Orbital-driven environmental changes recorded at ODP Site 959 (eastern Equatorial Atlantic) from the late Miocene to the early Pleistocene

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doi: 10.1007/s00531-016-1350-z
Author(s): Vallé, Francesca; Westerhold, Thomas; Dupont, Lydie M.
Author Affiliation(s): Primary:
MARUM-Center for Marine Environmental Sciences, Bremen, Germany
Volume Title: International Journal of Earth Sciences Geologische Rundschau
Source: International Journal of Earth Sciences = Geologische Rundschau, 106(3), p.1161-1174. Publisher: Springer, Berlin, Germany. ISSN: 1437-3262 CODEN: GERUA3
Note: In English. 81 refs.; illus., incl. 1 table, sketch map
Summary: Palaeorecords from tropical environments are important to explore the linkages between precipitation, atmospheric circulation and orbital forcing. In this study, new high-resolution XRF data from ODP Site 959 (3°37'N, 2°44'W) have been used to investigate the relationship between palaeoenvironmental changes in West Africa and sedimentation in the tropical East Atlantic Ocean. Iron intensity data have been used to build a 91-m composite depth record that has been astronomically tuned allowing the development of a detailed age model from 6.2 to 1.8 Ma. Based on this new stratigraphy, we studied the variations of Ti/Al, Ti/Ca and Al/Si ratios, proxies for aeolian versus fluvial supply, as dust indicator and fine versus coarse grain size, respectively. We discuss sedimentation patterns at ODP Site 959 associated with the environmental changes from the late Miocene until the early Pleistocene. During the interval corresponding to the earlier stages of the Messinian Salinity Crisis, our proxy records indicate enhanced run-off from the West African continent and major supply of fine material at ODP Site 959, suggesting a stronger monsoon and increased precipitation during eccentricity minima. A long-term decrease of river supply is documented after 5.4 Ma until the end of the Pliocene. From the increased values and variability of Ti/Al and Ti/Ca ratios, we suggest that after 3.5 Ma dust started to reach the study site probably as a result of the southward shift of the Intertropical Convergence Zone during winter. Between 3.2 and 2.9 Ma, ODP Site 959 Ti/Ca ratios exhibit three maxima corresponding to eccentricity maxima similarly to other dust records of northern Africa. This suggests continent-wide aridity or larger climate variability during that interval. Eccentricity forcing (405 and 100 kyr) and precession frequencies are found in the entire studied interval. The variations of Ti/Al ratio suggest stronger seasonality between 5.8 and 5.5 Ma and after 3.2 Ma. Copyright 2016 Springer-Verlag Berlin Heidelberg
Year of Publication: 2017
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Atmospheric circulation; Cenozoic; Chemical composition; Chemical ratios; Climate change; Climate forcing; Equatorial Atlantic; Intertropical convergence zone; Leg 159; Lower Pleistocene; Major elements; Marine sediments; Messinian; Messinian Salinity Crisis; Metals; Minor elements; Miocene; Neogene; North Atlantic; ODP Site 959; Ocean Drilling Program; Orbital forcing; Paleoclimatology; Paleoenvironment; Paleosalinity; Pleistocene; Quaternary; Seasonal variations; Sediments; Spectra; Tertiary; Upper Miocene; X-ray fluorescence spectra
Coordinates: N033740 N033740 W0024408 W0024408
Record ID: 2017083856
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by Springer Verlag, Berlin, Federal Republic of Germany