نتایج جستجو برای: crustal contamination
تعداد نتایج: 61183 فیلتر نتایج به سال:
Isosta.tica,lly compensated crusta,1 thickness variations and associated topographic contrasts a,t the surface of a planet result in lateral pressure gradients, which may cause the lower crust to flow and reduce the relief. Areas of thicker crust are genera, lly associated with more rapid relaxation of topography. On Mars, topographic features such as impa, ct basins a, nd the hemispheric dicho...
Genetic algorithm inversion of the average 1D crustal structure using local and regional earthquakes
Knowing the best 1Dmodel of the crustal and uppermantle structure is useful not only for routine hypocenter determination, but also for linearized joint inversions of hypocenters and 3D crustal structure, where a good choiceof the initialmodel canbevery important.Here,we tested thecombinationof a simpleGA inversionwith the widely used HYPO71 program to find the best three-layer model (upper cru...
High-quality seismic data obtained from a dense broadband array near Kimberley, South Africa, exhibit crustal reverberations of remarkable clarity that provide well-resolved constraints on the structure of the lowermost crust and Moho. Receiver function analysis of Moho conversions and crustal multiples beneath the Kimberley array shows that the crust is 35 km thick with an average Poisson’s ra...
Introduction: Crustal plateaus are a major class of tectonic features on Venus surface, and its study is essential in order to understand the geological evolution previous to the global resurfacing process. These regional units are flat topped highlands formed by tessera terrain, characterized by superposition of crosscutting structures [1-2], with complex tectonic patterns; also intratessera v...
[1] As the solar wind is incident upon the lunar surface, it will occasionally encounter lunar crustal remanent magnetic fields. These magnetic fields are small-scale, highly non-dipolar, have strengths up to hundreds of nanotesla, and typically interact with the solar wind in a kinetic fashion. Simulations, theoretical analyses, and spacecraft observations have shown that crustal fields can re...
Crustal thickness is a critical parameter for understanding the processes of continental rifting and breakup and the evolution of petroleum systems within passive margins. However, direct measurements of crustal thickness are sparse and expensive, highlighting the need for methodologies using gravity anomaly data, jointly with other geophysical data, to estimate crustal thickness. We evaluated ...
Laboratory experiments have established that many earth materials are strongly anisotropic. Observations of azimuthal and radial anisotropy in the upper mantle are attributed to the lattice-preferred orientation (LPO) of olivine caused by the shear strains associated with deformation, and provide some of the most direct evidence for deformation and flow within Earth’s interior. Although observa...
We present global and regional correlations between whole-rock values of Sr/Y and La/Yb and crustal thickness for intermediate rocks from modern subduction-related magmatic arcs formed around the Pacific. These correlations bolster earlier ideas that various geochemical parameters can be used to track changes of crustal thickness through time in ancient subduction systems. Inferred crustal thic...
High-quality seismic data recorded during the 1999 Taiwan Chi-Chi earthquake (Mw=7.6) show that a smallscale orogenic process of both mountain-building and crust-thickening was simultaneously accomplished along one set of crustal-scale conjugated faults. Mountain-building near the surface was primarily produced by the main shock along an eastward low-angle thrust fault in the upper crust. In th...
The goal of the 1993 Los Angeles Region Seismic Experiment (LARSE93) passive phase was to collect waveform data from local and distant earthquakes to study lower crust and upper mantle structural features in southern California, particularly under the San Gabriel Mountains and San Andreas fault. During LARSE93, approximately 88 stations were deployed in a 175-km-long, linear array across the Lo...
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