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Morphology and origin of the Osbourn Trough

Billen, Magali I. and Stock, Joann (2000) Morphology and origin of the Osbourn Trough. Journal of Geophysical Research B, 105 (B6). pp. 13481-13489. ISSN 0148-0227. doi:10.1029/2000JB900035.

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The Osbourn Trough is a 900 km long, east-west trending gravity low, visible in satellite altimetry data, which intersects the Tonga Trench at 25°30′S. A recent survey collected gravity, magnetic, echo sounder, and swath bathymetry data on three adjacent, north-south trending ship tracks centered on the trough. The linear gravity low is 20–30 mGal less than the regional value and is accompanied by a flat-lying, 200–500 m deep sediment-filled valley. Swath bathymetry images reveal several parallel, east-west trending linear ridges and valleys on either side of the main trough as well as other morphologic features characteristic of relict spreading centers, including a prominent inside corner high and possible pseudo-fault trace. The presence of magnetic anomalies (possibly anomalies 33 and 32) suggests that the seafloor here was formed after the end of the Cretaceous Normal Superchron (anomaly 34). These data support the conclusion that this trough is a spreading center, which stopped spreading in Late Cretaceous time. The existence of this feature has important implications for tectonic reconstructions in this region. The Osbourn Trough could be part of the fossil spreading center between the Pacific Plate and a fragment of the Phoenix Plate, the Bellingshausen Plate. This would require the seafloor between the Osbourn Trough and the Chatham Rise to the south to be a remnant fragment of the Bellingshausen Plate. This remnant may have joined to the Pacific Plate when the Hikurangi Plateau entered the Gondwana subduction zone at the Chatham Rise possibly causing the cessation of spreading on the Osbourn Trough.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle PublisherCorrection
Billen, Magali I.0000-0002-7316-1791
Stock, Joann0000-0003-4816-7865
Additional Information:© 2000 American Geophysical Union. Received July 22, 1999; revised December 16, 1999; accepted January 26, 2000. This research was supported by NSF OPP 9317318 and OCE 9416779. Dallas Abbott, Bruce Luyendyk and Associate Editor Keith Louden provided helpful reviews of this paper. We thank Antarctic Support Associates, the crew and Captain Joe Borkowski of the RVIB Nathaniel B. Palmer, and Suzanne O'Hara for their help in collecting and processing the data, and Steve Cande for his helpful comments. California Institute of Technology, Division of Geological and Planetary Science, contribution 8618.
Group:Seismological Laboratory
Funding AgencyGrant Number
NSFOPP 9317318
NSFOCE 9416779
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Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences8618
Issue or Number:B6
Record Number:CaltechAUTHORS:20140414-140339355
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Official Citation:Billen, M. I., and J. Stock (2000), Morphology and origin of the Osbourn Trough, J. Geophys. Res., 105(B6), 13481–13489, doi:10.1029/2000JB900035
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44934
Deposited By: Tony Diaz
Deposited On:14 Apr 2014 22:10
Last Modified:10 Nov 2021 16:58

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