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Changes in Southern Ocean export production have broad biogeochemical and climatic implications. Specifically, iron fertilization likely increased subantarctic nutrient utilization and enhanced the efficiency of the biological pump during glacials. However, past export production in the subantarctic Southeast Pacific is poorly documented, and its connection to Fe fertilization, potentially related to Patagonian Ice Sheet dynamics is unknown. We report on biological productivity changes over the past 400 ka, based on a combination of 230Thxs-normalized and stratigraphy-based mass accumulation rates of biogenic barium, organic carbon, biogenic opal, and calcium carbonate as indicators of paleo-export production in a sediment core upstream of the Drake Passage. In addition, we use fluxes of iron and lithogenic material as proxies for terrigenous matter, and thus potential micronutrient supply. Stratigraphy-based mass accumulation rates are strongly influenced by bottom-current dynamics, which result in variable sediment focussing or winnowing at our site. Carbonate is virtually absent in the core, except during peak interglacial intervals of the Holocene, and Marine Isotope Stages (MIS) 5 and 11, likely caused by transient decreases in carbonate dissolution. All other proxies suggest that export production increased during most glacial periods, coinciding with high iron fluxes. Such augmented glacial iron fluxes at the core site were most likely derived from glaciogenic input from the Patagonian Ice Sheet promoting the growth of phytoplankton. Additionally, glacial export production peaks are also consistent with northward shifts of the Subantarctic and Polar Fronts, which positioned our site south of the Subantarctic Front and closer to silicic acid-rich waters of the Polar Frontal Zone, as well as a with a decrease in the diatom utilization of Si relative to nitrate under Fe-replete conditions. However, glacial export production near the Drake Passage was lower than in the Atlantic and Indian sectors of the Southern Ocean, which may relate to complete consumption of silicic acid in the study area. Our results underline the importance of micro-nutrient fertilization through lateral terrigenous input from South America rather than aeolian transport, and exemplify the role of frontal shifts and nutrient limitation for past productivity changes in the Pacific entrance to the Drake Passage.

The Antarctic Circumpolar Current is the world’s largest current system connecting all major ocean basins of the global ocean. Its flow, driven by strong westerly winds, is constricted to its narrowest extent in the Drake Passage, located between South America and the Antarctic Peninsula. Due to the remoteness of the area, harsh weather conditions and strong bottom currents, sediment recovery is difficult and data coverage is still inadequate. Here, we report on the composition of 51 surface sediments collected during the R/V Polarstern PS97 expedition (February–April 2016) across the western and central Drake Passage, from the Chilean/Argentinian continental margin to the South Shetland Islands and the Bransfield Strait (water depth: ∼100–4000 m). We studied microfossils (diatoms), bulk sediment composition and geochemical proxies (biogenic opal, organic carbon, calcium carbonate, carbon and nitrogen stable isotopes, sterols and photosynthetic pigments), and evaluated how they respond to, and reflect oceanic domains and polar to subpolar frontal systems in this region. Our multi-proxy approach shows a strong relationship between the composition of surface sediments and ocean productivity, terrigenous input, intensity of ocean currents, and ice proximity, clearly differentiating among 4 biogeographical zones. The Subantarctic Zone was characterized by warmer-water diatoms, high carbonate (>45%) and low organic carbon contents (avg. 0.26%), as well as low concentrations of pigments (avg. 1.75 μg/g) and sterols (avg. 0.90 μg/g). A general N-S transition from carbonate-rich to opal-rich sediment was observed at Drake Passage sites of the Polar Front and Permanently Open Ocean Zone. These sites were characterized by low organic carbon content (0.22%), high relative abundances of heavily silicified diatoms (≥60% Fragilariopsis kerguelensis), and abundant foraminifera at shallower stations. Approaching the Antarctic Peninsula in the Transitional Zone, an increase in the concentrations of pigments and sterols (avg. 2.57 μg/g and 1.44 μg/g, respectively) and a strong decrease in carbonate content was observed. The seasonal Sea-Ice Zone in the southern section of the study area, had the highest contents of biogenic opal (avg. 14.6%) and organic carbon (avg. 0.7%), low carbonate contents (avg. 2.4%), with the occurrence of sea-ice-related diatoms and sterols. In all zones, terrigenous input was detected, although carbon/nitrogen ratios and δ13Corg suggest a predominance of marine-derived organic matter; lower values of δ13Corg occurred south of the Polar Front. The new results presented here constitute a highly valuable reference dataset for the calibration of microfossil and geochemical proxies against observational data and provide a useful regional baseline for future paleo-research.

Salt-marsh sediments of the southeastern North Sea provide an archive to unravel the influences of coastal management and natural processes such as storm-tide deposition on salt-marsh development. We present a record of salt-marsh evolution during the past century from the Bay of Tumlau (northwestern Germany) based on fossil foraminiferal assemblages and sedimentological data. After diking the hinterland of the Bay of Tumlau in 1935 CE and commencing marsh management, the environment at the study site changed from a tidal flat to a salt marsh. Salt-marsh sediment accretion is influenced by recurrent dredging events, as indicated by layers rich in calcareous tidal-flat foraminifera, and redeposition of siliciclastic particles from the surrounding tidal flats during storm tides. The latter fostered the establishment of a typical salt-marsh foraminiferal fauna dominated by the agglutinating species Entzia macrescens. Storm-tide layers have a lighter sediment color and commonly a more negatively skewed grain-size distribution with variable sorting. The observed long-term coarsening of the salt-marsh sediment likely reflects the landward progression of the vertical erosional cliff and the depletion of fine-grained sediment particles in the tidal flats under the influence of sea-level rise. Supra-tidal conditions, resulting from natural protection measures and abandonment of dredging, are indicated by the occurrence of Balticammina pseudomacrescens around 2001 CE. This species is adapted to only occasional submergence during storm tides. The recent increase in elevation is accompanied by establishment of high-marsh vegetation and characterized by a present height of the marsh surface 50 cm above mean high water springs. During the past sixty years, average sediment accretion rates decreased from 18 to 11 mm yr−1 reflecting the maturing of the salt marsh. These rates clearly outpace the recent mean sea-level rise in the southern North Sea demonstrating that the regional salt marshes are still resilient to sea-level rise.

