ANALISIS FASIES VULKANOKLASTIK DESA SIDODADI, PAGELARAN, KABUPATEN PRINGSEWU PROVINSI LAMPUNG

Abstract

Sumatra Island is a subduction zone between the Indian-Australian plate which subducts under the Sundaland plate obliquely during the Oligocene-Quarter age. This event was followed by the formation of volcanoes in the fault segment and produced a lot of volcanic material due to the volcanism that occurred, one of which was pyroclastic material. Until now, there are still few studies that discuss pyroclastic materials in this area. The research was conducted with the aim of identifying facies and facies associations in the research area. Data collection was carried out in Sidodadi Village, Pagelaran, Pringsewu Regency, Lampung Province, by direct observation of outcrops and making lateral stratigraphic cross sections. The results of this study divided the outcrop into eight facies, based on the differences in the physical characteristics of the field and its stratigraphic data. The eight facies are: massive coarse tuff facies (F1), coarse tuff parallel laminated facies (F2), cross layered facies cross layered wedget coarse tuff (F3), massive lapilli facies (F4), normal cross-bedded lapilli facies (F5) , laminated facies parallel to fine tuff (F6), laminated facies parallel to lapilli (F7), and massive facies fine tuff (F8), with facies associations belonging to the pyroclastic density current (PDC). The results showed that there was a similarity in lithology, which was mostly dominated by pumice, with a unique structure in the form of layers and ambiguous crosses on the outcrop which became a marker that this research area was included in the Lampung Formation.