Entry from British & World English dictionary
(Of an igneous rock) containing a higher proportion (taken together) of sodium and potassium than of aluminium.
- During the mid-1980s to early 1990s more research took place that involved detailed petrographical and geochemical studies on the syenites, alkaline, and peralkaline rocks.
- This suggests that the peralkaline volcanic magma was derived from a lithospheric mantle source that had not been previously depleted in incompatible elements.
- Continental rifting started in the Early Cambrian with intrusion of crust-derived metaluminous to slightly peraluminous A-type granites, and culminated in the Mid-Cambrian with eruption of peralkaline rhyolites.
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