Volcanic ash layers are important markers for the chronostratigraphy of paleoclimate and paleoenvironmental archives at the southern tip of South America. However, this requires that tephras are well-dated. We report geochemical data from the MA1 stalagmite formed in a non-karst cave near Mt. Burney volcano in southernmost Patagonia (~53°S). High-resolution LA-ICP-MS analyses, SEM imagery, and NanoSIMS enable to identify volcanogenic signals during the last 4.5 kyrs BP from sub-annual trace element variations and tephra particles in distinct laminae. The new 230Th/U-chronology of MA1 provides precise dating of tephra from Mt. Burney (MB) and Aguilera (A) at 4216 +93/−193 yrs BP (MB2), 2291 ± 33 yrs BP (MB3), 853 +41/−60 yrs BP (MB4) and 2978 +91/−104 yrs BP (A1). This unique high-resolution record of MA1 holds potential to date further eruptions from Southern Andean volcanoes for the tephrochronology in this critical region, and potentially also large-volume explosive volcanism off South America.

The Black Sea experienced pronounced millennial-scale changes in temperature and rainfall during the last glacial coinciding with Dansgaard-Oeschger cycles. However, little is known regarding the amount and sources of freshwater reaching this inland basin. Here, we present detailed ostracod δ18O data from the glacial Black Sea showing subdued Dansgaard-Oeschger cyclicity and four prominent longer-term saw-tooth shaped Bond-like cycles. We propose that the δ18Oostracods signature primarily reflects changes in the atmospheric circulation in response to the waxing and waning Eurasian Ice Sheet. The millennial-scale ice sheet variations likely resulted not only in latitudinal migrations of atmospheric frontal systems but also in shifts of dominant moisture sources for the Black Sea. Heavier isotopic precipitation arrived from the North Atlantic-Mediterranean realm during the warmer interstadials and lighter isotopic precipitation from the Eurasian continental interior during the colder stadials. The subdued Dansgaard-Oeschger variability likely reflects an integrated precipitation signal additionally affected by the long mixing times of the large Black Sea volume up to 1,500 years as suggested from hydrologic-isotope-balance modelling. Moisture sources to the Black Sea changed in response to atmospheric frontal displacements driven by Eurasian Ice Sheet dynamics during the last glacial period, according to analyses of ostracod oxygen and strontium isotope data from Black Sea sediments.

Our understanding of glacial isostatic rebound across Patagonia is highly limited, despite its importance to constrain past ice volume estimates and better comprehend relative sea-level variations. With this in mind, our research objective is to reconstruct the magnitude and rate of Late Glacial to Holocene glacial isostatic adjustment near the center of the former Patagonian Ice Sheet. We focus on Larenas Bay (48°S; 1.26 km2), which is connected to Baker Channel through a shallow (ca. 7.4 m) and narrow (ca. 150 m across) inlet, and hence has the potential to record periods of basin isolation and marine ingression. The paleoenvironmental evolution of the bay was investigated through a sedimentological analysis of a 9.2 m long, radiocarbon-dated, sediment core covering the last 16.8 cal. kyr BP. Salinity indicators, including diatom paleoecology, alkenone concentrations and CaCO3 content, were used to reconstruct the bay’s connectivity to the fjord. Results indicate that Larenas Bay was a marine environment before 16.5 cal. kyr BP and after 9.1 cal. kyr BP, but that it was disconnected from Baker Channel in-between. We infer that glacial isostatic adjustment outpaced global sea-level rise between 16.5 – 9.1 cal. kyr BP. During the Late Glacial - Holocene transition, the center of the former Patagonian Ice Sheet rose ca. 96 m, at an average rate of 1.30 cm/year. During the remainder of the Holocene, glacial isostatic adjustment continued (ca. 19.5 m), but at a slower average pace of 0.21 cm/year. Comparisons between multi-centennial variations in the salinity indicators and existing records of global sea-level rise suggest that the glacial isostatic adjustment rate fluctuated during these time intervals, in agreement with local glacier dynamics. More specifically, most of the glacial isostatic adjustment registered between 16.5 – 9.1 cal. kyr BP seems to have occurred before meltwater pulse 1A (14.5 – 14.0 kyr BP). Likewise, it appears that the highest Holocene glacial isostatic rebound rates occurred during the last 1.4 kyr, most likely in response to glacier recession from Neoglacial maxima. This implies a relatively rapid response of the local solid earth to ice unloading, which agrees with independent modelling studies investigating contemporary uplift. We conclude that the center of the former Patagonian Ice Sheet experienced a glacial isostatic adjustment of ca. 115 m over the last 16.5 kyr, and that >80% occurred during the Late Glacial and early Holocene.

