K-Rich Cumulate Diorite at the Base of a Tilted Granodiorite Pluton from the New England Batholith, Australia
Petrological, isotopic, and gravity data for a massive granodiorite with K-rich biotite-diorite and tonalite variants in the New England Batholith, Australia, indicate that the more mafic rock types form the lower parts of a pluton that has been tilted so as to expose the base along its southwestern margin. The mafic rocks are inferred to be cumulates of refractory and phenocrystal phases and not the products of independent K-rich basic magmas. This evidence of tilting in the unfoliated granodiorite Uralla pluton suggests that granite samples should be used cautiously in palaeomagnetic-palaeolatitude studies, for the absence of metamorphic foliation is not sufficient evidence that the granite has not been tilted.