Accession Number : AD0692100

Title :   THE NATURE OF THE MOHOROVICIC DISCONTINUITY (Mo-ho chieh-mien ti hsing-chih),

Corporate Author : AERONAUTICAL CHART AND INFORMATION CENTER ST LOUIS MO LINGUISTIC SECTION

Personal Author(s) : Tseng,Jung-sheng

Report Date : JUL 1969

Pagination or Media Count : 20

Abstract : The paper discusses the various theories on the nature of the Mohorovicic discontinuity and the difficulties encountered by the phase-change hypothesis. By examining the velocity distribution data recently obtained by use of seismic body and surface waves, the following conclusions can be made: (1) The Mohorovicic discontinuity, either under the continents of the oceans, cannot be interpreted as a surface of phase transition. (2) The chemical composition of the upper mantle is not homogeneous in the vertical direction. The low-velocity layer in the upper mantle is probably caused by a change in composition rather than by the temperature effects. (3) The top surface of the asthenospheric low-velocity layer is deeper under the oceans than under the continents. (4) The chemical composition of the upper mantle, according to the data of radioactive measurements, may be some mixtures of eclogites or other ultra-basic rocks, their change of velocity due to temperature effects being very small. (Author)

Descriptors :   (*MOHOROVICIC DISCONTINUITY, THEORY), SEISMIC WAVES, STRUCTURAL GEOLOGY, PHASE STUDIES, CHEMICAL PROPERTIES, OCEANS, BASALT, TEMPERATURE, PRESSURE, CHINA

Subject Categories : Geology, Geochemistry and Mineralogy

Distribution Statement : APPROVED FOR PUBLIC RELEASE