15 research outputs found
Forming the Moon from terrestrial silicate-rich material
Recent high-precision measurements of the isotopic composition of lunar rocks
demonstrate that the bulk silicate Earth and the Moon show an unexpectedly high
degree of similarity. This is inconsistent with one of the primary results of
classic dynamical simulations of the widely accepted giant impact model for the
formation of the Moon, namely that most of the mass of the Moon originates from
the impactor, not Earth.
Resolution of this discrepancy without changing the main premises of the
giant impact model requires total isotopic homogenisation of Earth and impactor
material after the impact for a wide range of elements including O, Si, K, Ti,
Nd and W. Even if this process could explain the O isotope similarity, it is
unlikely to work for the much heavier, refractory elements. Given the
increasing uncertainty surrounding the giant impact model in light of these
geochemical data, alternative hypotheses for lunar formation should be
explored. In this paper, we revisit the hypothesis that the Moon was formed
directly from terrestrial mantle material. We show that the dynamics of this
scenario requires a large amount of energy, almost instantaneously generated
additional energy. The only known source for this additional energy is nuclear
fission. We show that it is feasible to form the Moon through the ejection of
terrestrial silicate material triggered by a nuclear explosion at Earths
core-mantle boundary (CMB), causing a shock wave propagating through the Earth.
Hydrodynamic modelling of this scenario shows that a shock wave created by
rapidly expanding plasma resulting from the explosion disrupts and expels
overlying mantle and crust material.Comment: 26 pages, 5 figures, 1 tabl
Geoantineutrino Spectrum, 3He/4He-ratio Distribution in the Earth's Interior and Slow Nuclear Burning on the Boundary of the Liquid and Solid Phases of the Earth's Core
The description problem of geoantineutrino spectrum and reactor antineutrino
experimental spectrum in KamLAND, which takes place for antineutrino energy
\~2.8 MeV, and also the experimental results of the interaction of uranium
dioxide and carbide with iron-nickel and silicaalumina melts at high pressure
(5-10 GP?) and temperature (1600-2200C) have motivated us to consider the
possible consequences of the assumption made by V.Anisichkin and coauthors that
there is an actinid shell on boundary of liquid and solid phases of the Earth's
core. We have shown that the activation of a natural nuclear reactor operating
as the solitary waves of nuclear burning in 238U- and/or 232Th-medium (in
particular, the neutron- fission progressive wave of Feoktistov and/or
Teller-Ishikawa-Wood) can be such a physical consequence. The simplified model
of the kinetics of accumulation and burnup in U-Pu fuel cycle of Feoktistov is
developed. The results of the numerical simulation of neutron-fission wave in
two-phase UO2/Fe medium on a surface of the Earth's solid core are presented.
The georeactor model of 3He origin and the 3He/4He-ratio distribution in the
Earth's interior is offered. It is shown that the 3He/4He ratio distribution
can be the natural quantitative criterion of georeactor thermal power. On the
basis of O'Nions-Evensen-Hamilton geochemical model of mantle differentiation
and the crust growth supplied by actinid shell on the boundary of liquid and
solid phases of the Earth's core as a nuclear energy source (georeactor with
power of 30 TW), the tentative estimation of geoantineutrino intensity and
geoantineutrino spectrum on the Earth surface are given.Comment: 28 pages, 12 figures. Added text, formulas, figures and references.
Corrected equations. Changed content of some section
Spectroscopic study of impurities and associated defects in nanodiamonds from Efremovka (CV3) and Orgueil (CI) meteorites
The results of spectroscopic and structural studies of phase composition and
of defects in nanodiamonds from Efremovka (CV3) and Orgueil (CI) chondrites
indicate that nitrogen atomic environment in meteoritic nanodiamonds (MND) is
similar to that observed in synthetic counterparts produced by detonation and
by the Chemical Vapour Deposition (CVD)-process. Most of the nitrogen in MND
appears to be confined to lattice imperfections, such as crystallite/twin
boundaries and other extended defects, while the concentration of nitrogen in
the MND lattice is low. It is suggested that the N-rich sub-population of MND
grains may have been formed with high growth rates in environments rich in
accessible N (i.e., N in atomic form or as weakly bonded compounds). For the
first time the silicon-vacancy complex (the "silicon" defect) is observed in
MND by photoluminescence spectroscopy.Comment: 33 pages, 5 figures, submitted to Geochimica et Cosmochimica Act