On the possible density inversion in the upper mantle of the earth

1978 ◽  
Vol 17 (4) ◽  
pp. 290-294 ◽  
Author(s):  
A.P. Tarkov
Keyword(s):  
Upper Mantle ◽  
Density Inversion ◽  
The Earth

Reflections from discontinuities beneath antarctica

1971 ◽  
Vol 61 (5) ◽  
pp. 1441-1451
Author(s):  
R. D. Adams
Keyword(s):  
North American ◽  
Upper Mantle ◽  
Deep Structure ◽  
Low Velocity ◽  
Crust And Upper Mantle ◽  
Nuclear Explosions ◽  
Novaya Zemlya ◽  
The Earth ◽  
Velocity Channel ◽  
Upper Boundary

abstract Early reflections of the phase P′P′ recorded at North American seismograph stations from nuclear explosions in Novaya Zemlya are used to examine the crust and upper mantle beneath a region of eastern Antarctica. Many reflections are observed from depths less than 120 km, indicating considerable inhomogeneity at these depths in the Earth. No regular horizons were found throughout the area, but some correlation was observed among reflections at closely-spaced stations, and, at many stations, reflections were observed from depths of between 60 and 80 km, corresponding to a likely upper boundary of the low-velocity channel. Deeper reflections were found at depths of near 420 and 650 km. The latter boundary was particularly well-observed and appears to be sharply defined at a depth that is constant to within a few kilometers. The boundary at 420 km is not so well defined by reflections of P′P′, but reflects well longer-period PP waves, arriving at wider angles of incidence. This boundary appears to be at least as pronounced, but not so sharp as that near 650 km. The deep structure beneath Antarctica presents no obvious difference from that beneath other continental areas.

scholarly journals Crustal and Upper Mantle Density Structure Beneath the Qinghai-Tibet Plateau and Its Surrounding Areas Derived from EGM2008 Geoid Anomalies

2016 ◽  
Author(s):  
Honglei Li ◽  
Jian Fang
Keyword(s):  
Upper Mantle ◽  
Initial Density ◽  
Density Model ◽  
Indian Plate ◽  
Tibet Plateau ◽  
Jinsha River ◽  
The Earth ◽  
Surrounding Areas ◽  
Geoid Anomalies ◽  
Qinghai Tibet Plateau

As the most active plateau on the Earth, the Qinghai-Tibet Plateau has a complex crust-mantle structure. Knowledge of the distribution of such a structure provides information for understanding the underlying geodynamic processes. We obtains a three-dimensional density model of crustal and upper mantle beneath Qinghai-Tibet plateau and its surrounding areas from the residual geoid anomalies using the Earth Gravitational Model (EGM) 2008. We estimate a refined density model by iterations, using an initial density contrast model. We confirm that the EGM2008 mission products can be used to constrain the crust-mantle density structures. Our major findings are: (1). At 300-400 km depth, high-D anomalies terminate around Jinsha River Suture (JRS) in the central TP, suggesting that the Indian plate has been reached over the Bangong Nujiang Suture (BNS) and almost reach to the JRS. (2). On the eastern TP, low-D anomalies at the depth of 0-300 km together with high-D anomalies at 400-670 km further verified the current eastward subduction of Indian plate. The ongoing subduction provides forces to the occurrences of frequent earthquakes and volcano. (3). At 600 km depth, low-D anomalies inside the TP illustrate the existence of hot weak material beneath there, contributing to the external material inward-thrusting.

3. Minerals and the interior of the Earth

2014 ◽  
Author(s):  
David Vaughan
Keyword(s):  
Upper Mantle ◽  
Lower Mantle ◽  
Plate Tectonics ◽  
Inner Core ◽  
Indirect Evidence ◽  
Outer Core ◽  
The Earth ◽  
Granite Formation ◽  
Temperature And Pressure

‘Minerals and the interior of the Earth’ looks at the role of minerals in plate tectonics during the processes of crystallization and melting. The size and range of minerals formed are dependent on the temperature and pressure of the magma during its movement through the crust. The evolution of the continental crust also involves granite formation and processes of metamorphism. Our understanding of the interior of the Earth is based on indirect evidence, mainly the study of earthquake waves. The Earth consists of concentric shells: a solid inner core; liquid outer core; a solid mantle divided into a lower mantle, a transition zone, and an upper mantle; and then the outer rigid lithosphere.

