Integrating Aster Images Processing and Fieldwork for Identification of Hydrothermal Alteration Zones at the Oumjrane-Boukerzia District, Moroccan Anti-Atlas

Abstract

Mapping from remote sensing has become more effective in the field of geology, mainly in lithological discrimination and identification of hydrothermal alteration zones. The use of this technique consists in obtaining information about the rock mass and the main ones existing in the inaccessible areas. Satellite data from the ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) sensor represent a favorable potential for detecting the spectral signatures of mineral zones and identifying their nature. These data are more reliable in places where the climate is arid with less abundant vegetation, as at the Oumjrane-Boukerzia mining district. This region which is part of the Eastern Anti-Atlas, is composed of several mineralized veins which still require detailed studies and exploration by the technique of remote sensing. In this work we applied several processing techniques on ASTER imagery such as Colored Composition, Principal Component Analysis and Ratio Bands. The use of the reports of the specialized Bands makes it possible to identify some hydrothermal alteration minerals within the mining district of Oumjrane Boukerzia. These minerals are represented mainly by iron oxides and hydroxides (Hematite, jarosite, limonite and goethite), carbonate minerals (dolomite, calcite), clay minerals (Illite, kaolinite and chlorite) and quartz minerals. This work allows us to produce a map of hydrothermal alteration zones which can be used as a valuable reference in the strategy of mining exploration for the base metals (Cu, Pb, Zn and Ba), in the mining district of Oumjrane-Boukerzia and in the entire Eastern Anti-Atlas.

Lithological discrimination and mineralogical mapping using Landsat-8 OLI and ASTER remote sensing data: Igoudrane region, jbel saghro, Anti Atlas, Morocco

“…In addition, the VNIR-SWIR bands of Landsat-8 OLI highlighted alteration minerals, including ferrous Iron [(band7/band5) +(band3/band4)], hydroxides (band7/band4), ferric oxides (band6/band5), Iron oxide (band4/band2), and alteration-laterite (band6/band7), which are more concentrated at the level of the granitic rocks notably the pluton of Oussilkane, with a concentration of oxides and hydroxides. The [ 10 ] mapped the ferric oxides alteration in the Bas Drâa inlier using also the (band6/band5) BR and confirmed the great potential of ASTER data in lithological discrimination, while (band5/band3+band1/band2) BR detected effectively the regions of a high concentration of iron oxides and hydroxide minerals [ 36 ].…”

“…The sericite-illite-smectite were determined using the ratios (band5+band7)/band6 [ 69 ], muscovite (band7/band6) [ 70 ] as well as phengite (band5/band6) [ 70 ] extended at the sedimentary Paleozoic cover (q), the quartz diorites of the Tazzouakt pluton (j), the andesitic flows (d), the granodiorites and tonalites of the Igoudrane pluton (b). The basic degree Index SiO2 used the ratios of (band12/band13) [ 36 , 71 ], where it has a fairly large area, and this were confirmed by the X-Ray diffraction analysis with also the filed survey in which several veins of quartz and acid rocks were found. The Carbonate-Chlorite-epidote with a ratio of (band7+band9)/band 8 [ 69 ] is scattered in the western part at the Cenozoic formations (s), the Mesozoic (r), the rhyolitic flows of Jbel Igoudrane (h), the andesitic flows (d), the biotite monzogranite and hornblende (m) and the Oussilkane Pluton (c).…”

“…BR is a useful technique in remote sensing [ 13 , 44 ]. It requires dividing one band by another one to boost specified items and proprieties which can not be identified in a single band, depending mostly on the concentration of the following minerals: amphibole, carbonate, chlorite, epidote, SiO2, dolomite, ferrous silicates, muscovite, phengite, sericite, illite and smectite with ASTER, as well as iron oxides, ferric oxides, hydroxides and ferrous iron which were highlighted by Landsat-8 OLI band ratios [ 31 , 36 ]. The spectral profiles of alteration minerals were extracted from the IGCP spectral library of ENVI [ 45 ], then resampled to ASTER and Landsat-8 OLI images, showing the absorption of minerals in the VNIR and SWIR regions.…”

“…Several processing techniques was applied, included PCA, MNF, ICA and false color composites [ 35 ]. Ouhoussa (2023) Identified hydrothermal alteration areas at the Oumjrane Boukerzia, mining District, Anti Atlas, and this was accomplished by using RGB composites, PCA and BR [ 36 ].…”

ASTER Data Processing by Discrete Wavelets Transform and Band Ratio Techniques for the Identification of Lineaments and Hydrothermal Alteration Zones in Poli, North Cameroon

“…This coloration is attributed to the presence of ferric and ferrous ions in the rocks. The band ratio (B5/B3 + B1/B2), as described by Ouhoussa et al (2023), was also applied in our case to highlight oxide and hydroxide minerals in the study area. Spectral analysis of the identified zones revealed high reflectance values for wavelengths ranging from 0.1 to 1.0 μm (Figure 5 The map in Figure 5(a) displays the distribution of these minerals in red color, showing a concentration of these minerals at the center of the study area, mainly on the slopes of the hills.…”