Active Hematite Concretion Formation in Modern Acid Saline Lake Sediments, Lake Brown, Western Australia

Abstract

Concretions can provide valuable records of diagenesis and fluid-sediment interactions, however, reconstruction of ancient concretion-forming conditions can be difficult. Observation of modern hematite concretion growth in a natural sedimentary setting provides a rare glimpse of conditions at the time of formation. Spheroidal hematite-cemented concretions are actively precipitating in shallow subsurface sediments at Lake Brown in Western Australia. Lake Brown is a hypersaline (total dissolved solids up to 23%) and acidic (pH not, vert, similar 4) ephemeral lake. The concretion host sediments were deposited between not, vert, similar 1 and 3 ka, based on dating of stratigraphically higher and lower beds. These age constraints indicate that the diagenetic concretions formed < 3 ka, and field observations suggest that some are currently forming. These modern concretions from Lake Brown provide an example of very early diagenetic formation in acid and saline conditions that may be analogous to past conditions on Mars. Previously, the hematite concretions in the Burns formation on Mars have been interpreted as late stage diagenetic products, requiring long geologic time scales and multiple fluid flow events to form. In contrast, the Lake Brown concretions support the possibility of similar syndepositional to very early diagenetic concretion precipitation on Mars.

Department(s)

Geosciences and Geological and Petroleum Engineering

Second Department

Biological Sciences

Keywords and Phrases

Acid; Concretions; Hematite; Lake, Mars; Fluid-Sediment Interactions; Precipitation (Meteorology); Saline Water; Sediments; Geophysics; Dating Method; Diagenesis; Hypersaline Environment; Lacustrine Deposits; Aline Lake; Australasia; Australia; Lake Brown; Western Australia

Geographic Coverage

Western Australia

International Standard Serial Number (ISSN)

0012-821X

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2008 Elsevier, All rights reserved.

Publication Date

15 Apr 2008

Link to Full Text

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