Intertidal coastal wetlands are regularly exposed to storm surges and associated flooding, resulting in the recurrent accretion of reworked sediments on the salt-marsh surfaces. In this context, well-stratified salt-marsh sediment sequences provide an exceptional archive to evaluate the response of coastal wetlands to past storm-climate variability. Hence, this study focusses on the investigation of two sedimentary salt-marsh sequences from the south-eastern German North Sea coast (Bay of Tumlau and Friedrichskoog) to understand how and to which extent changes in the storm-surge climate are transferred into the sediment archive. This objective is particularly challenging as German mainland salt marshes have been greatly altered by human activities over the last century. To overcome this problem, this study combines different sedimentological and geochemical proxy data, using mean grain sizes together with ln(Br/Cl), Br/Corg, and ln(Zr/Rb) ratios, to allow for the identification of storm-surge layers. Local changes in the sedimentary organic matter supply are reflected by the ln(Br/Cl) ratio. There, abrupt drops in the ln(Br/Cl) data coincide with relatively coarser textured sand layers, indicating impacts by regional storm surges during winter, while intervals of comparable higher ln(Br/Cl) values may represent deposition during spring to fall. The Br/Corg record reflects the marine versus terrestrial organic matter input and reveals a long-term increase starting during the first half of the 20th century towards recent times, resembling the observed amplification in North Sea storminess. A similar trend is reflected by the ln(Zr/Rb) ratio (since 1950 CE), which can be used as a proxy for the grain-size distribution. Periodic fluctuations in the ln(Zr/Rb) ratio at inter-decadal timescales (10–19 years) suggest a close linkage between local sediment accretion and large-scale atmosphere-ocean climate oscillations over the North Atlantic and Europe, and thus related storm-surge frequency and intensity. Periodic variability on decadal scales was also identified in the ln(Br/Cl) record at the less human-modified and more naturally developed salt marsh at the Bay of Tumlau (12–22 years), likewise indicating a relation between North Sea storminess and associated shifts in the seasonal signal of the primary production and sediment texture to oscillations in the atmosphere-ocean system. On the contrary, similar periodicities are lacking for the intense modified salt marsh at Friedrichskoog. Apparently, the salt-marsh depositional system in the Bay of Tumlau reacts more sensitively to super-regional climatic changes, respectively, the natural depositional processes in the salt marsh at Friedrichskoog are superimposed by the more intense local human activities.

Understanding hemisphere-wide millennial-scale temperature variability during past glacials in response to ice sheet dynamics and orbital forcing is one of the key targets for Quaternary climate research. While an inland propagation of abrupt temperature changes into Eurasia from the North Atlantic realm during the last glacial (Weichselian) receives increasingly broad support, much less is known regarding the penultimate glacial (Saalian) temperature variability, especially from a continental interior perspective. Here, we present a TEX86-derived lake surface temperature (LST) record from the former Black Sea ���Lake��� covering nearly the entire Marine Isotope Stage (MIS) 6. While orbital-scale LST cooling likely relates to meltwater discharge from the retreating Eurasian Ice Sheet during insolation maxima, millennial-scale LST variability suggests interstadial warming in phase with Greenland and northern Mediterranean Sea temperature records during the first half of MIS 6. Although summer insolation reached an interglacial-like level during this period, we propose that the reduced extent of the Eurasian Ice Sheet associated with northward shifted atmospheric fronts was ultimately responsible for the inland propagation of Dansgaard-Oeschger-like temperature variability. During the second half of MIS 6, temperature patterns across the North Atlantic-Eurasian corridor were more variable and less comparable with each other, likely because of the larger continental ice sheet weakening northern hemisphere atmospheric teleconnections. Temperature records across the North Atlantic-Eurasian realm suggest a weaker atmospheric teleconnection during MIS 6 compared to MIS 3, likely related to a stronger imprint of the Eurasian Ice Sheet on the continental and regional climate.

Salt marshes are of substantial importance for the adaptation of coastal regions to present-day and predicted future climate changes, and accompanied sea-level fluctuations. This gives the motivation to investigate salt-marsh archives from the southern North Sea region, which provide an exceptional archive to understand the response of coastal systems to climate variability of the recent past. For this study, well-stratified sediment sequences from two different salt-marsh systems were analysed by scanning XRF spectroscopy. The study sites are affected by both natural processes and anthropogenic interventions on different time scales. To address the complex interplay between storm surges, human-induced coastal management, and coupled internally forced atmosphere-ocean mechanisms during the last century, this study focuses on the ln(Zr/Rb) ratio as proxy for the relative particle-size distribution, and the Br/Corg ratio as an indicator for the marine versus terrestrial organic matter input to the sediment. Additional information about local changes in the sedimentary organic matter quality is provided by the alteration of ln(Br/Cl) ratios. The ln(Zr/Rb) records reveal periodic fluctuations at inter-annual, inter-decadal to multi-decadal time scales, suggesting a close link of sediment accretion to the atmospheric-ocean climate oscillation over the North Atlantic and Europe, which is accompanied by variations in the wind field, precipitation and river runoff. By contrast, the Br/Corg ratios exhibit a long-term increase starting from the mid-twentieth century towards recent times, resembling the observed increasing trend in North Sea storminess. Abrupt drops in the ln(Br/Cl) records coincide with relatively coarser sand layers, indicating impacts by regional storm surges during winter, while intervals of comparable higher ln(Br/Cl) values represent times of generally calm weather conditions of periods with less frequent storm surges. Our results imply that past regional to super-regional climate changes have been transferred into the sedimentary salt-marsh archives of the southern North Sea region.

