TY - JOUR

T1 - Fate of water transported into the deep mantle by slab subduction

AU - Ohtani, Eiji

AU - Yuan, Liang

AU - Ohira, Itaru

AU - Shatskiy, Anton

AU - Litasov, Konstantin

PY - 2018/11

Y1 - 2018/11

N2 - The roles of water in the mantle transition zone, lower mantle, and the core-mantle boundary are investigated. The evidence for a wet mantle transition zone has been suggested based on hydrous mineral inclusions in diamond. Seismic wave velocity and electrical conductivity profiles together with mineral physics data are consistent with existence of stagnant slabs in a wet mantle transition zone. The transition zone may contain continental crustal components in these stagnant slabs. Dense hydrous magmas may exist at the base of the upper mantle. Fluids or volatile-rich magmas may also exist at the top of the lower mantle due to the large contrast in water contents between the mineral assemblages in the mantle transition zone and the lower mantle, and the crossing of the convective descent of the cold hydrated materials. Dense magmas are not likely to be formed at the top of the lower mantle and hydrous magmas generated in this region move upwards and metasomatize the overlying mantle transition zone. Water can be transported deeper into the lower mantle by gravitational collapse of the stagnant slabs, which supply water into the lower mantle, including the core-mantle boundary. Hydrous δ-H solid solution may be the most important hydrous phase in lower mantle, and existence of this phase reduces the aluminum content in coexisting bridgmanite and post-perovskite, and thus modifies the physical properties of the lower mantle. Hydrous δ-H solid solution can accumulate at the base of the lower mantle. The iron-water reaction at the core-mantle boundary can also create pyrite-type FeOOH which can be a potential candidate material for the ultralow velocity zone (ULVZ).

AB - The roles of water in the mantle transition zone, lower mantle, and the core-mantle boundary are investigated. The evidence for a wet mantle transition zone has been suggested based on hydrous mineral inclusions in diamond. Seismic wave velocity and electrical conductivity profiles together with mineral physics data are consistent with existence of stagnant slabs in a wet mantle transition zone. The transition zone may contain continental crustal components in these stagnant slabs. Dense hydrous magmas may exist at the base of the upper mantle. Fluids or volatile-rich magmas may also exist at the top of the lower mantle due to the large contrast in water contents between the mineral assemblages in the mantle transition zone and the lower mantle, and the crossing of the convective descent of the cold hydrated materials. Dense magmas are not likely to be formed at the top of the lower mantle and hydrous magmas generated in this region move upwards and metasomatize the overlying mantle transition zone. Water can be transported deeper into the lower mantle by gravitational collapse of the stagnant slabs, which supply water into the lower mantle, including the core-mantle boundary. Hydrous δ-H solid solution may be the most important hydrous phase in lower mantle, and existence of this phase reduces the aluminum content in coexisting bridgmanite and post-perovskite, and thus modifies the physical properties of the lower mantle. Hydrous δ-H solid solution can accumulate at the base of the lower mantle. The iron-water reaction at the core-mantle boundary can also create pyrite-type FeOOH which can be a potential candidate material for the ultralow velocity zone (ULVZ).

KW - Core-mantle boundary

KW - Hydrous phase

KW - Lower mantle

KW - Mantle transition zone

KW - Stagnant slab

KW - Water

KW - SEISMIC EVIDENCE

KW - HIGH-PRESSURE

KW - EARTHS MANTLE

KW - STABILITY

KW - ELECTRICAL-CONDUCTIVITY

KW - TRANSITION ZONE BENEATH

KW - X-RAY-OBSERVATION

KW - PHASE DELTA-ALOOH

KW - TEMPERATURE PROFILE

KW - HYDROUS SILICATE MELT

UR - http://www.scopus.com/inward/record.url?scp=85046829785&partnerID=8YFLogxK

U2 - 10.1016/j.jseaes.2018.04.024

DO - 10.1016/j.jseaes.2018.04.024

M3 - Article

AN - SCOPUS:85046829785

VL - 167

SP - 2

EP - 10

JO - Journal of Asian Earth Sciences

JF - Journal of Asian Earth Sciences

SN - 1367-9120

ER -