scholarly journals Earth as a Gravitational-Wave Interferometr

2019 ◽  
Vol 224 ◽  
pp. 03012
Author(s):  
Vadim Il’chenko
Keyword(s):  
Gravitational Wave ◽  
Upper Mantle ◽  
Oscillatory System ◽  
Average Depth ◽  
Lunar Tide ◽  
Crust And Upper Mantle ◽  
The Earth ◽  
Order Of Magnitude ◽  
Gravitational Wave Interferometer ◽  
Gravitational Influence

Based on the principle of Equivalence of Gravitating Masses (EGM) and tectonostratigraphic model of the Earth outer shell structure (the Earth crust and upper mantle), the average depth of the lunar mass gravitational influence on the Earth was calculated as ~1600 km. The developed model is based on the mechanism of rocks tectonic layering of the Earth crust-mantle shell as an oscillatory system with dynamic conditions of a standing wave, regularly excited by the lunar tide and immediately passing into the damping mode. After comparing the average depth of solid lunar tide impact of ~1600 km with the height of the solid lunar tide “hump” on the Earth surface of 0.5 m, a “tensile strain” was calculated with an amplitude only one order of magnitude larger than the amplitude of the gravitational wave recorded by the Advanced LIGO interferometer: A≈10-18 m (the merger result of a black holes pair ca 1.3 Ga ago). The results of the present study suggest that the crust-mantle shell of the Earth may be used as a gravitational-wave interferometer.

scholarly journals Symposium on the Crust and Upper Mantle of the Earth

1964 ◽  
Vol 73 (3) ◽  
pp. 137-138
Author(s):  
Hisashi KUNO ◽  
Hitoshi TAKEUCHI ◽  
Seiya UEDA
Keyword(s):  
Upper Mantle ◽  
Crust And Upper Mantle ◽  
The Earth

Micromechanisms of flow and fracture, and their relevance to the rheology of the upper mantle

1978 ◽  
Vol 288 (1350) ◽  
pp. 59-95 ◽  
Keyword(s):  
Shear Stress ◽  
Upper Mantle ◽  
Crystalline Solids ◽  
Dominant Response ◽  
Additional Variable ◽  
The Earth ◽  
The Way

Crystalline solids respond to stress by deforming elastically and plastically, and by fracturing. The dominant response of a given material depends on the magnitude of the shear stress (0 s ), on the temperature (T) and on the time (t) of its application. This is because a number of alternative mechanisms exist which permit the solid to flow, and its fracture, too, occurs by one of a number of competing mechanisms. Their rates depend on 0 8 , T and t: it is the fastest one which appears as dominant. In geophysical problems, pressure appears as an additional variable. At pressures corresponding to depths of a few kilometres below the surface of the Earth, the mechanisms of fracture are the most affected; but at depths of a few hundred kilometres, plasticity, too, is influenced in important ways. This paper outlines the mechanisms of flow and fracture which appear to be relevant in the deformation of materials of interest to the geophysicist, and the way pressure affects them. The results are illustrated and their shortcomings emphasized by using them to calculate the mechanisms of flow and fracture to be expected in the upper mantle of the Earth.

The concept of cluster evolution minerageny in the Earth’s history

2018 ◽  
pp. 3-17
Author(s):  
V. A. Krivitsky ◽  
V. I. Starostin
Keyword(s):  
Nuclear Matter ◽  
Upper Mantle ◽  
Chemical Elements ◽  
Superheavy Elements ◽  
Stellar Matter ◽  
Cluster Evolution ◽  
The Earth ◽  
Plume Flows

The new concept of cluster evolutionary mineralogy is based on the idea of the formation of the Earth from the primary stellar matter, which was preserved in the cores of the planets. The consequent destruction of it, as a result of the decay of heavy nuclear matter, leads to fragmentation of the substance until the appearance of superheavy elements with their further nuclear dissociation. As a result, a protomagma emerges, which enters the upper mantle in the form of plume flows. This process supports the reactions that result in the formation of chemical elements, minerals, ores and rocks, from which the upper mantle and the crust are formed. The processes of nuclear dissociation lead to the release of energy and the decomposition of matter, which initiates the growth of the earth's volume, its geotectonic activity, and the appearance of the hydrosphere and the atmosphere.

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