Use and Abuse of the Terms Calcalkaline and Calcalkalic
Date
2003
Authors
Arculus, Richard
Journal Title
Journal ISSN
Volume Title
Publisher
Oxford University Press
Abstract
The terms calcalkalic and calcalkalic are currently defined and used in multiple and non-equivalent ways. Generally, the variation of total Fe as FeO/MgO within evolving subalkaline rock suites is regarded as the most distinctive character of calcalkaline compared with tholeiitic suites, reflecting the relative timing of phase saturation with Fe-Ti oxides, plagioclase, and ferromagnesian silicates. Other classification schemes are widely used, including a minority of adherents to the original formalized definition of 'calcalkalic' by Peacock (1931, Journal of Geology 39, 54-67). Given the prevailing contradictory and confusing usage of these terms, which leads to miscommunication, it is proposed that the spectrum of subalkaline rocks be divided into high-, medium-, and low-Fe suites, complementing divisions made on the basis of K contents. The terms calcalkaline and calcalkalic should be restricted to rock suites that conform to Peacock's definition.
Description
Keywords
Keywords: calc alkaline rock; classification; geochemistry; petrology; terminology; tholeiite Calcalkalic; Calcalkaline; Rock classification; Subalkaline; Tholeiitic
Citation
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Source
Journal of Petrology
Type
Journal article