Carbon analyses and sedimentation rate of sediment core MD97-2140

To reconstruct past fire activity in the West Pacific–East Asian region, we investigate a 360-ky pelagic sedimentary record from the Caroline Basin in the Western Pacific Warm Pool (WPWP) (core MD97-2140, 2547 m. water depth). In the lack of standard protocol and terminology for the determination of combustion-derived products in sedimentary archives, three proxies were compared with other paleoceanographic proxies: Oxidation Resistant Elemental Carbon (OREC), Black Carbon (BC), and microcharcoal. The mineral (CaCO3) and organic carbon (Corg) records of core MD97-2140 generally covary with the oxygen isotope record, suggesting that glacial/interglacial changes in ice-volume and sea-level control the preservation of CaCO3 and terrigeneous inputs of Corg in the deep-sea sediments of the Caroline Basin. The changes in OREC are primarily connected to the changes in Corg record. In contrast, the BC and charcoal records, which better reflect the input of biomass burning products, are tightly connected with changes in the precession band (23 ky), likely through low-latitude atmospheric circulation patterns. A peculiar control by the competing influence of the long-term El Niño-Southern Oscillation (ENSO)-like forcing and the glacial/interglacial cycle on the East Asian summer monsoon (30-, 19-, 11- and 6-ky periods) is suggested. In addition, large increases in BC and charcoal are observed between ca. 53–43 and 12–10 ky BP. These events strikingly correspond to the main Late Pleistocene and Early Holocene periods of human colonization in the region, likely suggesting an additional anthropic impact on the fire activity.