Receiver function investigations of mantle transition zone and crustal structure in East Africa and Northeast Asia

<p>"In spite of numerous geophysical studies have been conducted in East Africa and Northeast Asia, the structure and evolution of the crust, upper mantle, and the mantle transition zone (MTZ) are still controversial. The MTZ discontinuities beneath the study area are imaged by stacking an unprecedented volume of receiver functions (RFs). The normal MTZ thickness beneath the Western Branch of the EARS and Tanzania Craton indicates the absence of present-day thermal upwelling from the lower mantle. In contrast, beneath the Eastern Branch, a significant MTZ thinning reveals the existence of thermal upwelling from either the upper MTZ or the lower mantle. A normal MTZ thickness beneath southern Africa and the negligible disparity of the mean MTZ thicknesses between on and off cratonic regions suggest the absence of thermal influence from the African Superswell and cratonic keels on the MTZ beneath southern Africa. The major volcanoes in northeast China are underlain by a thickened MTZ, which can be interpreted by an anomalously high-water concentration in the MTZ released from the stagnated slab. An abnormally thin MTZ beneath the Hangay Dome suggests the possible existence of thermal upwelling from the lower mantle.</p> <p>Additionally, the crustal structure in the Malawi Rift Zone (MRZ) has been investigated using RFs and gravity modeling. The small crustal stretching factor is consistent with the general absence of volcanism in the MRZ. The high V_p/V_s beneath the southern MRZ may indicate the existence of partial melting. Abnormally low V_p/V_s along the western boundary of the MRZ may be related to the CO₂ suffusion of rift boundary faults"--Abstract, page iv.</p>

Name thesis:degree_name

Ph. D. in Geology and Geophysics

Grantor

Missouri University of Science and Technology

Author dc:creator

• Sun, Muchen

• Crustal structure
• East Africa
• Mantle transition zone
• Northeast Asia
• Receiver function
• Geophysics and Seismology

Repository record dc:identifier

https://scholarsmine.mst.edu/doctoral_dissertations/2793

OAI identifier oai:identifier

oai:scholarsmine.mst.edu:doctoral_dissertations-3798