Abstract
Rocks from the Cordon Syenite Complex, located in the Philippine island arc, correspond to miaskitic (metaluminous) potassic lavas from the Roman Region and the Indonesian arc in terms of bulk rock chemistry. However, the mineral chemistry indicates a complex history of multiple equilibrations with liquids of different nature. T-site (Si + Al) occupancy in some clinopyroxenes and Ca contents of alkali feldspar phenocrysts indicate that these phases crystallized under the temperature-pressure subvolcanic regime from host liquids with progressively decreasing (Na + K)/Al ratio. In contrast to current views on the genesis of potassic rocks, it is suggested that differentiated leucite tephrite suites may be derived from peralkaline liquids by alkali loss. Magmas with affinities to lamproites may occur in the Philippine island arc, but a direct genetic relationship between subduction and alkaline/peralkaline magmatism remains questionable.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
