A Comparison of Continental Extension Estimates Across the Margins of the Woodlark Basin, Papua New Guinea
Abstract
Previous studies have shown that depth dependent extension is commonly observed across rifted margins. This has resulted in a discrepancy between the estimates of extension made through whole lithosphere/crust vs fault heave calculations (for example northwest Australia, South China Sea, Galicia). In the Woodlark Basin, the amount of extension estimated from observed subsidence and brittle extension also do not match. Taking into account sub-seismic resolution and poly-phase faulting reduces this mismatch. In the Woodlark Basin continental extension can also be estimated by extending Euler pole kinematics from the oceanic domain. Previous studies show that this predicts almost double the extension calculated from subsidence and brittle extension. Extension in the Woodlark Basin began at 8.4 Ma and transitioned to sea-floor spreading in the east at 6 Ma. The basin is an ideal place to study the extension discrepancy because of its young age and thin sediments. Seismic reflection easily images basement and fault structures. High resolution bathymetry permits tracing of major faults on the seafloor. A previous study focused on the extension discrepancy at the rifting to spreading transition. This study will focus on the discrepancy further east where seafloor spreading began just after 2 Ma and opening rates are faster. Data used in this study include bathymetry, magnetics, gravity, and low-fold 2-D seismic reflection data. Using the available data, extension estimates have been calculated through brittle extension and subsidence. Euler pole derived extension rates from previous studies were used for comparison. Results indicate that Euler pole kinematics predict far more extension than estimates calculated through subsidence and brittle extension. This provides important insights into processes in the low crust and supports earlier hypotheses that the mantle lithosphere and upper crust may be moving at different rates prior to continental breakup.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.T31B2892N
- Keywords:
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- 1645 Solid Earth;
- GLOBAL CHANGEDE: 8110 Continental tectonics: general;
- TECTONOPHYSICSDE: 8157 Plate motions: past;
- TECTONOPHYSICSDE: 8178 Tectonics and magmatism;
- TECTONOPHYSICS