Introduction to Minerals, Inclusions and Volcanic Processes

Abstract

Minerals are intrinsically resistant to the processes that homogenize silicate liquids—their compositions thus yield an archive of volcanic and magmatic processes that are invisible at the whole rock scale. Minerals and their inclusions record diverse magma compositions, the depths and temperatures of magma storage, the nature of open system processes, and the rates at which magmas ascend. The potential for understanding volcanic systems through minerals and their inclusions has long been recognized (Sorby 1858). Sorby’s (1863) study of James Hall’s reversal experiments helped resolve the “basalt controversy” in favor of a volcanic origin, while Zirkel’s (1863) discovery of quartz within a volcanic rock helped tip the balance in favor of a magmatic origin for granite (Young 2003). Studies of phenocrysts have also long illustrated the importance of wall rock assimilation and magma mixing (e.g., Fenner 1926; Finch and Anderson 1930; Larson et al. 1938), and the potential for geothermometry (Barth 1934). Darwin’s (1844) mineralogical field-studies in the Galapagos archipelago, followed by King’s (1878) studies at Hawaii, also inaugurated the establishment of fractional crystallization as an important evolutionary process (Becker 1897; Bowen 1915). Recent advances in micro-analytical techniques open a new realm of detail, building upon a long history of mineralogical research; this volume summarizes some of this progress. Our summary focuses on volcanologic and magmatic processes, but the methods reviewed here extend well beyond terrestrial applications. Samples from the Stardust return mission, for example, show that olivine, plagioclase and pyroxene pervade the solar system (Brownlee et al. 2006)—while the topics covered here surely apply to all terrestrial-like planetary bodies, relevance may extend to a cosmic scale. Our more modest hope is that this volume will aid the study of disparate fields of terrestrial igneous systems, and perhaps provide a catalyst for new collaborations and integrated studies. …