Geomorphology of the Lake Omeo Basin, Victoria

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Description :
Lake Omeo is a relic of a more extensive lake formed when a basalt flow, dated as Upper Pliocene in age, dammed the flow of Morass Creek. This larger lake is referred to as Lake Morass. Downfaulting of part of the Lake Omeo basin and upthrow of a narrow horst between the Morass Creek and Minute Creek catchments probably occurred at about the same time or later. Sedimentation of the natural overflow gap of the Lake Omeo basin during the existence of Lake Morass resulted in the basin becoming isolated from Morass Creek as the basalt flow was incised. Clay sediments over 40 m thick were deposited in the downfaulted part of the basin. Two clay lunettes to the southeast of the present lake, and material of fluvial and lacustrine origin provide evidence for alternation between wet periods when high water levels prevailed and dry periods with low water levels during which lunette building occurred. The evidence has been interpreted as indicating major changes in climate in the history of the lake. At least three lunette building phases are proposed, separated by periods of high lake levels. A palaeosol buried beneath a layer of clay of lacustrine origin is ascribed an Upper Pliocene origin.

Type de document :
Article de périodique

Source :
Proceedings of the Royal Society of Victoria Melbourne, 1984, vol. 96, n°. 2, p. 99-112

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