40Ar/39Ar constraints on the timing and origin of Miocene leucitite volcanism in southeastern Australia

Authors: Cohen, B. E.¹; Knesel, K. M.¹; Vasconcelos, P. M.¹; Thiede, D. S.¹; Hergt, J. M.²

Source: Australian Journal of Earth Sciences, Volume 55, Number 3, January 2008 , pp. 407-418(12)

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Abstract:

Laser incremental-heating 40Ar/39Ar geochronology of seven leucitites from southeastern Australia indicates that leucite-bearing lavas in individual geographic clusters were erupted in one million years or less. The eruption ages range from 17.9 ± 0.3 Ma (2σ) at El Capitan in northern-central New South Wales to 8.9 ± 0.2 Ma (2σ) at Cosgrove in northern Victoria. The 40Ar/39Ar results demonstrate that the southward migration of leucite-bearing lavas was near-contemporaneous with age-progressive central-volcano magmatism in southeastern Australia. As such, the 40Ar/39Ar results are consistent with a hotspot-related origin for the leucitites. However, the question of whether single or multiple hotspots are required to explain these volcanic chains, which are separated by a distance of about 300 km, awaits a more complete geochronological picture of the onset, duration and migration of leucitite and central-volcano magmatism in eastern Australia.

Keywords: argon-argon dating; Cenozoic; geochronology; hotspot; Intraplate volcanism; leucitite

Document Type: Research article

DOI: http://dx.doi.org/10.1080/08120090701769514

Affiliations: 1: Earth Sciences, University of Queensland, Qld, Australia 2: School of Earth Sciences, University of Melbourne, Vic, Australia

Publication date: 2008-01-01