Hydrothermal fluid pathways and mineralization potential in the High Atlas Massif (Morocco) using fuzzy logic and multifractal modeling

Abstract

• Mining exploration in the High Atlas. • Processing of high-resolution helicopter-borne radiometric and multispectral data. • Use of the multifractal concentration-area (C-A) and fuzzy logic modeling. • Modeling the pathways of hydrothermal fluid circulation. • Mapping mineral prospecting in the western high atlas. This study aims to develop a mineral favorability map by combining various data on hydrothermal and structural alterations using an Exploration Information System (EIS). It focuses on the Tizi n’Test region, located in the western part of the Moroccan High Atlas. The data comes from the processing of ASTER satellite images, with the application of mathematical algorithms such as the Relative Absorption Band Depth (RBD) method and Crosta’s Principal Component Analysis (CPCA), which allowed for the mapping of the spatial distribution of alteration minerals. This approach helped delineate zones of argillic, phyllic, and propylitic alterations, as well as areas containing iron oxides. Radiometric data was also used to identify potassic alterations by calculating K/eTh, K/eU ratios, and the F parameter. Structural data, including magnetic lineaments and geological faults primarily oriented in a NNE-SSW, NE-SW and E-W direction, were interpreted as preferred pathways for the circulation of hydrothermal fluids, leading to structural and lithological traps. All data was integrated into a GIS using fuzzy logic. The resulting mineral favorability map was classified using the concentration-area (C-A) multifractal method to differentiate the area’s most conducive to mineralization from background noise. The final map identifies five high-potential zones, with the first three situated near the Tichka granite. The fourth and fifth zones are found along the Tizi n’Test and Ouchden faults, as well as at the interface between the Ediacaran basement of the Ouzellarh block and its Paleozoic cover. This study highlights the significant role of magmatic and tectonic processes in the development of metalliferous deposits in this area.