Sediment Transfer through the Fluvial System (Proceedings of a symposium held in Moscow, August 2004). IAHS Publ. 288, 2004, 187–194

1 Faculty of Geography, Moscow State University, Vorob’evi Gory, Moscow 119892, Russia

2 Department of Applied Earth Sciences, Delft University of Technology, Mijnbouwstraat 120, PO Box 5028,
NL-2600GA, Delft, The Netherlands

Abstract Geochemical data on modern stream sediments in the Guadalhorce basin (Province of Malaga, Spain) were used to explore the role of parent lithology and drainage basin size as well as grain-size differentiation. Sand-sized sediments (189 samples) with median grain sizes ranging from 2 to 0.125 mm were collected at 136 locations along different river segments. These segments represent streams of various order draining areas with different rock types. For the individual sampling site the area of influence, i.e. the sample catchment, was defined. The catchments were classified on the basis of quantitative parameters: catchment size and the areal proportions of parent rock sources. Geochemical data were described in terms of the relative abundances of major elements (SiO₂, TiO₂, Fe₂O₃, Al₂O₃, MnO, MgO, CaO, Na₂O, K₂O, P₂O₅) in a bulk sample measured with X-ray fluorescence spectroscopy after pre-treatment of the samples, including loss on ignition (LOI) determination. The compositional data were used as the input for end-member modelling which allowed an objective unravelling of the distinct sediment populations.

Key words catchments; chemical composition; classification; end-member modelling; Guadalhorce basin; stream sediments