Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Palaeogeography Palaeoclimatology Palaeoecology 451-471 + corrigendum vol. 418, 386 Paleogene Marine incursion Amazonian foreland basin Tidal deposits Madre de Dios basin Peru PEROU AMAZONIE 2014 fdi:010062987 ENG Palaeogeography Palaeoclimatology Palaeoecology 0031-0182 ISI:000345202500037 10.1016/j.palaeo.2014.09.027 https://www.documentation.ird.fr/hor/fdi:010062987 https://www.documentation.ird.fr/intranet/publi/depot/2015-05-05/010062987.pdf 414 Horizon (IRD) This article presents new biostratigraphic dating, facies analysis, organic geochemical data and Nd-Sr isotopic provenance from five outcrops of southern Amazonia (MD-85, MD-177 MD-184, MD-255 and MD-256) to document for the first time the presence of a shallow marine ingression in the Paleocene of southern Amazonia basin. The co-occurrence of a selachian assemblage encompassing Potobatis sp., Ouledia sp., and Pristidae indet with the ostracod Protobuntonia sp. and the charophytes Peckichara cf. varians meridionalis, Platychara perlata, and Feistiella cf. gildemeisteri suggests a Paleocene age for the studied deposits (most likely Thanetian but potentially Danian). Fifteen fades have been recognized and have been grouped into three facies assemblages. Facies association A corresponds to the sedimentary filling of a tide-influenced meandering channel formed in the fluvial-tidal transition zone. Facies association B is related to more distal tidal-flats, little channelized tidal inlets and saltmarsh deposits. Facies association C corresponds to a stressed shallow marine environment such as a bay or a lagoon. The delta C-13(TOC) value (- 23.4%) of MD-184 is enriched in C-13 compared to the other samples suggesting the presence of substantial amounts of marine organic matter in MD-184. The delta C-13(TOC) values of samples from other outcrops ( - 27.3 to - 29.8%) indicate a mixed organic matter origin, from terrestrial to brackish environments. The analyzed sediments have similar Nd-Sr isotopic compositions as those of the Cenozoic sediments of the Altiplano (epsilon Nd(0) values from - 6.2 to - 10.7 and Sr-87/Sr-86 compositions from 0.712024 to 0.719026) indicating a similar volcanic source. This multidisciplinary dataset documents the presence of a tide-dominated estuary sourced by the proto-Westem Cordillera debouching into a shallow marine bay during Paleocene times. This transgression might be explained by subsidence created in response to the proto-Western Cordillera loading. Similar to Miocene marine incursions affecting the Pebas megawetland, Paleogene marine incursions in the Amazonian foreland basin associated with Andean uplift may have played a role in the Neotropical biodiversity dynamics in favoring biogeographical isolation and promoting allopatric speciation for terrestrial organisms. 064 UR154 / UR226 Pérou