St. Helena Chain - Magmatic Setting and Magma Generating Processes
Item
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Title
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St. Helena Chain - Magmatic Setting and Magma Generating Processes
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Description
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Ocean island basalts (OIB's), such as the St. Helena Chain, sit on an oceanic plate that glides over a stationary hotspot. The hot spot (Figure 1) is sourced from the deep mantle near the Core - Mantle Boundary (approximately 3,000 km. depth).
Figure 2 depicts the geothermal gradient under normal conditions where there is no magma being generated. Under observed conditions, the stationary Hot Spot increases local temperatures at constant pressures allowing for the generation of magma. This magma eventually works its way to the surface by processes such as doming, wall rock assimilation, lateral wall rock displacement, and ductile wall rock deformation.
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Subject
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Ocean Island Basalts
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Creator
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Robert Ashton
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Date
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May 5, 2015
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Mediator
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Tamara Carley
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Rights Holder
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Lafayette College Department of Geology & Environmental Geosciences
