The Dillon and Acheron sinistral faults, Marlborough Fault System, New Zealand: field studies and mechanical modelling

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New Zealand Journal of Geology and Geophysics

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Department or Program


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The Dillon and Acheron are newly discovered, presumably active, sinistral faults that link the oblique-dextral Clarence and Elliott Faults in the Marlborough Fault System and define the Clarence–Elliott duplex. The Dillon Fault is expressed by offset streams and ridges, scarps, and gouge along several long, sub-parallel fault traces. The Acheron Fault is characterized by subtly offset geomorphic features and numerous, short, variably striking fault strands. 3D mechanical models were run to investigate the influence of the antithetic faults on deformation within the duplex for a variety of velocity boundary conditions. Only those models with antithetic faults and a 30° oblique compressional velocity field yielded a topography similar to that in the Clarence–Elliott duplex and fault kinematics similar to those observed. The present-day strike-slip velocity field produced subsidence in the duplex. This argues that an earlier compressional velocity field may have been responsible for most of the topography in the duplex.


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