Depositional processes in coastal wetlands respond to a changing climate as documented in the sediment sequences of salt marshes. In this context, robust chronologies are crucial for the reconstruction of salt-marsh depositional processes in the past. However, salt-marsh sediments from the highly dynamic North Sea coast often lack a reliable stratigraphy due to the combined influences of natural processes and human activities, causing a reworking and re-deposition of the sediments. Here, a combination of absolute and relative dating methods has been applied in order to establish an integrated stratigraphic framework for active foreland salt marshes along the south-eastern North Sea coast. This stratigraphic framework is based on radionuclides (210Pb, 137Cs, 241Am, 14C) and mercury (Hg) contaminations, together with ln(Zr/Rb) as a grain-size proxy for additional inter-correlation between the four studied sites. The studied salt marshes encompass different environmental settings concerning the inundation frequency and intensity, and anthropogenic influences. As a result, the reconstructed mean sediment-accretion rates range from 1.16 cm yr–1 in the anthropogenically modified and grazed coastal salt marsh at Friedrichskoog, to 1.31 cm yr–1 in the more sheltered and semi-enclosed salt marsh in the Bay of Tümlau, and up to 1.75 cm yr–1 in the dynamic open coastal salt-marsh at Kaiser-Wilhelm-Koog. Similar mean high accretion rates of 1.72 cm yr–1 are documented for the Eider estuary until AD 1965, before they dropped to 0.72 cm yr–1 after completion of the Eider tidal barrier in AD 1973. The results highlight the advantage of combining independent dating methods for the establishment of salt-marsh chronologies, which proves to be essential to compensate for absence or blurring of distinct stratigraphic signals in highly dynamic coastal depositional settings, such as the salt-marsh systems at the south-eastern North Sea coastal region. The reconstructed sediment-accretion rates suggest a high resilience of salt-marsh systems to ongoing sea-level rise as long as sediment availability and natural flooding dynamics are maintained.

Present-day circulation patterns in the southeastern Pacific Ocean are driven by the Antarctic Circumpolar Current, directing subantarctic surface water into the Patagonian fjords since at least the early Holocene. In this way, bottom current patterns in the area are regulated by the regional climate, although the complex bathymetry of the fjords has a significant impact as well. To understand the potential interplay of climate, seafloor topography and circulation patterns, we study the sedimentary infill of Aysen Fjord (~45°S) and reveal the first active sediment drifts in the region. These allow constraining the present-day circulation patterns in northern Patagonia and show an incoming (southward) as well as returning (northward) flow direction. While the general sedimentary evolution of the fjord (and thus also the sediment drifts) is climate-driven (i.e., it reflects variability in southern westerly wind strength), the onset of drift formation at ~3.7 ka does not seem to have originated from an abrupt change in regional climate. Instead, we propose that a megathrust earthquake described in paleoseismic records in the area could have resulted in subsidence of one (or more) of the many bathymetric highs in the Patagonian fjords, thus contributing to enhanced spilling of subantarctic water into the fjord. This study underscores the importance of multidisciplinary research to understand past and present bottom current circulation patterns and disentangle different possible feedback mechanisms.

This study presents selected results of a sediment geochemical mapping program of German territorial waters in the south-western Baltic Sea. The field work was conducted mainly during the early 2000s. Due to the strong variability of sediment types in the study area, it was decided to separate and analyse the fine fraction (

The Saalian was one of the largest glaciations during the Quaternary with an ice sheet extending considerably wider into the Eurasian continent than during other glacials. Orbital variations caused the ice sheet to switch between growing and shrinking. The partial retreat of the ice sheet and meltwater discharge resulted in global sea-level rise and increased lake levels of inland seas with broader environmental implications. During Marine Isotope Stage 6 (MIS 6), meltwater entered the formerly enclosed Black Sea at least twice as documented in a δ18O record from Anatolian speleothems. Here we present a sedimentary record from the Black Sea “Lake” covering MIS 6 and provide evidence for three meltwater periods coinciding with insolation maxima (BSWP-6-1: 180-167 ka BP, BSWP-6-2: 160-145 ka BP, BSWP-II: 133-130 ka BP). While δ18Oostracods and Sr/Caostracods point to pronounced meltwater supply and decreasing salinity, 87Sr/86Srostracods shed light on meltwater sources and pathways. During all three periods, meltwater drained most likely via the Dnieper and Volga into the Black and Caspian Seas and connected both basins. Relatively low 87Sr/86Srostracods values during the oldest meltwater period suggest melting solely of the eastern Eurasian Ice Sheet. In contrast, during the younger meltwater periods, exceptional high 87Sr/86Srostracods values point towards additional meltwater from the western Eurasian Ice Sheet. A surplus from melting glaciers in the Tian Shan and Pamir Mountains that finally entered the Caspian Sea via the Amu Darya and Sry Darya probably amplified the input of high radiogenic Sr-isotope water. We also show that higher temperatures and productivity suggest Dansgaard-Oeschger-like climate variability during the first half of MIS 6.

The Baltic Sea is a shallow, semi-enclosed and intra-continental shelf sea characterized by anoxic bottom waters in the deepest basins, allowing for the preservation of sedimentary organic matter. In the present study, the most abundant, naturally-occurring lipids in surface sediments from the entire Baltic Sea and the Skagerrak area were identified and their potential sources were assigned. Together with long-chain n -alkanes derived from land plant leaf waxes, diploptene and branched glycerol dialkyl glycerol tetraethers (GDGTs) are of allochthonous origin, while isoprenoid GDGTs, hydroxylated isoprenoid GDGTs (OH-GDGTs), n -C 25:1 , n -C 27:1 and n -C 29:1 alkenes are autochthonous lipids. The isoprenoid and OH-GDGTs are probably derived from Thaumarchaeota and the long-chain n -alkenes from phototrophic organisms. Significant correlations were found between indexes based on isoprenoid and OH-GDGTs and Baltic Sea surface and bottom temperatures. The calibrations obtained for surface temperature have statistically similar slopes, but different intercepts than calibrations established for the Nordic Seas. The branched and isoprenoid tetraether index can be used to estimate the percentage of soil (terrestrial) organic matter in the sediments of the Baltic Sea. High values of the P aq’ ratio (defined here as the ratio of odd numbered n -C 23 and n -C 25 over n -C 23 to n -C 29 alkanes) in the northern Baltic Sea originate from the presence of both Sphagnum mosses in the drainage basin and submerged macrophytes, such as Potamogeton sp. and Myriophyllum sp., in the freshwater to brackish water of the coastal areas. The P aq’ ratio may thus reflect fluctuations in the regional expansion of freshwater to brackish coastal environments in the Baltic Sea.

