Interstitial acid glass and chlorophaeite in Iceland basalts

Document Type

Article

Date of Original Version

7-15-1978

Abstract

Rhyolitic glass occurs as an interstitial phase in Tertiary basaltic dikes from northwestern Iceland forming up to 8% of the mode. Chlorophaeite occurs as globules within the glass as well as in interstitial vugs and vesicles. The existence and textural relations of these iron-rich globules in a silica-rich glass is suggestive of liquid immiscibility such as observed in synthetic systems. Trace element data on these naturally occurring phases is, however, inconsistent with experimentally determined partition coefficients for, for example, Ti, P, and Zr in immiscible liquids indicating that the chlorophaeite does not represent an immiscible phase and is more likely an alteration product. The similarity of the interstitial acid glasses to Iceland rhyolites is suggestive evidence of an origin for at least some Icelandic rhyolites by shallow-level fractional crystallization of basaltic magmas. © 1978.

Publication Title, e.g., Journal

LITHOS

Volume

11

Issue

3

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