Linking arc volcanic fluxes and growth rates with Pleistocene climate change: Marine tephrostratigraphy of the Aleutian‐Alaska volcanic arc
Understanding of polar ice melt is advancing..
Susanne M. Straub and Gisela Winckler
Lamont Doherty Earth Observatory, Palisades, NY, U.S.A.
The long‐standing observation that the frequency of arc volcanism changesperiodically in intensity has led to many hypotheses and models as to cause‐and‐effect relationships and feedbacks mechanisms with the global climate (Cambray and Cadet, 1994; Jegen et al., 2010; Jicha et al., 2009; Kennett and Thunell, 1975; Prueher and Rea, 1998; Prueher and Rea, 2001). For example, global cooling has been proposed to follow the enhanced injection of climatically‐active gases and aerosols into the atmosphere (Jicha et al., 2009; Kennett and Thunell, 1975; Prueher and Rea, 1998; Prueher and Rea, 2001), that may possibly be followed by positive feedbacks, such as an increased albedo of snow covers and ice sheets, or the biological drawdown of CO2 driven by the release of nutrients from dissolving ash into the oceans (e.g. Jones and Gislason, 2008). In a recent study, Huybers and Langmuir (2009) proposed that glacially induced volcanism, triggered by the depressurization of the upper mantle increased the frequency of volcanic eruptions worldwide, and thus plays a key role in the atmospheric CO2 balance and ice‐age cycles. A link between arc volcanism and the 41 ka Milankovitch periodicity also emerges from a statistical evaluation of macroscopically visible marine tephra deposits near circum‐Pacific arcs (Jegen et al., 2010). On a more immediate scale, Tuffen (2010) concluded that ongoing glacier recession likely will result in intensification of eruptions worldwide, with a corresponding increase in associated hazards.
While these studies suggest causal links between volcanic frequency and climate change, the global approaches remain inconclusive as to magnitude, causes and feedback mechanisms. Testing time‐cause relationships between arc volcanism and climate needs an integrated approach where reliable data on the frequency of arc volcanism can be combined with data on volcanic emissions of climatically active volatiles and arc growth rates, and in addition can be directly related to the other parameters of climate change, such as ice volume data, IRD (ice‐rafted debris) input, etc..
We propose that the Pleistocene Aleutian‐Alaska arc system provides thesecharacteristics and therefore represents an ideal system for addressing a key question of the GeoPRISMS Draft Science Plan (Subduction and Deformation cycles): ‘How do surface processes and climate modulate volatile inputs and outputs at subducting margins and vice versa’
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