Journal of Coastal Research SI 48 29-34 III SCCG (Proccedings) Spain ISSN 0749-0208 Spatial changes in surface sediments derived from the different sediment sources and land uses at “El Jable” (Lanzarote, Spain). L. Cabrera†, I. Alonso† and J. Alcántara-Carrió‡ †Dept. Física ‡Dept. Ciencias Experimentales Univ. Las Palmas de Gran Canaria, Univ. Católica de Valencia 35017 Las Palmas, Spain 46003 Valencia, Spain lcabrera@becarios.ulpgc.es , javier.alcantara@ucv.es ialonso@dfis.ulpgc.es ABSTRACT CABRERA, L., ALONSO, I. AND ALCÁNTARA-CARRIÓ, J. 2006. Spatial changes in surface sediments derived from the different sediment sources and land uses at “El Jable” (Lanzarote, Spain). Journal of Coastal Research, SI 48 (Proccedings of the 3rd Spanish Conference on Coastal Geomorphology), 29-34. Las Palmas de Gran Canaria – Spain, ISSN 0749-0208. This paper describes the sedimentological properties of sedimentary materials along a North - South orientated sand strip (21 km long and 5 km wide on average) that crosses the island of Lanzarote (Canary Islands, Spain). The area is characterized as a sand sheet because it is mostly covered by aeolian sediments, which were blown southwards from the northern coast. This predominantly aeolian environment is interspersed with agricultural areas, volcanic cones and lava fields. Different sectors of the sand sheet can be distinguished on the basis of grain size properties and carbonate content of the surface sediments. Results are discussed and interpreted considering the geological origin, the human use and the sediment sources of the study area. ADITIONAL INDEX WORDS: Sedimentology, grain size, carbonate content, sand sheet, Lanzarote INTRODUCTION Grain size analysis has been widely used to distinguish between different sedimentary environments, as well as to give information on the processes of transport and deposition (FOLK AND WARD, 1957; FRIEDMAN, 1961; DONGHUAI ET AL, 2002; ABUODHA, 2003). Carbonate content analysis of the sediments gives information on the sediment source of these materials (MAGARITZ and JAHN, 1992). A combination of these textural and compositional properties of the sediments has been used to assess the aeolian sediment availability (ALCÁNTARA-CARRIÓ and ALONSO, 2001). Lanzarote Island began to form during the Miocene, through volcanic activity in the shield volcanoes of Los Ajaches in the south and Famara at the northernmost part of the island (COELLO et al, 1992). Both shield volcanoes were developed as independent volcanic islands (CARRACEDO and RODRIGUEZ BADIOLA, 1993) and were subsequently connected by eruptive products from a central rift during the Pleistocene (CARRACEDO et al, 2002) (Figure 1). Subsequent aeolian activity gave rise to development of extensive loess and wind-blown sand deposits. The aeolian sediments from this period are locally called ‘jables’, which cover wide lowlands of the central rift, southwards of Famara Beach. For this reason the area is called El Jable. Detailed studies of sediment transport processes have been carried out in the aeolian deposits located at Fuerteventura (CRIADO, 1987; ALCÁNTARA-CARRIÓ, 2003; ALONSO et al, in press) and Gran Canaria (HERNÁNDEZ, 2002), but not in Lanzarote. The aim of this paper is to characterize the sedimentological properties of the aeolian surface sediments that form El Jable, and particularly their spatial variations in grain size and carbonate content, in order to correlate these changes with sedimentary processes and land uses. Figure 1. Geologic map of Lanzarote. Modified from CARRACEDO et al, 2002. Journal of Coastal Research, Special Issue 48, 2006 29