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International Journal of Geophysics
Volume 2010, Article ID 146496, 16 pages
http://dx.doi.org/10.1155/2010/146496
Research Article

A Magma Accretion Model for the Formation of Oceanic Lithosphere: Implications for Global Heat Loss

1Coordenadoria de Geofísica, Observatório Nacional—MCT, Rua General José Cristino, CEP 20921-400, Rio de Janeiro, Brazil
2Instituto de Ciência e Tecnologia do Mucuri, Universidade Federal dos Vales do Jequitinhonha e Mucuri, CEP 39800-000, Teófilo Otoni, Brazil

Received 28 October 2009; Revised 24 February 2010; Accepted 7 March 2010

Academic Editor: Shuichi Kodaira

Copyright © 2010 Valiya M. Hamza et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A magma accretion model of oceanic lithosphere is proposed and its implications for understanding its thermal field examined. The new model (designated Variable Basal Accretion—VBA) assumes existence of lateral variations in magma accretion rates and temperatures at the boundary zone between the lithosphere and the asthenosphere. However, unlike the previous thermal models of the lithosphere, the ratio of advection to conduction heat transfer is considered a space dependent variable. The results of VBA model simulations reveal that the thickness of the young lithosphere increases with distance from the ridge axis, at rates faster than those predicted by Half-Space Cooling models. Another noteworthy feature of the new model is its ability to account for the main features in the thermal behavior of oceanic lithosphere. The improved fits to bathymetry have been achieved for the entire age range and without the need to invoke the ad-hoc hypothesis of large-scale hydrothermal circulation. Also, use of VBA model does not lead to artificial discontinuities in the temperature field of the lithosphere, as is the case with GDH (Global Depth Heat Flow) reference models. The results suggest that estimates of global heat loss need to be downsized by at least 25%.