Petrologic and experimental studies on the petrogenesis of Papua New Guinea ophiolites

The late Mesozoic Marum and Papuan ophiolites of Papua New Guinea dip from the continental margin towards accreted Paleogene island-arcs and appear to represent frontal-arc basement emplaced as a result of mid- Tertiary continent/arc collision. Both ophiolites comprise thick sequences of layered ultramafic and mafic cumulates overlying tectonite peridotite and have associated basaltic pillow lavas. The petrology and geochemistry of the cumulate sequences are not consistent with an origin from common mid-ocean ridge basalts (MORE). Discrimination between mid-ocean ridge or marginal basin origins for the Papua New Guinea ophiolites is more dependent on accurate dating of the rocks rather than geochemical characteristics.