Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wilson, C. K. Articles by Boyd, O. S. Search for Related Content GeoRef GeoRef Citation

Distributed deformation in the lower crust and upper mantle beneath a continental strike-slip fault zone: Marlborough fault system, South Island, New Zealand

¹ Department of Geological Sciences, University of Colorado, and Cooperative Institute for Research in Environmental Sciences (CIRES), Boulder, Colorado 80309, USA

Converted phases from teleseisms recorded by a seismic array spanning the northern half of the Marlborough fault system, South Island, New Zealand, show a continuous unbroken Moho underlying a seismically anisotropic lower crust beneath the two northernmost faults of the fault system. These observations suggest that distributed deformation, not slip on a narrow vertical fault, accommodates displacement in the lower crust below the 120–480 km of right-lateral slip across the Wairau fault, one splay of the Marlborough fault system, and the northward continuation of the Alpine fault. Beneath the Wairau fault, the Moho dips 25°–30° southeast from a depth of 26 km northwest of the fault to a depth of 34 km southeast of the fault. Farther to the southeast, Ps conversions from the Moho continue under the Awatere fault (34 ± 10 km of slip) with a constant amplitude and depth of 34 km. Across the two faults, converted energy from 16–20 km depth varies with back-azimuth in a manner suggesting the presence of anisotropy in the lower crust. These observations imply that one of the tenets of plate tectonics, that faults defining plate boundaries pass through both crust and upper mantle, does not apply to New Zealand, or to continents in general.

Key Words: strike-slip faults • rheology • tectonics • lower crust • seismic anisotropy • ductile deformation

This article has been cited by other articles:

				G. Hillers and S. G. Wesnousky Scaling Relations of Strike-Slip Earthquakes with Different Slip-Rate-Dependent Properties at Depth Bulletin of the Seismological Society of America, June 1, 2008; 98(3): 1085 - 1101. [Abstract] [Full Text] [PDF]

				M. S. Steckler, N. P. Agostinetti, C. K. Wilson, P. Roselli, L. Seeber, A. Amato, and A. Lerner-Lam Crustal structure in the Southern Apennines from teleseismic receiver functions Geology, February 1, 2008; 36(2): 155 - 158. [Abstract] [Full Text] [PDF]