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Geochemistry and significance of basaltic rocks dredged from the South Tasman Rise and adjacent seamounts


Crawford, AJ and Lanyon, R and Elmes, M and Eggins, SM, Geochemistry and significance of basaltic rocks dredged from the South Tasman Rise and adjacent seamounts, Australian Journal of Earth Sciences, 44, (5) pp. 621-632. ISSN 0812-0099 (1997) [Refereed Article]

DOI: doi:10.1080/08120099708728341


Basalts dredged from two seamounts separated by some 200 km and built on ca 50-35 Ma oceanic crust west of Tasmania have slightly LREE-depleted N-MORB affinities and were probably generated in a spreading ridge or near-ridge setting. They are compositionally very similar to 60 Ma basalts drilled at DSDP Site 282, midway between these seamounts. Taken together, these basalts provide a useful dataset for the compositional features of MORB erupted early in the rifting history of Tasmania separating from Antarctica. Well-preserved intraplate alkaline basalts with HIMU geochemical affinities have been sampled from Cascade Seamount, which forms the peak of the East Tasman Plateau. Far more altered alkaline intraplate basalts dredged at several other locations within the South Tasman Rise south of Tasmania, and on seamounts built on oceanic crust and thinned continental crust south of the East Tasman Plateau, also show typically HIMU affinities for immobile trace-element ratios (e.g. low Zr/Nb values, 3-5), but have undergone strong rare-earth element mobility associated with sea-floor weathering and replacement of glass by chemisorbed biogenic phosphate. Dolerites with some strong affinities to the Jurassic dolerites of Tasmania were dredged in the central section of the South Tasman Rise.

Item Details

Item Type:Refereed Article
Research Division:Earth Sciences
Research Group:Geology
Research Field:Igneous and metamorphic petrology
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the earth sciences
UTAS Author:Crawford, AJ (Professor Anthony Crawford)
ID Code:12111
Year Published:1997
Web of Science® Times Cited:13
Deposited By:Earth Sciences
Deposited On:1997-08-01
Last Modified:2011-08-15

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