Chapter 2 The path to understanding the central terranes of Zealandia

Abstract

Abstract This chapter traces the history of understanding the central terranes of New Zealand: Drumduan, Brook Street, Murihiku, Dun Mountain–Maitai and Caples. The terranes, mostly exposed in the South Island, are named from stratigraphic units of Late Paleozoic–Late Mesozoic age, including the Murihiku Supergroup, Brook Street Volcanics and Maitai groups, and the Dun Mountain ophiolite. European geologists in the mid-nineteenth century determined the stratigraphy of these rocks in the extremities of the island but in the succeeding half-century much effort was devoted to understanding widespread poorly fossiliferous ‘greywackes’: the ‘Maitai Controversy’. This was resolved in 1917 by palaeontology and the recognition of major faulting. In the 1940s the Alpine Fault, with an apparent 460 km dextral offset of the rocks at either end of the island, was recognized. In the following two decades, New Zealand was interpreted in terms of the geosynclinal hypothesis and then paired metamorphic belts. With plate tectonics, the basement rocks were assigned to terranes with the implication of being conveyed over considerable distances. The identification of source areas, coupled with the definition of the Cordilleran Median Batholith, has progressed the understanding of the present arrangement of the central terranes in the New Zealand part of Zealandia.