scholarly journals Water in the Earth's Interior. Is the mantle transition zone a water reservoir?

2000 ◽  
Vol 10 (2) ◽  
pp. 124-133 ◽  
Author(s):  
Toru INOUE
Keyword(s):  
Transition Zone ◽  
Water Reservoir ◽  
Mantle Transition Zone ◽  
Earth’S Interior ◽  
Earth's Interior

scholarly journals Heavy iron in large gem diamonds traces deep subduction of serpentinized ocean floor

2021 ◽  
Vol 7 (14) ◽  
pp. eabe9773
Author(s):  
Evan M. Smith ◽  
Peng Ni ◽  
Steven B. Shirey ◽  
Stephen H. Richardson ◽  
Wuyi Wang ◽  
...  
Keyword(s):  
Transition Zone ◽  
Ocean Floor ◽  
Reaction Products ◽  
Mantle Transition Zone ◽  
Tectonic Plates ◽  
Ni Alloys ◽  
Serpentinized Peridotite ◽  
Metallic Inclusions ◽  
Oceanic Basalts ◽  
Earth’S Interior

Subducting tectonic plates carry water and other surficial components into Earth’s interior. Previous studies suggest that serpentinized peridotite is a key part of deep recycling, but this geochemical pathway has not been directly traced. Here, we report Fe-Ni–rich metallic inclusions in sublithospheric diamonds from a depth of 360 to 750 km with isotopically heavy iron (δ56Fe = 0.79 to 0.90‰) and unradiogenic osmium (187Os/188Os = 0.111). These iron values lie outside the range of known mantle compositions or expected reaction products at depth. This signature represents subducted iron from magnetite and/or Fe-Ni alloys precipitated during serpentinization of oceanic peridotite, a lithology known to carry unradiogenic osmium inherited from prior convection and melt depletion. These diamond-hosted inclusions trace serpentinite subduction into the mantle transition zone. We propose that iron-rich phases from serpentinite contribute a labile heavy iron component to the heterogeneous convecting mantle eventually sampled by oceanic basalts.

scholarly journals Distribution, cycling and impact of water in the Earth's interior

2017 ◽  
Vol 4 (6) ◽  
pp. 879-891 ◽  
Author(s):  
Huaiwei Ni ◽  
Yong-Fei Zheng ◽  
Zhu Mao ◽  
Qin Wang ◽  
Ren-Xu Chen ◽  
...  
Keyword(s):  
Deep Water ◽  
Plate Tectonics ◽  
Water Distribution ◽  
Seismic Velocity ◽  
Water Cycle ◽  
Critical Role ◽  
Water Reservoir ◽  
Plate Motion ◽  
Earth’S Interior ◽  
Earth's Interior

Abstract The Earth's deep interior is a hidden water reservoir on a par with the hydrosphere that is crucial for keeping the Earth as a habitable planet. In particular, nominally anhydrous minerals (NAMs) in the silicate Earth host a significant amount of water by accommodating H point defects in their crystal lattices. Water distribution in the silicate Earth is highly heterogeneous, and the mantle transition zone may contain more water than the upper and lower mantles. Plate subduction transports surface water to various depths, with a series of hydrous minerals and NAMs serving as water carriers. Dehydration of the subducting slab produces liquid phases such as aqueous solutions and hydrous melts as a metasomatic agent of the mantle. Partial melting of the metasomatic mantle domains sparks off arc volcanism, which, along with the volcanism at mid-ocean ridges and hotspots, returns water to the surface and completes the deep water cycle. There appears to have been a steady balance between hydration and dehydration of the mantle at least since the Phanerozoic. Earth's water probably originates from a primordial portion that survived the Moon-forming giant impact, with later delivery by asteroids and comets. Water could play a critical role in initiating plate tectonics. In the modern Earth, the storage and cycling of water profoundly modulates a variety of properties and processes of the Earth's interior, with impacts on surface environments. Notable examples include the hydrolytic weakening effect on mantle convection and plate motion, influences on phase transitions (on the solidus of mantle peridotite in particular) and dehydration embrittlement triggering intermediate- to deep-focus earthquakes. Water can reduce seismic velocity and enhance electrical conductivity, providing remote sensing methods for water distribution in the Earth's interior. Many unresolved issues around the deep water cycle require an integrated approach and concerted efforts from multiple disciplines.

Theoretical modeling of the regular olivine intergrowths in the mimetic paramorphosis after ringwoodite and wadsleyite

2018 ◽  
pp. 3-12
Author(s):  
B. B. Shkursky
Keyword(s):  
Transition Zone ◽  
Theoretical Modeling ◽  
Mantle Transition Zone ◽  
Misorientation Angles

Theoretical modeling of regular olivine grains misorientations in mimetic paramorphoses after ringwoodite and wadsleyite, the formation of which during the ascension of matter from the Mantle Transition Zone is expected, has been carried out. The coordinates of the misorientation axes and the misorientation angles, characterizing 10 operations of alignment in the pair intergrowths of olivine grains, eight of which are twins, are calculated. Possible conditions for the formation of mimetic paramorphoses predicted here, and the chances of their persistence are discussed. The calculated orientations are compared with the known twinning laws of olivine.

scholarly journals A thin mantle transition zone beneath the equatorial Mid-Atlantic Ridge

Nature ◽  
2021 ◽  
Vol 589 (7843) ◽  
pp. 562-566
Author(s):  
Matthew R. Agius ◽  
Catherine A. Rychert ◽  
Nicholas Harmon ◽  
Saikiran Tharimena ◽  
J.-Michael Kendall
Keyword(s):  
Transition Zone ◽  
Mantle Transition Zone ◽  
Mid Atlantic Ridge
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