Chapter 5: Correlations between a heterogeneous mantle and multiple stages of crustal growth: a review of the Dun Mountain ophiolite, New Zealand
Published:May 08, 2019
D. Jugum, E. Stewart, J. M. Palin, N. Mortimer, R. J. Norris, W. M. Lamb, 2019. "Correlations between a heterogeneous mantle and multiple stages of crustal growth: a review of the Dun Mountain ophiolite, New Zealand", Paleozoic–Mesozoic Geology of South Island, New Zealand: Subduction-related Processes Adjacent to SE Gondwana, A. H. F. Robertson
Download citation file:
The mantle and crustal sections of the Permian Dun Mountain ophiolite (DMO) in New Zealand's South Island have similar and potentially related tectonic histories. The mantle section records a four-part sequence of mid-ocean ridge basalt, and boninite melt extraction, followed by refertilization from supra-subduction melts and, finally, the intrusion of mafic–felsic island-arc tholeiite dykes. The crustal sequence represents a progression from mid-ocean ridge basalts to transitional island-arc tholeiites and, finally, mafic–felsic, possibly calc-alkaline, lavas; overlain by the 6 km-thick sedimentary Maitai Group. Plagiogranite zircon geochronology shows that the crustal ocean-ridge volcanism had commenced by 277.6 ± 3.3 Ma, and the youngest granites and granodiorites crystallized by 269.3 ± 4.5 Ma. All lithologies of the DMO are inferred to have formed in a broad forearc setting, representing a sequence from subduction initiation to magmatic arc formation. Sedimentary blocks within the structurally underlying ophiolitic Patuki Melange are similar to the Maitai Group, supporting a formational relationship with the DMO.
Figures & Tables
Paleozoic–Mesozoic Geology of South Island, New Zealand: Subduction-related Processes Adjacent to SE Gondwana
CONTAINS OPEN ACCESS
This volume presents a set of research papers that provide new data and interpretations of the Permian–Triassic terranes of SE Gondwana, now exposed in South Island, New Zealand. Following an introduction for general readers, a historical summary and a review of biostratigraphy, the individual papers primarily focus on the Permian magmatic arc of the Brook Street Terrane, the classic Permian Dun Mountain ophiolite and the Permian–Triassic Maitai Group sedimentary succession. The new results emphasize the role of subduction and terrane displacement adjacent to the Permo-Triassic Gondwana margin, and present fundamental insights into three crustal processes: subduction initiation, supra-subduction zone oceanic crust genesis and forearc basin evolution. The volume concludes with a wide-ranging summary and synthesis of the regional Cambrian to Early Cretaceous tectonostratigraphy of New Zealand's South Island in relation to the wider areas of Zealandia, East Australia and West Antarctica. The volume will interest geoscientists, including stratigraphers, sedimentologists, palaeontologists, igneous petrologists, geochemists, geochronologists and economic geologists, and is aimed at professional geologists and advanced students of geology.