Unveiling the Transition From Paleolake Lisan to Dead Sea Through the Analysis of Lake Paleo Shorelines and Radiometric Dating of Fossil Stromatolites
By: Julius Jara‐Muñoz, Amotz Agnon, Jens Fohlmeister, Sara Tomás, Jürgen Mey, Norbert Frank, Birgit Schröder, Andrea Schröder‐Ritzrau, Yannick Garcin, Yaniv Darvasi, Daniel Melnick, Maria Mutti, and Manfred R. Strecker
Summarized by: Summarized by Megha Goswami, a senior at Binghamton University. She is currently working towards a B.S. in geology: geophysics and will graduate in Fall 2024. She plans to take a gap year and gain experience in the geology field, then return for a Master’s program. Outside of college, she likes to hike, paint, and garden.
What data were used? In this study, the researchers collected fossil stromatolites, once-living microbe organisms or blue-green algae, from the eastern and western coasts of the Dead Sea. Fossil stromatolites are great for tracking changes in ancient coastlines, as these blue-green algae form around the shorelines of lakes and seas (called paleo shorelines). The researchers used multiple photos of these geologic features to create 3D photogrammetric models of the shorelines of the paleo lake Lisan.
What is the goal of this paper? To gain a deeper understanding of the climate during the most recent cold period (the Last Glacial Maximum, approximately 120,000 to 11,500 years ago), scientists conducted radiometric dating on stromatolite fossils (see Figure 1). They reconstructed the paleo shorelines to establish the approximate timeline of when paleo Lake Lisan transitioned into what is now the Dead Sea. This data was then compared with previous studies, which indicated that during the last glacial period, the depression that once contained paleo Lake Lisan remained filled for roughly 10,000 years. As the lake dried up, the remnants of the paleo shorelines were left behind.
Methods: Stromatolite samples were collected from the western to eastern coast of the Dead Sea to explore the transition from Paleolake Lisan to the current Dead Sea. Scientific analyses were conducted in the laboratory on the fossil stromatolites and the ancient shorelines of the paleo-lake. The samples were dated using both radiocarbon and uranium-series dating methods. Radiocarbon dating estimates a sample’s age by measuring the amount of carbon-14 it contains. In contrast, the uranium-series dating method assesses uranium isotopes, such as U234, U238, and thorium-230, to estimate the ages of the stromatolite specimens. Additionally, temporal corrections were applied to the U-series ages to account for the presence of other materials or impurities in the samples that could influence the age determination of the stromatolite specimens. Scientists also implemented further corrections to the data to address changes in altitude, water levels, and tectonic activity that occurred since the time when these fossils were formed. After completing these tests and analyses, the researchers successfully determined the ages of the samples, reconstructed the shoreline levels of Paleolake Lisan, and compared their findings with those of previous studies.
Results: The scientists discovered that the highest (peak) lake level occurred between 30,000 and 28,600 years ago, with a decline starting around 28,500 and continuing until 18,000 years ago. During the peak period of Lake Lisan, water evaporation rates were also elevated, aligning with other models used for reconstructing past shorelines. Consequently, these findings suggest that the transition from paleo Lake Lisan to the Dead Sea happened 5,000 years earlier than indicated in earlier studies.
Why is this study important? This data offers researchers insights into the regional and local paleoclimate—specifically, the climate during the Last Glacial Maximum, which occurred roughly 120,000 to 11,500 years ago. The findings indicate that following the peak water levels of Lake Lisan, which declined between 28,500 and 18,000 years ago, the rate of water evaporation increased. This suggests that temperatures in the region began to rise during the Last Glacial Maximum, likely showing the transition out of this glacial period.
Broader implications beyond this study? By examining historical geological features, such as lakes and shorelines, scientists can gain insights into the climate conditions during Earth’s last glacial period. This study also enhances their understanding of how lakes reacted to climate change as temperatures increased. By learning about past climates, scientists can better comprehend current climate behavior and make informed predictions about future climate conditions.
Citation: Jara‐Muñoz, J., Agnon, A., Fohlmeister, J., Tomás, S., Mey, J., Frank, N., Schröder, B., Schröder‐Ritzrau, A., Garcin, Y., Darvasi, Y., Melnick, D., Mutti, M., & Strecker, M. R. (2024). Unveiling the transition from Paleolake Lisan to Dead Sea through the analysis of Lake paleo shorelines and radiometric dating of fossil stromatolites. Geochemistry, Geophysics, Geosystems, 25(8). https://doi.org/10.1029/2024gc011541