Proxies based on glycerol dialkyl glycerol tetraether (GDGT) lipids from archaea [isoprenoid GDGTs] and bacteria [branched (br) GDGTs] in 33 surface sediments from marine, fjord and lake systems between 25°S and 50°S in Chile were analyzed. The regional TEXH86 calibration obtained from the marine and fjord sediments and mean annual surface temperature (T = 59.6 × TEXH86 + 33.0; r2 0.9; n = 23) is statistically identical to the global ocean calibration based on suspended particulate material in terms of slope, but not in terms of intercept. The regional surface and subsurface TEXH86 calibrations were statistically different from the existing global ocean core top calibrations. The TEX86 calibration model based on most of the relatively large lakes studied here (T = 50.7 × TEX86 − 11.8; r2 0.9; n = 5) is statistically identical to the global lake calibration. The relatively high TEX86 values from smaller lakes suggested an additional source for isoprenoid GDGTs, likely terrestrial or aquatic methanogenic archaea. Application of the soil-calibrated MBT′/CBT (methylation and cyclization of br GDGTs, respectively) temperature proxy to the marine and fjord sediments resulted in an overestimation of continental mean annual air temperature (MAAT), suggesting in situ production of certain br GDGTs in the water column or surface sediment. For the lakes, MBT′/CBT-based surface air temperature estimates were 3–6 °C below MAAT. However, temperature estimates from the lake-specific MBT/CBT global calibration were in good agreement with mean annual surface temperature for all the lakes. The results highlight the need for testing local vs. global calibrations of GDGT-based proxies before their application for palaeoenvironmental reconstruction.

The Eurasian inland propagation of temperature anomalies during glacial millennial-scale climate variability is poorly understood, but this knowledge is crucial to understanding hemisphere-wide atmospheric teleconnection patterns and climate mechanisms. Based on biomarkers and geochemical paleothermometers, a pronounced continental temperature variability between 64,000 and 20,000 years ago, coinciding with the Greenland Dansgaard-Oeschger cycles, was determined in a well-dated sediment record from the formerly enclosed Black Sea. Cooling during Heinrich events was not stronger than during other stadials in the Black Sea. This is corroborated by modeling results showing that regular Dansgaard-Oeschger cycles penetrated deeper into the Eurasian continent than Heinrich events. The pattern of coastal ice-rafted detritus suggests a strong dependence on the climate background state, with significantly milder winters during periods of reduced Eurasian ice sheets and an intensified meridional atmospheric circulation.

Long-term changes in vegetation and climate of southern Brazil, as well as ocean dynamics of the adjacent South Atlantic, were studied by analyses of pollen, spores and organic-walled dinoflagellate cysts (dinocysts) in marine sediment core GeoB2107-3 collected offshore southern Brazil covering the last 73.5 cal kyr BP. The pollen record indicates that grasslands were much more frequent in the landscapes of southern Brazil during the last glacial period if compared to the late Holocene, reflecting relatively colder and/or less humid climatic conditions. Patches of forest occurred in the lowlands and probably also on the exposed continental shelf that was mainly covered by salt marshes. Interestingly, drought-susceptible Araucaria trees were frequent in the highlands (with a similar abundance as during the late Holocene) until 65 cal kyr BP, but were rare during the following glacial period. Atlantic rainforest was present in the northern lowlands of southern Brazil during the recorded last glacial period, but was strongly reduced from 38.5 until 13.0 cal kyr BP. The reduction was probably controlled by colder and/or less humid climatic conditions. Atlantic rainforest expanded to the south since the Lateglacial period, while Araucaria forests advanced in the highlands only during the late Holocene. Dinocysts data indicate that the Brazil Current (BC) with its warm, salty and nutrient-poor waters influenced the study area throughout the investigated period. However, variations in the proportion of dinocyst taxa indicating an eutrophic environment reflect the input of nutrients transported mainly by the Brazilian Coastal Current (BCC) and partly discharged by the Rio Itajai (the major river closest to the core site). This was strongly related to changes in sea level. A stronger influence of the BCC with nutrient rich waters occurred during Marine Isotope Stage (MIS) 4 and in particular during the late MIS 3 and MIS 2 under low sea level. Evidence of Nothofagus pollen grains from the southern Andes during late MIS 3 and MIS 2 suggests an efficient transport by the southern westerlies and Argentinean rivers, then by the Malvinas Current and finally by the BCC to the study site. Major changes in the pollen/spore and dinocyst assemblages occur with similar pacing, indicating strongly interlinked continental and marine environmental changes. Proxy comparisons suggest that the changes were driven by similar overarching factors, of which the most important was orbital obliquity.

