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Pacific-Antarctic-Australia motion and the formation of the Macquarie Plate

Cande, Steven C. and Stock, Joann M. (2004) Pacific-Antarctic-Australia motion and the formation of the Macquarie Plate. Geophysical Journal International, 157 (1). pp. 399-414. ISSN 0956-540X. https://resolver.caltech.edu/CaltechAUTHORS:20140416-090150847

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Abstract

Magnetic anomaly and fracture zone data on the Southeast Indian Ridge (SEIR) are analysed in order to constrain the kinematic history of the Macquarie Plate, the region of the Australian Plate roughly east of 145°E and south of 52°S. Finite rotations for Australia–Antarctic motion are determined for nine chrons (2Ay, 3Ay, 5o, 6o, 8o, 10o, 12o, 13o and 17o) using data limited to the region between 88°E and 139°E. These rotations are used to generate synthetic flowlines which are compared with the observed trends of the easternmost fracture zones on the SEIR. An analysis of the synthetic flowlines shows that the Macquarie Plate region has behaved as an independent rigid plate for roughly the last 6 Myr. Finite rotations for Macquarie–Antarctic motion are determined for chrons 2Ay and 3Ay. These rotations are summed with Australia–Antarctic rotations to determine Macquarie–Australia rotations. We find that the best-fit Macquarie–Australia rotation poles lie within the zone of diffuse intraplate seismicity in the South Tasman Sea separating the Macquarie Plate from the main part of the Australian Plate. Motion of the Macquarie Plate relative to the Pacific Plate for chrons 2Ay and 3Ay is determined by summing Macquarie–Antarctic and Antarctic–Pacific rotations. The Pacific–Macquarie rotations predict a smaller rate of convergence perpendicular to the Hjort Trench than the Pacific–Australia rotations. The onset of the deformation of the South Tasman Sea and the development of the Macquarie Plate appears to have been triggered by the subduction of young, buoyant oceanic crust near the Hjort Trench and coincided with a clockwise change in Pacific–Australia motion around 6 Ma. The revised Pacific–Australia rotations also have implications for the tectonics of the Alpine Fault Zone of New Zealand. We find that changes in relative displacement along the Alpine Fault have been small over the last 20 Myr. The average rate of convergence over the last 6 Myr is about 40 per cent smaller than in previous models.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1111/j.1365-246X.2004.02224.x DOIArticle
http://gji.oxfordjournals.org/content/157/1/399PublisherArticle
ORCID:
AuthorORCID
Stock, Joann M.0000-0003-4816-7865
Additional Information:© 2004 RAS. Accepted 2003 December 15. Received 2003 November 25; in original form 2002 November 25. This study was made possible through grants from the NSF-Office of Polar Programs supporting the acquisition of underway geophysical data on long transits of the R/VIB Nathaniel B. Palmer. We thank the officers, crew and scientific staff of the R/VIB Nathaniel B. Palmer and the many graduate students and other scientists, especially Stan Jacobs, who have contributed to this programme. M. Coffin, C. DeMets and R. Gordon gave helpful reviews. GMT software was used to produce the figures (Wessel & Smith 1991). This programme was supported by NSF grants OPP-0126340 (UCSD) and OPP-0126334 (Caltech). California Institute of Technology Division of Geological and Planetary Sciences contribution number 9032.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFOPP-0126340
NSFOPP-0126334
Subject Keywords:Alpine Fault; diffuse deformation; Hjort Trench; Macquarie Ridge; South Tasman Sea; Southeast Indian Ridge
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences9032
Issue or Number:1
Record Number:CaltechAUTHORS:20140416-090150847
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140416-090150847
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44970
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:21 Apr 2014 23:52
Last Modified:03 Oct 2019 06:24

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