Abstract

The Pacific plate is usually considered to host 14 hotspots, but most of this volcanism does not seem to originate from deep-mantle plumes. To reach this conclusion, we tried to establish how many of the seamount alignments on the Pacific plate correspond to classic hotspots, i.e., long-lived hotspots linked to oceanic basaltic plateaus. We retraced the tracks of the 14 Pacific hotspots by using (1) the absolute stage poles representing the Pacific plate absolute motion since 145 Ma, (2) an updated compilation of radiometric ages of seamounts and oceanic plateaus totaling 266 seamounts or islands, (3) the detailed bathymetry of the Pacific Ocean, and (4) the present locations of the hotspots. This analysis allowed us to correlate only three hotspots with the beginning of their tracks possibly corresponding in space and time to an oceanic plateau: Easter to the eastern Mid-Pacific Mountains, Louisville to the Ontong Java plateau, and, with less confidence, Marquesas to Hess Rise and Shatsky Ridge. In addition, the Hawaii hotspot has produced long-lived volcanism. These four are the only classic hotspots on the Pacific plate. However, seven hotspots present short tracks (<35 m.y.) that cannot be traced to an oceanic plateau and thus are not related to any deep-mantle phenomena: Foundation, Macdonald, Pitcairn, Rarotonga, Rurutu, Samoa, and Society. The two northeast Pacific hotspots, Kodiak-Bowie and Cobb, and the Caroline hotspot are unclassifiable because of close proximity to a subduction zone where the prior history of volcanism has been lost.

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