Textural and compositional characterization and provenance analysis of beach sediments in Golfo Nuevo, Chubut Province

A textural and compositional characterization of beach sediments in 17 coastal profiles is presented from cerro Prismático nor­thward to cerro Avanzado southward, in the golfo Nuevo, Chubut province. The aim of this work is to establish the main input source of sediments to the littoral system and the factors controlling their texture and composition. This work deepens and advances on sediments knowledge of Argentinean coast, establishing an accurate and quantitative background for futures resear­ches. High intertidal sediments are composed by sand (62%) and gravel (38%), showing poor sorting. Sediments from the low intertidal, backshore and coastal dune environments show well sorted sandy sediments (more than 90% on average). Petrographic composition is homogenous along the coast, mostly characterized on average by lithic fragments (35%), plagioclase (24%), quartz (23%), feldspar (6%) and alterites (5%). The rocky coastal outcrops present up between 40% and 70% of sand, according to various authors, and it is found that both the composition and the proportion of its majority components are equivalent to that presented for beach sands. Also, due to the golfo Nuevo is a partially protected environment and the absence of evidences of littoral drift as well as the absence of allochthonous fluvial input inside it, it is concluded that the main source of sand to the littoral system results from the erosion of the cliffs that dominate the coastal landscape (Gaiman and Puerto Madryn formations).