Skip to Main Content
Book Chapter

The Coorong Model for Penecontemporaneous Dolomite Formation in the Middle Proterozoic McArthur Group, Northern Territory, Australia

By
Marjorie Muir
Marjorie Muir
Bureau of Mineral Resources, Canberra, A.C.T.AustraliaC.R.A. Exploration Pty. Ltd., P.O. Box 656, Fyshwick 2609, Canberra Australia.
Search for other works by this author on:
David Lock
David Lock
School of Earth Sciences, Flinders University, Bedford ParkSouth AustraliaC/o Comalco, P.O. Box 20, Plympton, South Australia 5038.
Search for other works by this author on:
Chris Von Der Borch
Chris Von Der Borch
School of Earth Sciences, Flinders University, Bedford ParkSouth Australia
Search for other works by this author on:
Published:
January 01, 1980

Abstract

Many types of penecontemporaneous dolomites have been explained in the literature by involving the well-known sabkha model which is typically associated with an arid climate. The various carbonates now precipitating in the ephemeral lakes of the South Australian Coorong Lagoon, however, are the products of a more humid climatic and hydrologie regime. The distribution of carbonates in the Coorong region is largely controlled by the hydrology of the depositional environment. Characteristic suites of sedimentary structures are formed in specific parts of the Coorong system, including desiccation features and stromatolites. These suites can also be identified with a remarkable degree of confidence in the 1600 m.y. old Yalco Formation of the McArthur Group, Northern Territory, Australia. The following conclusions can be drawn from the comparison. (1) All penecontemporaneous dolomites are not necessarily formed in an arid sabkha-like environment; the Yalco Formation dolomites formed in a more humid environment analogous to that of the Coorong, in which distinct climatic and seasonal controls prevail. (2) The lack of evaporite minerals or evaporitic casts in an ancient dolomite sequence does not mean that concentrated brines were never present. Evaporite minerals may be precipitated during dry summer months, but are flushed out during winter by a reflux mechanism as occurs in the Coorong dolomite region. (3) By comparison with the Coorong system, ancient water table movements can be inferred from vertical sequences of sedimentary structures in the Yalco Formation, in conjunction with evidence from the underlying and overlying formations. The stratigraphy of the Lynott Formation, Yalco Formation, and Stretton Sandstone can be explained as a diachronous regressive sequence using the hydrological model developed in this paper.

You do not currently have access to this article.

Figures & Tables

Contents

SEPM Special Publication

Concepts and Models of Dolomitization

Donald H. Zenger
Donald H. Zenger
Pomona College, Claremont, California
Search for other works by this author on:
John B. Dunham
John B. Dunham
Union Oil Research Center, Brea, California
Search for other works by this author on:
Raymond L. Ethington
Raymond L. Ethington
Ethington, University of Missouri-Columbia
Search for other works by this author on:
SEPM Society for Sedimentary Geology
Volume
28
ISBN electronic:
9781565761582
Publication date:
January 01, 1980

GeoRef

References

Related

Citing Books via

A comprehensive resource of eBooks for researchers in the Earth Sciences

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal