GEOLOGI DAN ANALISIS FASIES PADA PIROKLASTIK FORMASI RANAU DAERAH TANJUNGMENANG ILIR DAN SEKITARNYA, OGAN KOMERING ULU (OKU) SELATAN, SUMATERA SELATAN
Daftar Isi:
- The research area is in the village of Tanjung Menang Ilir and its surroundings, South Ogan Komering Ulu (OKU), South Sumatra Province. The study was conducted aimed at knowing the geomorphic processes that affect the formation of landforms, the condition of the development of structures that work, the spread of rock lithology in the study area. Specifically analyzing volcanic facies in pyroclastics and compiling the geological history that developed in the study area. The research methods carried out in the form of field observations, studio work and laboratory analysis. The study area has a morphology of hills, included in the category of flat or very flat slopes to steep slopes with slope class 0% - 38%. Geomorphic units of the study area are divided into four units namely; irregular meanders and pointbar deposits (IMPD), low hills with flat-sloping slopes (PRD), hills with flat-sloping slopes (PDT), hills with rather steep slopes (PCT). The research area consists of 3 formations namely; Baturaja Formation in the form of limestone unit lithology, Gumai Formation in the form of sandstones, siltstone, and siltstone and tuff lithology which is the youngest depositional part of the Ranau Formation. In the first deposition phase there was a transgression phase in the Early-Middle Miocene which formed limestone deposition from the Baturaja Formation. Furthermore, in the Middle Miocene, the Gumai Formation deposited by tilting which consisted of sandstone, sandstone, and siltstone. Then in the next phase there was a silt volcano eruption which produced tuff rock units. During the process of settling the tuff unit at the age of Pliocene, there was an ongoing disharmony. This area is a pyroclastic fallout with tuff lithology in the Ranau Formation (Qtr). This tuff formation process is derived from Quaternary volcanic material. Based on aspects of the data obtained in the form of lithology, profile and morphology, the study area is included in the medial-distal facies, namely pyroclastic flow rich in pumis and distal fine ash fall.