Geochemistry and terrane affiliation of Haast Schist from the western Southern Alps, New Zealand

The Haast Schist comprises a polygenetic metamorphic suite derived from Caples, Aspiring, and Torlesse terrane lithologies. High‐grade Alpine Schist, occurring immediately east of the Alpine Fault, has been ascribed previously to either the Caples or Torlesse terranes. Chemical analyses are presented of schist suites from (1) the Whitcombe River area, including samples that both stratigraphically overlie and structurally underlie the Pounamu Ultramafics, and (2) the lower Haast River, west of a greenschist‐rich sequence correlated with the Aspiring terrane. Discriminant function analysis of these suites, and of published data from the Fox‐Franz Josef area, indicates that the Alpine Schist has Torlesse affinities. This conclusion is also supported by ratio‐ratio plots of trace elements. A Torlesse terrane affiliation is also suggested for a small population of psammitic schists from within the Aspiring terrane. The Aspiring terrane sequence at Haast River, like the Pounamu Ultramafic Belt to the north, is bounded to the east and west by Torlesse metasediments. Both sequences are interpreted as imbricate thrust slices of a regionally variable basementto the Torlesse terrane, tectonicallyemplaced during early Rangitata collision and accretion.