Igneous and metamorphic enclaves in the S-type Deddick Granodiorite, Lachlan fold Belt, SE Australia: Petrographic, geochemical and Nd-Sr isotopic evidence for crustal melting and magma mixing

Abstract

The Deddick Granodiorite, a mafic S-type pluton in the Lachlan Fold Belt, contains abundant enclaves. Most are derived from high-grade metasediments of pelitic-psammitic composition, and migmatites are common. Among these, discrete fragments of melanosomes rich in cordierite and garnet are restites from partial melting. However, compositional and Nd-Sr isotopic data indicate they are not restite in equilibrium with the melt component of the host magma, but may have formed part of a spectrum of diverse magma source lithologies. Alternatively, they may be accidental xenoliths. Regardless of their origin, data for these enclaves suggest their precursors could represent deeply buried age equival..