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 6: Coupled deformation and melt-migration events recording subduction initiation, Dun Mountain ophiolite, New Zealand
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Published:May 08, 2019
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CiteCitation
E. Stewart, J. Newman, B. Tikoff, S. Donnelly, L. German, V. Chatzaras, W. M. Lamb, B. Miller, S. C. Kruckenberg, 2019. "Coupled deformation and melt-migration events recording subduction initiation, Dun Mountain ophiolite, New Zealand", 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, South Island, New Zealand, records complex overprinting of mantle fabrics. Using structural observations, microstructural analysis, geothermometry, geobarometry, geochronology and rheological constraints from the Red Hills and Dun Mountain massifs, we propose that three deformation events occurred during the early stages of subduction initiation along the Permian margin of Gondwana. During the first deformation event, the lineated Two Tarns Harzburgite from the Red Hills formed in a transtensional setting associated with subduction initiation. Deformation was pervasive, homogeneous and simultaneous with boninitic melt migration through the unit; it also occurred at very fast strain rates (10−9–10−8 s−1). During the second deformation event, progressive exhumation to c. 5 kbar and cooling to 1000°C led to the localization of melt and deformation into distinct zones (Dun Mountain, and the Plateau Complex, Plagioclase Zone and Ellis Stream Complex of the Red Hills). The third deformation event resulted in continued cooling and exhumation along serpentinized faults. This history provides a rare glimpse of the coupled fabric development and melt migration that sequentially develop in the early mantle wedge during the initiation of a subduction zone.
- Australasia
- chain silicates
- crystallography
- deformation
- fabric
- feldspar group
- framework silicates
- geochronology
- geologic barometry
- geologic thermometry
- harzburgite
- igneous rocks
- kinematics
- mantle
- melts
- microstructure
- mineral composition
- New Zealand
- ophiolite
- ophiolite complexes
- outcrops
- Paleozoic
- peridotites
- Permian
- petrography
- plagioclase
- plate tectonics
- plutonic rocks
- preferred orientation
- pyroxene group
- rheology
- silicates
- South Island
- strain
- structural analysis
- subduction
- tectonics
- tectonite
- U/Pb
- ultramafics
- Dun Mountain Ophiolite
- Red Hills Massif
- Porter Fault
- Two Tarns Harzburgite
- Ellis Stream Complex