ANALISIS FASIES PADA FORMASI HULUSIMPANG PEKON WAY MANAK, SUKAAGUNG, SUKAMARA, KABUPATEN TANGGAMUS, LAMPUNG

The Hulusimpang Formation is located in the Bukit Barisan strip and is part of the Woyla terrane associated with Cretaceous volcanic arcs. Research on the Lampung formation, especially the Hulusimpang Formation, is still a little researched. This research was conducted to determine the facies, facies association and depositional environment of the Hulusimpang Formation. The study of facies analysis uses a measured stratigraphic cross section and divides the rock into several facies and facies associations. The facies analysis data was taken from Pekon Way Manak, Sukaagung, Sukamara, Tanggamus Regency. The Hulusimpang Formation consists of seven facies, namely tuff facies (F1), claystone facies (F2), siltstone facies (F3), black siltstone facies (F4), sandstone facies (F5), limestone facies (F6), mudstone facies (F7) . The facies found were grouped into four facies associations, namely channel facies association (AF1) and levee facies association (AF2), creverse splay facies association (AF3), and exposure facies association (AF4). AF1 consists of F1, AF2 consists of F2, F3, F4, F5, AF3 consists of F6, and AF4 consists of F7. Based on the facies association found in the Hulusimpang Formation, it indicates that the depositional environment is Fluvial-Shallow Sea.