Mapping of Potential Alteration Zones for Mineralization Prospects Using Remotely Sensed Data: Case of Mankayan Mineral District, Benguet in Cordillera Administrative Region (CAR), Philippines

Abstract. Mineral exploration through remote sensing has become integral, employing satellite or airborne imagery, to assess and characterize surface features indicative of concealed mineral deposits. Multispectral imagery is used to detect surface features including mineral alteration zones, vegetation stress, and soil geochemical anomalies, which are often associated with subsurface mineralization. This study focuses on the Mankayan Quadrangle, with emphasis on the Far Southeast (FSE) Project in northeastern Luzon, Philippines. The FSE is a copper-gold porphyry deposit. The mineral district serves as a calibration site for geological mapping, lineament delineation, and alteration zone identification. However, challenges arise due to the tropical climate and dense vegetation. This study evaluates the suitability of remote sensing for updating geological maps and generating potential mineralization maps. Data include Sentinel-2 L2A imagery and existing geological maps. Preprocessing involves spatial subsetting and resampling, while processing techniques involve contrast enhancement, color composites, spectral ratioing, and principal component analysis. The results reveal that Sentinel-2 L2A imagery effectively identifies intrusive complexes, metasedimentary rocks, pyroclastic and volcaniclastic rocks, and recent deposits. Lineament analysis reveals NE- and NW-trending splays of Ambuklao Fault. High band ratio values, >1.0 for 4/3 (ferric iron), >1.0 for 11/8 (ferric oxide), and >2.2 for 11/12 (hydroxyl and clay minerals), indicate hydrothermal alteration. Areas within approximately 2 km of fault splay intersections and hosted by pyroclastic or volcaniclastic rocks are classified as having inferred mineral resource potential. These areas include Cadad-anan, Mabaay, Lenga, Sadsadan, Dacudac, northern Monamon Sur, and the northeastern flank of Mount Data.