The Partial Melting of Basalt and Its Enclosed Mineral-Filled Cavities at Scawt Hill, Co. Antrim

D. E. Kitchen
Department of Environmental Studies, University of Ulster, Jordanstown, Co. Antrim, Northern Ireland BT37 0QB

Abstract: Partially melted basalts enclosing amygdales which have been completely melted formed at Scawt Hill adjacent to a Tertiary dolerite plug. Melting of the basalts commenced in a clay-rich mesostasis to produce a feldspathic liquid which then crystallized to an assemblage of dendritic olivine, skeletal hypersthene, opaque oxide and Mg-hercynite in a microcrystalline plagioclase matrix. An original mineral assemblage of zeolite, calcite, and saponite-nontronite in the amygdales melted and quenched to a brown glass now containing complexly zoned pyroxenes with plagioclase and opaque oxide. Melting commenced between 700–800°C, reaching a maximum temperature of 1168°C, and was followed by rapid cooling. The assimilation of remelted basalt may alter the course of crystallization of contaminated magmas.

Keywords: basalts • melting • amygdales • Scawt Hill • Co. Antrim • Northern Ireland

Mineralogical Magazine; December 1985 v. 49; no. 354; p. 655-662; DOI: 10.1180/minmag.1985.049.354.04
© 1985, The Mineralogical Society
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