Arc crust formation of Lesser Antilles revealed by crustal xenoliths from Petit St. Vincent

Melekhova, Elena; Camejo-Harry, Michal; Blundy, Jon; Wallis, Simon R; Annen, Catherine; Kunz, Barbara E; Jenner, Frances and Thirlwall, Matthew (2022). Arc crust formation of Lesser Antilles revealed by crustal xenoliths from Petit St. Vincent. Journal of Petrology, 63(5), article no. egac033.

DOI: https://doi.org/10.1093/petrology/egac033

Abstract

The Lesser Antilles volcanic arc is known for its magmatic diversity and unusually abundant plutonic xenoliths. Xenoliths from Petit St. Vincent (Grenadines archipelago) are particularly interesting because of their textural and petrogenetic range. Here we combine petrographic observations, Electron Backscatter Diffraction (EBSD) analysis, major and trace element chemistry of xenoliths and lavas, and geochemical and thermal modelling to explore the construction of arc crust beneath Petit St. Vincent.

Petit St. Vincent xenoliths are dominated by calcic plagioclase, clinopyroxene and amphibole, and can be divided into two main categories, igneous and meta-igneous. Igneous xenoliths typically have cumulate textures; meta-igneous xenoliths range texturally from those that preserve vestiges of primary magmatic fabrics to intensely deformed varieties characterised by grain-size reduction and foliation development. Meta-igneous xenoliths also contain the most calcic plagioclase (An_98-100).