New types of loess, not related to glaciation

IRIONDO, MARTIN; KROHLING, DANIELA

Delmenhorst, Alemania.

Workshop; International Workshop “From particle size to sediment dynamics”; 2004

Hanse Institute for Advanced Studies (Editores: B.Flemming y D. Hartmann)

Loess is an aeolian sediment dominantly formed by silt or silty loam, which normally generates rich soils. Consequently, it is an object of permanent interest in sedimentology and soilscience. The world's major loess deposits have correctly been linked to glacial processes (North America and North Europe loess) or to cold weathering processes (Chinese and Central Asianloess). Such a particular pattern influenced the theory so strongly that today specialists assume some kind of relation with ice. The fact that such an assumption is frequently implicit is not less negative for the development of the knowledge on this issue. Deposits clearly disconnected of acold system are “a priori” disregarded by most loess specialists. Sometimes non-sedimentological theories are used, such as rock alteration, mass movements, etc. The real fact is that transport of silt and clay in suspension by wind is a universal process. Observations and measurementsof the general movement of atmospheric dust and studies made on Quaternary fine sediments elsewhere suggest that the loess question is more ubiquitous, and it also occurs innon-glacial-related systems.The present contribution proposes a more comprehensive rationale including the scattered available information about alternative origins in the general concept of loess. Someimportant loess deposits recently identified in South America can not be explained by the commonly accepted “strict orthodox” theory. A few cases are discussed in thiscontribution.