in the Eastern Hoggar (Tuareg Shield, Sahara). Multi-spectral band fusion, filtering, and transformation techniques, i.e., band combination, band-rationing and principal component analysis of ETM+ and ASTER data are used for better spectral discrimination of the different rocks units. A thematic map assessed by field data and available geologic information is compiled by supervised classification of satellite data with high overall accuracy (>90%). The automated extraction technique efficiently aided the detection of the structural lineaments, i.e., faults, shear zones, and joints. Airborne magnetic and Gamma-ray spectrometry data showed the pervasiveness of the large structures beneath the Paleozoic sedimentary cover and aeolian sands. The aeroradiometric K-range is used for discrimination of the high-K granitoids of Djanet from the peralumineous granites of Edembo, and to verify the Silurian sediments with their high K-bearing minerals. The new geological map is considered to be a high resolution improvement on all pre-existing maps of this hardly accessible area in the Tuareg Shield. Integration of the airborne geophysical and space-borne imagery data can hence provide a rapid means of geologically mapping areas hitherto poorly known or difficult to access.

A general framework of TOPSIS method for integration of airborne geophysics, satellite imagery, geochemical and geological data

This work presents the promising application of three variants of TOPSIS method (namely the conventional, adjusted and modified versions) as a straightforward knowledge-driven technique in multi criteria decision making processes for data fusion of a broad exploratory geo-dataset in mineral potential/prospectivity mapping. The method is implemented to airborne geophysical data (e.g. potassium radiometry, aeromagnetic and frequency domain electromagnetic data), surface geological layers (fault and host rock zones), extracted alteration layers from remote sensing satellite imagery data, and five evidential attributes from stream sediment geochemical data. The central Iranian volcanic-sedimentary belt in Kerman province at the SE of Iran that is embedded in the Urumieh–Dokhtar Magmatic Assemblage arc (UDMA) is chosen to integrate broad evidential layers in the region of prospect. The studied area has high potential of ore mineral occurrences especially porphyry copper/molybdenum and the generated mineral potential maps aim to outline new prospect zones for further investigation in future. Two evidential layers of the downward continued aeromagnetic data and its analytic signal filter are prepared to be incorporated in fusion process as geophysical plausible footprints of the porphyry type mineralization. The low values of the apparent resistivity layer calculated from the airborne frequency domain electromagnetic data are also used as an electrical criterion in this investigation. Four remote sensing evidential layers of argillic, phyllic, propylitic and hydroxyl alterations were extracted from ASTER images in order to map the altered areas associated with porphyry type deposits, whilst the ETM+ satellite imagery data were used as well to map iron oxide layer. Since potassium alteration is generally the mainstay of porphyry ore mineralization, the airborne potassium radiometry data was used. The geochemical layers of Cu/B/Pb/Zn elements and the first component of PCA analysis were considered as powerful traces to prepare final maps. The conventional, adjusted and modified variants of the TOPSIS method produced three mineral potential maps, in which the outputs indicate adequately matching of high potential zones with previous working and active mines in the region.

Airborne Geophysical Survey in Kosova

Airborne Geophysical Survey in Kosova

Review of the Senegalo-Malian shear zone system – Timing, kinematics and implications for possible Au mineralisation styles

The Kédougou Kénieba Inlier (KKI) of eastern Senegal forms a typical Paleoproterozoic greenstone belt characterised by low-metamorphic sequences of volcanic rocks and volcano-sediments that have been intruded at various stages by gabbroic suites and calc-alkaline granitoids. The main structures of the KKI comprise two anastomosing structures about N–S trending shear belts that are distinguished into the western Main Transcurrent Zone (MTZ) and the eastern Senegalo-Malian shear zone system (SMSZ). These shear belts are taken to define the limits between the western Mako, the central Diale-Kéniebandi and the eastern Daléma-Kofi domains even though transitions exist between their characteristic deposition sequences.Remote sensing analysis of airborne geophysics and satellite data (Landsat, ENVI, SRTM) in combination with geological field mapping, structural analysis and geochronology suggests that the SMSZ represents a Birimian structure that records a main stage of deformation that could characterise the major transcurrent Eburnean tectonics (D2) dated from 2105Ma (Feybesse et al., 2006a–e). This sinistral transpressive deformation marked by a major constraint oriented NNW–SSE, is accompanied by a NNE–SSW extension leading to the opening of dilational areas such as small pull-apart basins marked by local calk-alkaline volcanic sequences and several coeval intrusions of the Boboti Suite dated 2080±0.9Ma (Hirdes and Davis, 2002). A post-Birimian to pre-Neoproterozoic deformation post dates the transcurrent phase and is marked by regional N–S extension.Review of the existing Au-mineralisation models in combination with the spatial analysis of soil geochemical data suggest seven possible mineralisation styles that are related to the transpressional tectonics and coeval magmatism.

Controls on porphyry Cu mineralization around Hanza Mountain, south-east of Iran: An analysis of structural evolution from remote sensing, geophysical, geochemical and geological data

Hanza Mountain in Urmia–Dokhtar Magmatic Arc, southeast of Iran, consists of monocline of Eocene volcanic rocks into which the Oligocene granitoid rocks have been intruded. This area has excellent potential for economic porphyry copper deposits with Bondar Hanza, Daralu, and Sarmesk deposits among them. Hanza Mountain is located between NW–SE horsetail thrust faults derived from the Gowk and Sabzevaran strike-slip faults. The analysis of the kinematics of these strike-slip faults shows that they were not the cause of the formation of the pull-apart basin; thus they have not directly played any effective role in localizing the final emplacement of porphyries responsible for the formation of these copper deposits, but the Cu mineralization occurred mainly within a set of normal and thrust faults in the region. The alteration types and faults in Bondar Hanza were distinguished using detailed local geology, including distribution of known mineralization, supported by remote sensing (ASTER), airborne geophysics, and topography; the relationship between mineralization and faults was examined using Rose diagrams and Fry Analysis. This investigation of Bondar Hanza deposit has revealed that the trend of faults and dykes, as well as the distribution of copper analyses within drill cores, is aligned with the main trend of mineralization. The NW–SE trending faults in the Urmia–Dokhtar Magmatic Arc are effective in localizing the emplacement of porphyry copper ore deposits and those that trend between N125°–N145° are key to further exploration.

Using AHP Method in GIS for PCDs Potential Mapping in Southeast of Iran

Generally, during the preliminary exploration stages of porphyry copper deposits (PCDs), the mineralization and exploration targets will be evaluated using mineral potential modeling that includes recognizable mineralization determination criteria, data preparation, generating factor maps, and combining of factor maps into the appropriate inference networks. The most important PCDs are related to subduction activity (Guilbert, 1986; Sawkins, 1990). Urmia– Dokhtar Magmatic Arc (UDMA) Porphyry copper deposit belt, which passes through Iran, is one of the most important examples of this kind of geodynamic setting. Several PCDs include Sarcheshmeh, which is the world’s eighth in terms of contained copper and gold (Cook et al, 2005), are located in the NW-SE trending (UDMA). This study area is located in southern part of UMDA in Southeast of Iran in 1:100000 Sarduiye geology sheet. There are some occurrences and PCDs in this region among which are Sarmashk, Daralou, and Bondar Hanza. In fact, Sarduiyeh area is a monocline from volcanic rocks, such as rhyolite and andesite, of Eocene age with intrusions of younger granodiorite and granite rocks. The aim of this paper is the predication of copper porphyry mineralization in the study area by using of the Analytical Hierarchy Process (AHP) method in GIS. To this end, geological data, Aster satellite images, airborne geophysics, and stream sediment geochemical data have been used.