Campus Units

Geological and Atmospheric Sciences

Document Type


Publication Version

Published Version

Publication Date


Journal or Book Title

Journal of Geophysical Research: Biogeosciences




To elucidate the role of (bio)geochemical processes that fueled iron and carbon cycling in early Earth oceans, modern environments with similar geochemical conditions are needed. As the range of chemical, physical, and biological attributes of the Precambrian oceans must have varied in time and space, lakes of different compositions are useful to ask and answer different questions. Tropical Lake Matano (Indonesia), the largest known ferruginous lake, and Lake Pavin (France), a meromictic crater lake, are the two best studied Precambrian ocean analogs. Here we present seasonal geochemical data from two glacially formed temperate ferruginous lakes: Brownie Lake (MN) and Canyon Lake (MI) in the Upper Midwest, USA. The results of seasonal monitoring over multiple years indicate that (1) each lake is meromictic with a dense, anoxic monimolimnion, which is separated from the less dense, oxic mixolimnion by a sharp chemocline; (2) below this chemocline are ferruginous waters, with maximum dissolved iron concentrations >1 mM; (3) meromixis in Brownie Lake is largely anthropogenic, whereas in Canyon Lake it is natural; (4) the shallow chemocline of Brownie Lake and high phosphorus reservoir make it an ideal analog to study anoxygenic photosynthesis, elemental ratios, and mineralogy; and (5) a deep penetrating suboxic zone in Canyon Lake may support future studies of suboxic microbial activity or mineral transformation.


This article is published as Lambrecht, Nicholas, Chad Wittkop, Sergei Katsev, Mojtaba Fakhraee, and Elizabeth D. Swanner. "Geochemical characterization of two ferruginous meromictic lakes in the Upper Midwest, USA." Journal of Geophysical Research: Biogeosciences (2018). doi: 10.1029/2018JG004587. Posted with permission.

Copyright Owner

American Geophysical Union



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