نتایج جستجو برای: crustal matter

تعداد نتایج: 222571  

2015
Tian-Yu Zheng Yu-Mei He Jin-Hui Yang Liang Zhao

Crustal rejuvenation is a key process that has shaped the characteristics of current continental structures and components in tectonic active continental regions. Geological and geochemical observations have provided insights into crustal rejuvenation, although the crustal structural fabrics have not been well constrained. Here, we present a seismic image across the North China Craton (NCC) and...

2011
Simon Lloyd Suzan van der Lee George Sand França Marcelo Assumpção Mei Feng

[1] We estimate crustal structure and thickness of South America north of roughly 40°S. To this end, we analyzed receiver functions from 20 relatively new temporary broadband seismic stations deployed across eastern Brazil. In the analysis we include teleseismic and some regional events, particularly for stations that recorded few suitable earthquakes. We first estimate crustal thickness and av...

2012
J. Korenaga W. W. Sager

[1] We present results from a wide-angle seismic refraction survey over Shatsky Rise, a large oceanic plateau in the northwestern Pacific. A new Monte Carlo sampling scheme is developed to explore comprehensively the model space of crustal velocity structure by joint refraction and reflection seismic tomography. The new scheme, which is founded on the notion of adaptive importance sampling, is ...

2010
V. Lekić M. Panning

S U M M A R Y Accurate accounting for the effects of crustal structure on long-period seismic surface waves and overtones is difficult but indispensable for determining elastic structure in the mantle. While standard linear crustal corrections (SLC) have been shown to be inadequate on the global scale, newer non-linear correction (NLC) techniques are computationally expensive when applied to wa...

2011
Egill Hauksson

S U M M A R Y The geographical distribution of the (1981–2005) seismicity in southern California forms a ±150 km broad zone adjacent to the Pacific–North America plate boundary, ranging from depths of ∼1–∼30 km, with the bulk of the focal depths in the range of 2–12 km. The distribution of the seismicity that includes both mainshock–aftershock sequences and background events is affected by both...

2003
D. Canil M. Mihalynuk J. M. MacKenzie S. T. Johnston L. Ferreira B. Grant

Kimberlite and lamproite magmas sample diamonds deep in the mantle and depending on the rapidity of ascent and emplacement, bring them to the surface in various states of preservation. Economic diamond deposits are usually hosted in primary kimberlite and lamproite diatremes that intrude Archean crustal provinces. Placer deposits of diamonds that are sourced in kimberlite from Archean crustal p...

2007
U. Meier A. Curtis J. Trampert

[1] We use neural networks to find 1-dimensional marginal probability density functions (pdfs) of global crustal parameters. The information content of the full posterior and prior pdfs can quantify the extent to which a parameter is constrained by the data. We inverted fundamental mode Love and Rayleigh wave phase and group velocity maps for pdfs of crustal thickness and independently of verti...

2002
Andrew Meigs Doug Yule Ann Blythe Doug Burbank

Spatial and temporal patterns of exhumation are inextricably linked to patterns of crustal deformation because crustal deformation drives rock uplift. A new interpretation of a segment of the Pacific-North America transpressional plate boundary in southern California is analyzed in the context of crustal shortening, rock uplift, and exhumation. Deformation is partitioned between two structural ...

2016
D. M. Winslow A. T. Fisher P. H. Stauffer C. W. Gable G. A. Zyvoloski

We present three-dimensional simulations of coupled fluid and heat transport in the ocean crust, to explore patterns and controls on ridge-flank hydrothermal circulation on the eastern flank of the Juan de Fuca Ridge. Field studies have shown that there is large-scale fluid flow in the volcanic ocean crust in this region, including local convection and circulation between two basement outcrops ...

2013
Kevin W. Lewis Frederik J. Simons

[1] The crustal remanent magnetic field of Mars remains enigmatic in many respects. Its heterogeneous surface distribution points to a complex history of formation and modification, and has been resistant to attempts at identifying magnetic paleopoles and constraining the geologic origin of crustal sources. We use a multitaper technique to quantify the spatial diversity of the field via the loc...

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