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Figure 14-1.After Crough (1983) Ann.Rev. Earth Planet. Sci., 11, 165-193.
This map shows important hot spots and hot spot tracks over the world.
Note that many tracks have kinks, indicating changing plate motions.
Ocean Intraplate Volcanism
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Types of OIB Magmas
Two principal magma series:
Tholeiitic series (dominant type), parental to ocean island tholeiitic
basalt, or OIT. This magma is similar to MORB, but with some distinct
chemical and mineralogical differences.
Alkaline series (subordinate), parental to ocean island alkaline basalt,
or OIA.
There are two principal alkaline sub-series:
Silica undersaturated sub-series (more common).
Slightly silica oversaturated sub-series (less common).
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Magma evolution in the oceanic island lava series
After Wilson, 1989, Igneous
Petrogenesis. Kluwer.
Strongly alkaline
Mildly alkalineTholeiitic
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Alkalinity of oceanic island lavasAlkalinity is highly variable among various oceanic islands. Alkalis are
incompatible and little affected by
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Spider diagrams
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Simple Mixing Models
Winter, 2001, An
Introduction to Igneous and
Metamorphic Petrology.Prentice Hall.
Binary mixing
All analyses fall along a line
between two end members assource regions or magmas mix.
Ternary mixing
All analyses fall within a triangle
of three end members as sourceregions or magmas mix.
A d l f i i
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Cartoon illustrating a conceptual model for the origin of various ocean
magmas, and the mantle reservoirs from which they ultimately come.
Nomenclature from Zindler and Hart, 1986, After Wilson, 1989, and Rollinson, 1993.
Depletedmantle
E
nriched
mantle
A model for oceanic magmatism
Continentalreservoirs
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