Quantitative parameters of Pleistocene pelagic sedimentation in the Atlantic Ocean

Resumo

Lithological–facies maps of Eopleistocene and Neopleistocene sediments (with 10 and 20 m isopachs) are compiled for the pelagic part of the Atlantic Ocean based on materials recovered by 283 ocean drilling sites. Data for both maps were calculated using A.B. Ronov’s volumetric method. The calculated results include such quantitative sedimentation parameters of major sediment types as the areas covered by these sediments, their volumes, masses of the dry sedimentary material, and masses of sedimentary material deposited per specified time unit. These parameters are compared for both Eopleistocene and Neopleistocene time, and the data are utilized to separately interpret the results for terrigenous, carbonate, and siliceous sediments. The supply of terrigenous material is proved to have been enhanced in the Pleistocene as a result of both tectonic uplift of continents and climatic changes, including intensification of continental glaciation at high latitudes in both hemispheres. The growth in the productivity of carbonate plankton was overridden by growing generation of bottom and deep water masses and ensuing intensification of the dissolution of pelagic carbonates. The productivity of siliceous plankton practically did not change, perhaps, because of a favorable combination of the supply of dissolved silica and other nutrients from both West and East Antarctica.