HR: 1340h
AN: V53B-1557    [Abstracts]
TI: Morne aux Diables. a potentially active volcano in northern Dominica, Lesser Antilles
AU: * Rheubottom, A N
EM: alsmith@csusb.edu
AF: Department of Geological Sciences, California State Unniversity, San Bernardino, CA 92407 United States
AU: Smith, A L
EM: alsmith@csusb.edu
AF: Department of Geological Sciences, California State Unniversity, San Bernardino, CA 92407 United States
AU: Roobol, M J
EM: alsmith@csusb.edu
AF: Saudi Geological Survey, PO Box 54141, Jeddah, 21514 Saudi Arabia
AB: The island of Dominica, which is located near the center of the Lesser Antilles island arc, comprises at least 8 potentially active volcanoes. One of these is Morne aux Diables, an isolated composite cone situated at the extreme northern end of the island. Age dating suggests that the main cone building activity occurred between 1.5 and 1.0 million years ago. Exposed on the volcano's flanks however are a number of unconsolidated valley-fill block and ash flow deposits suggesting more recent activity. One of these deposits, on the north-east flank of the volcano, has been recently dated at > 46,000 years B.P. Other evidence of potential activity from this center includes the presence of warm (27°C), acidic (pH 1.6), sulfate-rich springs on the summit of the volcano, hot springs on the coast, and the occurrence in 2002 and 2003 of shallow earthquake swarms partially located beneath the volcano. Morne aux Diables is dominantly composed of deposits of block and ash flows and associated domes from Pelean-style activity, however, semi-vesicular andesite block and ash flows and surges (Asama-style activity) and pumiceous lapilli falls (Plinian-style activity) are locally abundant. The Pelean domes are located both in the summit region and along the southern flanks of the volcano. Petrologically, the volcano is composed of a monotonous series of porphyritic andesites and dacites containing phenocrysts of plagioclase+augiteñhypersthene with very sparse crystals of hornblende and quartz. Petrological models suggest the Morne aux Diables andesites and dacites can be produced by fractional crystallization of basaltic magma (such as those erupted from centers such as Morne Anglais and Morne Plat Pays in the south). Minor variations within this suite of andesites and dacites can be related to upper crustal fractionation of phenocryst phases.
DE: 8413 Subduction zone processes (1031, 3060, 3613, 8170)
DE: 8428 Explosive volcanism
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005