Geological Summary

Gunung Tanggamus is of Quaternary age (van Bemmelen 1949b). Its products, which mostly consist of lavas, breccias, and tuffs of predominantly dacitic and andesitic composition, dominate the geology of the western part of the Lampung Province in southern Sumatra (Zulkarnain, 2011). Older Tanggamus products close to the main cone are generally pyroclastic breccias, consisting of porphyritic andesite and lapilli tuff. The younger products that make up the relatively undissected cone are of intermediate composition, and those deposits in the proximal zone surrounding the cone and in more distal regions are pyroclastic and laharic breccias and ignimbrites (Husein et al., 2015). The ignimbrites appear to be younger than the pyroclastic breccias (Husein et al., 2015). The lavas on Tanggamus are vesicular and porphyritic, and at about 1.4 million years old, are younger than the pyroclastic breccias and ignimbrites. The laharic breccias, consisting of porphyritic andesite and pumice, yielded an age of 1.5 Ma; however, field observations indicate that these units may be younger (Husein et al., 2015).

References

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

Husein S, Setianto A, Nurseto S T, Koestono H, 2015. Tectonic control to geothermal system of Way Panas, Lampung, Indonesia. Proceedings, World Geothermal Congress: Melbourne, Australia, 19-25 April 2015.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior.

van Bemmelen R W, 1949. The Geology of Indonesia. The Hague: Government Printing Office, v 1, 732 p.

Zulkarnain I, 2011. Geochemical evidence of Island-Arc origin for Sumatra Island; a new perspective based on volcanic rocks in Lampung Province, Indonesia. Indonesian Journal of Geology, v. 6, no. 4, p. 213-225.