scholarly journals TARGETING HYDROTHERMAL ALTERATIONS UTILIZING LANDSAT-8 ANDASTER DATA IN SHAHR-E-BABAK, IRAN

2017 ◽  
Vol XLII-4/W5 ◽  
pp. 153-157
Author(s):  
M. Safari ◽  
A. B. Pour ◽  
A. Maghsoudi ◽  
M. Hashim
Keyword(s):  
Mineral Exploration ◽  
Porphyry Copper ◽  
Color Space ◽  
Sensor Data ◽  
Color Contrast ◽  
Landsat 8 ◽  
Porphyry Copper Deposits ◽  
Alteration Zones ◽  
Magmatic Arc ◽  
Band Combinations

Shahr-e-Babak tract of the Kerman metalogenic belt is one of the most potential segments of Urumieh–Dokhtar (Sahand-Bazman) magmatic arc. This area encompasses several porphyry copper deposits in exploration, development and exploitation hierarchy. The aim of this study is to map hydrothermal alterations caused by early Cenozoic magmatic intrusions in Shahr-e-Babak area. To this purpose, mineral mapping methods including band combinations, ratios and multiplications as well as PCA and MNF data space transforms in SWIR and VNIR for both ASTER and OLI sensors. Alteration zones according to spectral signatures of each type of alteration mineral assemblages such as argillic, phyllic and propylitic are successfully mapped. For enhancing the target areas false color composites and HSI-RGB color space transform are performed on developed band combinations. Previous studies have proven the robust application of ASTER in geology and mineral exploration; nonetheless, the results of this investigation prove applicability of OLI sensor from landsat-8 for alteration mapping. According to the results, evidently OLI sensor data can accurately map alteration zones. Additionally, the 12-bit quantization of OLI data is its privilege over 8-bit data of ASTER in VNIR and SWIR, thus OLI high quality results, which makes it easy to distinguish targets with enhanced color contrast between the altered and unaltered rocks.

scholarly journals EVALUATING CROSTA TECHNIQUE FOR ALTERATION MINERAL MAPPING IN MALANJKHAND COPPER MINES, INDIA

2018 ◽  
Vol XLII-5 ◽  
pp. 251-254
Author(s):  
S. Guha ◽  
H. Govil ◽  
M. Tripathi ◽  
M. Besoya
Keyword(s):  
Iron Oxides ◽  
Near Infrared ◽  
Mineral Exploration ◽  
Landsat 8 ◽  
Carbonate Minerals ◽  
Diagnostic Features ◽  
Alteration Zones ◽  
Mineral Mapping ◽  
Copper Mines ◽  
Band Combinations

<p><strong>Abstract.</strong> Landsat-8 Operational Land Imager (OLI) data has been successfully employed in the field of mineral exploration to detect important minerals. In this study, Crosta technique was applied to identify the diagnostic features of hydroxyl minerals, carbonate minerals and iron oxides in Malanjkhand copper mines, India. The Crosta technique was applied to six [blue, green, red, near-infrared (NIR), shortwave infrared1 (SWIR1), shortwave infrared2 (SWIR2) bands and two sets of four (blue, red, NIR, SWIR1; and blue, near-infrared, SWIR1, SWIR2) bands of OLI data. Results show that the areas with alteration zones are enhanced much better by using six bands of OLI data. The alteration differences are examined with the Crosta technique using four band combinations. Crosta technique is very useful in generating the images of hydroxyl minerals, carbonate minerals, and iron oxides.</p>

Porphyry Copper Discovery Beneath the Valeriano Lithocap, Chile

SEG Discovery ◽  
2016 ◽  
pp. 1-20
Author(s):  
Richard H. Sillitoe ◽  
Claudio Burgoa ◽  
David R. Hopper
Keyword(s):  
Gold Mineralization ◽  
Porphyry Copper ◽  
Northern Chile ◽  
Porphyry Copper Deposits ◽  
Copper Deposits ◽  
Alteration Zones ◽  
Copper Gold ◽  
Drill Holes

ABSTRACT Exploration for porphyry copper deposits beneath barren or poorly mineralized, advanced argillic lithocaps is becoming common­place; however, there have been few discoveries except in cases where the copper ± gold ± molybdenum mineralization has been partly exposed, typically as a result of partial lithocap erosion. At Valeriano, in the high Andes of northern Chile, completely concealed Miocene porphyry copper-gold mineralization was recently discovered beneath a lithocap. Here, the results of the staged drilling program that led to the discovery are summarized, with emphasis on the key geologic, alteration, and mineralization features that provided guidance. The final deep drill holes of the 16-hole program cut well-defined advanced argillic and sericitic alteration zones before entering chalcopyrite ± bornite–bearing, potassic-altered porphyry, with grades of 0.7 to 1.2% Cu equiv, at depths of ~1,000 to &gt;1,800 m.

