Pore throat network by feldspar replacement with potassium-rich fluids on the top of granitic magma during supercritical fluid processes

Abstract

In this study, we report novel pores that are developed within plagioclase in the hornblende schist of Kinkasan Island. In the matrix, the original plagioclase grains (An48Ab52) are replaced by patchy grains of albite (An4Ab94) and alkali feldspar (Ab1Or99), yielded a large number of porosities with the throat size of ~0.1 - 5 μm. These pores formed along the grain boundaries of newly-produced albite formed 3-D pore networks and increased the porosity of the rock up to ~2%. They suggest the self-generation of porosities during replacement induced by infiltration of reactive fluids.