Abstract: Sedimentation in Lake Reeve, Victoria, Australia--Modern Barrier-Island Ephemeral Lagoon

Richard A. Davis, Jr.

Lake Reeve is an intermittent coastal lagoon located between the older, inner barrier and the modern, outer barrier island of the Gippsland Lakes area of southeastern Victoria. This lagoon has a maximum width of 1.5 km throughout its 60-km extent. Water rarely covers the entire lagoon and its presence and depth is directly dependent on rainfall and runoff from the adjacent drainage basins. Commonly nearly half of the area of the lagoon is supratidal and maximum depth is about 1.5 m near the northeast end. Salinity may range from fresh to strongly hypersaline locally. Astronomic tides are negligible.

Modern physical processes are dominated by infrequent storms which create widespread "microcheniers" along the lagoon margin. These features are dominant on the southwest (downwind) side. They generally display 30 to 50 cm of relief and may be continuous for several kilometers. Another widespread feature is the circular shallow pits which resemble bedforms and which are developed on the sandy substrate. These are 60 to 80 cm in diameter and display 15 to 20 cm of relief. They completely cover several-square-kilometer parts of the lagoon bed and are formed by black swans during feeding.

Recent changes in sedimentation are evidenced by coring which shows algal mats and pelleted mud overlying thin layers of carbonate mud. This 10 to 15-cm thick sequence lies on clean, sorted sand and muddy sands containing a normal marine fauna.

AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC