کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6428314 | 1634735 | 2015 | 10 صفحه PDF | دانلود رایگان |
- Identification of â¼71-50 Ma subduction zone at northern edge of Australian plate.
- Subduction termination coincides with obduction in New Guinea and plate slowdown.
- Sinking slab caused southward migration of dynamic topography subsidence over plate.
- Fossil slab now below central-SE Australia causing Eyre-Murray-Darling depression.
- Dynamic topography evolution couples geological processes to a mantle reference frame.
Unravelling causes for absolute plate velocity change and continental dynamic topography change is challenging because of the interdependence of large-scale geodynamic driving processes. Here, we unravel a clear spatio-temporal relation between latest Cretaceous-Early Cenozoic subduction at the northern edge of the Australian plate, Early Cenozoic Australian plate motion changes and Cenozoic topography evolution of the Australian continent. We present evidence for a â¼4000 km wide subduction zone, which culminated in ophiolite obduction and arc-continent collision in the New Guinea-Pocklington Trough region during subduction termination, coinciding with cessation of spreading in the Coral Sea, a â¼5 cm/yr decrease in northward Australian plate velocity, and slab detachment. Renewed northward motion caused the Australian plate to override the sinking subduction remnant, which we detect with seismic tomography at 800-1200 km depth in the mantle under central-southeast Australia at a position predicted by our absolute plate reconstructions. With a numerical model of slab sinking and mantle flow we predict a long-wavelength subsidence (negative dynamic topography) migrating southward from â¼50 Ma to present, explaining Eocene-Oligocene subsidence of the Queensland Plateau, â¼330 m of late Eocene-early Oligocene subsidence in the Gulf of Carpentaria, Oligocene-Miocene subsidence of the Marion Plateau, and providing a first-order fit to the present-day, â¼200 m deep, topographic depression of the Lake Eyre Basin and Murray-Darling Basin. We propound that dynamic topography evolution provides an independent means to couple geological processes to a mantle reference frame. This is complementary to, and can be integrated with, other approaches such as hotspot and slab reference frames.
Journal: Earth and Planetary Science Letters - Volume 421, 1 July 2015, Pages 107-116