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The Geochronology of Hotspot Trails in the Pacific and the Timing of the Hawaii-Emperor Bend Anthony Koppers Scripps Institution of Oceanography, IGPP, San Diego, USA. Predictions of the “Fixed Hotspot” Hypothesis Related to Geochronology. Constant Angular Plate Velocities
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The Geochronology of Hotspot Trails in the Pacific and the Timing of the Hawaii-Emperor BendAnthony KoppersScripps Institution of Oceanography, IGPP, San Diego, USA
Predictions of the “Fixed Hotspot” Hypothesis Related to Geochronology • Constant Angular Plate Velocities • Linear Age Progressions • Consistency in Observed Local Plate Velocities between Multiple Seamount Trails on the Same Tectonic Plate • Changes in Plate Motion Should Cause Similar and Synchronous Bends in Multiple Seamount Trails • Same Curvature of Seamount Trails • Same Timing
Do we have Different Kinds of Hotspots ? Are Different Processes Involved ? • PRIMARY / STRONGHotspot Trails that are Continuously Active with a Monotonous Age Progression, Flood Basalt Initiation, Deep Mantle 3He/4He Signature, Large Buoyancy Flux, Low Shear Wave Velocity in Mantle • SECONDARY / WEAKAny Other Hotspot Trail that is Typically Short Lived • TERTIARYExtensional Features, Like the Puka Puka Ridge Courtillet et al. 2003
What I will Cover in the Rest of this Talk … • Louisville Seamount Trail as a Primary Hotspot • Secondary Hotspots in the West Pacific • The Timing of the Hawaii-Emperor Bends in the Gilbert Ridge
Conclusions ( I ) • The elegant “hotspot” model may (still) explain the primary hotspots such as Hawaii and Louisville, if we allow for significant (inter) hotspot motion • However, it seems unable to explain the age distributions and origins of secondary hotspots in the West Pacific
Conclusions ( II ) • Hotspot motion, the structure of the overlying lithosphere and changing litho-spheric stress regimes may play an important role in the creation of the seamount trails • However, no conclusive data exists at this moment to determine which of these processes is the best candidate …