Gas filter-pressing origin for segregation vesicles in dykes
By: Sanders, I.S
.
Material type: 
ArticleDescription: 67-72pp ; Illustration.Subject(s): Crystal chemistry | Irish dolerite dykes | Petrology | Framework silicates | Vesicular texture
In:
Geological magazine : Vol. 123 Iss. 1-6 Year. 1986Summary: Segregation vesicles have been recognized in two plagiophyric dolerite dykes in northwestern Ireland. The vesicles are each outlined by a rim of tangentially arranged plagioclase, and filled to a variable extent by a fine-grained, crescent-shaped lining of fractionated residual melt. They closely resemble segregation vesicles reported from Atlantic ocean-floor basalts.
It is suggested (1) that the vesicles began as CO2-rich bubbles released during decompression; (2) that these bubbles grew very little during crystallization, while H2O became concentrated in the residual melt; and (3) that exsolution and expansion of H2O-rich vapour forced interstitial residual melt through the rigid but permeable framework of crystals and into the existing CO2-rich bubble cavities.
| Item type | Current location | Collection | Call number | Status | Date due | Barcode |
|---|---|---|---|---|---|---|
Article
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Library and Information Centre Periodical Section | Bound Journal Collection | Not for loan | 002533_06 | ||
Serials/Scientific Journal
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Library and Information Centre Periodical Section | Bound Journal Collection | 550 GEO (Browse shelf) | Available | 002533 |
Segregation vesicles have been recognized in two plagiophyric dolerite dykes in northwestern Ireland. The vesicles are each outlined by a rim of tangentially arranged plagioclase, and filled to a variable extent by a fine-grained, crescent-shaped lining of fractionated residual melt. They closely resemble segregation vesicles reported from Atlantic ocean-floor basalts.
It is suggested (1) that the vesicles began as CO2-rich bubbles released during decompression; (2) that these bubbles grew very little during crystallization, while H2O became concentrated in the residual melt; and (3) that exsolution and expansion of H2O-rich vapour forced interstitial residual melt through the rigid but permeable framework of crystals and into the existing CO2-rich bubble cavities.
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