One visible volcanic ash layer and 21 non-visible, cryptotephra horizons have been identified in the M72/5-25-GC1 core from the south-east Black Sea that spans the last ∼60 ka. Glass chemistry suggests that the tephras derive from Italian, Hellenic and Turkish sources. The visible tephra layer is trachytic in composition and has been correlated to the ∼39 ka Campanian Ignimbrite super-eruption from Campi Flegrei caldera, Italy. Two cryptotephra layers are associated with eruptions from Acigol volcano (Turkey) around the Last Glacial Maximum, another is linked to activity at Erciyes Dagi in the Early Holocene (Perikartini or Karagullu), and a cryptotephra layer near the top of the core correlates to the ∼3.6k cal a BP Minoan (marine Z2) tephra from Santorini (Thera), Greece. This extends the known dispersal area for all these volcanic ash units. Many other calc-alkaline rhyolite layers preserved in the core are likely to be from central Anatolian sources but the lack of detailed proximal data for many of the volcanoes in the region prohibits further correlations. The tephrostratigraphy and glass compositional data presented here allow the tephra layers to be used to correlate sedimentary archives across the region, and help to extend the Mediterranean tephrochronology framework towards the east.

High-resolution pollen and dinoflagellate cyst records from sediment core M72/5-25-GC1 were used to reconstruct vegetation dynamics in northern Anatolia and surface conditions of the Black Sea between 64 and 20 ka BP. During this period, the dominance of Artemisia in the pollen record indicates a steppe landscape and arid climate conditions. However, the concomitant presence of temperate arboreal pollen suggests the existence of glacial refugia in northern Anatolia. Long-term glacial vegetation dynamics reveal two major arid phases ~64–55 and 40–32 ka BP, and two major humid phases ~54–45 and 28–20 ka BP, correlating with higher and lower summer insolation, respectively. Dansgaard–Oeschger (D–O) cycles are clearly indicated by the 25-GC1 pollen record. Greenland interstadials are characterized by a marked increase in temperate tree pollen, indicating a spread of forests due to warm/wet conditions in northern Anatolia, whereas Greenland stadials reveal cold and arid conditions as indicated by spread of xerophytic biomes. There is evidence for a phase lag of ~500 to 1500 yr between initial warming and forest expansion, possibly due to successive changes in atmospheric circulation in the North Atlantic sector. The dominance of Pyxidinopsis psilata and Spiniferites cruciformis in the dinocyst record indicates brackish Black Sea conditions during the entire glacial period. The decrease of marine indicators (marine dinocysts, acritarchs) at ~54 ka BP and increase of freshwater algae (Pediastrum, Botryococcus) from 32 to 25 ka BP reveals freshening of the Black Sea surface water. This freshening is possibly related to humid phases in the region, to connection between Caspian Sea and Black Sea, to seasonal freshening by floating ice, and/or to closer position of river mouths due to low sea level. In the southern Black Sea, Greenland interstadials are clearly indicated by high dinocyst concentrations and calcium carbonate content, as a result of an increase in primary productivity. Heinrich events show a similar impact on the environment in the northern Anatolia/Black Sea region as Greenland stadials. Open-Access-Publikationsfonds 2013 peerReviewed

The southern tip of South America is year-round influenced by the southern westerly wind belt (SWW) causing extremely high precipitation along the Chilean coast and the Andes south of 33°S with maximum values of 3000 to >10 000 mm/year within the SWW core between 49 to 55°S which is unique for temperate regions on the global scale. Due to this key position within the global atmospheric and oceanic framework we have investigated a large number of Late Quaternary climate archives during the last decade including fjord and lake sediments, peats, stalagmites and tree rings. To improve our proxy understanding in these various archives, climate as well as hydrological monitoring stations were operated since 1999. Here we present one-year monitoring data, which document the short term variability of climate and thermohaline conditions and related fertility in the fjord surface water. In this context we also analysed the interplay between palaeo-precipitation and related freshening of surface water (low nitrate and phosphate) and the terrestrial nutrient supply to the fjords during the last 5 ka BP using new salinity and productivity proxies of a fjord sediment core. Lake sediment cores and a stalagmite record document high chemical denudation rates, and metal leaching occurs on a weakly buffered granitoid basement and areas covered by acidic peaty soils. The partly climate-controlled changes in the iron and trace metal mobility have profound implications for both terrestrial and aquatic ecosystems. Based on the investigated archives we also reviewed SWW changes and regional temperature variations during the past 30 ka BP and their implication for Glacial and Holocene glacier advances.

Holocene denudation rates and their regional variations in the superhumid and temperate climate of the southernmost Patagonian Andes are poorly surveyed. Therefore we have investigated denudation in five small lake catchments (0.11–1.62 km 2 ) across a precipitation gradient from 600 to > 9000 mm yr − 1 in southernmost Chile at 53°S. Variations in denudation rates can be defined most precisely by using small catchments and short time spans (Holocene) thus can be related to variable bedrock types, vegetation cover, elevation, and climate. Minimum physical denudation rates were determined from sediment budgets based on sediment echosounder data and physical properties of sediment cores. The Holocene denudation rates vary from 0.08 mm kyr − 1 in the highly elevated, bare granitic rock catchments to 9.01 mm kyr − 1 in the low and vegetated catchments with a basement of sedimentary rocks. These values are comparable with those from similar areas in Norway, Sweden, and NW Iceland. The high annual precipitation in the study area has only a minor effect on denudation. Enhanced geomorphic activity during paraglacial conditions caused a faster denudation after the glacier retreat until either the clastic, glacial detritus was removed or the catchment was covered with vegetation. Chemical comparisons between basement rocks and lake sediments indicate a pronounced chemical denudation in catchments with peaty soils and low soil water pH values of 3 to 5. The Holocene surface lowering rates are on average 200 fold lower than Cenozoic surface lowering rates calculated from fission-track data for the southern Andes. This discrepancy can be explained by significantly higher erosion rates during glacial periods.

