LOESSFEST'09 | Aug. 31st – Sept. 3rd, 2009 |Novi Sad-Serbia
Grain Size of Loessic Sediment:
A Powerful Proxy for Process Identification
Jeff Vandenberghe1
1Vrije Universiteit, De Boelelaan 1085-1087, 1081 HV Amsterdam, The Netherlands
Wind transport in suspension is not a uniform process but may occur in different modes according to transport height and distance. Subsequently, these differences are expressed in terms of grain-size and fluxes of the loess deposits. Transport distances may vary from several tens of meters to ten thousands of kilometers, while the height accordingly may vary from meters to more than thousand meters. A relation with grain-size distributions may be established on the base of type occurrences of different loess facies. At least 5 populations may be defined according to their grain size. Each of them reflects a specific aeolian process and transport conditions.
Apart from pure wind deposition loess may also be affected by post-depositional processes: examples are settling of loess particles in a lacustrine setting and reworking by rivers or surface runoff. Also these kinds of processes leave their imprint in the grain-size distribution. An interesting question is whether such relationships may be used to reconstruct former processes and depositional (climatic) conditions.