Revised slip rates for the Alpine fault at Inchbonnie: Implications for plate boundary kinematics of South Island, New Zealand

• DOI: 10.1130/l88.1
• Publication Date: 2010-05-25T17:38:46Z
• Authors: R.M. Langridge; P. Villamor; R. Basili; P. Almond; J.J. Martinez-Diaz; C. Canora
• Keywords: Alluvial fan

The northeast-striking, dextral-reverse Alpine fault transitions into the Marlborough Fault System near Inchbonnie in central South Island, New Zealand. slip-rate estimates for are presented following a reassessment of geomorphology and age displaced late Holocene alluvial surfaces Taramakau River at Inchbonnie. Progressive avulsion abandonment floodplain, aided by movements during Holocene, have preserved left-stepping scarp that grows height to northeast. Surveyed dextral (22.5 ± 2 m) vertical (4.8 0.5 displacements across left stepover an surface combined with precise maximum from remnant tree stump (≥1590–1730 yr) yield dextral, vertical, reverse-slip rates 13.6 1.8, 2.9 0.4, 3.4 0.6 mm/yr, respectively. These values larger (dextral) smaller (dip slip) than previous this site, but they reflect advances local chronology represent improved time-averaged results over 1.7 k.y. A geological kinematic circuit constructed Island demonstrates (1) 69%–89% Australian-Pacific plate motion is accommodated major faults (Alpine-Hope-Kakapo) transitional area, (2) 50% drop slip rate on between Hokitika taken up Hope Kakapo southwestern edge System, (3) new more compatible contemporary models strain partitioning geodesy.