Open AccessMacquarie Island mapping reveals three tectonic phases
Author(s) -
Goscombe B. D.,
Everard J. L.
Publication year - 1999
Publication title -
eos, transactions american geophysical union
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.316
H-Index - 86
eISSN - 2324-9250
pISSN - 0096-3941
DOI - 10.1029/99eo00038
Subject(s) - transtension , geology , transpression , magmatism , seafloor spreading , sinistral and dextral , tectonics , seismology , paleontology , plate tectonics
The first detailed mapping of Macquarie Island, perhaps the world's quintessential ophiolite has revealed three tectonic phases—extension, transtension, and transpression. Nearly all of the crust and most deformational structures formed during the first phase (D1), which involved extension along the paleo‐Macquarie seafloor spreading axis. Magmatism, block tilting, and large‐scale differential block uplift were synchronous, resulting in juxtaposition of disparate rock associations characteristic of different crustal levels. As D1 waned, the second phase (D2) developed. Involving transtension with a north‐south extension axis, it produced minor late‐stage dolerite dikes and seafloor volcanic centers.The third phase (D3), still in progresses dextral transpression. Its initiation along the Australia‐Pacific plate boundary terminated igneous activity and extension on the island.The D3 shortening axis trends east‐west to northeast‐southwest.