Provenance of Cretaceous accretionary wedge sediments: The Mangapokia Formation, Wairarapa, New Zealand

The middle Cretaceous Mangapokia Formation (pahaoa Group) near Te Awaiti, southeastNorth Island, New Zealand, consists of a submarine‐fan turbidite‐conglomerate sequence incorporated into the Torlesse terrane accretionary wedge during Mesozoic plate convergence along the eastern margin of Gondwana. Bedded turbiditic sandstones are feldspatholithic (mean Q 23 F4 42 L 35 ) and similar to other Cretaceous Torlesse rocks. Petrographic features and modal compositions of sandstones indicate a partly dissected magmatic arc provenance, and the geochemistry of the sandstone‐argillite suite suggests derivation from an Andean‐type active continental margin. Conglomerate clast compositions are variable with many sedimentary and silicic igneous rock types being indicative of mixed magmatic arc, recycled Torlesse, and cmtonic sources. A variety of conglomemtic detritus was derived from the New Zealand part of eastern Gondwana and tmnsported across the forearc transversely to the trench. Sandstone‐argillite detritus was derived either from a similar westerly source, and/or from south of the New Zealand region, where it was transported northward parallel to the trench. A partial modern analogue to the inferred Cretaceous sediment transport pathways is the oblique subduction‐tmnsform Hikurangi Margin. The Hikurangi Trough consists of a Quaternary sedimentary wedge comprising both longitudinally and transversely derived components from various source rocks.