Description: In a deep-sea sediment core recovered from a site lying well above the local lysocline, several organic geochemical proxies, and two different calcite dissolution indicators, are compared in order to evaluate the relationship between calcite dissolution and paleoproductivity over the past three glacial-interglacial cycles. The degree of foraminiferal break-up, and the CaCO3 particle size distribution, both point to significant periods of dissolution every 22 kyr during glacial stages and substages. These dissolution events are concomitant with periods of enhanced primary productivity, as indicated by the abundance of several biomarkers (alkenones, cholesterol, brassicasterol, keto-ol), used here to indicate changes in paleoproductivity. Dissolution fluctuations are highly coherent and in phase with the estimated paleoproductivity variations providing strong evidence that the observed dissolution is due to organic matter remineralization within the sediments rather, than to changes in CO32? concentration in the overlying water column.

Description: 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.