The magnetic properties of Serbian loess and its environmental significance

This paper reports a loess-paleosol sequence located in the Danube River basin, Serbia, which formed at least since the latest part of the early Pleistocene, and before the paleomagnetic B/M boundary. Various magnetic parameters of the Serbian V-L-1-V-S-4 loess-paleosol sequence have been measured and analyzed in the Titel Loess Plateau. These parameters show a very similar magnetic behavior compared with that of the Chinese loess. There is a general positive relationship between magnetic susceptibility (chi) and pedogenesis. The main contributors to chi are the magnetic grains of SP (superparamagnetic) and SD (single domain) magnetic domains, while MD (multi domain) contributes only a small percentage. The difference in chi between loess and paleosol mainly is caused by pedogenesis. The very fine magnetic minerals increase gradually with increasing soil development (from loess to soil), and they lead to higher chi. The thermomagnetic curves show thatmagnetic minerals in the loess layers are magnetite and maghemite, both providing a major contribution to chi. In contrast the paleosol layers mainly are composed of magnetite, with almost no or a very small amount of maghemite, as implied by a reversible thermomagnetic behavior. This indicates that pedogenic conditions during V-S-3 and V-S-4 strong soil development have resulted in maghemite that is no longer stable, and has been resolved or converted to other stable phase minerals. This likely indicates that soil moisture during V-S-3 and V-S-4 development exceeded a critical condition of maghemite stability.