Physics
Scientific paper
Feb 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994e%26psl.121..385c&link_type=abstract
Earth and Planetary Science Letters (ISSN 0012-821X), vol. 121, no. 3/4, p. 385-402
Physics
22
Anomalous Temperature Zones, Earth Mantle, Structural Properties (Geology), Temperature Distribution, Convection, Core-Mantle Boundary, Heterogeneity, Mathematical Models, Seismology, Subduction (Geology), Tomography
Scientific paper
The long-wavelength thermal anomalies in the lower mantle have been mapped out using several seismic tomographic models in conjunction with thermodynamic parameters derived from high-pressure mineral physics experiments. These parameters are the depth variations of thermal expansivity and of the proportionality factor between changes in density and seismic velocity. The giant plume-like structures in the lower mantle under the Pacific Ocean and Africa have outer fringes with thermal anomalies around 300-400 K, but very high temperatures are found in the center of the plumes near the base of the core-mantle boundary. These extreme values can exceed +1500 K and may reflect large hot thermal anomalies in the lower mantle, which are supported by recent measurements of high melting temperatures of perovskite and iron. Extremely cold anomalies, around -1500 K, are found for anomalies in the deep mantle around the Pacific rim and under South America. Numerical simulations show that large negative thermal anomalies in the mid-lower mantle have modest magnitudes of around -500 K. correlation pattern exists between the present-day locations of cold masses in the lower mantle and the sites of past subduction since the Cretaceous. Results from correlation analysis show that the slab mass-flux in the lower mantle did not conform to a steady-state nature but exhibited time-dependent behavior.
Cadek Ondřej
Chopelas A.
Matyska Ctirad
Steinbach Volker
Yuen Dave A.
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