Identification of alteration zones using a Landsat 8 image of densely vegetated areas of the Wayang Windu Geothermal field, West Java, Indonesia

• Published in: IOP conference series. Earth and environmental science Vol. 254; no. 1; pp. 12004 - 12013
• Main Authors: Salamba, Kristian Edwin, Hawu Hede, Arie Naftali, Nur Heriawan, Mohamad
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.04.2019
• Subjects: Andesite; Anomalies; Basalt; Breccia; Composition; Cristobalite; Fault detection; Fluorescence; Fractures; Ground truth; Image acquisition; Landsat; Landsat satellites; Mineral composition; Minerals; Polls & surveys; Principal components analysis; Pumice; Quaternary; Reflectance; Remote sensing; Satellite imagery; Satellites; Soil analysis; Spacecraft recovery; Spatial data; Spectral reflectance; Tuff; X-ray diffraction; X-ray fluorescence; West Java Indonesia; Indonesia
• ISSN: 1755-1307; 1755-1315; 1755-1315
• DOI: 10.1088/1755-1315/254/1/012004

Remote sensing is a method usually used for conducting geothermal reconnaissance surveys by mapping surface alteration anomalies, which are captured by a satellite sensor. This study analyzes the characteristics of the surface alteration zones in the Wayang Windu geothermal field (WWGF). It employs a remote sensing method using multispectral Landsat 8 imagery and is validated by ground truth data from field surveys. The WWGF is located in Pangalengan, West Java with an elevation of 1500-2600 m.a.s.l., and lies in a quaternary volcanic arc. The rock types in Wayang Windu consist of andesite, basalt, tuff, breccia, and pumice. Fractures and faults are identified as lineaments in this area and based on their structures, were directed to be oriented northwest-southeast and northeast-southwest. This research combined a field survey and remote sensing methods to enhance the spatial data. Field surveys yield 18 spots for obtaining soil samples and laboratory analyses were performed. Spectral reflectance analysis was performed to determine the reflectance and mineral composition of the samples, X-ray diffraction was performed to determine the mineral composition, and X-ray fluorescence was performed to determine the abundance of elements. A scene from Landsat 8 image acquired on September 10, 2013 was evaluated using a principal component analysis-based method. The surface alteration zones in the WWGF correlated with joints and faults. Based on the mineral composition, the surface alteration zones in WWGF were identified as advanced argillic zone with the occurrence of secondary minerals such as cristobalite and halloysite, and a propylitic zone with the occurrence of secondary minerals such as epidote and chlorite.