Petrological Constraints on Potential Temperature
The existence of an active volcanic center or "hot spot " has commonly been taken as evidence of a hot diapir or "plume " ascending from the core-mantle boundary. Because many of these centers are located near or on volcanically active ridges, the origin of both types of volcanis...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.489.7443 http://www.mantleplumes.org/Penrose/PenPDFAbstracts/Presnall_Dean_abs.pdf |
| Summary: | The existence of an active volcanic center or "hot spot " has commonly been taken as evidence of a hot diapir or "plume " ascending from the core-mantle boundary. Because many of these centers are located near or on volcanically active ridges, the origin of both types of volcanism must be considered together. Determination of the potential temperature (Tp) is fundamental to correct modeling of the magma generation process, and would also address the issue of whether or not enhanced volcanic activity at a ridge (Iceland) or remote from a ridge (Hawaii) is driven by a hot diapir originating at the core-mantle boundary, with consequent implications for mantle dynamics. Large disagreements about Tp at Hawaii and along spreading ridges have persisted for decades. In Hawaii, olivine-controlled fractionation is well-documented and various authors have suggested that the parental magmas for this fractionation lie either toward the olivine-rich (high Tp) or olivine-poor (low Tp) end of this trend. Picritic glass shards on the ocean floor from the Puna Ridge of Kilauea (Clague et al., 1995) are compositionally between the two extremes and require a minimum Tp of about 1420˚C (Gudfinnsson and Presnall, 2003). No comparable picritic glass compositions have been found at Iceland or anywhere else along a spreading ridge. |
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