Petrography and geochemistry preliminary study of Pucangan Serpentinite Geosite Karangsambung – Karangbolong Geopark Central Java, Indonesia

Geosite is a Geological Heritage object in the Geopark area with specific characteristics and is an integral part of the evolutionary history of forming an area. Serpentinite Pucangan is one of the Geosite located in Karangsambung – Karangbolong geopark. This study aims to find out the characteristics of petrography and geochemistry of Serpentinite Pucangan Geosite. The methods used in this study include literature studies, fieldwork research, petrography analysis, ore microscopy analysis, whole rock analysis consist of major element analysis using fusion inductively coupled plasma (Fus ICP) methods, trace element analysis, and rare earth element analysis using inductively coupled plasma mass spectrometry (ICP-MS) methods. Serpentine minerals with antigorite type dominate the petrography composition of Pucangan serpentinite with a little magnetite mineral. SiO₂, MgO, and Fe₂O₃(t) are the major elements with the largest percentage of 37.93%, 5.78%, and 9.73% that have an agreement with the mineralogical composition of the rock that dominated by ferromagnesian minerals. This Geosite is interpreted to be formed due to the metasomatic process when the subduction process is happening in this area in the Pre-tertiary period.