HR: 1330h
AN: V12B-0573    [PDF]
TI: The Effect of a Major Change in Plate Motion on Hotspot Volcanism
AU: * Kroenke, L W
EM: kroenke@soest.hawaii.edu
AF: School of Ocean and Earth Science and Technology, University of Hawaii 1680 East-West Rd, Honolulu, HI 96822
AU: Wessel, P
EM: pwessel@hawaii.edu
AF: School of Ocean and Earth Science and Technology, University of Hawaii 1680 East-West Rd, Honolulu, HI 96822
AB: Noticeable changes in Pacific hotspot volcanic edifice construction appear to have occurred following the change in Pacific plate motion that produced the Hawaiian Emperor bend (HEB). In addition to the Hawaiian Emperor trail, the same bend is also visible in seven other seamount trails across the Pacific Basin. Shortly after the HEB, volcanic edifice construction abruptly decreased along the Hawaiian trail, followed by a gradual increase over the next 10 myrs. Whereas, after the bends in the three collinear Marshall-Gilbert-Tuvalu trails and the two Tokelau trails, edifice construction completely stopped and never restarted. In contrast, after the bend in the Louisville trail, which was only a slight bend because of its distance from the stage pole, volcanic edifice construction actually increased. After the bend in the Tuamoto trail, which formed close to the spreading ridge, the Tuamoto plateau was emplaced. Modern hotspot volcanism appears to be located in upwelling regions formed between upper mantle rolls that are visible as geoid undulations, which are aligned parallel to plate motion. Assuming that plate motion parallel upper mantle rolls were also present prior to the HEB, the concurrence of the above events following the change in plate motion may indicate a disruption in the upper mantle convective flow pattern caused by the change, particularly in regions where the change was pronounced. Strong hotspots, such as Hawaii, continued to construct edifices, albeit more sparsely, until the convective flow pattern became reestablished. Weak hotspots, such as those forming the Marshall-Gilbert-Tuvalu and the Tokelau trails, were completely shut down. The time frame for the return to robust Hawaiian edifice construction, i.e. about 10 myrs., is in agreement with three dimensional modeling studies of planforms of convection required for the establishment of mantle rolls.
DE: 1025 Composition of the mantle
DE: 3035 Midocean ridge processes
DE: 3640 Igneous petrology
DE: 5480 Volcanism (8450)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting