Global ETD Search
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Showing 1 to 16 of 16 for “"mantle transition zone"”.
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Seismic Studies of the Mantle Transition Zone
For the continental collision zone, I show that due to high VP near the bottom of the mantle transition zone, the contrast in VP across the 660-km discontinuity beneath central Tibet is small (around 3.1%): only about 70% of that beneath the northern Indian shield. This sub-horizontal anomaly of …
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Seismic imaging of the mantle transition zone
… high-resolution seismo-stratigraphy of the upper mantle transition zone. The generalized Radon transform (GRT) is based on the single scattering approximation and maps singularities (reflections) in broad-band data into singularities (reflectors/scatters) in the medium. It is able to detect and …
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Receiver function imaging of mantle transition zone discontinuities beneath Alaska
… processes, yet many aspects of subduction zone geodynamics remain unsolved and poorly understood, such as the depth extent of the subducted slab and its geometry. The Alaska subduction zone, which is associated with the subduction of the Pacific Plate beneath the North America plate, has a …
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Probing the Mantle Transition Zone beneath the Central Pacific Region Using PP Precursors
The mantle transition zone (MTZ) of the Earth is bounded by globally observed discontinuities at depths of about 410 and 660 km, which are mainly attributed to the spinel and post-spinel phase transitions of olivine. The temperature-pressure relationships of phase transitions at the …
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Receiver function investigations of mantle transition zone and crustal structure in East Africa and Northeast Asia
… the structure and evolution of the crust, upper mantle, and the mantle transition zone (MTZ) are still controversial. The MTZ discontinuities beneath the study area are imaged by stacking an unprecedented volume of receiver functions (RFs). The normal MTZ thickness beneath the Western Branch of …
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Fine scale imaging of structures at and near the mantle transition zone using a generalized Radon transform
… Radon transform (GRT) to the study of the transition zone discontinuities. The transition zone discontinuities, e.g. the '410' and '660', result from mineral phase changes that occur at depths constrained by temperature and chemistry, and can provide information about the conditions of the …
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Global Structure of the Mantle Transition Zone Discontinuities and Site Response Effects in the Atlantic and Gulf Coastal Plain
… seismology: imaging the global structures of the mantle transition zone discontinuities and studying the site response effects in the Atlantic and Gulf Coastal Plain. Global structures of the mantle transition zone discontinuities provide important constraints on thermal structures and dynamic …
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From the Foreland and Retroarc Thrust Belts to the Mantle Transition Zone: First Multi-Scale Retrodeformable Transect of the Active 90 mm/yr Taiwan Arc-Continent Collision
… crust and the pelagic sequence provides a zone of detachment that is the locus of deep massive laccolithic intrusions at ~1 Ma imaged in our reprocessed seismic reflection profiles. The ~2-3 km thick roof stratigraphy has been flexed upward by 2-3.5 km laccolithic inflation. Chapter 3 …
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Imaging of crust and mantle structures with teleseismic reflected waves
… waves to study discontinuities in the crust and mantle. Specifically, we further developed virtual deep seismic sounding (VDSS) to probe the Moho and we used SS precursors to study mantle transition zone discontinuities. To extend the applicability of VDSS, we developed a source deconvolution …
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A broad Iceland plume associated with two phase transitions at the 660 km discontinuity: Constraints from receiver functions
… frequently regarded as the archetypal example of mantle plumes, the existence, depth extent, origin, dimension and excess temperature of the hypothesized plume remain enigmatic and hotly debated. The controversy mostly originates from the limited vertical resolution of seismic tomography …
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Seismic discontinuities and order estimation using wavelets : a receiver function approach
… and scale of velocity discontinuties in the mantle transition zone through waveform analysis of Pds converted waves. The converted phases are isolated through a single station/multiple event receiver function technique which uses a wavelet deconvolution and denoising known as WaRD. It is an …
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Seismological structure of the Carpathian-Pannonian region of central Europe
… reveal the velocity structure of the mantle to a depth of 850 km throughout the Carpathian-Pannonian region. The tomographic models reduce the P-wave rms residual by 71% from 0.446 s to 0.130 s, and the S-wave rms residual by 59% from 1.513 s to 0.624 s. The effect of applying a …
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Layered crustal and mantle structure and anisotropy beneath the Afar Depression and Malawi Rift Zone
… acquired within the vicinity of continental rift zones, the mechanisms responsible for the breakup of stable continental lithosphere are ambiguous. Eastern Africa is host to the largest contemporary rift zone on Earth, and is thus the most prominent site with which to investigate the processes …
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The character of the core-mantle boundary : a systematic study using PcP
… interacts with the solid silicate-rich lower mantle the influence on the core-mantle reflected phase PcP is studied. If the core-mantle boundary is not a sharp discontinuity, this becomes apparent in the waveform and amplitude of PcP. Iron-silicate mixing would lead to regions of partial …
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Seismic structure beneath Southeast Asia from adjoint waveform tomography
… seismic model of the lithosphere and underlying mantle beneath Southeast Asia obtained from adjoint waveform tomography (often referred to as full-waveform inversion or FWI) is presented. FWI is a non-linear imaging method, where an initial model is updated in order to minimise the difference …
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The effect of iron on the stability, water content and compressibility of mantle silicates – Implications for a hydrous Martian interior
… of Fe on the properties of nominally anhydrous transition minerals and dense hydrous Mg-silicates. Furthermore, the potential presence of dense hydrous Mg-Fe silicates (DHMS) in the Martian interior and the water storage potential of a hydrous Martian mantle are evaluated. 1. The effect of iron …