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Mantle dynamics: Influence of the transition zone
Author(s) -
Tackley Paul J.
Publication year - 1995
Publication title -
reviews of geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.087
H-Index - 156
eISSN - 1944-9208
pISSN - 8755-1209
DOI - 10.1029/95rg00291
Subject(s) - downwelling , geology , transition zone , mantle (geology) , geophysics , upwelling , mantle convection , endothermic process , convection , phase transition , lithosphere , mechanics , condensed matter physics , physics , seismology , tectonics , chemistry , oceanography , organic chemistry , adsorption
The question of whether the mantle convects as a single layer, or whether the convection is split vertically into two or more layers, is perhaps the most fundamental unanswered question concerning the structure and dynamics of the mantle, and has ramifications throughout solid Earth geosciences. The most likely mechanism for enforcing layered convection is the action of the major phase transitions of the transition zone, and in particular, the strong endothermic phase transition between γ‐spinel and perovskite+magnesiowiistite that occurs at around 660 km depth. Because this transition is endothermic, it is deflected downwards in cold downwellings, and upwards in hot upwellings, resulting in a mass anomaly that impedes the penetration of the downwelling or upwelling. In the past few years, there has been a huge resurgence of interest and modeling activity devoted to studying the influence of the 400 and 660 km phase transitions, and the effects identified in these studies may provide the key to reconciling various seemingly contradictory geophysical observations.