Deoxygenation of the southwestern margin of Baja California Peninsula: A foraminiferal-based record over the last 1 kyr Yaima

The present research aims to analyze the diversity indices of BFs to infer the concentration of DO in the southwestern margin of Baja California Sur during the last 1200 years. [...] The following methodology will be used: quantification of the percentages of disoxic, hypoxic and oxic foraminifera; calculate the BF association index and estimate the OD concentration, under the assumption that in the warm periods of the Holocene would expect to find BF associations indicative of severe hypoxic conditions and in the cold periods BF associations that suggest oxic conditions. [...] During the period of AC 1100 to 1350 (LIA), the estimation of [O2] from the BF assemblage suggests oxic conditions in the water column, simultaneously in this same period of time, the low content of biogenic opal and organic carbon indicate decreased Disoxic assemblage productivity, indicating unfavorable conditions for upwelling development, a weak California Current, and a strengthened and/or mo. [...] On the other hand, the δ15N of bulk sedimentary matter in the Magdalena margin points to a decrease in water column denitrification during the LIA. [...] From AC 1400 to the present, the estimation of [O2] from the BF assemblage suggests hypoxic conditions, on the other hand, the δ15N values exhibited high values and the biogenic opal and Suboxic assemblage organic carbon contents showed a constant increase, and this suggests favorable conditions for the development of upwelling Fig.