Zircon Petrochronology of the Meghri-Ordubad Pluton, Lesser Caucasus: Fingerprinting Igneous Processes and Implications for the Exploration of Porphyry Cu-Mo Deposits

2019 ◽  
Vol 114 (7) ◽  
pp. 1365-1388 ◽  
Author(s):  
Hervé Rezeau ◽  
Robert Moritz ◽  
Jörn-Frederik Wotzlaw ◽  
Samvel Hovakimyan ◽  
Rodrik Tayan
Keyword(s):  
Trace Element ◽  
Mineral Exploration ◽  
Porphyry Copper ◽  
Trace Element Composition ◽  
Element Composition ◽  
Porphyry Copper Deposits ◽  
Copper Deposits ◽  
Magmatic Processes ◽  
Lesser Caucasus ◽  
Intrusive Suite

Abstract The trace element composition of zircon, especially in tandem with U-Pb geochronology, has become a powerful tool for tracing magmatic processes associated with the formation of porphyry copper deposits. However, the use of the redox-sensitive Eu and Ce anomalies as a potential mineral exploration proxy is controversial. This study presents a comprehensive, temporally constrained data set of zircon trace element compositions (n = 645) for three compositionally distinct magmatic series identified in the Meghri-Ordubad pluton, southernmost Lesser Caucasus. The 30 million years of Cenozoic magmatism in the Meghri-Ordubad pluton are associated with several ore-forming pulses leading to the formation of porphyry copper deposits and epithermal-style mineralization. Our zircon geochemical data constrain the thermal and chemical evolution of this complex intrusive suite and allow an evaluation of the usefulness of zircon as a mineral exploration proxy for porphyry copper deposits. Our results combined with Rayleigh fractionation modeling indicate that the trace element composition of zircon (Th/U, Hf, Ti, YbN/DyN, Eu anomalies) is influenced by the composition and the water concentration of the parental magma, as well as by co-crystallizing titanite and apatite. In contrast, the variations of Ce anomalies remain difficult to explain by magmatic processes and could rather be ascribed to relative fluctuations of the redox conditions. In the Meghri-Ordubad pluton, we do not observe any systematic patterns between the trace element composition in zircons and the different ore-forming pulses. This questions the reliability of using the trace element composition in zircon as an exploration mineral proxy, and it rather emphasizes that a good knowledge of the entire magmatic evolution of a metallogenic province is required.

scholarly journals A Comparative Study of Porphyry-Type Copper Deposit Mineralogies by Portable X-ray Fluorescence and Optical Petrography

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 431 ◽  
Author(s):  
Connor Gray ◽  
Adrian Van Rythoven
Keyword(s):  
Mineral Exploration ◽  
Porphyry Copper ◽  
Fluorescence Analysis ◽  
Copper Deposit ◽  
Porphyry Copper Deposits ◽  
Rock Composition ◽  
X Ray ◽  
Core Logging ◽  
Ore Minerals ◽  
Optical Mineralogy

Porphyry-type deposits are crucial reserves of Cu and Mo. They are associated with large haloes of hydrothermal alteration that host particular mineral assemblages. Portable X-ray fluorescence analysis (pXRF) is an increasingly common tool used by mineral prospectors to make judgments in the field during mapping or core logging. A total of 31 samples from 13 porphyry copper deposits of the Western Cordillera were examined. Whole-rock composition was estimated over three points of analysis by pXRF. This approach attempts to capture the rapid and sometimes haphazard application of pXRF in mineral exploration. Modes determined by optical petrography were converted into bulk rock compositions and compared with those determined by pXRF. The elements S, Si, Ca, and K all were underestimated by optical mineralogy, and the elements Cu, Mo, Al, Fe, Mg, and Ti were overestimated by optical mineralogy when compared with pXRF results. Most of these porphyry samples occur in veined porphyritic quartz monzonite that is characteristic of these deposits. Sulfide and silicate vein stockworks are pervasive in most of the samples as well as dissemination of sulfides outwards from veinlets. Ore minerals present include chalcopyrite and molybdenite with lesser bornite. Chalcocite, digenite, and covellite are secondary. Potential sources of analytical bias are discussed.

scholarly journals Tectonic setting of Cretaceous porphyry copper deposits of northern Chile (28°-30° S) and its relations with magmatic evolution and metallogeny

2020 ◽  
Vol 47 (3) ◽  
pp. 469
Author(s):  
Christian Creixell ◽  
Javier Fuentes ◽  
Hessel Bierma ◽  
Esteban Salazar
Keyword(s):  
Early Cretaceous ◽  
Late Cretaceous ◽  
Porphyry Copper ◽  
Northern Chile ◽  
Porphyry Copper Deposits ◽  
The West ◽  
Copper Deposits ◽  
Magmatic Arc ◽  
Fault Systems ◽  
Back Arc

