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Detailed Reference Information |
Persano, C., Stuart, F.M., Bishop, P. and Dempster, T.J. (2005). Deciphering continental breakup in eastern Australia using low-temperature thermochronometers. Journal of Geophysical Research 110: doi: 10.1029/2004JB003325. issn: 0148-0227. |
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First-order topographical features at high-elevation passive margins have the potential to store information about the early stages of continental rifting, which are usually lost in the sediment record. In this study we present a new combination of apatite fission track and (U-Th)/He analyses from two coast-perpendicular traverses to decipher the time of formation and evolution of the escarpment at the southeastern Australian margin. A combination of inverse and forward modeling of the apatite fission track (AFT) and He data indicates that the coast experienced a rapid denudational event starting at 110 ¿ 10 Ma, at least 15 Myr before seafloor spreading (85 Ma), in agreement with the hypothesis that rifting at magma-poor margins evolves slowly. Thus the enhanced denudation is not related to the synbreakup base level drop, but it may have been related to a thermally driven transient surface uplift. Considerations on isostatic flexure and rigidity of the lithosphere indicate that unless significant synrift brittle movements are assumed to have occurred along margin-parallel faults that are no more visible, the coast must have experienced a higher geothermal gradient than normal. The evolution of the rest of the coastal plain may have taken up to ~90 Myr, in agreement with numerical models of passive margins evolution. The (U-Th)/He ages across the coastal plain are consistent with an in-place-excavation scenario of a high rift shoulder, and they rule out the possibility of a constant retreat of the escarpment. AFT + He data from the plateau indicate that the highlands remained stable throughout continental breakup, experiencing rates of erosion of 5--10 m/Myr since, at least, 200 Ma. |
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Abstract![](/images/icons/spacer.gif) |
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Keywords
Geochronology, Geomorphological geochronology, Geochronology, Thermochronology, Tectonophysics, Continental margins, divergent (1212, 8124), Tectonophysics, Plate boundary, general, Geographic Location, Australia, apatite (U-Th)/He thermochronometry, apatite fission track thermochronometry, continental breakup, denudation, escarpments, eastern Australia |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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