 Incapillo is found on a crust 70 kilometres ( 43 mi ) thick , among the thickest in volcanic regions of the Earth . Several studies by Suzanne Mahlburg Kay and others indicate that trends in the isotope ratios are because of a thickening crust and increased contribution thereof to the magmas . At the latitude of Incapillo , the northern Antofalla terrane borders the Cuyania terrane , both of which were attached to South America during the Ordovician but are of different provenance . 
