Torlesse greywacke and Haast Schist source for Pliocene conglomerates nearReefton, New Zealand

Late Miocene-Quaternary conglomerates in the Inangahua valley record proven ance changes which can be related to tectonic activity in the northern Sout h Island. Conglomerate clasts within the early Miocene Rotokohu Coal Measur es comprise mainly metamorphosed quartzose greywacke with subordinate grani toids, consistent with an essentially local elastic source from west of the Alpine Fault. In contrast, conglomerates of the late Pliocene Old Man Grou p (Larry Schist and Cronadun Conglomerates) are dominated by Rakaia Terrane (Older Torlesse) greywacke and Haast Schist clasts from east of the Alpine Fault, which is c. 50 km southeast of the study area. A complete range of textural and metamorphic grades is present, confirming that oligoclase zone Alpine Schist was being exhumed during Pliocene time. The 50-70 degrees -d ipping Pliocene beds are unconformably overlain by subhorizontally dipping late Quaternary gravels (Tophouse and Speargrass Formations), which, like t he Miocene conglomerates, are composed of quartzose greywacke and granitoid rock types. Significant Quaternary deformation isolated the Inangahua vall ey area from the Southern Alps and resulted in a return to a local elastic provenance.