New Zealand tectonostratigraphic terranes and panbiogeography

Abstract

Tectonostratigraphic terranes of New Zealand, grouped for purposes of the present discussion into six groups, are briefly reviewed as to their role in the biogeographic evolution of the present day biota of New Zealand. Of all the terranes so far recognised, only the Torlesse (Rakaia) terrane is thought to have originated outside the New Zealand region; of the various models proposed to explain its origin and emplacement, only that by McKinnon (1983) would allow it to have acted as a “raft” that could have transported a biota en masse. The former existence of a “lost continent” (Pacifica), suggested as apossible source for Torlesse sediments, is regarded as improbable. The long time (at least 140 Ma, and probably 190 Ma) since terrane accretion, and the extreme degree of geological (and geographical) complexity and change that New Zealand has undergone since accretion, make it most improbable that the present day distribution of plants and animals among the terranes reflects the original distribution of their ancestors.

Keywords:

• accretion
• panbiogeography
• biotic transport
• Pacifica
• terranes
• Torlesse