Tracking the Australian plate motion through the Cenozoic: Constraints from 40Ar/39Ar geochronology

Cohen, Benjamin E., Knesel, Kurt M., Vasconcelos, Paulo M. and Schellart, Wouter P. (2013) Tracking the Australian plate motion through the Cenozoic: Constraints from 40Ar/39Ar geochronology. Tectonics, 32 5: 1371-1383. doi:10.1002/tect.20084

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Author Cohen, Benjamin E.
Knesel, Kurt M.
Vasconcelos, Paulo M.
Schellart, Wouter P.
Title Tracking the Australian plate motion through the Cenozoic: Constraints from 40Ar/39Ar geochronology
Journal name Tectonics   Check publisher's open access policy
ISSN 0278-7407
Publication date 2013-01-01
Year available 2013
Sub-type Article (original research)
DOI 10.1002/tect.20084
Open Access Status File (Publisher version)
Volume 32
Issue 5
Start page 1371
End page 1383
Total pages 13
Place of publication Hoboken, NJ United States
Publisher Wiley-Blackwell Publishing, Inc.
Language eng
Subject 1908 Geophysics
1906 Geochemistry and Petrology
Abstract Here we use geochronology of Australian intraplate volcanoes to construct a high-resolution plate-velocity record and to explore how tectonic events in the southwest Pacific may have influenced plate motion. Nine samples from five volcanoes yield ages from 33.6 ± 0.5 to 27.3 ± 0.4 Ma and, when combined with published ages from 30 to 16 Ma, show that the rate of volcanic migration was not constant. Instead, the results indicate distinct changes in Australian plate motion. Fast northward velocities (61 ± 8 and 57 ± 4 km/Ma) prevailed from 34 to 30 (±0.5) and from 23 to 16 (±0.5) Ma, respectively, with distinct reductions to 20 ± 10 and 22 ± 5 km/Ma from 30 to 29 (±0.5) Ma and from 26 to 23 (±0.5) Ma. These velocity reductions are concurrent with tectonic collisions in New Guinea and Ontong Java, respectively. Interspersed between the periods of sluggish motion is a brief 29-26 (±0.5) Ma burst of atypically fast northward plate movement of 100 ± 20 km/Ma. We evaluate potential mechanisms for this atypically fast velocity, including catastrophic slab penetration into the lower mantle, thermomechanical erosion of the lithosphere, and plume-push forces; none are appropriate. This period of fast motion was, however, coincident with a major southward propagating slab tear that developed along the northeastern plate margin, following partial jamming of subduction and ophiolite obduction in New Caledonia. Although it is unclear whether such an event can play a role in driving fast plate motion, numerical or analogue models may help address this question. Key Points We determine nine 40Ar/39Ar ages from five Cenozoic volcanoes in Australia Slow velocities correlate with New Guinea and Ontong Java collisions Anomalously fast velocity of 100 +/- 20 km/Ma is identified from 29-26 Ma
Keyword Collision
New Caledonia
New Guinea
Slab tear
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Earth Sciences Publications
Official 2014 Collection
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