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KoppersAnthonyCEOASConstraintsPastPlate.pdf

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https://ir.library.oregonstate.edu/concern/articles/jq085m70c

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  • Estimates of the relative motion between the Hawaiian and Louisville hot spots have consequences for understanding the role and character of deep Pacific-mantle return flow. The relative motion between these primary hot spots can be inferred by comparing the age records for their seamount trails. We report ⁴⁰Ar/³⁹Ar ages for 18 lavas from 10 seamounts along the Hawaiian-Emperor Seamount Chain (HESC), showing that volcanism started in the sharp portion of the Hawaiian-Emperor Bend (HEB) at ≥47.5 Ma and continued for ≥5 Myr. The slope of the along-track distance from the currently active Hawaiian hot spot plotted versus age is constant (57 ± 2 km/Myr) between ~57 and 25 Ma in the central ~1900 km of the seamount chain, including the HEB. This model predicts an age for the oldest Emperor Seamounts that matches published ages, implying that a linear age-distance relationship might extend back to at least 82 Ma. In contrast, Hawaiian age progression was much faster since at least ~15 Ma and possibly as early as ~27 Ma. Linear age-distance relations for the Hawaii-Emperor and Louisville seamount chains predict ~300 km overall hot spot relative motion between 80 and 47.5 Ma, in broad agreement with numerical models of plumes in a convecting mantle, and paleomagnetic data. We show that a change in hot spot relative motion may also have occurred between ~55 Ma and ~50 Ma. We interpret this change in hot spot motion as evidence that the HEB reflects a combination of hot spot and plate motion changes driven by the same plate/mantle reorganization.
  • Keywords: Mantle geodynamics, Plate motion, Hawaiian-Emperor seamounts, Plumes, Seamounts, Hot spots
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file details KoppersAnthonyCEOASConstraintsPastPlate.pdf 2017-07-25 Público Descargar