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The southern westerly wind belt (SWW) interacts with the Antarctic Circumpolar Current and strongly impacts the Southern Ocean carbon budget, and Antarctic ice-sheet dynamics across glacial–interglacial cycles. We investigated precipitation-driven sediment input changes to the Southeast Pacific off the southern margin of the Atacama Desert over the past one million years, revealing strong precession (19/23-ka) cycles. Our simulations with 2 ocean–atmosphere general circulation models suggest that observed cyclic rainfall changes are linked to meridional shifts in water vapor transport from the tropical Pacific toward the southern Atacama Desert. These changes reflect a precessional modulation of the split in the austral winter South Pacific jet stream. For precession maxima, we infer significantly enhanced rainfall in the southern Atacama Desert due to a stronger South Pacific split jet with enhanced subtropical/subpolar jets, and a weaker midlatitude jet. Conversely, we derive dry conditions in northern Chile related to reduced subtropical/subpolar jets and an enhanced midlatitude jet for precession minima. The presence of precessional cycles in the Pacific SWW, and lack thereof in other basins, indicate that orbital-scale changes of the SWW were not zonally homogeneous across the Southern Hemisphere, in contrast to the hemispherewide shifts of the SWW suggested for glacial terminations. The strengthening of the jet is unique to the South Pacific realm and might have affected winter-controlled changes in the mixed layer depth, the formation of intermediate water, and the buildup of sea-ice around Antarctica, with implications for the global overturning circulation and the oceanic storage of atmospheric CO2.

Through the interplay of a stabilising cold-water coral framework and a dynamic sedimentary environment, cold-water coral carbonate mounds create distinctive centres of bio-geological accumulation in often complex (continental margin) settings. The IODP Expedition 307 drilling of the Challenger Mound (eastern Porcupine Seabight; NE Atlantic) not only retrieved the first complete developmental history of a coral carbonate mound, it also exposed a unique, Early-Pleistocene sedimentary sequence of exceptional resolution along the mid-latitudinal NE Atlantic margin.In this study, a comprehensive assessment of the Challenger Mound as an archive of Quaternary palaeo-environmental change and long-term coral carbonate mound development is presented. New and existing environmental proxy records, including clay mineralogy, planktonic foraminifer and calcareous nannofossil biostratigraphy and assemblage counts, planktonic foraminifer oxygen isotopes and siliciclastic particle-size, are thereby discussed within a refined chronostratigraphic and climatic context.Overall, the development of the Challenger Mound shows a strong affinity to the Plio-Pleistocene evolution of the Northern Hemisphere climate system, albeit not being completely in phase with it. The two major oceanographic and climatic transitions of the Plio-Pleistocene - the Late Pliocene/Early Pleistocene intensification of continental ice-sheet development and the mid-Pleistocene transition to the more extremely variable and more extensively glaciated late Quaternary - mark two major thresholds in Challenger Mound development: its Late Pliocene (>2.74Ma) origin and its Middle-Late Pleistocene to recent decline. Distinct surface-water perturbations (i.e. water-mass/polar front migrations, productivity changes, melt-water pulses) are identified throughout the sequence, which can be linked to the intensity and extent of ice development on the nearby British-Irish Isles since the earliest Pleistocene. Glaciation-induced

Through the interplay of a stabilising cold-water coral framework and a dynamic sedimentary environment, cold-water coral carbonate mounds create distinctive centres of bio-geological accumulation in often complex (continental margin) settings. The IODP Expedition 307 drilling of the Challenger Mound (eastern Porcupine Seabight; NE Atlantic) not only retrieved the first complete developmental history of a coral carbonate mound, it also exposed a unique, Early-Pleistocene sedimentary sequence of exceptional resolution along the mid-latitudinal NE Atlantic margin. In this study, a comprehensive assessment of the Challenger Mound as an archive of Quaternary palaeo-environmental change and long-term coral carbonate mound development is presented. New and existing environmental proxy records, including clay mineralogy, planktonic foraminifer and calcareous nannofossil biostratigraphy and assemblage counts, planktonic foraminifer oxygen isotopes and siliciclastic particle-size, are thereby discussed within a refined chronostratigraphic and climatic context. Overall, the development of the Challenger Mound shows a strong affinity to the Plio-Pleistocene evolution of the Northern Hemisphere climate system, albeit not being completely in phase with it. The two major oceanographic and climatic transitions of the Plio-Pleistocene – the Late Pliocene/Early Pleistocene intensification of continental ice-sheet development and the mid-Pleistocene transition to the more extremely variable and more extensively glaciated late Quaternary – mark two major thresholds in Challenger Mound development: its Late Pliocene (>2.74 Ma) origin and its Middle–Late Pleistocene to recent decline. Distinct surface-water perturbations (i.e. water-mass/polar front migrations, productivity changes, melt-water pulses) are identified throughout the sequence, which can be linked to the intensity and extent of ice development on the nearby British–Irish Isles since the earliest Pleistocene. Glaciation-indu

