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– 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 …