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Late Pleistocene signals of calcium carbonate, organic carbon, and opaline silica concentration and accumulation are documented in a series of cores from a zonal/meridional/depth transect in the equatorial Atlantic Ocean to reconstruct the regional sedimentary history. Spectral analysis reveals that maxima and minima in biogenous sedimentation occur with glacial‐interglacial cyclicity as a function of both (1) primary production at the sea surface modulated by orbitally forced variation in trade wind zonality and (2) destruction at the seafloor by variation in the chemical character of advected intermediate and deep water from high latitudes modulated by high‐latitude ice volume. From these results a pattern emerges in which the relative proportion of signal variance from the productivity signal centered on the precessional (23 kyr) band decreases while that of the destruction signal centered on the obliquity (41 kyr) and eccentricity (100 kyr) periods increases below ∼3600‐m ocean depth.

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A technique is described for measuring charcoal in small samples (5 mg) of marine sediments to quantify the contribution of charcoal to the total organic carbon loading of marine sediments. Charcoal is measured as elemental carbon by gas chromatography after acidification with hot concentrated nitric acid in situ within aluminum sample cups to remove calcium carbonate and refractory carbon such as coal, pollen, and humic acids. The in situ acidification eliminates sample loss during sequential decarboxylation and oxidation and provides a precise (±2.2% of the measured value) and rapid (~50 analyses per week per analyst) means to measure charcoal in marine sediments. The absolute detection limit of the charcoal determinations is 0.70 µg C (3 times mean blank value) and the relative detection limit is 0.01%.

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