FN Archimer Export Format PT J TI Methanogenesis and clay minerals diagenesis during the formation of dolomite nodules from the Tortonian marls of southern Spain BT AF PIERRE, Catherine ROUCHY, Jean-Marie BLANC-VALLERON, Marie-Madeleine ETOUBLEAU, Joel FOUQUET, Yves AS 1:1;2:2;3:2;4:3;5:3; FF 1:;2:;3:;4:PDG-REM-GM-LGM;5:PDG-REM-GM-LGM; C1 Univ Paris 06, Univ Paris 04, LOCEAN, F-75252 Paris 05, France. Univ Paris 06, CNRS, MNHN, Univ Paris 04,CR2P, F-75005 Paris, France. IFREMER, Geosci Marines, F-29280 Plouzane, France. C2 UNIV PARIS 06, FRANCE UNIV PARIS 06, FRANCE IFREMER, FRANCE SI BREST SE PDG-REM-GM-LGM IN WOS Ifremer jusqu'en 2018 copubli-france copubli-univ-france IF 2.788 TC 7 UR https://archimer.ifremer.fr/doc/00266/37752/35803.pdf LA English DT Article DE ;Authigenic dolomite nodules;Elemental geochemistry;Oxygen and carbon isotopes;Methanogenesis;Clay minerals diagenesis AB Dolomite nodules are widespread within the Tortonian marls of Fortuna and Lorca basins in southern Spain. They occur as large bodies of various forms (round, ovoid, tabular) that are parallel or secant relative to the stratification. They are massive and present sometimes internal conduits that are considered as drains used for the migration of fluids. This study brings new results on the mineralogy and elemental and isotopic geochemistry of these dolomite nodules to better describe the processes that were occurring during their formation. The diagenetic reactions that have driven authigenic dolomite precipitation within the sediments involved on the one hand methanogenesis that produced 13C-poor CH4 and 13C-rich CO2, on the other hand carbonate and silicate weathering by the CO2-rich solutions, that released respectively alkalinity and cations in pore solutions. Moreover, the distribution of the major elements (Si, Al, K, Na, Ca, Mg, Fe) in the marls and dolomite nodules indicates that these elements were redistributed within the sedimentary formation during the diagenetic reactions without external inputs by the circulating fluids. These observations thus confirm the link between authigenic dolomite formation and clay minerals diagenesis in sediments where methanogenesis was active. PY 2015 PD SEP SO Marine And Petroleum Geology SN 0264-8172 PU Elsevier Sci Ltd VL 66 UT 000365056000010 BP 606 EP 615 DI 10.1016/j.marpetgeo.2015.04.017 ID 37752 ER EF