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Structural expression of oblique seafloor spreading in the Macquarie Island ophiolite, Southern Ocean

The Macquarie Island ophiolite is an uplifted block of oceanic crust formed at the Australia-Pacific spreading center between 12 and 9 Ma. The sense of motion and geological processes across this plate boundary reflect an evolution from orthogonal spreading through progressively more oblique spreadi...

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Bibliographic Details
Published in:Geology (Boulder) 2004-02, Vol.32 (2), p.125-128
Main Authors: Rivizzigno, Peter A, Karson, Jeffrey A
Format: Article
Language:English
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Summary:The Macquarie Island ophiolite is an uplifted block of oceanic crust formed at the Australia-Pacific spreading center between 12 and 9 Ma. The sense of motion and geological processes across this plate boundary reflect an evolution from orthogonal spreading through progressively more oblique spreading to the present-day transpressional regime. The crust that makes up the island was formed during an interval of oblique spreading along east-trending spreading segments punctuated by a series of northwest-trending discontinuities. The discontinuities are accommodation zones marked by oblique-slip dextral-normal faults, localized dikes and lava flows, and extensive hydrothermal alteration, indicating that these zones were active near the spreading axis. These features provide a window into the internal structure of oceanic crust generated by oblique spreading.
ISSN:0091-7613
1943-2682
DOI:10.1130/G19906.1