HR: 1340h
AN: V43D-1640    [Abstracts]
TI: Island-arc magmatic processes beneath South Pagan Volcano, Northern Mariana Islands
AU: * Marske, J P
EM: marske@hawaii.edu
AF: Department of Geology and Geophysics, SOEST, University of Hawaii, 1680 East West Rd., Honolulu, HI 96822, United States
AU: Trusdell, F A
EM: trusdell@usgs.gov
AF: Hawaii Volcano Observatory, United States Geological Survey, 51 Crater Rim Dr., Hawaii National Park, HI 96718, United States
AU: Garcia, M O
EM: garcia@soest.hawaii.edu
AF: Department of Geology and Geophysics, SOEST, University of Hawaii, 1680 East West Rd., Honolulu, HI 96822, United States
AU: Pietruszka, A J
EM: apietrus@geology.sdsu.edu
AF: Department of Geological Sciences, San Diego State University, 5500 Campanile Dr., San Diego, CA 92182, United States
AB: The island-arc volcanoes that make up the Northern Mariana Islands are among the most historically active stratovolcanoes along the Pacific plate, yet they have been poorly studied due to their remote location and difficult accessibility. One of the least studied areas in the Northern Mariana Islands is Pagan Island, located near the center of the Mariana ridge. Pagan Island consists of two Holocene stratovolcanoes, Mount Pagan and South Pagan. Remarkably little is known about South Pagan including its eruptive history, potential volcanic hazards, and geochemical evolution due to a small population of inhabitants, a short and intermittent recorded history, and few geological studies. There is abundant evidence that eruption of South Pagan could pose significant hazards to both residents of the Northern Mariana Islands and to aircraft flying in the western Pacific. For example, following Mount Pagan's most recent explosive eruption (VEI = 4) in 1981, destructive rain-triggered volcanic debris flows buried large tracts of land, including the site of a village that contained a school, dispensary, church, and power generating buildings. Preliminary field studies in May 2006 by the USGS showed that a full spectrum of hazardous phenomena originated from South Pagan in the past, including pyroclastic flows and surges, caldera collapses, and volcanic debris flows. Two previously unrecognized active fumaroles near the summit of South Pagan were discovered suggesting that potential volcanic hazards currently exist in this area. A majority of the new lava samples are vesicular, clinopyroxene-plagioclase basalts with minor plagioclase xenocrysts and gabbroic xenoliths. The purpose of this study is to understand the compositional history of South Pagan and how it relates to the crustal and mantle magmatic processes beneath the central Northern Mariana Islands. Pb, Sr and Nd isotope ratios, major and trace element abundances, and mineral chemistry were determined and will be presented.
DE: 1036 Magma chamber processes (3618)
DE: 1040 Radiogenic isotope geochemistry
DE: 1065 Major and trace element geochemistry
DE: 3613 Subduction zone processes (1031, 3060, 8170, 8413)
DE: 3620 Mineral and crystal chemistry (1042)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting