Lehmann discontinuity as the base of an anisotropic layer beneath continents.
نویسندگان
چکیده
Long-period surface-wave (R(1), G(1)), body-wave (S, SS, SSS), and ScS-reverberation data have been inverted to obtain anisotropic structures along seismic corridors that sample Australia and the western Pacific. These models support the proposal that the Lehmann discontinuity beneath stable continents represents a transition from an anisotropic lithosphere to a more isotropic material in the lower part of the continental tectosphere.
منابع مشابه
The deep structure of continents
The Lehmann discontinuity at 220-km depth is an important global feature which occurs under both oceans and continents. It is a barrier to penetration by young lithosphere and marks the base of seismicity in regions of continent-continent collision. The strong lateral variation in upper mantle velocities occurs mainly above this depth. Continental roots extend no deeper than about 150-200 km. T...
متن کاملThe Lehmann Discontinuity Due to Dehydration of Subducted Sediment
Recent high-pressure experiments have led to the conclusion that water release from subducted sediments lying under continents in subduction regions occurs at about 220 km depth. This dehydration reaction is in good agreement with the seismological signature of the discontinuity indicating that sediment dehydration causes the Lehmann discontinuity in
متن کاملMantle discontinuities beneath Southern Africa
[1] Seismic velocity discontinuities within the top 1000 km of the Earth beneath southern Africa are imaged by stacking about 1300 source-normalized broadband seismograms recorded by the Southern African Seismic Experiment. The Moho, 410, and 660 kilometer discontinuities are clearly detected. The mean mantle transition zone thickness is 245 km, essentially the same as the global average, sugge...
متن کاملThe role of chemical boundary layers in regulating the thickness of continental and oceanic thermal boundary layers
An important feature of continents and oceans is that they are underlain by chemically distinct mantle, made intrinsically buoyant and highly viscous by melt depletion and accompanying dehydration, respectively. Of interest here are the influences of these preexisting chemical boundary layers on small-scale convective processes (as opposed to large-scale processes, which govern the drift of con...
متن کاملEffect of Initial Stress on Propagation of Love Waves in an Anisotropic Porous Layer
In the present paper, effect of initial stresses on the propagation of Love waves has been investigated in a fluid saturated, anisotropic, porous layer lying in welded contact over a prestressed, non-homogeneous elastic half space. The dispersion equation of phase velocity has been derived. It has been found that the phase velocity of Love waves is considerably influenced by porosity and anisot...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Science
دوره 268 5216 شماره
صفحات -
تاریخ انتشار 1995