Influence of localised igneous activity on cleat dawsonite formation in Late Permian coal measures, Upper Hunter Valley, Australia
✍ Scribed by Alexandra N. Golab; Paul F. Carr; Daniel R. Palamara
- Publisher
- Elsevier Science
- Year
- 2006
- Tongue
- English
- Weight
- 393 KB
- Volume
- 66
- Category
- Article
- ISSN
- 0166-5162
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✦ Synopsis
Stable (δ 13 C and δ 18 O) and radiogenic 87 Sr/ 86 Sr isotopic data have been used to investigate the origin of cleat dawsonite (NaAlCO 3 (OH) 2 ) in the Late Permian Wittingham Coal Measures of the Upper Hunter region in the Sydney Basin, New South Wales. The δ 13 C PDB values have a narrow range (-1.7‰ to + 2.4‰), with an average of + 0.3‰, suggesting a magmatic source for the carbon. In contrast, δ 18 O SMOW values have a wide range (+ 13.6‰ to +19.8‰), and decrease systematically with decreasing distance from a major intrusion. This systematic variation reflects establishment of localised hydrothermal cells. Water-rock interaction between fluids associated with these hydrothermal cells, and Rb-poor volcaniclastic detritus in the coal measures, produced mantle-like 87 Sr/ 86 Sr (0.705032 to 0.706464) in the dawsonite.