Geochemistry and physics on sediment cores from the Peru Basin

• Main Authors: Weber, Michael E, Wiedicke-Hombach, Michael, Riech, Volkher, Erlenkeuser, Helmut
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 1995
• Subjects: B_LANDER; BCR; Bottom lander; Box corer (Reineck); GIK15555-1; GIK15556-1; GIK15557-1; GIK15558-1; GIK15560-1; GIK15561-1; GIK15562-1; GIK15564-1; GIK15565-1; GIK15566-1; GIK15567-1; GIK15568-1; GIK15569-1; GIK15570-1; GIK15571-1; GIK15573-1; GIK15574-1; GIK15575-1; GIK15576-1; GIK15577-1; GIK15578-1; Gravity corer (Kiel type); KAL; Kasten corer; KL; MUC; MultiCorer; Peru Basin; Piston corer (BGR type); SEDIPERU - TUSCH; SL; SO79; SO79_100KA; SO79_106KG; SO79_108KL; SO79_108SL; SO79_10KG; SO79_117KG; SO79_119KL; SO79_11MC; SO79_120MC; SO79_122KG; SO79_123KL; SO79_125MC; SO79_129KG; SO79_130KL; Antarc*; Antarctic; Ice cap
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.761570; https://doi.org/10.1594/PANGAEA.761570

We studied preservation/dissolution cycles and paleoproductivity in eight sediment cores from the Peru Basin south of the highly productive surface waters of the eastern equatorial Pacific. Stratigraphy is based on stable oxygen isotopes and on combined magnetostratigraphy and biostratigraphy. Sediment cores which span the last 8 m.y., were retrieved during cruise 79 with RV SONNE close to the carbonate compensation depth (CCD). In general, sediments show Pacific-type carbonate cycles. We interpret a pronounced carbonate peak between 6 and 7 Ma as the result of a western and northern extension of the highly productive Peru Current. Decreased carbonate contents from the late Miocene to the late Pliocene might be associated with a slow contraction of the latitudinal extent of the high-productivity belt north of the study areas. During the Pliocene, carbonate variations showed 400 kyr cycles indicating the growth and decay of ice sheets, which should have been associated with pulsations of the Antarctic ice cap. An abrupt collapse of the carbonate system occurred at 2.4 Ma. Higher frequency variations of the carbonate record indicate the major increase of the northern hemisphere glaciation. During the Quaternary, carbonate fluxes are high during glacials and low during interglacials. Large amplitude variations with long broad minima and maxima, associated with small migrations of the lysocline and the CCD (< 200 m), are indicative of the preservation/dissolution history in the Peru Basin. During the early Pleistocene, climatic forcing by the 41 kyr obliquity cycle is not observed in the carbonate record. During the last 800 kyr, variability in the carbonate record was dominated by the 100 kyr eccentricity cycle. Fluxes of biogenic material (calcium carbonate, organic carbon, opal, and barium) were greatest during glacials, which imply higher productivity and export production of the Peru Current during cold climatic periods. Dissolution was greatest during interglacials as inferred from the relatively poor ...