TY - JOUR
T1 - Possible presence of high-pressure ice in cold subducting slabs
AU - Bina, Craig R.
AU - Navrotsky, Alexandra
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2000/12/14
Y1 - 2000/12/14
N2 - During the subduction of oceanic lithosphere, water is liberated from minerals by progressive dehydration reactions1,2 and is thought to be critical to several geologically important processes such as island-arc volcanism3, intermediate-depth seismicity4 and chemical exchange between the subducting lithosphere and mantle5. Although dehydration reactions would yield supercritical fluid water in most slabs, we report here that the stable phase of H2O should be solid ice VII in portions of the coldest slabs. The formation of ice VII as a dehydration product would affect the generation, storage, transport and release of water in cold subduction zones and equilibrium conditions of dehydration would shift, potentially affecting the dephts of seismogenesis and mag-magenesis. Large amounts of pure ice VII might accumulate during subducion and, as a sinking slab warms, eventual melting of the ice would release large amounts of water in a small region over a short period of time, with a significant positive volume change. Moreover, the decreasing availability of fluid water, owing to the accumulation of ice VII and its subsequent reaction products in a cooling planetary interior (for example, in Mars or the future Earth), might eventually lead to a decline in tectonic ectivity or its complete cessation.
AB - During the subduction of oceanic lithosphere, water is liberated from minerals by progressive dehydration reactions1,2 and is thought to be critical to several geologically important processes such as island-arc volcanism3, intermediate-depth seismicity4 and chemical exchange between the subducting lithosphere and mantle5. Although dehydration reactions would yield supercritical fluid water in most slabs, we report here that the stable phase of H2O should be solid ice VII in portions of the coldest slabs. The formation of ice VII as a dehydration product would affect the generation, storage, transport and release of water in cold subduction zones and equilibrium conditions of dehydration would shift, potentially affecting the dephts of seismogenesis and mag-magenesis. Large amounts of pure ice VII might accumulate during subducion and, as a sinking slab warms, eventual melting of the ice would release large amounts of water in a small region over a short period of time, with a significant positive volume change. Moreover, the decreasing availability of fluid water, owing to the accumulation of ice VII and its subsequent reaction products in a cooling planetary interior (for example, in Mars or the future Earth), might eventually lead to a decline in tectonic ectivity or its complete cessation.
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U2 - 10.1038/35048555
DO - 10.1038/35048555
M3 - Article
C2 - 11130720
AN - SCOPUS:0034649518
SN - 0028-0836
VL - 408
SP - 844
EP - 847
JO - Nature
JF - Nature
IS - 6814
ER -