A sporadic low-velocity layer atop the western U.S. mantle transition zone and short-wavelength variations in transition zone discontinuities

A Sporadic Low-Velocity Layer Atop the Western Us Mantle Transition Zone and Short-Wavelength Variations in Transition Zone Discontinuities

[1] Teleseismic receiver function analysis of data from six dense arrays in the western U.S. is used to inves­ tigate mantle transition zone (MTZ) discontinuities and the prevalence of a low‐velocity layer atop the 410 km discontinuity (410‐LVL). Negative polarity Ps arrivals indicative of a low‐velocity layer with a top 25–60 km above the 410 are identified in 8–11 out of 18 stacks of receiver...

Multiple transition zone seismic discontinuities and low velocity layers below western United States

With P-to-S converted waves recorded at seismic stations of the US Transportable Array we image the fine structure of upper mantle and transition zone (TZ) beneath the western US. We map the topographies of seismic discontinuities by stacking data by common conversion points along profiles. Systematic depth and amplitude measurements are performed not only for the well-known ‘410’ and ‘660’ int...

Mantle transition zone discontinuities beneath the contiguous United States

Using over 310,000 high-quality radial receiver functions recorded by the USArray and other seismic stations in the contiguous United States, the depths of the 410 km and 660 km discontinuities (d410 and d660) are mapped in over 1,000 consecutive overlapping circles with a radius of 1◦. The average mantle transition zone (MTZ) thickness for both the western and central/eastern U.S. is within 3 ...

S velocity reversal in the mantle transition zone

Spin transition zone in Earth's lower mantle.

Mineral properties in Earth's lower mantle are affected by iron electronic states, but representative pressures and temperatures have not yet been probed. Spin states of iron in lower-mantle ferropericlase have been measured up to 95 gigapascals and 2000 kelvin with x-ray emission in a laser-heated diamond cell. A gradual spin transition of iron occurs over a pressure-temperature range extendin...