Volatile Fluxes Through the Northern Kamchatkan Volcanic Arc


DOEI Project Funded: 2006

Klyuchevsky volcano, located in northern Kamchatka is one of the most active and productive volcanoes in the world (Fig. 1, below). It has been proposed that this exceptional productivity is related to a tear in the subducting Pacific plate which allows for influx of fertile mantle material to a region characterized by a high degree of melting due to fluid inputs from the subducting Pacific plate. Fluids released from sediments and the oceanic lithosphere of the subducting plate play a pivotal role in the melting process beneath volcanic arc systems. Through combined gas and melt inclusion work, this study aims to 1) test whether the absolute flux of volatiles such as CO2 and SO2 from Klyuchesky volcano is high relative to other arc volcanoes given its high magma productivity, and 2) evaluate whether the influx of fertile melt has modified the melting process at Klyuchevsky volcano.

An estimate of the present day volatile flux will be obtained by analyzing He-C abundances and isotopes of gas samples collected in the field, whereas melt inclusion studies combined with magma production rates will yield a historical record of volatile fluxes. Melt inclusions (Fig. 2, below) are trapped during crystal growth and are thought to preserve primary melt compositions, thereby yielding valuable information regarding mantle source characteristics. Using WHOI’s ion probe facility, major volatiles (techniques to be developed on the 1280 instrument through this proposal) and trace elements will be measured on the same inclusions, allowing for the degree of melting and the source components (fertile mantle, sediments, altered oceanic crust) to be identified. The multi-analysis approach of this project will clarify the role of fluids fluxing through the Kamchatkan volcanic arc and assess whether the mantle supply is distinct from typical arc volcanoes sources.

Volcanic rocks, as well as gas and hot spring fluids at various geothermal localities will be collected by A. Shaw at Klyuchevsky volcano in September of 2006. This expedition, funded through the National Astrobiology Institution, is a collaborative effort with astrobiologists from various institutions (Carnegie Institution of Washington, the Australian Center for Astrobiology and the Russian Astrobiology Center) whose goal is to test the limits of life using various isotopic and microanalytical techniques in the extreme environment surrounding Klyuchevsky volcano. Understanding the chemical characteristics of magmatic inputs at this site is fundamental if any attempts to distinguish abiogenic from biogenic signatures are to be made.