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Terrane boundary reactivation, barriers to lateral fault propagation and reactivated fabrics - Rifting across the Median Batholith Zone, Great South Basin, New Zealand

Phillips, Thomas B.; McCaffrey, Ken J.W.

Terrane boundary reactivation, barriers to lateral fault propagation and reactivated fabrics - Rifting across the Median Batholith Zone, Great South Basin, New Zealand Thumbnail


Authors

Thomas B. Phillips

Ken J.W. McCaffrey



Abstract

Prominent pre‐existing structural heterogeneities within the lithosphere may localise or partition deformation during tectonic events. The NE‐trending Great South Basin, offshore New Zealand, formed perpendicular to a series of underlying crustal terranes, including the dominantly granitic Median Batholith Zone, which along with the boundaries between individual terranes, exert a strong control on rift physiography and kinematics. We find that the crustal‐to‐lithospheric scale southern terrane boundary of the Median Batholith Zone is associated with a crustal‐scale shear zone that was reactivated during Late Cretaceous extension between Zealandia and Australia. This reactivated terrane boundary is oriented at a high‐angle to the faults defining the Great South Basin. We identify a large granitic laccolith along the southern margin of the Median Batholith, expressed as sub‐horizontal packages of reflectivity and acoustically transparent areas on seismic reflection data. The presence of this strong granitic body inhibits the lateral south‐westward propagation of NE‐trending faults, which segment into a series of splays that rotate to align along the margin as they approach. Further, we also identify two E‐W and NE‐SW oriented basement fabrics, likely corresponding to prominent foliations, which are exploited by small‐scale faults across the basin. We show that different mechanisms of structural inheritance are able to operate simultaneously, and somewhat independently, within rift systems at different scales of observation. The presence of structural heterogeneities across all scales need to be incorporated into our understanding of the structural evolution of complex rift systems.

Citation

Phillips, T. B., & McCaffrey, K. J. (2019). Terrane boundary reactivation, barriers to lateral fault propagation and reactivated fabrics - Rifting across the Median Batholith Zone, Great South Basin, New Zealand. Tectonics, 38(11), 4027-4053. https://doi.org/10.1029/2019tc005772

Journal Article Type Article
Acceptance Date Oct 10, 2019
Online Publication Date Nov 24, 2019
Publication Date Dec 26, 2019
Deposit Date Oct 11, 2019
Publicly Available Date Mar 28, 2024
Journal Tectonics
Publisher European Geosciences Union
Peer Reviewed Peer Reviewed
Volume 38
Issue 11
Pages 4027-4053
DOI https://doi.org/10.1029/2019tc005772

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Copyright Statement
Phillips, Thomas B. & McCaffrey, Ken J.W. (2019). Terrane boundary reactivation, barriers to lateral fault propagation and reactivated fabrics - Rifting across the Median Batholith Zone, Great South Basin, New Zealand. Tectonics 38(11): 4027-4053. 10.1029/2019TC005772. To view the published open abstract, go to https://doi.org/ and enter the DOI.




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