Details

Autor(en) / Beteiligte

• Knesel, Kurt M.
• Cohen, Benjamin E.
• Vasconcelos, Paulo M.
• Thiede, David S.

Titel

Rapid change in drift of the Australian plate records collision with Ontong Java plateau

Ist Teil von

• Nature, 2008-08, Vol.454 (7205), p.754-757

Ort / Verlag

London: Nature Publishing Group UK

Erscheinungsjahr

2008

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The advance of the Australian plate Earth's largest and thickest oceanic plateau, the Ontong Java plateau, is currently colliding with the Australian plate, but it has been difficult to date the start of this momentous event with much accuracy. Now a team from the University of Queensland presents strong evidence for a collision starting about 26 million years ago. The dating comes from geochronological data on hotspot volcanoes in the Tasman Sea, east of Australia, which reveal a link between collision of the plateau with the Melanesian arc and motion of the Australian plate. The timing and brevity of this collisional event correlate well with offsets in hotspot seamount tracks in the Pacific, including the archetypal Hawaiian chain, suggesting that immense oceanic plateaus, like Ontong Java, can contribute to initiating rapid change in plate boundaries and motions on a global scale. Geochronological data on hotspot volcanoes in eastern Australia are presented, which reveal a strong link between collision of the plateau with the Melanesian arc and motion of the Australian plate. The timing and brevity of this collisional event correlate well with offsets in hotspot seamount tracks in the Pacific, including the archetypal Hawaiian chain, and thus provide strong evidence that immense oceanic plateaus can contribute to initiating rapid change in plate boundaries and motions on a global scale. The subduction of oceanic plateaux, which contain extraordinarily thick basaltic crust and are the marine counterparts of continental flood-basalt provinces, is an important factor in many current models of plate motion 1 , 2 , 3 , 4 and provides a potential mechanism for triggering plate reorganization 5 . To evaluate such models, it is essential to decipher the history of the collision between the largest and thickest of the world’s oceanic plateaux, the Ontong Java plateau, and the Australian plate, but this has been hindered by poor constraints for the arrival of the plateau at the Melanesian trench. Here we present 40 Ar– 39 Ar geochronological data on hotspot volcanoes in eastern Australian that reveal a strong link between collision of the Greenland-sized Ontong Java plateau with the Melanesian arc and motion of the Australian plate. The new ages define a short-lived period of reduced northward plate motion between 26 and 23 Myr ago, coincident with an eastward offset in the contemporaneous tracks of seamount chains in the Tasman Sea east of Australia. These features record a brief westward deflection of the Australian plate as the plateau entered and choked the Melanesian trench 26 Myr ago. From 23 Myr ago, Australia returned to a rapid northerly trajectory at roughly the same time that southwest-directed subduction began along the Trobriand trough 6 . The timing and brevity of this collisional event correlate well with offsets in hotspot seamount tracks on the Pacific plate, including the archetypal Hawaiian chain 7 , and thus provide strong evidence that immense oceanic plateaux, like the Ontong Java, can contribute to initiating rapid change in plate boundaries and motions on a global scale.