
Diagenetic magnetic minerals as recorders of limnological changes in Lake Kinneret
Moshe T. (1), Shaar R. (1), Beeri Y. (2), Antler G. (3)
(1) The Fredy and Nadine Herrmann Institute of Earth Sciences, The Hebrew University of Jerusalem, Israel
(2) Other Institute (insert manually)
(3) Department of Earth and Environmental Sciences, Ben Gurion University of the Negev, Beer Sheva 84105
The Laboratory Limnological Kinneret Alon Yigal
Magnetic minerals are highly sensitive to limnological changes in lake sediments, including variations in redox conditions, biogenic productivity, pore-water chemistry, ion diffusion, and sedimentation rates. In this talk, I will demonstrate how magnetic properties can be used as indicators for such limnological changes in Lake Kinneret. Ten sediment cores, ranging in length from 40 to 300 cm, were recovered from Station A at a water depth of 38m. The cores were sampled and analyzed in a 2cm resolution for rock-magnetism and pore-water geochemistry. Our results demonstrate large variations in magnetic properties with depth, reflecting mineralogical changes due to diagenetic processes. The most prominent changes are high increase at ~50 cm depth and occur as a result of sulfate–methane transition (SMT). We identified two SMT: The first, at ~50 cm depth, is attributed to sulfate propagating from the water-sediment interface, while the second, at ~270 cm, is likely driven by sulfate diffusion from underlying brines. In addition, we found disturbance in sedimentary fabric using anisotropy of magnetic susceptibility (AMS) at ~2 m – coinciding with the 1202 AD (~M7) earthquake. The paleomagnetic signal remains reliable in the methane-bearing intervals between the SMT zones, which make the Kinneret sediments a promising archive for paleomagnetic reconstructions. Overall, the data demonstrates that magnetic methods provide a useful proxy for reconstructing limnological and paleoenvironmental changes in Lake Kinneret.