The Plio-Pleistocene intensification of Northern Hemisphere continental ice-sheet development is known to have profoundly affected the global climate system. Evidence for early continental glaciation is preserved in sediments throughout the North Atlantic Ocean, where ice-rafted detritus (IRD) layers attest to the calving of sediment-loaded icebergs from circum-Atlantic ice sheets. So far, Early-Pleistocene IRD deposition has been attributed to the presence of high-latitudinal ice sheets, whereas the existence and extent of ice accumulation in more temperate, mid-latitudinal regions remains enigmatic.Here we present results from the multiproxy provenance analysis of a unique, Pleistocene-Holocene IRD sequence from the Irish NE Atlantic continental margin. There, the Challenger coral carbonate mound (IODP Expedition 307 site U1317) preserved an Early-Pleistocene record of 16 distinctive IRD events, deposited between ca 2.6 and 1.7 Ma. Strong and complex IRD signals are also identified during the mid-Pleistocene climate transition (ca 1.2 to 0.65 Ma) and throughout the Middle-Late Pleistocene interval. Radiogenic isotope source-fingerprinting, in combination with coarse lithic component analysis, indicates a dominant sediment source in the nearby British–Irish Isles, even for the oldest, Early-Pleistocene IRD deposits. Hence, our findings demonstrate, for the first time, repeated and substantial (i.e. marine-terminating) ice accumulation on the British–Irish Isles since the beginning of the Pleistocene. Contemporaneous expansion of both high- and mid-latitudinal ice sheets in the North Atlantic region is therefore implied at the onset of the Pleistocene. Moreover, it suggests the recurrent establishment of (climatically) favourable conditions for ice sheet inception, growth and instability in mid-latitudinal regions, even in the earliest stages of Northern Hemisphere glacial expansion and in an obliquity-driven climate system.

During IODP Expedition 307, the first complete sequence through a cold-water coral carbonate mound (a bio-geological seafloor feature created through successive stages of cold-water coral mediated sediment accumulation) was successfully acquired. The full recovery of the Challenger Mound, one of the large (ca. 155 m high) coral carbonate mounds along the NE Atlantic continental margin (Belgica mound province, eastern Porcupine Seabight) facilitates for the first time the study of the entire development of a coral carbonate mound and, hence, allows the identification of the environmental conditions driving and maintaining the entire build-up of these remarkable seafloor habitats. In this study, the different sediment contributors to the Challenger Mound are identified and assessed throughout its entire 2.6 Ma long development. High-resolution siliciclastic particle-size end-member modelling and its ground-truthing (XRD, quartz-sand surface microtextures) indicate the influence of an all dominant contour-current system, operating in variable energetic modes, for most of the sediment accumulation history of the Challenger Mound. Only local, short-distance current-controlled sediment re-dispersal is evidenced, while iceberg rafting is identified as an important depositional mechanism throughout the whole mound development period. Furthermore, evidence for icebergs repeatedly reaching the eastern Porcupine Seabight continental margin, even in the early stages of Northern Hemisphere glacial expansion, is preserved in the mound sequence. Supporting the existing coral-stratigraphy, the Challenger Mound depositional sequence reveals a two-phase development, separated by a significant hiatus. The lower mound-phase (M1; 2.6–1.7 Ma) indicates a semi-continuous, steadily changing, fast accumulating current-controlled depositional environment. The condensed upper mound-phase (M2; 998–1.5 ka) bears witness of a distinct shift to a more glacially-influenced, low accumulation enviro

Through the interplay of a stabilising cold-water coral framework and a dynamic sedimentary environment, cold-water coral carbonate mounds create distinctive centres of bio-geological accumulation in often complex (continental margin) settings. The IODP Expedition 307 drilling of the Challenger Mound (eastern Porcupine Seabight; NE Atlantic) not only retrieved the first complete developmental history of a coral carbonate mound, it also exposed a unique, Early-Pleistocene sedimentary sequence of exceptional resolution along the mid-latitudinal NE Atlantic margin.In this study, a comprehensive assessment of the Challenger Mound as an archive of Quaternary palaeo-environmental change and long-term coral carbonate mound development is presented. New and existing environmental proxy records, including clay mineralogy, planktonic foraminifer and calcareous nannofossil biostratigraphy and assemblage counts, planktonic foraminifer oxygen isotopes and siliciclastic particle-size, are thereby discussed within a refined chronostratigraphic and climatic context.Overall, the development of the Challenger Mound shows a strong affinity to the Plio-Pleistocene evolution of the Northern Hemisphere climate system, albeit not being completely in phase with it. The two major oceanographic and climatic transitions of the Plio-Pleistocene – the Late Pliocene/Early Pleistocene intensification of continental ice-sheet development and the mid-Pleistocene transition to the more extremely variable and more extensively glaciated late Quaternary – mark two major thresholds in Challenger Mound development: its Late Pliocene (>2.74 Ma) origin and its Middle–Late Pleistocene to recent decline. Distinct surface-water perturbations (i.e. water-mass/polar front migrations, productivity changes, melt-water pulses) are identified throughout the sequence, which can be linked to the intensity and extent of ice development on the nearby British–Irish Isles since the earliest Pleistocene. Glaciation-induce