Sofía Barragán Montilla

Methane seepage activity of NW Africa during the last deglaciation and its relation with global climate change; paleoenvironmental multiproxy analysis using foraminifera

The oce­ans oc­cu­py ∼ 71 % of the ear­t­h’s sur­face and play an im­portant role in cli­ma­te sta­bi­li­ty through the in­ter­ch­an­ge of car­bon with the at­mo­s­phe­re. This in­ter­ac­tion has led to past chan­ges in the ear­t­h’s cli­ma­te that can help us com­pre­hend the cur­rent cli­ma­tic cri­sis and where we are headed in the feature. One of the factors influencing global climate is Methane seepage. De­po­sits from this greenhouse gas are for­med un­der low tem­pe­ra­tu­re and high-pres­su­re con­di­ti­ons, and the va­ria­ti­ons of these parameters since the Last Glacial Period have re­sulted in the re­lease of methane from marine deposits into the oce­an and the at­mo­s­phe­re. Part of this gas is pro­ces­sed by deep oce­an bac­te­ria through an­ae­ro­bic oxi­da­ti­on of me­tha­ne (AOM) enhancing ocean acidification, and the re­mai­ning tra­vels to shal­lo­wer sea wa­ters fi­nal­ly being re­leased to the at­mo­s­phe­re contributing to glo­bal war­ming.

Bent­hic fo­ra­mi­ni­fe­ra ad­apt to en­vi­ron­ments with ac­tive me­tha­ne seeps, and cer­tain spe­cies thrive al­beit di­ver­si­ty and po­pu­la­ti­on den­si­ty tend to stron­gly de­crea­se. Such chan­ges in these as­sem­bla­ge­s re­cord past cli­ma­te chan­ges and pro­vi­de information of how tem­pe­ra­tu­re, oxy­ge­na­ti­on and tro­phic le­vels have changed and their part on glo­bal cli­ma­te re­gu­la­ti­on. For this reason, I intend to integrate taxonomical and quantitative analysis of benthic foraminifera, with geochemical records (δ13C and δ18O and Mg/Ca ratios), to reconstruct environmental trends in the last 30.000 years and observe how methane seepage has influenced environmental changes in the upper slope of Mauritania (NW Africa) and the role these phenomena play in climate change.