Carbonate platform development and drowning on Wombat plateau margin: history of development or rifting off northwestern Australia
A four-site transect drilled on the Wombat Plateau during ODP Leg 122 provided critical information regarding the development of Mesozoic rifting and relative sea level changes. The Wombat Plateau is an isolated tilted horst at the northern margin of the Exmouth Plateau, off northwestern Australia, with steeply dipping, fault-bounded sides to the south and north. At the four sites, a Carnian-Rhaetian deltaic and carbonate sequence was recovered, bounded by a major post-Triassic unconformity. Rhaetian strata are overlain by post-unconformity Lower Cretaceous to Quaternary pelagic chalk and ooze. The southern edge of the plateau is uptilted, and Middle to Upper Triassic deltaic strata and interbedded carbonate bank deposits are eroded. Locally, the succession is reduced and incomplete, and lower to middle Carnian units are inferred to pinch out against an angular unconformity. In the central plateau, the succession consists of Rhaetian shallow-water carbonates and lagoonal mudstones unconformably overlying Norian deltaic clastics. At the northern rim of the plateau, a platform-edge coral-reef complex is developed. The succession progressively thickens from the south to the north. Uppermost Rhaetian Triasina beds record the initial deepening of the Wombat Plateau. Correlation of the four sites suggests that the onset of differential subsidence began in the early Late Triassic.
- Research Organization:
- Univ. of Calabria, Cosenza (Italy)
- OSTI ID:
- 5795541
- Report Number(s):
- CONF-890404-
- Journal Information:
- AAPG Bull.; (United States), Vol. 73:3; Conference: AAPG annual convention with DPA/EMD Divisions and SEPM, San Antonio, TX, USA, 23-26 Apr 1989
- Country of Publication:
- United States
- Language:
- English
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