[S-RD24] Cutting-edge sensing technology applied to geology and resource exploration

[SRD24-05] Utilizing Landsat 8 and ASTER to Map Hydrothermally Altered Minerals in Mankayan, Benguet, Philippines

★Invited Papers

*Jenielyn Tuando Padrones¹、Jayson L. Arizapa¹、Jan Joseph V. Dida¹、Cristino L. Tiburan Jr ¹、Arvin Trinidad²、Eric S. Andal²、Ryohei Takahashi³ (1.Institute of Renewable Natural Resources, College of Forestry and Natural Resources, University of the Philippines Los Baños, College, Laguna、2.Apex Mining Company Inc. Ortigas Center, Pasig City, Metro Manila、3.Graduate School of International Resource Sciences, Akita University, Tegatagakuen-machi, Akita, Japan)

キーワード：hydrothermal alteration, remote sensing, spectral analysis

Multi-spectral mapping using available remote sensing methods and remotely-sensed images have recently been utilized in delineating alteration zones. This study exemplifies the use of such technology in one of the areas in the tropical regions where extensive vegetation cover is prevalent. The study area is located in Mankayan, Benguet Province which is a part of the several mining districts in the region. Mankayan mining district is home to several small-scale mining operations as well as large mining tenements such as the Lepanto Cu-Au, Victoria Au deposits, Far Southeast porphyry Cu, Buaki and Palidan porphyry Cu, Nayak and Suyok epithermal Cu, and several other metals. Mineralization and primary minerals alteration are brought about by hydrothermal fluids, which changed the physicochemical characteristics of the surrounding rocks. In the study area, advanced argillic to argillic zones consisting of primarily quartz-alunite exist alongside potassic and propylitic zones of chlorite-kaolinite and smectite were observed. An initial hydrothermal-alteration map was created using Principal Components Transformation and Band Rationing for Landsat OLI and ASTER data. In order to lessen the impact of the dense vegetation cover in the research location, further processing also included software defoliation. The sites of the hydrothermally altered mineral assemblage were determined by combining the resulting images from both Landsat OLI and ASTER. Spectral wavelengths of quartz, smectite, chlorite-kaolinite, and plagioclase were used to identify pure pixels in the ASTER image, which show better capability in differentiating among minerals but have limited capability in differentiating iron oxides. Moreover, Landsat OLI mineral mapping is better for hydroxyl-bearing groups and Fe- oxide minerals. Combining the resultant maps showed the locations of the various alteration zones in Mankayan. XRD validation of minerals show accurate detection in both the sensors.