Nature of the clinopyroxene and iron enrichment in alkalic and transitional basaltic magmas

✍ Scribed by F. Barberi; H. Bizouard; J. Varet

• Publisher: Springer
• Year: 1971
• Tongue: English
• Weight: 936 KB
• Volume: 33
• Category: Article
• ISSN: 0010-7999
• DOI: 10.1007/bf00386108

✦ Synopsis

Iron enrichment and elinopyroxene composition are considered to be good indicators of the magmatic parentage of volcanic series produced by fraetionation of basaltic magma. Tholeiitic series are in fact believed to be constantly more iron enriched than alkalic series and systematic differences in the clinopyroxene mineralogy of the two suites seem also to be well established. The aim of this paper is to demonstrate that such generalization cannot be accepted, as natural conditions can be realized under which the fractionation of alkalie or mildly alkalic basalts may produce series with strong iron enrichment and with clinopyroxene mineralogy "atypical" for basalts of alkaline affinity.

In the Erta'Ale volcanic range (Northern Danakil Depression, Ethiopia), an example of such a serie is found, with a mildly alkalic basaltic magma fractionating under low and falling oxygen fugacity and giving rise to a series with some "tholeiitic" chemical and mineralogical features.