This dataset contains whole-rock geochemical and mineral chemical data for ultrapotassic volcanic rocks of the Efogi Volcanic Field, Papua New Guinea.

Abstract:

Continental subduction is the major cause of regional heterogeneities in the lithospheric mantle and contrasting types of magmatism and mineralization in post-collisional settings. We illustrate the relation between the nature of the subducted crust and the character of magmatism for the Late Miocene New Guinea orogen, that formed by the collision of the Australian continental margin with an island arc. The bipartite nature of the subducted Australian plate margin, with Precambrian crust in the west and Phanerozoic accreted arcs in the east, is reflected in the contrasting magmatism along the suture of the orogen. The chemical signature of the subducted crust is particularly prominent in small-volume Late Miocene–Quaternary ultrapotassic rocks. In the west, ultrapotassic lavas have low εNd values (–12.6 to –20.9), indicating the recycling of ancient continental material. Conversely, high εNd values of +3.5 to +4.5 are found in ultrapotassic lavas from eastern New Guinea. This suggests recycling of juvenile continental material, similar to the orthogneisses of the Late Miocene D'Entrecasteaux ultrahigh-pressure metamorphic complex exposed further to the east. By comparison with ultrapotassic rocks from other orogenic belts, we show that crustal recycling is responsible for regionally contrasting redox conditions in the lithospheric mantle, which may explain why porphyry-type deposits are important in some regions but absent in others.