Geology of Sitimulyo, Puncakwangi-Todanan district, Pati-Blora regency, Central Java Province

Abstract

Eisar, M., 2008. Geology of Sitimulyo, Puncakwangi-Todanan district, Pati-Blora regency, Central Java Province. Geological Mapping Report, Unpublished, Geological Engineering Department, Engineering Faculty, Diponegoro University, Semarang, Central Java, Indonesia. By physiographic region, including research into the zone Rembang is part of the sedimentary basin north of East Java. This curvature extends from the West-East, approximately 250 km. Changes gradually towards the north into the North Java Sea basin, to the west associated with the North West Java Basin, south again until Kendeng Basin and East continues to include the island of Madura. In Rembang zone as a whole is characterized by facies changes namely from a regression Transgresi facies. The striking difference litologi zone of Rembang caracteristic marked with rocks yield high sand content in addition to increasing carbonate and disappearance pyroclastic deposits. Zone sediments suggest a Rembang shallow marine sediments that are not far from the beach with sedimentation environment litoral zone to zone batial with depth 500 meters. Zenith zone by tectonic systems can be classified into back arc basins ( "back arc basin") is filled by sediments thick Cenozoic age and over again starting from the Eocene to Pleistocene. In the Miocene-Pliocene basin underwent tectonic regime of compression, geological structure resulting in folds and fault-fault. State structures folded in the North East Java Basin generally Western-directional East, is caused by compression forces from the North-South. While directional fracture structure Northeast - Southwest. There is also one piece wing anticline (monocline) in the research area shown with the direction of strike / dip the same in each layer of rock with the direction of East-West strike and dip directions to the North. Mountain Zone Rembang - Madura structural units that are better known under the name "Northern Java Hinge Belt" can be separated into 2 parts of the northern ( "Northern Rembang Anticlinorium ") and southern (" Middle Rembang Anticlinorium "). Section north have experienced a stronger adoption compared with the south resulting in erosion until the formation Tawun, sometimes even until the formation Kujung Down. In the study there are 5 formations, from older to younger; Ngrayong formation (just above Tawun Formation), Upper Feather Formation, Formation Wonocolo, Formation Ledok, and Mundu Formation. Each formation from older to younger undergo a process of precipitation in the plain gradually. Keywords: Zone of Rembang, Transgression, Regression, Anticlinorium