Cretaceous porphyry copper deposits of northern Chile (28º-29º30’ S) are genetically related with dacitic to dioritic porphyries and they represent a still poorly-explored target for Cu resources. The porphyries correspond to stocks distributed into two separated discontinuous NS trending belts of different age. The location of these porphyries is generally adjacent to orogen-parallel major fault systems that extend along the studied segment and also have a marked temporal relationship with deformation events registered along these structures. A first episode of Cu-bearing porphyry emplacement took place between 116 and 104 Ma (Mina Unión or Frontera, Cachiyuyo, Punta Colorada, Dos Amigos, Tricolor porphyries). These Early Cretaceous dacite to diorite porphyries are spatially associated with the eastern segments of the Atacama Fault System, which records sinistral transpression that started at 121 Ma producing ground uplift, consequent denudation and exhumation of the Early Cretaceous magmatic arc. This resulted in a change from marine to continental deposition with an angular unconformity in the site of the back-arc basin after of eastward migration of the deformation around 112-110 Ma. At the scale of the continental margin, this deformation is correlated with early stage of the Mochica Orogenic event described in Perú. A second episode of Cu-bearing porphyry emplacement occurred between 92 and 87 Ma (Elisa, Johana, Las Campanas and La Verde deposits), which are spatially and temporally associated with the regional-scale Las Cañas-El Torito reverse fault, active between 89 and 84 Ma, during the Peruvian Orogenic Phase. This fault up thrust to the west part of the Chañarcillo Group rocks (Lower Cretaceous) over the younger upper levels of the Cerrillos Formation (Upper Cretaceous). The integrated geological mapping and geochemical data of the Early to Late Cretaceous volcanic rocks indicates that both Early Cretaceous sinistral transpression and Late Cretaceous east-west compression were not significant in promote changes in magma genesis, except for slight changes in trace element ratios (increase in Th/Ta, Nb/Ta and La/Yb) suggesting that the Late Cretaceous deformation event produced only slightly increase in crustal thickness (>40 km), but far from being comparable to major Cenozoic orogenic phases, at least along the magmatic arc to back-arc domains in the study area. Finally, our study give insights about regional geological parameters that can be used as a first order guide for exploration of Cu resources along Cretaceous magmatic belts of northern Chile, where both Early and Late Cretaceous Cu-bearing porphyry intrusions are restricted to a large structural block bounded to the west and east by Cretaceous fault systems.

MAPPING PORPHYRY COPPER DEPOSITS IN THE PHILIPPINES WITH IP

Geophysics ◽  
1976 ◽  
Vol 41 (1) ◽  
pp. 106-122 ◽  
Author(s):  
William H. Pelton ◽  
Peter K. Smith
Keyword(s):  
Structural Control ◽  
Electrical Response ◽  
Porphyry Copper ◽  
Geographical Area ◽  
Structural Features ◽  
The Philippines ◽  
Induced Polarization ◽  
Porphyry Copper Deposits ◽  
Copper Deposits ◽  
Alteration Zones

The induced polarization (IP) method has played a very important role in the recent discovery of several new Philippine porphyry copper deposits. It was found, however, that the electrical response measured over different deposits can be extremely variable, even in a limited geographical area. Four main classes of response have been recognized; these appear to arise primarily from different structural control and possibly from differing levels of erosion in the Lowell and Guilbert (1970) and Hollister et al. (1974) porphyry copper models. Since the distribution of economic mineralization is highly dependent upon erosional level and structural control. It is important in IP interpretation to (1) recognize the type of deposit (2) determine the position of controlling structural features, and (3) map the existing alteration zones, before attempting to define the location of economic mineralization.

scholarly journals The Mineralization and Structural Geology of the Porphyry Copper Deposits of Pakistan

2021 ◽  
Vol 19 (2) ◽  
pp. 130-136
Author(s):  
Syed Tallataf Hussain Shah ◽  
Nangyal Ghani Khan ◽  
Muhammad Imran Hafeez Abbasi ◽  
Kamran Tabassum ◽  
Syed Khaizer Wahab Shah
Keyword(s):  
Porphyry Copper ◽  
Island Arc ◽  
Fault System ◽  
Thrust Belt ◽  
Porphyry Copper Deposits ◽  
Copper Deposits ◽  
Magmatic Arc ◽  
The North ◽  
Fold And Thrust Belt ◽  
Late Tertiary

The purpose of this review is to shed light on copper deposits found in different regions of Pakistan. The geological attributes of copper deposits have been considered with their tectonic context. The porphyry copper deposits can be traced in Pakistan from the north through Kohistan Island Arc (KIA) up to the south to Chaghi Magmatic Arc (CMA). These deposits are mainly found in and around the Late Tertiary–Early Tertiary Himalayan Belt, Kohistan magmatic arc, Karakorum Block Foreland fold and thrust belt, Ophiolite Thrust belt, Suture zone and Chaghi Magmatic Arc. These deposits in Pakistan are chiefly established in different episodes of tectonic regimes, including subduction processes, oceanic island arc, continental arc, along with Chaman- OrnachNal Fault system and post-collisional settings.

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