Document Type

Article

Publication Date

8-2010

Keywords

Fault growth, Terrace deformation, Ostler fault, Lateral propagation, Wind gap, Listric thrust

Abstract

Rarely are geologic records available to constrain the spatial and temporal evolution of thrust‐fault growth as slip accumulates during repeated earthquake events. Here, we utilize multiple generations of dated and deformed fluvial terraces to explore two key aspects of the along‐strike kinematic development of the Ostler fault zone in southern New Zealand over the past ∼100 k.y.: accumulation of fault slip through space and time and fixed‐length thrust growth that results in patterns of drainage diversion suggestive of laterally propagating faults. Along the Ostler fault, surface deformation patterns revealed by topographic surveying of terrace profiles in nine transverse drainages define systematic variations in fault geometry and suggest deformation over both listric and planar thrust ramps. Kinematic modeling of folded terrace profiles and >100 fault‐scarp surveys along major fault sections reveals remarkably similar slip distributions for multiple successions of geomorphic surfaces spanning ∼100 k.y. Spatially abrupt and temporally sustained displacement gradients across zones of fault section overlap suggest that either persistent barriers to fault propagation or interference between overlapping faults dominate the interactions of fault tips from the scale of individual scarps to the entire fault zone. Deformed terrace surfaces dated using optically stimulated luminescence and cosmogenic radionuclides indicate steady, maximum rates of fault slip of ∼1.9 mm/yr during the Late Quaternary. Slip data synthesized along the central Ostler fault zone imply that displacement accumulated at approximately constant fault lengths over the past ∼100 k.y. A northward temporal progression of abandoned wind gaps along this section thus reflects lateral tilting in response to amplification of displacement, rather than simple fault lengthening or lateral propagation. Oscillations of climate at ∼104‐yr time scales modulate the formation and incision of geomorphic surfaces during successive glacial stages. Superimposed on apparently steadier rates of fault slip, such climate‐dependent surfaces contribute to a pattern of progressive drainage deflection along the central Ostler fault zone that is largely independent of fault propagation.

Publication Title

Tectonics

Volume

29

Issue

4

DOI

10.1029/2009TC002613

Required Publisher's Statement

Copyright 2010 by the American Geophysical Union.

Link to publisher version: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2009TC002613

https://doi.org/10.1029/2009TC002613

Type

Text

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

Language

English

Format

application/pdf

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