The Gulf of California is a unique continental sea for its extraordinary preservation of high resolution laminated sediments. We analyzed two box cores and one kasten core from the La Paz basin located in the western margin of the lower Gulf of California to explore the paleoceanographic potential of its sediments and to make some inferences on the observed sediment variability for the last 7500 years. In order to understand the relation between the sedimentary record and the oceanographic variability we reviewed the instrumental record for the last 100 years. We analized sea surface temperature, wind speed, rainfall and sea level series from the region and compared them with the indices of El Niņo-Southern Oscillation (ENOS) and the North Pacific Decadal Oscillation (PDO). We found how the climatic and oceanic variability can be explained by two remote forcings. The first one comes from the south, represented by ENSO, and is significantly associated with rainfall, sea surface temperature and sea level. The second one, the North Pacific influence, represented by NPO, while showing a stronger association with winds it further affects, although to a lesser extent, SSTs and rainfall.
In the sediments we measured the concentration of three main biogenic sedimentary components: biogenic opal, organic carbon and calcite. In the box cores the sediment variability is mainly driven by changes in opal and calcite. We established 3 pulses with high opal percentage and a high organic carbon to inorganic carbon ratio which we interpret as productivity indices. These pulses coincide with an increase in the terrigenous component and a strong decrease in calcite. We propose a model in which the pulses are controlled by the amount of calcite preserved in the sediment, which in turn is dependent on surface productivity. Calcite productivity decreases when biogenic opal production is more important, this situation is favoured by a nutrient rich ocean. Our reconstructions show how the last two biogenic opal pulses coincide with cool conditions at the end of the XIX century and during the Little Ice Age.
In the longer record the observed variability falls in two different periodicities. In the higher frequencies, periods shorter than 500 years, high productivity pulses occur every 330 years in average. In the lower frequencies there is a decreasing trend in the terrigenous component parallel to the decrease in summer insolation values for the summer at 20°N. We further observe an important change between 3000 and 5000 years BP, from relatively oligotrophic conditions to higher productivity conditions towards the present.
We further present some results from stable isotopes determinations (delta18O and delta13C) in planktic foraminifera from the two box cores. We found G. bulloides oxygen isotopic composition is a fairly good record of the mean sea surface temperature during winter from its comparison with the instrumental record, however, its utility as paleoceanographic proxy is limited by calcite dissolution downcore.

Keywords: Gulf of California, laminated sediments, Paleoceanography.