نتایج جستجو برای: earth crust
تعداد نتایج: 101888 فیلتر نتایج به سال:
Introduction: According to the canonical lunar magma ocean (LMO) model, ferroan anorthosites (FANs) were part of the lunar anorthosite crust formed via plagioclase flotation and subsequent solidification in a globally distributed LMO [1-4]. The solidification time for a globally distributed LMO is model dependent and ranges from 10 4-10 8 yrs [3,5,6]. At a given time during lunar crust formatio...
Much of the Earth's mantle was melted in the Moon-forming impact. Gases that were not partially soluble in the melt, such as water and CO2, formed a thick, deep atmosphere surrounding the post-impact Earth. This atmosphere was opaque to thermal radiation, allowing heat to escape to space only at the runaway greenhouse threshold of approximately 100 W m(-2). The duration of this runaway greenhou...
Part 1: The Earth and its Lithosphere Chemical composition and structure of the Earth. . . . . . . . . . . . . . . . . . . . . . . . . 3 The structure of the Earth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Primordial chemistry: Origin of the elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Formation and evolution of the earth. . . ...
Much of the Earth’s mantle was melted in the Moon-forming impact. Gases that were not partially soluble in the melt, such as water and CO2, formed a thick, deep atmosphere surrounding the postimpact Earth. This atmosphere was opaque to thermal radiation, allowing heat to escape to space only at the runaway greenhouse threshold of approximately 100 W m−2. The duration of this runaway greenhouse ...
As the most active plateau on the Earth, the Qinghai-Tibet Plateau (TP) has a complex crust–mantle structure. Knowledge of the distribution of such a structure provides information for understanding the underlying geodynamic processes. We obtain a three-dimensional model of the density of the crust and the upper mantle beneath the TP and surrounding areas from height anomalies using the Earth G...
Introduction: A long-standing, fundamental question in planetary geoscience is: "How similar are the geological histories of Earth and Venus, and when and how did their evolution diverge?" Did Venus once have oceans and a more Earth-like climate, as suggested by Pioneer-Venus data [1]? If so, when, how, and why did it transition to current conditions, and are traces of this early period, and th...
In the past decade, the availability of spacederived crustal deformation data has transformed the solid Earth geophysics field. Global Positioning System (GPS) networks deployed globally provide precise timedependent information on how the Earth’s crust responds to earthquakes and plate tectonic processes. Interferometric Synthetic Aperture Radar (InSAR) data reveal spatially dense information ...
Preferred orientation of crystallites (or texture) is an intrinsic feature of metals, ceramics, polymers, and rocks and has an influence on physical properties such as strength, electrical conductivity, wave propagation, particularly the anisotropy of properties. The directional characteristics of many polycrystalline materials were first recognized not in metals but in rocks and were described...
Editor: T.M. Harrison Non-arc basalts of Archean and Proterozoic age have model primary magmas that exhibit mantle potential temperatures TP that increase from 1350 °C at the present to a maximum of ∼1500–1600 °C at 2.5–3.0 Ga. The overall trend of these temperatures converges smoothly to that of the present-day MORB source, supporting the interpretation that the non-arc basalts formed by the m...
It is shown that the Ocean-Earth crust interface can propagate gravity-sound Rayleigh waves. Dispersion properties of waves and flux of energy are derived. It is shown that the waves split into low and fast velocity branches. The fast branch has a multimode structure and has a cutoff in frequency and wave number. Numerical solutions are discussed.
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