Pemetaan Geologi dan Struktur Geologi Daerah Pemalang, Jawa Tengah

Abstract

This research was conducted in Watukumpul and surrounding areas, Pemalang Regency, Central Java with an area of approximately 45 km2. The research locations include the sub-districts of Watukumpul, Bodeh, Wanarata, Bodas, Medayu, Majakerta, and Gapura. In practice, this research was conducted to determine the geological history and surface geological conditions of the related area and specifically to study the presence and sequence of geological structures in the research area based on geometric, kinematic, and dynamic analysis. There are 5 methods used in this study including the preparation stage, the mapping stage, the data analysis stage, the report preparation stage, and the report presentation. The geomorphology of the research area is divided into 5 geomorphological units, namely the Anticlinal Hills, Denudational Plains, Syncline Hills, Anticlinic Valleys, and Intrusion Hills. The unofficial stratigraphy of this research area is the Claystone Insertion Sandstone Unit, the Claystone - Sandstone Unit, the Andesite Unit, and the Diorite Unit. The structures that developed in the area formed at the Pliocene age are the Performance Factoring Fault, the Gapura Descending Fault, the Bodas Descending Fault, and the Wanarata Menan Up Fault, and at the Holocene age namely the Medayu Upward Right-hand Sliding Fault, Longkeyang Right-hand Shear Fault, Performance Factoring Fault, Wanarata Right-Sliding Fault, Right-Sliding Fault Down the Gate. The geological history of the research area begins with the deposition of Claystone - Sandstone units at the Middle Miocene age in the Lateral Lobe environment in the Sub Marine Fan, then continues with the deposition of Sandstone - Claystone units at the Middle Miocene - Late Miocene age in the Off-Axis - Frontal Lobe environment in the Sub Marine Fans. Then experienced a great fold at the Pliocene age, followed by magmamatism activity at the Pleistocene age, and experienced a fault at the Holocene age due to the Inflation and Deflation of Mount Slamet.