A Comparison of Some Triassic Rocks in the Hokonui and Alpine Belts of South Island, New Zealand

Abstract

Kaihikuan (upper Middle Triassic) clastics of the Hokonui belt fine from west to east, and hence were derived from the west. Deep erosion of a volcanic terrane and associated shallow intrusives contributed most of the sediment, but reworking of contemporaneous pyroclastic debris was also an important process. In the Alpine belt, the source of Kaihikuan sediments was a deep-seated acidic plutonio terrane. At least some of the deposits formed in nearshore, shallow-marine environments. The Alpine belt sequences do not fit lateral extrapolations of sedimentologic or petrologie trends of the Hokonui belt, and thus cannot be explained as distal facies of the same sedimentary basin. The two belts probably were juxtaposed by faulting.