Changes in western Mediterranean thermohaline circulation in association with a deglacial Organic Rich Layer formation in the Alboran Sea Pérez Asensio, José Noel Rodríguez Tovar, Francisco J. Micropaleontology Foraminifers Ichnology Stable isotopes Organic matter flux Thermohaline circulation Paleoceanography Organic Rich Layer (ORL) Western Mediterranean Late glacial Holocene We thank the constructive comments of three anonymous reviewers that substantially improved this manuscript. JNPA has been funded by a Postdoctoral fellowship Beatriu de Pinós funded by the AGAUR from the Generalitat de Catalunya and the European Union through the Marie Curie-COFUND actions. LDP acknowledges support from the Ramón y Cajal program (MINECO, Spain), JF from the Serra Húnter Programme (Generalitat de Catalunya) and IC from the ICREA-Academia program from the Generalitat de Catalunya. We are indebted to Albert Català and Montse Guart (University of Barcelona), and Joaquim Perona and Regina Roca (CCiT-UB) for their support with the laboratory work. Supplementary data to this article can be found online at https://doi.org/10.1016/j.quascirev.2019.106075. The accumulation of an Organic Rich Layer (ORL) during the last deglaciation in the Alboran Sea (western Mediterranean Sea) and its link to changes in deep and intermediate water circulation are here investigated. Benthic foraminiferal assemblages and the shallow infaunal foraminifer Uvigerina peregrina δ13C record support the establishment of sustained high organic matter fluxes, and thus eutrophic conditions at the sea floor, during the late phase of the ORL (Younger Dryas to early Holocene periods). Since organic matter fluxes were lower (mesotrophic conditions) during the Bølling-Allerød period, they cannot be solely responsible for the ORL initiation. Geochemical, sedimentological and micropalaeontological proxies support a major weakening of the deep-water convection in the Gulf of Lion as the main driver for the development of poorly-ventilated conditions from intermediate depths (946 m) to the deep western Mediterranean basin that promoted the beginning of the ORL deposition. Nevertheless, a better ventilation at intermediate depths was established during the late ORL, while the deep basin remained poorly ventilated. We propose that our data reflect the arrival of a new better-ventilated intermediate water mass analogue to the current Levantine Intermediate Water (LIW) and/or a new intermediate water mass from the Gulf of Lion. The ultimate source of this water mass needs to be further explored but chronologies of the changes recorded here indicate that intermediate and deep ventilation phases were decoupled between the western and eastern Mediterranean basins during the deglaciation and early-middle Holocene. 2020-03-27T12:15:43Z 2020-03-27T12:15:43Z 2019-12-05 journal article J.N. Pérez-Asensio et al. Quaternary Science Reviews 228 (2020) 106075 [https://doi.org/10.1016/j.quascirev.2019.106075] http://hdl.handle.net/10481/60735 10.1016/j.quascirev.2019.106075 eng http://creativecommons.org/licenses/by-nc-nd/3.0/es/ open access Atribución-NoComercial-SinDerivadas 3.0 España Elsevier