Figure F40. Percentage estimates of biosiliceous material of late Neogene to Quaternary sediments from smear slides plotted vs. depth in meters below seafloor (mbsf) for Sites 12071213. Site 1214 has been excluded on the basis that only 1.32 m of late NeogeneQuaternary sediments were recovered. This figure illustrates that biosiliceous material is more abundant within the late NeogeneQuaternary sections on the Northern and Central High than on the Southern High of Shatsky Rise. The expanded Pleistocene to Miocene sedimentary sections at Sites 1207 and 1208 can partly be attributed to relatively high sea-surface productivity inferred from the higher occurrence of diatoms, radiolarians, and silicoflagellates relative to the other sites further south. The trends in biogenic silica abundance correlate strongly with sedimentation rate, as the more southerly Sites 1209 through 1212 were characterized by lower sedimentation rates.
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