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.
Chapter 8: Mid–Late Permian Upukerora Formation, South Island, New Zealand: fault-controlled mass wasting of the Early Permian Dun Mountain ophiolite and initiation of the Permian–Triassic Maitai continental margin forearc basin
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Published:May 08, 2019
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CiteCitation
Alastair H. F. Robertson, 2019. "Mid–Late Permian Upukerora Formation, South Island, New Zealand: fault-controlled mass wasting of the Early Permian Dun Mountain ophiolite and initiation of the Permian–Triassic Maitai continental margin forearc basin", Paleozoic–Mesozoic Geology of South Island, New Zealand: Subduction-related Processes Adjacent to SE Gondwana, A. H. F. Robertson
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Abstract
The Dun Mountain ophiolite and related oceanic-arc rocks (Otama Complex) formed above a westward-dipping subduction zone within Panthalassa, with implications for the emplacement of Cordilleran-type ophiolites and arcs elsewhere. The ophiolite is overlain by the Mid–Late Permian Upukerora Formation (up to 850 m), a predominantly very coarse breccia-conglomerate that mainly accumulated by mass flow. Lesser amounts of sediment accumulated from turbidity currents and as background hemipelagic sediments. The succession unconformably overlies ophiolitic basaltic or, rarely, gabbroic rocks after a regional hiatus. Much of the coarse clastic debris was derived from the underlying ophiolite. However, clasts of plagioclase-phyric basalt, felsic volcanics and quartz-bearing intrusive rocks, including plagiogranite, are over-represented compared to the ophiolite. The evolved igneous material was derived from an incipient oceanic arc (the Otama Complex) that bordered or covered the ophiolite, especially in the south. The coarse clastic material accumulated following the activation of north–south-trending, subaqueous, extensional growth faults within the underlying oceanic crust. Large blocks of mainly basalt, diabase and gabbro were also shed down fault scarps from relatively shallow-water to deeper-water settings. Fault-controlled talus accumulated soon after Mid-Permian docking of the ophiolite and oceanic arc with SE Gondwana to initiate the Mid-Permian–Mid-Triassic Maitai continental margin forearc basin.
- age
- Australasia
- basalts
- basins
- clastic sediments
- continental margin
- currents
- degradation
- deposition
- emplacement
- faults
- fore-arc basins
- geochemistry
- hemipelagic environment
- igneous rocks
- lithofacies
- lithostratigraphy
- Lower Permian
- Lower Triassic
- magmatism
- marine environment
- marine sediments
- mass movements
- Mesozoic
- mid-ocean ridge basalts
- Middle Permian
- New Zealand
- ophiolite
- ophiolite complexes
- outcrops
- Paleozoic
- Panthalassa
- Permian
- Permian-Triassic boundary
- petrography
- plate tectonics
- point counts
- provenance
- sediments
- South Island
- stratigraphic boundary
- subduction
- subduction zones
- succession
- tectonics
- Triassic
- turbidity currents
- Upper Permian
- volcanic rocks
- Dun Mountain Ophiolite
- Upukerora Formation
- Otama Complex