LEBONG SIMPANG

Geology) 
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Diposting oleh Naim Emel Prahana

The Lebong Simpang thermal area is about 23 km NE, along the Sumatera Fault Zone, from the regional capital of Curup. Only one spring is present in the area and it has a temperature of 95oC with a flow of 0.25 l/s and a pH of 3.87. The ground is hydrothermally altered surrounding the spring but the total natural heat flow from the field will be very small.
Directly to the south is the inactive volcano of Bukit Daun which has had two periods of andesitic volcanism in the Plio-Pleistocene and upper Quaternary. The pumice breccia and lithic tuff breccia sequence through which the spring emerges is considered to be the youngest erupted material from Bk.Daun (Akbar & Hasan, 1986). 3 km to the SE of the spring is an obsidian flow and pyroclastics which was erupted in the period between the phases of andesitic volcanism on Bk.Daun. Tertiary volcanics, sandstones and fine grained carboaceous volcanogenic sediments underlie the Plio-Pleistocene andesites.
Several semi-continuous NW-SE trending Sumatera Fault Zone faults cut the area near Lebong Simpang and the permeability of the area may also be affected by the N-S to NE-SW faults which occur to the north (Akabar & Hasan, 1986).
Positive factors indicating a possible resource in the area are the proximity of young Quaternary volcanics including silicic lithologies and the high temperatures of the spring. The field however is situated in an active tectonic zone and more surface feature would be expected if a major resource was present but the permeability may also be affected by the presence of the fine grained sediments at depth.

REFERENCES
Bachri, S., 1972. Inventarisasi dan penyelidikan pendahuluan terhadap gejala-gejala panasbumi di Provinsi Bengkulu. Unpublished Report, Direktorat Vulkanologi, Departemen Pertambangan Dan Energi, Bandung Indonesia.
Van Padang, N., 1951.