Resumen del producto

A high-resolution record of d18O and d13C of Uvigerina peregrina (hereinafter: d18OU and d13CU) andbiogenic opal was used to reconstruct water column conditions in the SW margin of the Baja Californiapeninsula for the last 6e60 kyr. The core was collected from a depth of 700 m in the oxygen deficientzone of the Magdalena margin. Although the d18OU values showed a large change associated with thepassage from glacial conditions to the Holocene, the MIS-3 and MIS-2 were characterized by a lowvariability. Our results indicated a rapid cooling and/or increase in salinity immediately after H5 thatpersisted until H1. However, the d13CU values showed significant variability associated to the incursionsof the Antarctic Intermediate Water (AAIW) in the Magdalena margin during the MIS-3 and MIS-2. Thisagrees with the d13C composition of water mass end-members at intermediate depths in the PacificOcean. Enhanced ventilation during MIS-3 was inferred from the d13CU values, which were very similar tothe d13C values of the AAIW end-members evidencing the persistence of the AAIW in the region. Thisconclusion is also supported by the trend of sedimentary d15N and other dissolved oxygen proxies in thearea. A depletion of the d13CU at a millennial scale suggests intermittent pulses of a water mass richer innutrients, which generated an increase in exported productivity, and thus, concomitantly depleted thedissolved oxygen levels at intermediate depths. Moreover, exported productivity showed a decreasinglong-term trend during the second half of MIS-3, briefly punctuated by millennial-scale increases inexported productivity sustained by nutrient export from the Southern Ocean via the AAIW.

Palabras clave: Oxygen and carbon stable isotopes; Foraminifera; Marine productivity; Eastern boundary upwelling system; biogenic opal

Para obtener una copia del documento contacta la personal de la biblioteca a través del correo bibliocicimar{a}ipn.mx