135 Aplicaciones paleoclimáticas y paleoambientales de los estudios mineralógicos al yacimiento de vertebrados miocenos de Somosaguas Ángel Carrasco, Sara Sacristán, Guillermo Benítez-López, Daniel Romero-Nieto, Omid Fesharaki & Nieves López Martínez Abstract: The middle Miocene fossil site of Somosaguas (Madrid) has provided vertebrate fossil remains from arkosic alluvial fan sediments, whose source area is the Spanish Central System. Analyses of preceding data on clay mineral assemblages in detrital sediments and calcretes have provided palaeoclimatic and palaeoenvironmental indications comparable to those previ- ously obtained from the mammalian communities. Smectite predominance suggests chemical alteration in semiarid climate with seasonal rainfalls. These results agree with the existence of a savanna environment, as it was inferred from the mammalian assemblage. Presence of montmorillonite in the detrital levels indicates poor drainage conditions, whereas calcretes lev- els indicate deposition in vadose zone. Calcrete and detrital alternation may indicate variations of the local phreatic level. Keywords: Somosaguas, Miocene, alluvial fan, clay minerals, montmorillonite, calcretes, pal- aeoenvironment, subtropical seasonal climate. Palabras clave: Somosaguas, Mioceno, abanico aluvial, minerales de la arcilla, montmorillo- nita, calcretas, paleoambientes, clima subtropical estacional. Dpto. Paleontología, Fac. Ciencias Geológicas, Universidad Complutense de Madrid, C/ José Antonio No- vais 2, 28040 (Madrid). A.C.: A.C.:angelurico@hotmail.com; S.S.:shairaSJ@hotmail.com; G.B.L.:nitezlopez@ hotmail.com; D.R.N.:rome_vk@yahoo.es; O.F.:omidfesharaki@hotmail.com; N.L.M.:lopezmar@geo. ucm.es Palaeontologica Nova. SEPAZ 2008 (8) I. S. B. N: 978-84-96214-96-5