Terrestrial record of cyclic early Eocene warm-humid events in clay mineral assemblages from the Salta basin, northwestern Argentina

The Eocene continental sequence investigated in this study belongs to the Salta Group; it was deposited an intracontinental rift, Basin (NW Argentina) that evolved from Lower Cretaceous middle Paleogene. Group contains Maíz Gordo and Lumbrera Fms, spans Paleocene-early Eocene, shows excellent exposures region of Valles Calchaquíes. This research is focused on facies Fm, which correspond early Eocene. We studied mineralogy fine-grained beds Fm five locations (Valle Encantado, Tonco, Tin Tin, Luracatao, Obelisco) by X-ray diffraction scanning electron microscopy order examine vertical variations clay their relations with global paleoclimatic changes registered during microtexture authigenic smectite-type clays (Sm I/Sm R0) suggests they mainly originated crystallization glassy volcanic materials. high reactivity glass precludes use smectite-type-clay formation as indicator specific conditions sediments. In contrast, kaolinite sections very low smectite proportions a strong degree weathering crystalline silicates reflects intense useful proxy terrestrial Significant kaolinite/muscovite ratios at base intermediate bed Valle Encantado suggest presence cyclic hyperthermals through Ypresian stage may be tentatively correlated Thermal Maxima 2 3, are largest events have been identified scale marine