Analysis of composition and chronology of dome emplacement at Black Peak, Alaska utilizing ASTER remote sensing data and field-based studies
J.N. Adleman 

Introduction:

Black Peak caldera is one of approximately 80 volcanic centers that erupted during the Holocene along the 2,760km long Aleutian Arc that stretches from southern Alaska to Russia’s Kamchatka Peninsula (Fig. 1; Miller, 1998). Breaching the caldera wall spilling out onto the southeastern flank and within the caldera are approximately one dozen overlapping, post-caldera lava domes that are generally coeval in age and have bulk rock compositions that range from andesite to dacite. Brief reconnaissance fieldwork conducted prior to the 2003 field season (McGimsey and Neal, 2001) and the 2003 field campaign at Black Peak provides the first comprehensive mapping investigation and opportunity to collect data on the composition and surface textures of the domes within and surrounding Black Peak caldera. The presence of approximately one dozen overlapping lava domes and associated flows which may have contrasting ages, mineralogies, compositions, and alterations make Black Peak caldera an excellent location to use thermal infrared (TIR) remote sensing data in combination with ground based field work, petrology and geochemistry, to formulate a remote sensing based map of the features of the domes.

Satellite remote sensing techniques are currently being applied to examine volcanic regions and can provide important information on the spatial coverage of volcanic deposits. Launched on board NASA’s Earth Observing Satellite (EOS) Terra in 1999, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is the first sun-synchronous, polar orbiting satellite collecting more than two bands in the TIR (Kuhn, 2003). Thus, ASTER satellite data is unique in its capacity to be utilized for studies discerning textural, compositional and mineralogic variations on silicic domes using the emissivity properties of the ground surface collected in multiple thermal bands. ASTER has been used to look at petrologic and compositional variations in the silicic domes of Medicine Lake Volcano, CA and at Bezymianny volcano in Kamchatka, Russia (Eisinger, 2000; Ramsey, 2004). Additionally, laboratory derived spectroscopic signatures are often used to augment and verify the satellite data and associate specific spectral characteristics with rock and surface properties and the proportions of different rock types and/or surface features included within each pixel for a given area covered by a satellite image (Ramsey, 1998). Previous work (Ramsey, 1993, 1997, 1999) has focused on applying satellite remote sensing techniques to study variations in vesicularity and mineralogy to better understand lava dome formation and vesiculation processes.

The focus of this study combines petrological, geochemical, field, and remote sensing methods to assess the viability of using TIR remote sensing data in a complex volcanic region. This study applies processed satellite imagery (Ramsey, 1998) combined with field observations and petrologic analyses to better understand the timing of emplacement, age relations, and relative chemistry and petrology of the overlapping domes and flows within Black Peak caldera. The goal of this study is to present a method for applying processed ASTER satellite imagery to field and laboratory studies of volcanic rocks in order to constrain spatial and age relationships and test the ability of satellite data to discern chemical and petrological differences among overlapping lava domes.. Given the amount of unstudied and unmapped volcanic regions in Alaska, the use of ASTER for preliminary investigation of remote volcanoes may be cost effective and efficient, and will be valuable in directing the focus of future studies along the Alaska Peninsula and Aleutian arc.

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