Large variations in vent fluid CO2/3He ratios signal rapid changes in magma chemistry at Loihi seamount, Hawaii

Article Abstract:

The Loihi seamount, Hawaii, has been intensely studied because it is the youngest manifestation of the hotspot which caused the Hawaiian islands and the Emperor-Hawaiian seamount chain. The seamount experienced an intense period of seismic activity in July-August 1996, following which hydrothermal vent fluids were collected. Data from these samples shows large variations in the CO2/3He ratios of the vent fluids compared with pre-activity calculations and suggest that the expected evolution of the Hawaiian plume to a stage of shield-building tholeiitic magmatism is not yet completed.

Natural history, Volcanoes, Hawaii, Seamounts, Hawaii Island

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dynamic topography, plate driving forces and the African superswell

Article Abstract:

Deep mantle structure is shown to account well for observed surface gravity field and motions of tectonic plates. However the origin of some large scale feature continue to be controversial. Global seismic tomography studies have indicated the existence of a major low-velocity anomaly below the African plate. It is now shown that the mantle flow induced by density variations from such anomalies can support the excess elevation of the African superswell.

Earth, Africa, Geology, Structural, Structural geology, Mantle (Geology)

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