Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/6470
AuthorsLangridge, R. M.* 
Villamor, P.* 
Basili, R.* 
Almond, P.* 
Martinez-Diaz, J. J.* 
Canora, C.* 
TitleRevised slip rates for the Alpine fault at Inchbonnie: Implications for plate boundary kinematics of South Island, New Zealand
Other TitlesRevised slip rates for the Alpine fault at Inchbonnie
Issue Date25-May-2010
Series/Report no.3/2(2010)
DOI10.1130/L88.1
URIhttp://hdl.handle.net/2122/6470
KeywordsAlpine fault
plate boundary
slip rate
New Zealand
Subject Classification04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology 
04. Solid Earth::04.04. Geology::04.04.02. Geochronology 
04. Solid Earth::04.04. Geology::04.04.03. Geomorphology 
04. Solid Earth::04.04. Geology::04.04.09. Structural geology 
04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution 
04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics 
04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics 
04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics 
AbstractThe northeast-striking, dextral-reverse Alpine fault transitions into the Marlborough Fault System near Inchbonnie in the central South Island, New Zealand. New slip-rate estimates for the Alpine fault are presented following a reassessment of the geomorphology and age of displaced late Holocene alluvial surfaces of the Taramakau River at Inchbonnie. Progressive avulsion and abandonment of the Taramakau floodplain, aided by fault movements during the late Holocene, have preserved a left-stepping fault scarp that grows in height to the northeast. Surveyed dextral (22.5 ± 2 m) and vertical (4.8 ± 0.5 m) displacements across a left stepover in the fault across an alluvial surface are combined with a precise maximum age from a remnant tree stump (≥1590–1730 yr) to yield dextral, vertical, and reverse-slip rates of 13.6 ± 1.8, 2.9 ± 0.4, and 3.4 ± 0.6 mm/yr, respectively. These values are larger (dextral) and smaller (dip slip) than previous estimates for this site, but they refl ect advances in the local chronology of surfaces and represent improved time-averaged results over 1.7 k.y. A geological kinematic circuit constructed for the central South Island demonstrates that (1) 69%–89% of the Australian-Pacific plate motion is accommodated by the major faults (Alpine-Hope-Kakapo) in this transitional area, (2) the 50% drop in slip rate on the Alpine fault between Hokitika and Inchbonnie is taken up by the Hope and Kakapo faults at the southwestern edge of the Marlborough Fault System, and (3) the new slip rates are more compatible with contemporary models of strain partitioning presented from geodesy.
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