There is ongoing debate about the relative influence of aquatic production, flux, and sedimentation of aquatic and terrestrial organic matter on mercury accumulation in lake sediments. In this study, lake sediments spanning the past 4,250 years, were collected from remote, organic-rich Lake Hambre, Patagonia (53° S) and investigated for changes in the accumulation of pre-anthropogenic mercury and organic matter of aquatic and terrestrial origin. Natural mercury accumulation varied by up to a factor of four, comparable to the recent anthropogenic forcing of the mercury cycle (factor 3–5). Hydrogen and Oxygen indices (HI and OI, Rock–Eval©) and nitrogen/carbon ratios of the organic matter, combined with multi-element sediment data, reveal intense changes in aquatic productivity as well as influx of terrestrial organic matter into the lake. Evaluation of the multi-element dataset using Principal Component Analysis shows clear covariation of mercury with other soil-derived elements such as copper and yttrium. This covariance reflects a common transport mechanism, i.e. leaching of trace-element-bearing organic matter complexes from catchment soils. Correlation between changes in aquatic productivity and mercury concentrations occurs in some sections of the record, but we do not suggest they are linked by a direct causal relationship. Mass balance approaches suggest that mercury scavenging and accumulation in this organic-rich lake is controlled by the supply of mercury from catchment soils rather than the amount of organic material produced within the water column. A common controlling mechanism, i.e. changing climate, however, is thought to independently drive variations in both the flux of terrestrial organic matter mercury complexes and aquatic productivity.

The present paper introduces a new approach for deriving information about local forearc tectonics and related uplift rates based on the study of lake sediments. We investigated two coastal lakes at the south-central Chile margin, lakes Lanalhue and Lleu Lleu, located south of the Arauco Peninsula (38°S). Both lakes developed within the valleys of ancient rivers that once drained to the Pacific Ocean, being subsequently dammed by rising sills in the late Pleistocene/early Holocene. Seismic profiling and sedimentological analyses of cores from both lakes revealed similar successions consisting of marine to brackish sediments covered by lacustrine deposits. Radiocarbon dating indicates that the marine–lacustrine transition occurred at 8 ka and 8.15 ka, respectively. The correlation of this transition with global sea-level curves allowed the calculation of local uplift rates for the Holocene. Uplift rates for the lake basins amount to 0.42 ± 0.71 and 0.49 ± 0.44 mm/a, respectively, which are consistent with rates determined from a late Pleistocene marine terrace in the area. However, conspicuously higher, though likely transient, vertical movements at 8.83 ± 2.7 mm/a and 11.36 ±1.77 mm/a, respectively, were calculated for the sills that block both lakes nowadays. These barriers are interpreted to be the surface expression of a blind reverse fault associated to the Morguilla fault system, a seismically-active structure that controls uplift and folding along the adjacent Arauco Peninsula.

Based on a radiocarbon and paleomagnetically dated sediment record from the northern Red Sea and the exceptional sensitivity of the regional changes in the oxygen isotope composition of sea water to the sea-level-dependent water exchange with the Indian Ocean, we provide a new global sea-level reconstruction spanning the last glacial period. The sea-level record has been extracted from the temperature-corrected benthic stable oxygen isotopes using coral-based sea-level data as constraints for the sea-level/oxygen isotope relationship. Although, the general features of this millennial-scale sea-level records have strong similarities to the rather symmetric and gradual Southern Hemisphere climate patterns, we observe, in constrast to previous findings, pronounced sea level rises of up to 25 m to generally correspond with Northern Hemisphere warmings as recorded in Greenland ice-core interstadial intervals whereas sea-level lowstands mostly occur during cold phases. Corroborated by CLIMBER-2 model results, the close connection of millennial-scale sea-level changes to Northern Hemisphere temperature variations indicates a primary climatic control on the mass balance of the major Northern Hemisphere ice sheets and does not require a considerable Antarctic contribution.

One of the most important factors controlling fjord primary production in southernmost Patagonia is the variability in the thermohaline structure of the water column. In the present-day environment, thermal stratification is mostly related to freshwater input and in particular, the seasonal melting of glaciers. Here we assess whether this relation between fjord productivity and freshwater input holds true for the Holocene, using a sediment record from the central basin of the Strait of Magellan (core MD07-3132, 53°44.17'S; 70°19.03'W, 301 m). Our approach relies on a proxy-based reconstruction of fjord sea surface temperature (alkenone SST), paleosalinity, freshwater input, and paleoproductivity. The results indicate that, during the early Holocene, the accumulation rate (AR) of marine organic carbon was low (< 20 kg m- 2 kyr- 1), most likely due to high freshwater contribution resulting in low salinity and low SSTs. After 8.5 kyr BP and during the mid and late Holocene all the productivity proxies increase. The AR's of marine organic carbon (~ 30 kg m- 2 kyr- 1), biogenic CaCO3 (~ 60 kg m- 2 kyr- 1) and biogenic opal (425 kg m- 2 kyr- 1) reached the highest values during the last millennium. This increase was probably driven by the marine transgression where marine macronutrient-rich waters entered into the central basin, while lowered precipitation and decreased meltwater input contributed to increase the basin's SSTs and salinity. The late Holocene rise in productivity was interrupted by a low salinity phase between 3.2 and 2.2 kyr BP, during which productivity returned to early Holocene conditions in response to increased input of glacial clays, as suggested by high values of K/Si ratio (~ 1.2). Our results indicate that meltwater contribution from glaciers plays a crucial role in controlling fjord productivity on seasonal to millennial timescales.

