In this section
@article{Davies:2016:10.1002/2015GC006125,
author = {Davies, DR and LeVoci, G and Goes, S and Kramer, SC and Wilson, CR},
doi = {10.1002/2015GC006125},
journal = {Geochemistry Geophysics Geosystems},
pages = {78--100},
title = {The Mantle Wedge's Transient 3-D Flow Regime and Thermal Structure},
url = {http://dx.doi.org/10.1002/2015GC006125},
volume = {17},
year = {2016}
}
TY - JOUR
AB - Arc volcanism, volatile cycling, mineralization, and continental crust formation are likely regulated by the mantle wedge's flow regime and thermal structure. Wedge flow is often assumed to follow a regular corner-flow pattern. However, studies that incorporate a hydrated rheology and thermal buoyancy predict internal small-scale-convection (SSC). Here, we systematically explore mantle-wedge dynamics in 3-D simulations. We find that longitudinal “Richter-rolls” of SSC (with trench-perpendicular axes) commonly occur if wedge hydration reduces viscosities to inline image Pa s, although transient transverse rolls (with trench-parallel axes) can dominate at viscosities of inline image Pa s. Rolls below the arc and back arc differ. Subarc rolls have similar trench-parallel and trench-perpendicular dimensions of 100–150 km and evolve on a 1–5 Myr time-scale. Subback-arc instabilities, on the other hand, coalesce into elongated sheets, usually with a preferential trench-perpendicular alignment, display a wavelength of 150–400 km and vary on a 5–10 Myr time scale. The modulating influence of subback-arc ridges on the subarc system increases with stronger wedge hydration, higher subduction velocity, and thicker upper plates. We find that trench-parallel averages of wedge velocities and temperature are consistent with those predicted in 2-D models. However, lithospheric thinning through SSC is somewhat enhanced in 3-D, thus expanding hydrous melting regions and shifting dehydration boundaries. Subarc Richter-rolls generate time-dependent trench-parallel temperature variations of up to inline image K, which exceed the transient 50–100 K variations predicted in 2-D and may contribute to arc-volcano spacing and the variable seismic velocity structures imaged beneath some arcs.
AU - Davies,DR
AU - LeVoci,G
AU - Goes,S
AU - Kramer,SC
AU - Wilson,CR
DO - 10.1002/2015GC006125
EP - 100
PY - 2016///
SN - 1525-2027
SP - 78
TI - The Mantle Wedge's Transient 3-D Flow Regime and Thermal Structure
T2 - Geochemistry Geophysics Geosystems
UR - http://dx.doi.org/10.1002/2015GC006125
UR - http://hdl.handle.net/10044/1/28808
VL - 17
ER -