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Background and Aims: The morphological characteristics of the basins were studied using an echo sounder and a TOPAS profiler in a previous oceanographic cruise (WAG-1, May 2007), and were described by Vázquez-Figueroa et al. (2009) and Canet et al. (2010). Mineralogical composition of the superficial sediments consists mainly of detrital quartz and feldspars. However, in the north-eastern edge of the Wagner Basin there are sediments rich in authigenic barite and pyrite, and in the Consag Basin calcite and dolomite are abundant (Vázquez-Figueroa et al., 2011). These minerals are associated with intense gas venting through the Wagner Fault (Canet et al., 2010). The most prominent bubble flares were observed in May 2007 along the eastern edge of Wagner and Consag basins, mostly in NE Wagner Basin; moreover, mud domes were found on the southeastern Consag Basin (Canet et al., 2010). There are no reports on pore water studies in sediments of the Wagner and Consag basins. In this study we present the chemical results of the pore water extracted from superficial marine sediments of the Wagner and Consag basins. Objective: In this work we study the chemical processes that occur as a result of the interaction between gases, minerals and pore water in superficial sediments of the Consag and Wagner basins. Methods: Pore water samples were collected during the WAG-2 cruise (August, 2010) aboard R/V “El Puma” (UNAM). Superficial sediments were obtained from 23 sample stations using a Smith Mc-Intyre grab sampler and the pore waters were extracted using the centrifugation method. Trace elements of filtered pore water samples were done ICP-OES and ICP-MS at Actlabs (Canada). Hydrogen sulphide concentration was measured on the pore water samples immediately after extraction by the methylene blue colorimetric method. The pH values were measured immediately after the pore water extraction using a glass electrode. Box plot statistical analyses as well as data exploratory analyses were applied to the interpretation of results. Results: pH values measured in the study area are within the range from 6.06 to 7.34 and the mean value is 7.00. The stations with low pH (< 6.9) are located over the Wagner Fault, mainly on the eastern edge of the Wagner Basin but also in the sill that separates Wagner and Consag basins. The highest H2S concentration was measured in the station WE73-A (0.07 mmol L-1), where sediment had a characteristic smell upon recovery. This station is located on the eastern edge of the Wagner Basin, roughly over the Wagner Fault. The components and elements significantly enriched with respect to seawater were: silica among the minor components, and Zn, Cu, Al, Sb, Fe, Mn, Ti and Pb among the trace elements. Iodine, barium and molybdenum were slightly enriched in the pore water with respect to seawater. Pore water chemical anomalies are essentially distributed along the trajectory of the Wagner Fault, in locations where Canet et al. (2010) reported large bubble flares. In the NE edge of the Wagner Basin the anomalously enriched elements are Na, Ca, Sr, Si, Li, Rb, I, Ba, Mo, Zn, Cu, Al, Sb, Fe, Mn and Pb, whereas in the SE edge of the Consa

Palabras clave: Northern Gulf of California; Pore water; surficial sediments; Wagner and Consag basins

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