Mid-to-Late Holocene organic carbon export variability at the southern boundary of the California Current: An approach based on diffuse spectral reflectance of marine sediment cores

Here we present the results obtained from diffuse spectral reflectance (DSR) on the visible wave spectra on a 4.5 m-long Calypso Kasten core (MD02-2506-C2), collected from the San Lázaro Basin (SLB), with the aim of reconstructing the Mid-to-Late Holocene variability in export production in the California Current System (CCS). We applied an R-mode maximum likelihood factor analysis on the first derivative of the diffuse spectral reflectance. We then compared the factor scores obtained with this method and the organic carbon (OC) content of the core in order to establish a statistical transfer function between both variables. We eliminated high-frequency noise with the aid of Singular Spectral Analysis (SSA) from both records, increasing the correlation between both variables (r = − 0.71, p < 0.001). These results indicated that DSR can be used as a reliable proxy of the OC content in high-resolution SLB sediments, which we used to reconstruct past CCS organic carbon export variability. Our findings suggest changes in organic carbon production and export from the Mid-to-Late Holocene, most likely resulting from changing influences on the SLB due to the interaction of the Pacific Decadal Oscillation (PDO) and El Niño.