High-temperature restite enclave as an evidence of deep-seated parent magma melting of the Będkowska Valley granodiorite (Silesian-Cracow area, South Poland) - preliminarypetrographic and mineralogical study

Abstract

Wysokotemperaturowy restyt jako dowód głębokiego wytapiania macierzystej magmy granodiorytu z Doliny Będkowskiej (obszar śląsko-krakowski) In the borehole DB-5, at a depth 1370.0 m dark micaceous enclave in granodiorite from Będkowska Valley was found. A sharp contact enclave/granodiorite is observed. The transition zone is irregularly developed around the enclave studied. It is a small enclave ( 3 x 6 cm), discoidal in shape. The microstructure of micaceous enclave is fine-blastic; crystalloblasts of rock-forming minerals are 0.2-0.5 mm in size. This enclave consists of: Fe-biotite (56-62 vol.%), plagioclase Ca-Na (34-40 vol. %), spinel (magnetite), corundum, and sericitic pseudotnorphs after cordierite. Its mineralogical composition is different from the Będkowska Valley granodiorite, what suggests that this rock is a medium/high-temperature restite. This rock represents residuum after partial melting of granodiorite magma in deep levels of basement of the Małopolska Massif.