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| Titel: |
Significance of hummocky cross-stratification and quasi-planar lamination in the lower Devonian Walhalla group at Cape Liptrap, Victoria |
| Auteur: |
Dyson, I. A. |
| Verschenen in: |
Australian journal of earth sciences |
| Paginering: | Jaargang 43 (1996) nr. 2 pagina's 189-199 |
| Jaar: |
1996-04 |
| Inhoud: |
The Lower Devonian Walhalla Group in the Melbourne Trough has been invariably interpreted as a turbidite or shallow-marine succession. This study has recognised storm-influenced sedimentary structures in fine-grained sandstone of the Walhalla Group at Cape Liptrap. They include hummocky cross-stratification, quasi-planar lamination, micro-hummocky cross-stratification and Bouma sequences. The hummocky cross-stratified and quasi-planar-laminated sandstones were deposited above storm wave-base. Thin-bedded sandstone beds resembling turbidites display Bouma sequences. They were deposited near or below storm wave-base where current-dominated tempestite deposition took place. There is no apparent evidence of deposition above fairweather wave-base. Storm-influenced sedimentary structures such as hummocky cross-stratification and quasi-planar lamination can be placed in an idealised vertical facies succession which can be used to infer hydrodynamic conditions at the time of deposition. Sandstone beds at Cape Liptrap are interpreted to have been deposited in an inner to outer shelf setting. There is no need to invoke a deep-water turbidite origin for these sandstones. Furthermore, thin-bedded sandstone elsewhere in the Melbourne Trough is more likely to represent tempestites deposited in a storm-dominated shallow-marine environment. This study suggests that palaeogeographic reconstructions of the Melbourne Trough should take into account sedimentary structures which are diagnostic of storm deposition. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 7 van 9 gevonden artikelen
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