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In this study, fourteen superficial sandy sediment samples and fifteen core samples, taken at 2 to 30 m in depth, were analyzed in order to determine the granulometry and mineralogical features of the dune system named duna costera El Socorro (DCES), San Quintin, Baja California, Mexico. In addition, we investigated the sediment provenance by analyzing twelve samples collected from three nearby arroyos and sand bars. The main components of the DCES are plagioclase and quartz (35 - 39 % and 36 - 58 % plagioclase, and 50 - 56 % and 38 - 60 % monocrystalline quartz for core samples and superficial samples, respectively). The remaining components include scarce lithic fragments and abundant heavy minerals, mostly hornblende and traces of pyroxene, but also small amounts of magnetite and ilmenite (> 1 % in volume). The samples from arroyo El Socorro (south of the DCES) and arroyo Santo Domingo (similar to 45 km north of the DCES) contain 69 and 52 % monocrystalline quartz, respectively, while arroyo San Simon, located north of the DCES, has 63 % plagioclase. Mineralogical characterization in the study area and modal analysis suggest that the main DCES sediment source is the arroyo Santo Domingo.