Metamorphic zones, terranes, and Cenozoic faults in the Marlborough Schist, New Zealand

Abstract

Abstract The northeast‐striking Picton Fault Zone is a major structural and metamorphic break that divides the Marlborough Schist into two separate blocks. The northwestern (Kaituna) block shows a regular increase in textural and metamorphic grade to the southeast from prehnite‐pumpellyite to greenschist facies and textural zone I to IV. The southeastern (Arapawa) block shows an irregular increase in grade to the southeast from prehnite‐pumpellyite to pumpellyite‐actinolite facies and textural zone I to IIB. The Kaituna block is correlated with the Caples and Torlesse Terranes and the Otago Schist of the southern South Island. The Arapawa block is correlated with the Waipapa Terrane (possibly also the Torlesse Terrane) and Kaimanawa Schist of the North Island. Isotects and the Picton Fault Zone are dextrally offset by 10–15 km across the ENE‐striking Queen Charlotte Fault Zone. The latter should be included with the late Cenozoic Marlborough faults.