Environmental magnetism

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Diagram illustrating magnetosome incorporation in lake sediments. In the littoral area, the oxic-anoxic interface (OAI) lies below the sediment-water interface, so magnetotactic bacteria live in the sediments and magnetosomes are preserved as relatively intact linear chains. In the profundal area, if the OAI is situated in the water column, magnetosome chains may undergo disruption during settling to the lake bottom (Lascu and Plank, 2013).

Magnetic minerals are ubiquitous in sedimentary environments, and they can be used to trace changes in paleoclimatic and environmental conditions on both local and global scales. Recent developments in the fields of mineral magnetism and paleoclimatology indicate that Fe-­bearing minerals with magnetic properties may hold key information that could help answer outstanding questions related to sediment provenance, nutrient availability, and in situ biogeochemical processes (such as Fe cycling) in sedimentary environments. Modern mineral magnetic techniques are well suited to characterize the magnetic fraction present in sediments, and to unravel the complexities hidden in their measured signal.

Some of the outstanding environmental-magnetic problems in paleoclimatological and paleoceanographic research I am interested in include tracing the source and pathways of terrigenous sediments that get deposited in lake and marine basins, discriminating the fraction of biogenic magnetic minerals in sediments and assessing their importance as natural magnetic remanence carriers, and determining the role of Fe as a limiting nutrient in small and large water bodies.

Papers

Lascu, I., McLauchlan, K., Myrbo, A., Leavitt, P. R. and Banerjee, S. K., 2012, Sediment-magnetic evidence for last millennium drought conditions at the prairie–forest ecotone of northern United States, Palaeogeography, Palaeoclimatology, Palaeoecology 337-338, p. 99-107, doi:10.1016/j.palaeo.2012.04.001.

Lascu, I. and Plank, C. P., 2013, A new dimension to sediment magnetism: Charting the spatial variability of magnetic properties across lake basins, Global and Planetary Change 110, p. 340-349, doi:10.1016/j.gloplacha.2013.03.013.

Lascu, I., Wohlfarth, B., Onac, B. P., Björck, S. and Kromer, B.,  2014, A Late Glacial paleolake record from an up-dammed river valley in northern Transylvania, Romania, Quaternary International, doi:10.1016/j.quaint.2014.11.041.

Blumentritt, D. J. and Lascu, I., 2014, A comparison of magnetic susceptibility measurement techniques and ferrimagnetic component analysis from recent sediments in Lake Pepin (USA). In Da Silva, A.-C., Whalen, M.T., Jindrich, H., Chadimova, L., Chen, D., Spassov, S., Boulvain, F., Devleeschouwer, X. (eds.), Magnetic susceptibility application: a window onto ancient environments and climatic variations, Geological Society, London, Special Publications 414, p.197-207, doi:10.1144/SP414.6.

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