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Future aridification would continue a documented drying as
evidenced by termination of perennial fluvial systems and shrinking
of large saline lakes in Australia during the late Tertiary and
Quaternary (Cohen et al., 2011; Salama, 1994; Van de Graaf et al.,
1978; Zheng et al., 1998). This predicted drier scenario for the
Yilgarn Craton suggests that ephemeral acid brine lakes will exist
in a desiccated stage more often than in a flooded or evapo-
concentrated stages. In addition, acid brine water tables may be
lower in the future. More evaporation would result in lower pH
and higher salinity. Therefore, the acid brine system across the
Yilgarn may become more extreme but less voluminous.
IMPLICATIONS FOR INTERPRETATIONS OF ANCIENT ACID
BRINES IN THE ROCK RECORD
Extreme acid brine environments similar to those in southern
Western Australia have been recognized on Earth and Mars
(e.g., Benison and Bowen, 2006; Benison et al., 1998; Kraus,
1998). In particular, some mid-Permian continental environ-
ments hosted extremely acid saline lakes and groundwaters that
deposited redbeds and evaporites (Benison et al., 1998). The
temporal and geographic extent of these Permian acid brine
settings, and their relationship to Permian climate change and
the end Permian mass extinction, are open scientific questions.
Understanding the origin, evolution, and maintenance of
modern natural acid brine environments may lead to more
informed paleoenvironmental, paleoclimatic, and paleobiolog-
ical interpretations about ancient acid brines.
ACKNOWLEDGMENTS
Partial funding was provided by National Science Foundation grants
EAR-0433040 and EAR-0719822 to K.C. Benison and EAR-0719892 to B.B.
Bowen. Acknowledgment is made to the donors of the American Chemical
Society–Petroleum Research Fund for partial support of this research. We
thank C. Botero Sanchez, M.C. Hein, B.-y. Hong, E.A. Jagniecki, J.P. Knapp,
D.A. LaClair, M. Mormile, F.E. Oboh-Ikuenobe, and S. Story for assistance in
the field. We are indebted to Wayne Hitchcock and Stephen Wyche for logis-
tical help and to Dave Long, Tim Lowenstein, and David Gray for discussions
about acid brines. We thank Steven Whitmeyer for editorial handling and
David Gray and an anonymous reviewer for constructive comments.
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