Аннотация
The alkaline mafic (lamprophyric) Gusinoozerskaya dyke in West Transbaikalia is composed of partially melted granite xenoliths. Among the xenoliths, two melted substrates are observed: (1) plagioclase and quartz, and (2) alkaline feldspar and quartz. Few millimeters thick microfelsite and microgranophiric rims are the products of melting around the granite xenoliths. Ultra-acid glass is observed in the inner parts of the xenoliths at the boundary of quartz and feldspars. A distinctive feature of the fresh melts (regardless of the composition of the protolithic substrate) is an increased content of potassium with K2O/Na2O≥2. Having compared the compositions of the products of contact melting with the experimental data, we conclude that melting took place in the presence of alkaline-chloride and/or alkaline-carbonic fluid released from the crystallizing host alkaline-basic magma. The probable geotectonic conditions for the occurrence of ultrapotassic acid magmas are estimated.
Язык оригинала | английский |
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Страницы (с-по) | 347-368 |
Число страниц | 22 |
Журнал | Geodynamics and Tectonophysics |
Том | 8 |
Номер выпуска | 2 |
DOI | |
Состояние | Опубликовано - 1 янв 2017 |