Alkaline lakes and paleolakes on Earth and Mars
Lindsay McHenry and Gayantha Kodikara, on the northwestern shore of Lake Natron with Shombole volcano in the background.
Saline-alkaline lakes on Earth leave behind mineralogical evidence of their conditions, in the form of zeolites, clays, and other authigenic minerals. At Olduvai Gorge, strata bearing these phases can help us to reconstruct the often cyclical changes in lake level as this hominin-inhabited landscape alternated between wetter and drier periods. Both in outcrop and in sediment cores retrieved by the Olduvai Gorge Coring Project in 2014 and 2023, authigenic minerals formed within the lake and lake sediments help tell this paleoenvironmental story.
A drill rig arrives at Olduvai Gorge, ready to core the paleolake deposits for the Olduvai Gorge Coring Project
Beyond Earth, Mars rover missions to Gale crater (Curiosity) and Jezero crater (Perseverance), plus remote sensing imaging and spectroscopy, have provided evidence for paleolakes, some of which were likely alkaline. By comparing terrestrial lakes and paleolakes to these potential equivalents on early Mars, we can assess the conditions that might have formed these ancient, potentially habitable environments, and the mineralogical evidence they leave behind.
Our search for terrestrial analogs for Martian paleolakes has taken us to paleolake Olduvai and Lake Natron, Tanzania, and to paleolake Tecopa, Mono Lake, and Panamint Valley in California. In addition to sampling and analyzing samples by X-ray Diffraction to characterize the mineral assemblages, we have also studied how these deposits might look from space, and whether their unique mineralogies would be detectable using orbital spectroscopy.
Thick outcrops of the Moinik Formation, a Pleistocene paleolake deposit near Lake Natron, Tanzania.
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Gayantha Kodikara at Mono Lake, California.
Related publications:
Kodikara, G.R.L., McHenry, L.J., Hynek, B.M., Njau, J.K., In Press. Mapping paleolacustrine deposits with a UAV-borne multispectral camera: Implications for future drone mapping on Mars. Planetary Science Journal. Accepted October 2024.
Kodikara, G.R.L., McHenry, L.J., Stanistreet, I.G., Stollhofen, H., Njau, J.K., Toth, N., Schick, K. 2024. Wide & Deep Learning for predicting relative mineral compositions of sediment cores solely based on XRF scans, a case study from Pleistocene Paleolake Olduvai, Tanzania. Artificial Intelligence in Geosciences 5, 100088. doi.org/10.1016/j.aiig.2024.100088
Kodikara, G.R.L., McHenry, L.J., 2023. Data-driven fuzzy weights-of-evidence model for identification of potential zeolite-bearing environments on Mars. Earth and Space Science 10, e2023EA002945. doi.org/10.1029/2023EA002945.
McHenry, L.J., Gebregiorgis, D., Foerster, V., 2023. Paleolakes of eastern Africa: Zeolites, clay minerals, and climate. Elements 19, 96-103. doi.org/ 10.2138/gselements.19.2.96.
Kodikara, G.R.L., McHenry, L.J., Grundl., T.J., 2023. Possible formation pathways for zeolites in closed-basin lakes on noachian Mars: Insights from geochemical modeling. Icarus 389, 115271. doi.org/10.1016/j.icarus.2022.115271
Kodikara, G.R.L., McHenry, L.J., Van der Meer, F., 2023. Spectral mapping of zeolite bearing paleolake deposits at Lake Tecopa, California and its implications for mapping zeolites on Mars. Geosystems and Geoenvironment, 2, p. 100119. doi.org/10.1016/j.geogeo.2022.100119
Kodikara, G.R.L., McHenry, L.J., Van der Meer, F., 2022. Application of deep learning and spectral deconvolution for estimating mineral abundances of zeolite, Mg-sulfate and montmorillonite mixtures and its implications for Mars. Planetary and Space Science. doi.org/10.1016/j.pss.2022.105579
Kodikara, G.R.L., McHenry, L.J., 2021. Self-Organizing Maps for identification of zeolitic diagenesis patterns in closed hydrologic systems. International Journal of Sedimentary Research 36: 567-576. doi.org/10.1016/j.ijsrc.2021.04.003.
McHenry, L.J., Kodikara, G.R.L.., Stanistreet, I.G., Stollhofen, H., Njau, J.K., Schick, K., Toth, N. 2020. Lake conditions and detrital sources of Paleolake Olduvai, Tanzania, reconstructed using X-Ray Diffraction analysis of cores. Palaeogeography Palaeoclimatology Palaeoecology 556, 109855. doi.org/10.1016/j.palaeo.2020.109855
Stanistreet, I.G., Boyle, J., Stollhofen, H., Deocampo, D., Deino, A., McHenry, L.J., Toth, N. Schick, K., Njau, J.K. 2020. Palaeosalinity and palaeoclimatic geochemical proxies (elements Ti, Mg, Al) vary with Milankovitch cyclicity (1.3 to 2.0 Ma), OGCP cores, Palaeolake Olduvai, Tanzania. Palaeogeography Palaeoclimatology Palaeoecology 546: 109656. doi.org/10.1016/j.palaeo.2020.109656
Stanistreet, I.G., Stollhofen, H., Deino, A., McHenry, L.J., Toth, N., Schick, K., Njau, J.K., 2020. New Olduvai Basin stratigraphy and stratigraphic concepts revealed by OGCP cores into the Palaeolake Olduvai depocentre, Tanzania. Palaeogeography Palaeoclimatology Palaeoecology 554: 109751. doi.org/10.1016/j.palaeo.2020.109751
McHenry, L.J., Chevrier, V., Schröder, C., 2011. Jarosite in a Pleistocene East African saline‐alkaline paleolacustrine deposit: Implications for Mars aqueous geochemistry. Journal of Geophysical Research 116: E04002. doi:10.1029/2010JE003680
McHenry, L.J., 2010. Element distribution between coexisting authigenic mineral phases in argillic and zeolitic altered tephra, Olduvai Gorge, Tanzania. Clays and Clay Minerals 58(5): 627-643. doi: 10.1346/CCMN.2010.0580504
McHenry, L.J., 2009. Element mobility during zeolitic and argillic alteration of volcanic ash in a closed-basin lacustrine environment: Case study Olduvai Gorge, Tanzania. Chemical Geology 265: 540-552. doi:10.1016/j.chemgeo.2009.05.019