Provenance analysis of aeolian sands from the Natural Park of the Dunes of Correlejo, Fuerteventura Island (Canary Islands)

Abstract

The Natural Park of Corralejo Dunes is located in the NNE of the island of Fuerteventura. The main objective of this work is to identify the source of the coastal aeolian sands associated with the dune-beach system of the Natural Park, as well as to know the influence of vegetation on the distribution of the sand grains. For this purpose, a petrographic analysis has been carried out with 27 samples of eolian sands distributed in three environmental units of this protected area: The N-W zone of semi-stabilized sands by vegetation, the central-S zone of moving sands, and the coastal zone of entry of sandy sediments into the eolian system. 27 thin sections of the samples have been studied using a Leitz Ortoplan geological microscope and a Petrog counting stage with its associated software (petroglite). In each thin section, 200 grains of sand have been identified according to 16 compositional types defined for this work. The abundance percentages of each type have been grouped into 4 main categories (bioclasts, sedimentary intraclasts, volcanic rock fragments, and minerals) for statistical treatment. Thus, the average results reveal that the sand grains are from marine biogenic origin (82%), carbonate intraclasts (9%), and volcanic rock mineral fragments (9%). The percentage of abundance of the samples does not present a uniform distribution throughout the study area as a consequence of the different sources of origin and environmental conditions (geologic, geomorphologic and anthropogenic factors). Bioclasts come from the hard parts of marine organisms (mainly remains of mollusks and coralline red algae). Intraclasts are fragments of sedimentary strata from aeolianites, paleosols, and beachrocks that appear on the coast and surrounding areas. The grains of volcanic rock and mineral fragments come from the erosion of surface water and wind of aerial basaltic rock substrates. On the other hand, regarding the dominance of the sand grains in semi-stabilized areas by vegetation, when these are arranged inside the plant, there is a very subtle increase of volcanic lithoclasts, with respect to the grains harbored outside the shrub vegetation.