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Tectonic implications of fault-scarp-derived volcaniclastic deposits on Macquarie Island: Sedimentation at a fossil ridge-transform intersection?

Citation

Daczko, NR and Mosher, S and Coffin, MF and Meckel, TA, Tectonic implications of fault-scarp-derived volcaniclastic deposits on Macquarie Island: Sedimentation at a fossil ridge-transform intersection?, Geological Society of America. Bulletin, 117, (1-2) pp. 18-31. ISSN 0016-7606 (2005) [Refereed Article]


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Copyright Statement

Copyright 2005 Geological Society of America

DOI: doi:10.1130/B25469.1

Abstract

Upper Miocene to lower Pliocene sedimentary rocks on Macquarie Island are dominantly volcaniclastic breccia, sandstone, and siltstone produced by the physical disintegration and tectonic abrasion of oceanic crust in fault zones and mass wasting of these tectonic features. They represent small debris fans and small-scale turbidites deposited at the base of active fault scarps, related to Late Miocene to Early Pliocene seafloor spreading. Most of the sediment is derived from basalts, but diabase and gabbro clasts in some sedimentary rocks indicate that middle and lower oceanic crust was exposed to erosion on the sea floor. A lack of exotic clasts and a low degree of clast roundness are consistent with a local source for the sediment and no input from continental rocks. Spatial relationships between sedimentary rocks and major faults associated with seafloor spreading on the island and correlation between sedimentary clast and adjacent up-thrown block compositions allow us to infer paleotectonic relief for Macquarie Island crust during deposition. Our data support a model involving the deposition of these rocks at the inside corner of a ridge-transform intersection. Furthermore, a tectonic reconstruction of the Australian-Pacific plate boundary for the approximate time that Macquarie Island crust formed (10.9 Ma) also shows that Macquarie Island crust most likely formed near a ridge-transform intersection. This paper describes sedimentation associated with active faulting at a ridge-transform intersection that has been uplifted in situ above sea level along with the surrounding oceanic crust, and demonstrates that high-angle faults have the most pronounced influence, compared with low-angle faults, on sedimentation in this tectonic environment.

Item Details

Item Type:Refereed Article
Keywords:sedimentology fault scarps ridges transform faults Macquarie Island
Research Division:Earth Sciences
Research Group:Geology
Research Field:Marine Geoscience
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Coffin, MF (Professor Mike Coffin)
ID Code:73703
Year Published:2005
Web of Science® Times Cited:10
Deposited By:Research Division
Deposited On:2011-10-24
Last Modified:2011-11-10
Downloads:0

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