Publications
° Wertz, K.L., Mosher, S., Daczko, N.R. and Coffin, M.F. 2003. Macquarie Island's Finch-Langdon fault: a ridge-transform
inside corner structure. Geology,
31, 661-664.
Abstract
Macquarie Island consists of uplifted oceanic crust, uniquely situated in
the ocean basin where it formed, thus allowing onshore structures to be placed
into their regional oceanic tectonic context. The Finch-Langdon fault, the
most significant spreading-related structure on the island, juxtaposes upper-crust
rocks against lowercrust and upper-mantle rocks. It consists of dominantly
oblique
strike-slip, northwest-, west-northwest–, and north-northeast– striking fault
segments that bear hydrothermal mineralization indicative of faulting during
seafloor spreading. Talus breccias and graywackes overlain by volcanic flows
proximal to the fault indicate a long-lived submarine fault scarp that exposed
diabase dikes and gabbros during volcanism. Swath reflectivity and bathymetry
reveal ridge-parallel spreading fabric and perpendicular fracture zones,
the closest ;7 km east of the island. On the basis of field and swath data,
we propose that this fault zone formed near the inside corner of a ridge-transform
intersection and that structures on the island are conformable with those
in the surrounding seafloor.
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ARC Centre of Excellence for Core to Crust Fluid Systems