Figure F20. Latitudinal transect of Si mass accumulation rates (MARs) for three time slices: Oligocene (25-34 Ma), middle Eocene (38-45 Ma), and early Eocene (50-55 Ma). Si accumulation in the early Eocene is low and probably has a major contribution from detrital aluminosilicates. Middle Eocene Si accumulation is high, about double modern SiO2 accumulation at the equivalent longitude. Early Oligocene Si accumulation resembles that of modern sediments (Lyle, 1992).

Figure F20. Latitudinal transect of Si mass accumulation rates (MARs) for three time slices: Oligocene (25-34 Ma), middle Eocene (38-45 Ma), and early Eocene (50-55 Ma). Si accumulation in the early Eocene is low and probably has a major contribution from detrital aluminosilicates. Middle Eocene Si accumulation is high, about double modern SiO₂ accumulation at the equivalent longitude. Early Oligocene Si accumulation resembles that of modern sediments (Lyle, 1992).