The Miocene Source-to-Sink Evolution of Fibrous ClayMinerals in Hyperalkaline Playa-Lakes, Duero Basin (Central Spain) del Buey, Pablo Sanz Montero, María Esther Rodríguez Aranda, Juan Pablo Sánchez-Román, Mónica Nieto García, Fernando TEM-AEM palygorskite chlorite Palygorskite is assumed to be the predominant clay mineral in playa-lakes, where it may be detrital or authigenic in origin. Discriminating between detrital and authigenic clays is crucial to elucidate paleoenvironmental conditions in lacustrine deposits. This study provides insight into the sedimentary evolution of clay minerals from source, lacustrine Miocene marlstones and mudstones, to sink, represented by three recent hyperalkaline playa-lakes in Central Spain. XRD, TEM, and AEM analyses show concomitant detrital and authigenic palygorskites in the three playa-lakes. The inherited palygorskites exhibit degradation features, larger widths, and common and ideal compositions, in contrast to neoformed particles. The latter are narrower. Depending on the hydrochemical composition of each playa-lake, neoformed palygorskites are enriched in a different octahedral cation (Al2O3, MgO, and Fe2O3). Iron-rich palygorskites are only formed in association with authigenic saponites in one of the playa-lakes. The same effect of magnesium competition between smectite and palygorskite is observed in Miocene mudstones, where palygorskite is relatively enriched in iron. In hyperalkaline, seasonal playa-lakes lying in the vicinity, slight physicochemical differences play a crucial role in the crystallochemical composition of authigenic palygorskites, highlighting the use of this mineral as a geochemical proxy. 2025-01-07T12:31:11Z 2025-01-07T12:31:11Z 2025-01-05 journal article del Buey, P. et. al. Minerals 2025, 15, 50 [https://doi.org/10.3390/min15010050] https://hdl.handle.net/10481/98538 10.3390/min15010050 eng http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional MDPI