Synergy of Remote Sensing Data for Exploring Hydrothermal Mineral Resources Using GIS-Based Fuzzy Logic Approach

Mohamed Abdelkareem,Nassir Al-Arifi

doi:10.3390/rs13224492

Abstract

The Arabian Nubian Shield (ANS) contains a variety of gold deposits in the form of veins and veinlets formed by hydrothermal fluids. Characterizing potential areas of hydrothermal alteration zones therefore provides a significant tool for prospecting for hydrothermal gold deposits. In this study, we develop a model of exploration for hydrothermal mineral resources in an area located in the ANS, Egypt, using multiple criteria derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Landsat-Operational Land Imager (OLI), and Sentinel-2 data and field work through GIS-based fuzzy logic approach. The hydrothermal alteration zones (HAZs) map extracted from combining mineral indices, spectral bands, and ratios is consistent with observed argillic alteration zones around the mineralized veins. Combining HAZs and lineament density led to identification of six zones based on their mineralization potential, and provides a tool for successful reconnaissance prospecting for future hydrothermal mineral deposits. The detected zones are labeled as excellent, very high, high, moderate, low, and very low, based on their potential for Au production, and the predictive excellent and very high zones cover about 1.6% of the study area. This model also shows that target prospective zones are quartz veins controlled by NNW-SSE trending fracture/fault zones all crosscutting Precambrian rocks of the ANS. Field observations and petrographic and X-ray diffraction analyses were performed to validate the mineral prospective map and revealed that quartz veins consist of gold–sulfide mineralization (e.g., gold, pyrite, chalcopyrite, and sphalerite). Consistency between the high potential hydrothermal alterations zones (HAZs) and the location of gold mineralization is achieved.

Highlights

The mineral exploration process is typically carried out at different scales using various tools such as remote-sensing, geological field work, geophysical exploration, and geochemical surveying (e.g., [1,2])
In this study, we focus on combining remote-sensing, geologic, field, and laboratory data sets to delineate the potential areas of hydrothermal mineral resources and develop a comprehensive scheme that would facilitate future exploration for hydrothermal ores in the Eastern Desert (ED) of Egypt
The data processing technique utilized shows no particular relationships between gold occurrences and specific lithological units, but rather displays a strong relationship between the distributions of auriferous quartz veins/dikes and zones of extensive hydrothermal alteration

Summary

Introduction

The mineral exploration process is typically carried out at different scales using various tools such as remote-sensing, geological field work, geophysical exploration, and geochemical surveying (e.g., [1,2]). The substantial progress in processing remotely-sensed images has allowed for identifying rocks and minerals based on their spectral properties using multispectral and/or hyperspectral sensors in the visible-near-infrared (VNIR) and the shortwave infrared (SWIR) regions of the electromagnetic spectrum (EMS) [1–13]. The use of remote-sensing has been extended to mineral exploration by careful characterization of fault/fracture zones and/or hydrothermal alteration minerals [1,8,9,14–17] containing Al-OH, Fe-OH, Mg-OH, Si-OH, and -CO3 radicals [1,18,19]. These key radicals are integral constituents of minerals that form by advanced argillic alteration (e.g., kaolinite and alunite) and phyllic alteration (e.g., sericite, illite), and they have recognized Al-OH absorption in the SWIR [15,20–22]. These HAZs are arranged based on their intensity around the center of the ores in successive zones [9]

Results

Discussion

Conclusion