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"Hotspots"; Uppermantle or Deep-Mantle Phenomena?

Anderson, Don L. (1995) "Hotspots"; Uppermantle or Deep-Mantle Phenomena? In: Study of the earth's deep interior: SEDI Symposium held on 7-12 August 1994. Elsevier , Amsterdam, pp. 131-132.

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Large igneous provinces (LIPs) such as continental flood basalt (CFB) and oceanic plateau basalt (OPB) provinces are usually attributed to the arrival of giant plume heads from deep mantle thermal plumes. Thermal instability in D" is the usually mentioned mechanism. The difficulties with this mechanism include the effects of internal heating, background mantle convection, upper mantle phase changes, pressure dependent thermodynamic properties (low a, high lattice conductivity in D"), cold downwellings and lack of a mechanism for fixing locations. In the mantle, upwellings are expected to be broad and to be seriously affected by both endothermic and exothermic phase changes, plate motions and by dense cold downwellings., The ability of the mantle to generate narrow, hot, low viscosity, fixed plumes, independent of plate motions and convection, has not been demonstrated. Furthermore, the chemistry of so-called hotspot or plume magmas does not favor a deep source, particularly one at the core-mantle boundary (D"). The strongest evidence against a plume origin in a thin layer in contact with the core is the high and chondritic siderophile chemistry of "plume" basalts. Other components of hotspot magmas are fairly convincingly due to recycled material (oceanic and continental sediments, dehydrated slab, slab fluids) of various ages. All of the chemical components of hotspot magmas are found in island arc magmas and xenoliths, suggesting that the enriched components of hotspots can be provided by the shallow mantle. In fact, it is difficult to conceive how any recycled material (sediments, altered oceanic crust components) can be carried beyond the dehydration, ecologitization fronts.

Item Type:Book Section
Additional Information:© 1995 Elsevier Science B.V.
Record Number:CaltechAUTHORS:20150204-144816478
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:54382
Deposited By: Tony Diaz
Deposited On:05 Feb 2015 23:16
Last Modified:03 Oct 2019 07:57

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