Jimenez P.

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Jimenez
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  • Preprint
    Sediment drifts and cold-water coral reefs in the Patagonian upper and middle continental slope
    ( 2012-05) Munoz, Araceli ; Cristobo, J. ; Rios, P. ; Druet, M. ; Polonio, V. ; Uchupi, Elazar ; Acosta, Juan ; Iglesias, S. ; Portela, J. ; del Rio, J. L. ; Parra, S. ; Sacau, M. ; Vilela, R. ; Patrocinio, T. ; Almon, B. ; Elvira, E. ; Jimenez, P. ; Fontan, A. ; Alcala, C. ; Lopez, V.
    The north flowing Falkland / Malvinas Current has generated sediment drifts at a depth of 1200-1600 m in the Patagonian middle continental slope out of early Holocene hemipelagics, late Pleistocene ice rafted clastics, and Neogene fluvial sediments. Possibly there may be two generations of drifts, Pleistocene on the outer middle slope and Holocene on the inner shelf. The ice rafted debris originated in Antarctica, at a distance of 2000 to 4000 km south of Patagonia. Scattered over the upper and middle slopes, at depths ranging from 300 to 1400 m, are cold-water coral reefs of less than a meter to about ten of meters in relief. It is inferred that most of cold-water coral structures flourish as a consequence of the Falkland /Malvinas Current that concentrates the food supply at the reef sites. Growth of cold-water coral reefs, documented by digital submarine photographs on the upper slope, at a depth of 300/400 m, may be promoted by upwelling of nutrient-rich waters and associated plankton blooms created by the intrusion of Falkland /Malvinas Current onto the outer shelf.
  • Article
    Global variability in seawater Mg:Ca and Sr:Ca ratios in the modern ocean
    (National Academy of Sciences, 2020-07-17) Lebrato, Mario ; Garbe-Schonberg, Dieter ; Müller, Marius N. ; Blanco-Ameijeiras, Sonia ; Feely, Richard A. ; Lorenzoni, Laura ; Molinero, Juan-Carlos ; Bremer, Karen ; Jones, Daniel O. B. ; Iglesias-Rodriguez, M. Debora ; Greeley, Dana ; Lamare, Miles D. ; Paulmier, Aurelien ; Graco, Michelle ; Cartes, Joan ; Barcelos e Ramos, Joana ; de Lara, Ana ; Sanchez-Leal, Ricardo ; Jimenez, Paz ; Paparazzo, Flavio E. ; Hartman, Susan ; Westernströer, Ulrike ; Küter, Marie ; Benavides, Roberto ; da Silva, Armindo F. ; Bell, Steven ; Payne, Chris ; Olafsdottir, Solveig R. ; Robinson, Kelly ; Jantunen, Liisa M. ; Korablev, Alexander ; Webster, Richard J. ; Jones, Elizabeth M. ; Gilg, Olivier ; Bailly du Bois, Pascal ; Beldowski, Jacek ; Ashjian, Carin J. ; Yahia, Nejib D. ; Twining, Benjamin S. ; Chen, Xue-Gang ; Tseng, Li-Chun ; Hwang, Jiang-Shiou ; Dahms, Hans-Uwe ; Oschlies, Andreas
    Seawater Mg:Ca and Sr:Ca ratios are biogeochemical parameters reflecting the Earth–ocean–atmosphere dynamic exchange of elements. The ratios’ dependence on the environment and organisms' biology facilitates their application in marine sciences. Here, we present a measured single-laboratory dataset, combined with previous data, to test the assumption of limited seawater Mg:Ca and Sr:Ca variability across marine environments globally. High variability was found in open-ocean upwelling and polar regions, shelves/neritic and river-influenced areas, where seawater Mg:Ca and Sr:Ca ratios range from ∼4.40 to 6.40 mmol:mol and ∼6.95 to 9.80 mmol:mol, respectively. Open-ocean seawater Mg:Ca is semiconservative (∼4.90 to 5.30 mol:mol), while Sr:Ca is more variable and nonconservative (∼7.70 to 8.80 mmol:mol); both ratios are nonconservative in coastal seas. Further, the Ca, Mg, and Sr elemental fluxes are connected to large total alkalinity deviations from International Association for the Physical Sciences of the Oceans (IAPSO) standard values. Because there is significant modern seawater Mg:Ca and Sr:Ca ratios variability across marine environments we cannot absolutely assume that fossil archives using taxa-specific proxies reflect true global seawater chemistry but rather taxa- and process-specific ecosystem variations, reflecting regional conditions. This variability could reconcile secular seawater Mg:Ca and Sr:Ca ratio reconstructions using different taxa and techniques by assuming an error of 1 to 1.50 mol:mol, and 1 to 1.90 mmol:mol, respectively. The modern ratios’ variability is similar to the reconstructed rise over 20 Ma (Neogene Period), nurturing the question of seminonconservative behavior of Ca, Mg, and Sr over modern Earth geological history with an overlooked environmental effect.