Field Relations and Petrography of Partially Melted Pelitic and Semi-Pelitic Rocks

Abstract

Evidence of partial melting is seen in pelitic and semi-pelitic metasediments within the Ballachulish aureole in many locations immediately adjacent to the intrusive complex (within Zone V of Pattison and Harte 1985, and Chap. 8, this Vol.). In this chapter we summarize that evidence as seen both in the field and under the optical microscope. We endeavour in our presentation to largely keep description and interpretation in separate sub-sections, in an attempt to lay out the evidence for melting as objectively as possible. The chapter is concerned with textures and structures, their interpretation, and their implications for the rheological and crystallization behaviour of the melts. The reader is referred to Pattison and Harte (1985, 1988; Sect. 8.5, this Vol.) for notes concerning the melting reactions.