Continental flood basalts: episodic magmatism above long-lived hotspots
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| Authors: | Johnston, ST; Thorkelson, DJ |
| Year: | 2000 |
| Journal: | Earth Planet. Sci. Lett. 175: 247-256 Article Link (DOI) |
| Title: | Continental flood basalts: episodic magmatism above long-lived hotspots |
| Abstract: | The eruption of continental flood basalt (CFB) may reflect episodic magmatism above long-lived mantle plumes, The Iceland and Yellowstone hotspots have generated successive CFB provinces, large intrusive complexes, anomalous uplift, basin formation, and rifting events, and linear volcanic chains dating back > 120 and > 70 Ma, respectively. Amagmatic intervals occurred: (1) when ascent of plumes to shallow levels-was impeded by impenetrable lithosphere, resulting in sub-lithospheric pending of plume mantle; and (2) in response to dispersion by subducting oceanic lithosphere in convergent margin settings. By comparison with the plume eruptive potential of typical oceanic hotspots, it is apparent that preservation of only a small portion of plume mantle ponded during an amagmatic interval is necessary to account for large volume of CFBs. Thermal erosion, lithospheric attenuation, translation of ponded hotspot mantle to the base of thinner penetrable lithosphere, and passage of plume mantle through slab windows in subducting oceanic lithosphere led to subsequent breakthrough and eruption of CFB. Since both mantle plume and plate tectonic processes have been operating since the Archean, it seems likely that the migration of continents over hotspots, with attendant magmatic and tectonic consequences,,is a common occurrence in the geological record. (C) 2000 Elsevier Science B.V. All rights reserved. |
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