Hunter Fracture Zone

The Hunter Fracture Zone is a sinistral (left-lateral) transform faulting fracture zone,[1] that to its south is part of a triple junction with the New Hebrides Trench, and the North Fiji Basin Central Spreading Ridge.[2] The Hunter Fracture Zone, with the Hunter Ridge, an area with recent volcanic activity to its north, is the southern boundary of the North Fiji Basin.[3] This boundary area in the south-western part of the Hunter Fracture Zone is associated with hot subduction, and a unique range of volcanic geochemistry.[4]

Hunter Fracture Zone
Geographical and geological relationships of the Hunter Fracture Zone. Zealandia is outlined in black.
EtymologyHunter Island
Coordinates20.667°S 177.0°W / -20.667; -177.0
Tectonics
PlateAustralian, New Hebrides and the Conway Reef Microplate
StatusActive
AgeMiocene-current

Geography

The Hunter Fracture Zone is located to the south and southwest of Fiji and starts where the southern part of the New Hebrides Trench ends due to the increasing obliqueness of convergence lending to more strike slip faulting than subducting. It terminates around the International Date Line, with the Kadavu Islands immediately to its north.[5] However some earlier work has postulated that the fault structures around Suva on Fiji itself are related and different authors have defined the zone variably.[6]

Seismicity

The western Hunter Fracture Zone is an area of fair shallow seismicity.[7] Large (more than Mw6) earthquakes have occurred in historic times.[8]

Tectonics

It defines part of the plate boundary between the New Hebrides and the Conway Reef Microplate with the Australian Plate, with the rest of the convergence being accommodated by subduction and rifting. The major present subduction and rifting is in an area where the Hunter Ridge is being split that is called the Monzier Rift.[9]. This is active volcanically as part of a separate subduction system to the rest of the Vanuatu subduction zone that has been called the Matthew and Hunter subduction zone.[10] The Hunter Ridge and Hunter Fracture Zone are the south eastern terminus of the Vanuatu subduction zone's subduction and its associated slab edge. From 3 million years ago the southernmost Central Spreading Ridge of the North Fiji Basin propagated southward and has now intersected with the New Hebrides Trench and the Hunter Fracture Zone to form the current triple junction.[1]

References
  1. Durance et al. 2012, p915
  2. Durance et al. 2012, p929
  3. Sigurdsson, IA; Kamenetsky, VS; Crawford, AJ; Eggins, SM; Zlobin, SK (1993). "Primitive island arc and oceanic lavas from the Hunter ridge-Hunter fracture zone. Evidence from glass, olivine and spinel compositions". Mineralogy and Petrology. 47 (2): 149–69. doi:10.1007/BF01161564.
  4. Durance et al. 2012, p929
  5. Begg, Graham (13 July 2002). "Arc dynamics and tectonic history of Fiji based on stress and kinematic analysis of dikes and faults of the Tavua Volcano, Viti Levu Island, Fiji". AGU Tectonics. 21 (4). doi:10.1029/2000TC001259. S2CID 129542546.
  6. Shorten, GG (1990). "Structural geology of Suva Peninsula and Harbour and its implications for the Neogene tectonics of Fiji". New Zealand Journal of Geology and Geophysics. 33 (3): 495–506. doi:10.1080/00288306.1990.10425704.
  7. Hamburger, MW; Isacks, BL (1994). Shallow seismicity in the north Fiji basin. In Basin Formation, Ridge Crest Processes, and Metallogenesis in the North Fiji Basin. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 21–32. Retrieved 4 July 2023.
  8. "Seismotectonics of the Eastern Margin of the Australia Plate" (PDF). Retrieved 3 July 2023.
  9. McCarthy et al. 2022, 1. Introduction.
  10. McCarthy et al. 2022, 2.1. The Vanuatu – Hunter Ridge subduction system.
Sources
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