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Russian Geology and Geophysics

2006 year, number 5

FRACTURED STRUCTURE OF THE CRUST AS ITS GENETIC FEATURE

V.N. Nikolaevskiy
Institute of the Earth's Physics, Russian Academy of Sciences,
10 ul. Bol. Gruzinskaya, Moscow, 123810, Russia
Keywords: Crust, faults, tectonics, geotherm, triaxial testing, strength limit, dilatancy, seismic interfaces, upper mantle, radon, helium, permeability
Pages: 642-654

Abstract

A universal theory that accounts for the structure of fractured crust is suggested using data on strength and finite failure of rocks in high-pressure and high-temperature triaxial deformation tests. Correlation of the experimental results to the seismic cross section of the crust and mathematical modeling data indicates that the conditions at the Moho correspond to closure of the cracks network and annihilation of its hydraulic permeability. Therefore, upper mantle is rather dry than water-saturated, which means that the existing views of rock physics need a revision. Variations in crustal thickness are controlled by the trend of the geotherm and, besides, by olivine-to-serpentinite transition by the Hess reaction in oceanic crust. The Conrad discontinuity fits the horizontal foot of listric faults, waveguides (low-velocity zones) correspond to the cracked-porous inclusions and the lower crust to cataclastic state of rocks. The crust cut into fault-bounded blocks is modeled in the context of rotation tectonic waves that follow the sin-Gordon equation.