Clay mineralogy of landslide occurrences in hydrothermally altered area: A case study of Durensari Area, Purworejo, Central Java

• Main Authors: Putra Ilham Dharmawan, Titisari Anastasia Dewi, Husna Hitznaiti Zaidini Khul
• Format: Article
• Language: English
• Published: EDP Sciences 2019-01-01
• Series: E3S Web of Conferences
• Online Access: https://doi.org/10.1051/e3sconf/20197602008

Landslide is one of the geological phenomena that can be found frequently in Indonesia, where several areas are damaged due to landslide occurrence. One of it is located in Durensari Area, Bagelen, Purworejo, Central Java as the study area. The study area is characterized by the presence of altered volcanic rocks formed by the tertiary eruption, followed by hydrothermal alteration that contains clay minerals that could enhance the landslide occurrence. This study is conducted to identify hydrothermal clay minerals that which enhanced the landslide in the study area. Field mapping is done as field observation, as well as the clay minerals are identified from 10 samples using X-Ray Diffraction (XRD) as the study method. The observation has resulted that there are at least ±25 landslide occurrence points in the study area, which is associated with alteration type that consists of several clays, named by smectite, kaolinite, and illite assemblages as argillic alteration and chlorite, smectite, illite, and kaolinite assemblages as propylitic alteration. The research concluded that the replacement process of primary minerals by clay minerals and the presence of smectite affect the landslide occurrence in the study area, where moderate to the large landslide is associated with Argillic alteration, meanwhile small to moderate landslide is associated with propylitic alteration.