Determining Relative Mantle Plume Motion Using Hotspot Track Geometry, Geochronology and Geochemistry.
Abstract
Age-progressive hotspot tracks are generated from the movement of Earth's lithosphere over mantle plumes. Assuming mantle plume conduits are fixed, coeval hotspot tracks erupted on the same tectonic plate should fit a consistent pole of rotation. However, paleomagnetic and geodynamic modeling evidence indicate that mantle plumes are not laterally fixed relative to each other. Here we use a combination of geochronology and isotope geochemistry to define a new long-lived age progressive hotspot track beneath the Pacific Plate, derived from the Rurutu plume. By comparing its hotspot track geometry to two other well-defined Pacific hotspot tracks (Hawaii-Emperor and Louisville) the relative motions of the three plumes can now be defined. The results indicate that Hawaii is unique in its rapid southward motion from 60 to 50 Myrs ago. The Louisville and Rurutu plumes appear to have had little independent plume motion or have moved in relative tandem during the last 70 Myrs. The bend in the Rurutu hotspot track ( 50.5-49 Ma) is coeval with the Hawaii-Emperor Bend. The difference in paleomagnetic data between Hawaii and Louisville, and the unchanging Louisville-Rurutu inter-hotspot distance, is consistent with subduction-driven plume motion changes in the northern Pacific, around Hawaii. However, the clear bend in the Rurutu hotspot track, if not derived from plume motion, infers a change in Pacific plate motion at 50 Ma. This methodology provides tangible constraints for testing and comparing ever-improving geodynamic models of Earth's mantle.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMGP23A..02K
- Keywords:
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- 1229 Reference systems;
- GEODESY AND GRAVITYDE: 1525 Paleomagnetism applied to tectonics: regional;
- global;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 8137 Hotspots;
- large igneous provinces;
- and flood basalt volcanism;
- TECTONOPHYSICSDE: 8158 Plate motions: present and recent;
- TECTONOPHYSICS