Authors / CoAuthors
Purdy, D. | Cross, A.J. | Brown, D.D.
Abstract
Interpretation of the Thomson Orogen and its context within the Tasmanides of eastern Australia is hampered by vast areas of deep sedimentary cover which also mask potential relationships between central and eastern Australia. Within covered areas, basement drill cores offer the only direct geological information. This study presents new detrital zircon isotopic data for these drill cores and poorly understood outcropping units to provide new age and provenance information on the Thomson Orogen. Two distinct detrital zircon signatures are revealed. One is dominated by Grenvillian-aged (1300900 Ma) zircons with a significant peak at ~1180 Ma and lesser peak at ~1070 Ma. These age peaks, along with Lu-Hf isotopic compositions (median Hf(t) = +1.5), dominantly mantle-like 18O values (median = 5.53) and model ages of ~1.89 Ga, support a Musgrave Province (central Australia) source. The dominance of Grenvillian-aged material additionally points to deposition during the Petermann Orogney (570530 Ma) when the Musgrave Province was uplifted shedding abundant material to the Centralian Superbasin. Comparable age spectra suggest that parts of the Thomson Orogen were connected to the Centralian Superbasin during this period. We use the term `Syn-Petermann to describe this signature which is observed in two drill cores adjacent to the North Australian Craton and scattered units in the outcropping Thomson Orogen. The second signature marks a significant provenance shift and is remarkably consistent throughout the Thomson Orogen. Age spectra exhibit dominant peaks at 600560 Ma, lesser 1300900 Ma populations and maximum depositional ages of ~496 Ma. This pattern is termed the `Pacific Gondwana detrital zircon signature and is recognised throughout eastern Australia, Antarctica and central Australia. LuHf isotope data for Thomson Orogen rocks with this signature is highly variable with Hf(t) values between -49 and +10 and dominantly supracrustal 18O values suggesting input from different and more diverse source regions.
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nonGeographicDataset
eCat Id
90678
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- External Publication
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- Queensland
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2016-01-01T00:00:00
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