Abstract

Broad Sound is situated at the confluence of four large estuaries. Freshwater inflow is restricted to the summer months. The Sound and its attendant estuaries are characterized by shallow water, a large tidal range (10 m), and strong tidal currents. In the shallow marine environment (the most seaward) pre- Holocene relict calcareous gravels are common. Calcareous sands, commonly occurring as sand ridges capped by megaripples, predominate in the open intertidal environment. Muds are most abundant in the mangrove swamp, mangrove channel, and supratidal flat environments, the muds become less calcareous and more saline in a landward direction. Textural studies revealed that grainsize parameters can be used to divide the sediments into environmentally significant groups; they also indicated that most of the sediments are brought into the estuaries during times of summer floods, and redistributed by tidal currents during the remainder of the year. The petrology and mineralogy of the sediments are consistent with some relative seaward movement of terrigenous sediment and landward movement of calcareous sediment. The relict nature of some of the sediments is revealed by their mineralogy, in particular their lack of less stable carbonates and heavy minerals. There is a seaward trend of increasing maturity in both the heavy-mineral and light-mineral assemblages. Drilling and radiocarbon dating have shown that most of the sediments are of late Holocene age. It appears from the Broad Sound evidence that sea level stabilized about 6000 years ago. Since that time there has been a marked seaward progradation of the shoreline producing a 'fining upward' regressive sequence. Regression appears to have been more rapid on the east side of the Sound, possibly a result of some late Holocene uplift. The Broad Sound study is valuable because it provides not only a regressive model for environmental interpretation in ancient sediments, but also a yardstick against which environmental changes in tropical estuaries can be measured.
Google map showing geographic bounding box with values North bound -22.0 East bound 150.0 West bound 149.5 South bound -23.0
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Product Type/Sub Type

nonGeographicDataset

Constraints

Creative Commons Attribution 4.0 International Licence

IP Owner

Commonwealth of Australia (Geoscience Australia)

Author(s)

Date (publication)

1977-01-01T00:00:00

Product Type

nonGeographicDataset

Topic Category

geoscientificInformation

GA Catalogue Number

81 Product http://www.ga.gov.au/metadata-gateway/metadata/record/81/

Keywords

GA Publication
Bulletin
marine
AU-QLD
Earth Sciences

Resource Language

English

Resource Character Set

utf8

Resource Security Classification

unclassified

Geographic Extent

North bound
-22.0
East bound
150.0
West bound
149.5
South bound
-23.0

Digital Transfer Options

onLine

Distributor

Role
distributor
Organisation Name
Commonwealth of Australia (Geoscience Australia)
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address

Metadata File Identifier

a05f7892-fe7d-7506-e044-00144fdd4fa6

Metadata Standard Name

ANZLIC Metadata Profile: An Australian/New Zealand Profile of AS/NZS ISO 19115:2005, Geographic information - Metadata

Metadata Standard Version

1.1

METADATA SECURITY CLASSIFICATION

unclassified

Metadata Contact

Role
pointOfContact
Organisation Name
Commonwealth of Australia (Geoscience Australia)
City
Canberra
Administrative Area
ACT
Postal Code
2601
Country
Australia
Email Address
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