The solid/liquid partitioning of major and radiogenic elements at lower mantle pressures: Implications for the core-mantle boundary region

1998 ◽  
pp. 119-130 ◽  
Author(s):  
Elise Knittle
Keyword(s):  
Lower Mantle ◽  
Boundary Region ◽  
Mantle Boundary ◽  
Core Mantle Boundary ◽  
The Core ◽  
Solid Liquid

scholarly journals Sequencing seismograms: A panoptic view of scattering in the core-mantle boundary region

Science ◽  
2020 ◽  
Vol 368 (6496) ◽  
pp. 1223-1228 ◽  
Author(s):  
D. Kim ◽  
V. Lekić ◽  
B. Ménard ◽  
D. Baron ◽  
M. Taghizadeh-Popp
Keyword(s):  
Seismic Waves ◽  
Learning Algorithm ◽  
Three Dimensional ◽  
Boundary Region ◽  
Marquesas Islands ◽  
Mantle Boundary ◽  
Core Mantle Boundary ◽  
Subsurface Structures ◽  
The Core ◽  
The Pacific

Scattering of seismic waves can reveal subsurface structures but usually in a piecemeal way focused on specific target areas. We used a manifold learning algorithm called “the Sequencer” to simultaneously analyze thousands of seismograms of waves diffracting along the core-mantle boundary and obtain a panoptic view of scattering across the Pacific region. In nearly half of the diffracting waveforms, we detected seismic waves scattered by three-dimensional structures near the core-mantle boundary. The prevalence of these scattered arrivals shows that the region hosts pervasive lateral heterogeneity. Our analysis revealed loud signals due to a plume root beneath Hawaii and a previously unrecognized ultralow-velocity zone beneath the Marquesas Islands. These observations illustrate how approaches flexible enough to detect robust patterns with little to no user supervision can reveal distinctive insights into the deep Earth.

The core-mantle boundary region

1995 ◽  
Vol 100 (B4) ◽  
pp. 6397-6420 ◽  
Author(s):  
David E. Loper ◽  
Thorne Lay
Keyword(s):  
Boundary Region ◽  
Mantle Boundary ◽  
Core Mantle Boundary ◽  
The Core

scholarly journals Double beam analysis of anomalies in the core-mantle boundary region

1993 ◽  
Vol 20 (14) ◽  
pp. 1475-1478 ◽  
Author(s):  
Frank Krüger ◽  
Michael Weber ◽  
Frank Scherbaum ◽  
Jörg Schlittenhardt
Keyword(s):  
Boundary Region ◽  
Mantle Boundary ◽  
Core Mantle Boundary ◽  
The Core ◽  
Beam Analysis ◽  
Double Beam

scholarly journals Hydrous SiO2 in subducted oceanic crust and water transport to the core-mantle boundary

2020 ◽  
Author(s):  
Yanhao Lin ◽  
Qingyang Hu ◽  
Jing Yang ◽  
Yue Meng ◽  
Yukai Zhuang ◽  
...  
Keyword(s):  
Partial Melting ◽  
Oceanic Crust ◽  
Lower Mantle ◽  
Oceanic Lithosphere ◽  
Low Velocity ◽  
Water Storage Capacity ◽  
Mantle Boundary ◽  
Core Mantle Boundary ◽  
The Core ◽  
Subducted Oceanic Crust

Abstract Subduction of oceanic lithosphere transports surface water into the mantle where it can have remarkable effects, but how much can be cycled down into the deep mantle, and potentially to the core, remains ambiguous. Recent studies show that dense SiO2 in the form of stishovite, a major phase in subducted oceanic crust at depths greater than ~300 km, has the potential to host and carry water into the lower mantle. We investigate the hydration of stishovite and its higher-pressure polymorphs, CaCl2-type SiO2 and seifertite, in experiments at pressures of 44–152 GPa and temperatures of ~1380–3300 K. We quantify the water storage capacity of these dense SiO2 phases at high pressure and find that water stabilizes CaCl2-type SiO2 to pressures beyond the base of the mantle. We parametrize the P-T dependence of water capacity and model H2O storage in SiO2 along a lower mantle geotherm. Dehydration of slab mantle in cooler slabs in the transition zone can release fluids that hydrate stishovite in oceanic crust. Hydrous SiO2 phases are stable along a geotherm and progressively dehydrate with depth, potentially causing partial melting or silica enrichment in the lower mantle. Oceanic crust can transport ~0.2 wt% water to the core-mantle boundary region where, upon heating, it can initiate partial melting and react with the core to produce iron hydrides, providing plausible explanations for ultra-low velocity regions at the base of the mantle.

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