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Jahn, Britta; Donner, Barbara; Müller, Peter J; Röhl, Ursula; Schneider, Ralph R; Wefer, Gerold (2003): Pleistocene sedimentation in the Benguela Current, southeastern Atlantic. PANGAEA, https://doi.org/10.1594/PANGAEA.703973, Supplement to: Jahn, B et al. (2003): Pleistocene variations in dust input and marine productivity in the northern Benguela Current: Evidence of evolution of global glacial-interglacial cycles. Palaeogeography, Palaeoclimatology, Palaeoecology, 193(3-4), 515-533, https://doi.org/10.1016/S0031-0182(03)00264-5

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Abstract:
We infer variations in paleoproductivity and eolian input at ODP Site 1082 in the Walvis Basin from stable oxygen isotope compositions of the planktonic foraminifera Globorotalia inflata, total organic carbon mass accumulation rates (TOC MAR), and X-ray fluorescence analyses of Fe content. The most pronounced paleoclimatic changes correspond to the time at about 0.9 Ma, when glacial conditions in the northern hemisphere (NH) led to the onset of pronounced 100-kyr glacial-interglacial cycles. We used Fe intensity as a proxy for eolian terrigenous input, and TOC MAR as a paleoproductivity indicator. Paleoproductivity and eolian input show generally higher-amplitude variations of glacial-interglacial cyclicity from 1.5 to 0.58 Ma, indicating pronounced variations in upwellingfavorable winds in this area. At 0.58 Ma, paleoproductivity and eolian input shifted abruptly to lower-amplitude variations with a periodicity of 100 kyr while delta18O values show a trend toward more negative isotope values for the past 0.65 Myr. Especially during glacial periods, oxygen isotope values indicate increasingly warmer sea-surface temperatures toward the end of the Pleistocene. To evaluate the relative influences of NH glaciation and southern hemisphere (SH) insolation as potential forcing mechanisms for variations of eolian input and productivity in the northern Benguela system, we filtered our proxy records at orbital frequencies. The filtered records of Fe intensity and TOC MAR indicate a strong influence of the 100-kyr and 41-kyr frequency bands, supporting our assumption that strong ice buildup in the NH is the dominant trigger for climate changes on the continent and probably in trade-wind intensity. SH insolation and low-latitude precession-related insolation changes were important for paleoproductivity variations in the northern Benguela system, modifying the nutrient supply by southern ocean intermediate waters and the zonal direction of upwelling-inducing trades by the African monsoon system, respectively.
Keyword(s):
XRF core scanner
Related to:
Jahn, Britta (2002): Mid to Late Pleistocene variations of marine productivity in and terrigenous input to the southeast Atlantic. Berichte aus dem Fachbereich Geowissenschaften der Universität Bremen, 199, 97 pp, urn:nbn:de:gbv:46-ep000103218
Coverage:
Median Latitude: -21.094096 * Median Longitude: 11.820562 * South-bound Latitude: -21.094470 * West-bound Longitude: 11.820520 * North-bound Latitude: -21.093940 * East-bound Longitude: 11.820580
Date/Time Start: 1997-09-13T04:45:00 * Date/Time End: 1997-09-16T08:55:00
Event(s):
175-1082A * Latitude: -21.093940 * Longitude: 11.820580 * Date/Time Start: 1997-09-13T04:45:00 * Date/Time End: 1997-09-16T00:05:00 * Elevation: -1279.3 m * Penetration: 600.6 m * Recovery: 502.01 m * Location: Benguela Current, South Atlantic Ocean * Campaign: Leg175 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 64 cores; 600.6 m cored; 0 m drilled; 83.6 % recovery
175-1082B * Latitude: -21.094190 * Longitude: 11.820520 * Date/Time Start: 1997-09-16T00:05:00 * Date/Time End: 1997-09-16T08:55:00 * Elevation: -1280.4 m * Penetration: 127 m * Recovery: 133.17 m * Location: Benguela Current, South Atlantic Ocean * Campaign: Leg175 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 14 cores; 127 m cored; 0 m drilled; 104.9 % recovery
175-1082C * Latitude: -21.094470 * Longitude: 11.820550 * Date/Time: 1997-09-16T08:55:00 * Elevation: -1282.1 m * Penetration: 202 m * Recovery: 217.83 m * Location: Benguela Current, South Atlantic Ocean * Campaign: Leg175 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 24 cores; 202 m cored; 0 m drilled; 107.8 % recovery
Size:
5 datasets

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