期刊
EARTH AND PLANETARY SCIENCE LETTERS
卷 306, 期 3-4, 页码 205-216出版社
ELSEVIER
DOI: 10.1016/j.epsl.2011.04.001
关键词
mantle convection; heat flux; supercontinent Pangea; magnetic polarity reversals
资金
- U.S. National Science Foundation [EAR-1015669, EAR-0855712]
- David and Lucile Packard Foundation
- Division Of Earth Sciences
- Directorate For Geosciences [1015669, 0855791, 0855712] Funding Source: National Science Foundation
The Earth's surface and core-mantle boundary (CMB) heat fluxes are controlled by mantle convection and have important influences on Earth's thermal evolution and geodynamo processes in the core. However, the long-term variations of the surface and CMB heat fluxes remain poorly understood, particularly in response to the supercontinent Pangea - likely the most significant global tectonic event in the last 500 Ma. In this study, we reconstruct temporal evolution of the surface and CMB heat fluxes since the Paleozoic by formulating three-dimensional spherical models of mantle convection with plate motion history for the last 450 Ma that includes the assembly and break-up of supercontinent Pangea. Our models reproduce well present-day observations of the surface heat flux and seafloor age distribution. Our models show that the present-day CMB heat flux is low below the central Pacific and Africa but high elsewhere due to subducted slabs, particularly when chemically dense piles are present above the CMB. We show that while the surface heat flux may not change significantly in response to Pangea assembly, it increases by similar to 16% from 200 to 120 Ma ago as a result of Pangea breakup and then decreases for the last 120 Ma to approximately the pre-200 Ma value. As consequences of the assembly and breakup of Pangea, equatorial CMB heat flux reaches minimum at similar to 270 Ma and again at similar to 100 Ma ago, while global CMB heat flux is a maximum at similar to 100 Ma ago. These extrema in CMB heat fluxes coincide with the Kiaman (316-262 Ma) and Cretaceous (118-83 Ma) Superchrons, respectively, and may be responsible for the Superchrons. (C) 2011 Elsevier B.V. All rights reserved.
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