Abstract
The Vema Fracture Zone orthogonally intersecting the Mid-Atlantic Ridge along 11° N is a complex tectono-sedimentary system, through which bottom water is transferred from the western to the eastern Atlantic. The southern surrounding of the fault valley is an extended (about 320 km) transverse ridge. At the early stages of the Vema System evolution, the ridge was located at shallow depths in the photosynthesis zone, which led to the formation of extensive biogenic carbonate buildups on its surface. Spreading, general sinking of the system, and associated movements along faults caused disintegration of ultramafic basement and bioherms with subsequent fractionation of colluvial–pelagic sediments and their eastward transport by bottom currents. The formation of coarse-grained residual sands completely devoid of pelitic material is associated with the high flow rates of Antarctic bottom waters. The presence of rounded pebbles of organogenic limestones and ultramafic rocks with traces of bioproductivity indicates that clastic material was transferred over a few hundred kilometers.
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ACKNOWLEDGMENTS
We are grateful to the crew of the R/V Akademik Nikolai Strakhov for help in the performance of studies. We are also grateful to A.V. Tikhonova (Laboratory of Paleoecology and Biostratigraphy, Institute of Oceanology, Russian Academy of Sciences) for consultation on micropaleontological issues.
R.R. Gabdullina (Geological Faculty, Moscow State University) is thanked for the constructive comments, which significantly improved the manuscript.
Funding
This work was fulfilled under state tasks of Geological Institute of the Russian Academy of Sciences (project nos. АААА-А18-118021690110-6, Tectono-Sedimentary Analysis; 0135-2019-0076, Link of Bottom Topography with Bottom Currents), and Institute of Oceanology of the Russian Academy of Sciences (project no. 0149-2019-0007, Paleontological Analysis).
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Chamov, N.P., Sokolov, S.Y. & Merenkova, S.I. Residual Sediments of the Vema Fracture Zone, Central Atlantic. Lithol Miner Resour 55, 338–344 (2020). https://doi.org/10.1134/S0024490220050028
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DOI: https://doi.org/10.1134/S0024490220050028