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| Titel: |
40Ar-39Ar and K-Ar age constraints on the Early Proterozoic Tennant Creek Block, northern Australia, and the age of its gold deposits |
| Auteur: |
Compston, D. M. McDougall, I. |
| Verschenen in: |
Australian journal of earth sciences |
| Paginering: | Jaargang 41 (1994) nr. 6 pagina's 609-616 |
| Jaar: |
1994-12 |
| Inhoud: |
40Ar-39Ar age spectra on minerals from granitic, metamorphic and hydrothermal rocks confirm that the Early Proterozoic Tennant Creek Block was affected by two thermal events during its evolution. Although extensive alteration of biotite and feldspar within the granites precludes the direct determination of their cooling history, 40Ar-39Ar analyses for hydrothermal muscovite from several nearby gold-copper deposits indicate that regional cooling to below ∼ 300°C was not prolonged. Flat, uniform muscovite age spectra were obtained from gold deposits east of the Tennant Creek town site and indicate a minimum age of 1825-1830 Ma for their formation. These ages are within error of those for the felsic volcanism of the Flynn Subgroup, and a genetic relationship between the two may exist. Samples from gold deposits elsewhere in the area indicate disturbance of the K-Ar isotope system. The second thermal event to affect the region occurred at around 1700 Ma, and is confirmed by the 40Ar-39Ar muscovite ages for the 'Warrego' granite (1677 ± 4 Ma) and for the metamorphism of the Wundirgi Formation (1696 ± 4 Ma). |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
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