Orbicular granite in North Chile
An orbicular granite was discovered at Caldera, North Chile, in the 1980s field work. The granite is actually granodiorite in composition, composed of a ball structure fringed with amphibole aggregates and the matrix filled with salic minerals. The granodiorite contains a disc shaped dioritic enclave (left upper), indicating that the orbicular granite was formed from fluids-rich melts at the latest stage of the granitic magmatism.
(Photograph and Caption by Shunso Ishihara)
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