Late Quaternary palaeoenvironments from southeastern (SE) Brazil have been reconstructed by pollen analysis of two marine sediment cores. The core GeoB 3229-2 (19°38′5″S, 38°43′0″W, 780 mbsl) from the central depression south of the Abrolhos Bank is 505 cm long and >80 kyr BP old. The core GeoB 3202-1 (21°37′0″S, 39°58′7″W, 1090 mbsl) from the upper continental slope off Rio Paraiba do Sul is 495 cm long and 52 kyr BP old. Chronological control for core GeoB 3202-1 is based on seven AMS radiocarbon dates from individuals of the foraminiferal species Globigerinoides sacculifer . The age scale for core GeoB 3229-2 was obtained by the detailed correlation of the oxygen isotope and X-ray fluorescence records of both cores. The two marine pollen records document vegetational changes in the drainage areas of two major SE Brazilian rivers, the Rio Doce and the Rio Paraiba do Sul, which probably transported most of the pollen and spores deposited in the marine sediments. During glacial times grassland vegetation dominated the landscape and Atlantic rainforest and semideciduous forest were markedly reduced. Small areas of subtropical Araucaria forest occurred in southeastern (SE) Brazil, while cerrado vegetation was rare. Maximal grassland expansion and Atlantic rainforest reduction were found during the last glacial maximum, reflecting cold and relatively dry climatic conditions. During the late-glacial period grassland decreased and lowland forest taxa increased, indicating wetter and warmer conditions. Comparison between the two marine pollen records with terrestrial records from the two river drainage areas confirms that grassland dominated the glacial age landscape reconstructed from terrestrial records.

This project aimed at investigating centennial to millennial-scale changes of the strength and position of the southern westerly wind belt (SWW) using multi-proxy paleoprecipitation and paleoceanographic records combined with transient model runs. The proxy data records reveal a distinct latitudinal anti-phasing of wind changes between the core and northern margin of the SWW over the Holocene. During the early Holocene, the SWW core was enhanced and the northern margin was reduced, whereas the opposite pattern is observed in the late Holocene. These Holocene changes resemble modern seasonal wind belt variations and can be best explained by varying sea-surface temperature fields in the eastern South Pacific. Transient modeling experiments from the mid- to late Holocene are not yet consistent with these proxy results. However, a good data-model agreement exists when investigating the potential impact of solar variability on the SWW at centennial time-scales during the latest Holocene with periods of lower (higher) solar activity causing equatorward (southward) shifts of the SWW.

This study provides the first detailed multi-proxy paleoenvironmental reconstructions of changes in the aquatic and terrestrial ecosystems during the Holocene, Eemian and the last two glacial/interglacial transitions (Terminations I and II) by studying sediment cores from the southeastern Black Sea and stalagmite studies from Sofular Cave in northwestern Anatolia. The terrestrial proxies document gradual changes from late glacial cold/arid conditions in northern Anatolia, dominated by steppe vegetation, to warm/humid forest dominated landscapes characteristic for interglacial periods. The Holocene and Eemian, however, developed differently, with warmer and moister conditions prevailing during the Eemian. Major fluctuations in the hydrological state of the Black Sea are closely linked to changes of terrestrial environments. Disrupted by large melt water pulses from the disintegrating Fennoscandian Ice Sheet, the limnic glacial Black Sea environment becomes more productive during the postglacial warming. Global sea-level rise finally reconnects the hydrological increasingly active Black Sea basin with the Mediterranean Sea leading to the development of marine, for the Eemian even fully marine, conditions with a stratified water column and sapropelic sedimentation.

Here we provide three new Holocene (11–0 cal ka BP) alkenone-derived sea surface temperature (SST) records from the southernmost Chilean fjord region (50–53°S). SST estimates may be biased towards summer temperature in this region, as revealed by a large set of surface sediments. The Holocene records show consistently warmer than present-day SSTs except for the past ~ 0.6 cal ka BP. However, they do not exhibit an early Holocene temperature optimum as registered further north off Chile and in Antarctica. This may have resulted from a combination of factors including decreased inflow of warmer open marine waters due to lower sea-level stands, enhanced advection of colder and fresher inner fjord waters, and stronger westerly winds. During the mid-Holocene, pronounced short-term variations of up to 2.5°C and a cooling centered at ~ 5 cal ka BP, which coincides with the first Neoglacial glacier advance in the Southern Andes, are recorded. The latest Holocene is characterized by two pronounced cold events centered at ~ 0.6 and 0.25 cal ka BP, i.e., during the Little Ice Age. These cold events have lower amplitudes in the offshore records, suggesting an amplification of the SST signal in the inner fjords.

Late Quaternary paleoenvironments from northeastern (NE) Brazil have been studied by pollen analysis of marine sediment. The studied core GeoB 3104-1 (3°40′ S, 37°43′ W, 767 m b.s.l.) from the upper continental slope off NE Brazil is 517 cm long and >42,000 14 C yr BP old. Chronological control was obtained by 12 radiocarbon (AMS) dates from individuals of the foraminiferal species Globigerinoides sacculifer. Modern pollen analogs were received from 15 river, lake and forest soil surface samples from NE Brazil. Marine pollen dates indicate the predominance of semi-arid caatinga vegetation in NE Brazil during the recorded period between >42,000 and 8500 14 C yr BP. The increased fluvial input of terrigenous material, with high concentrations of pollen and specially fern spores, into the marine deposits, about 40,000, 33,000 and 24,000 14 C yr BP and between 15,500 and 11,800 14 C yr BP, indicate short-term periods of strong rainfall on the NE Brazilian continent. The expansion of mountain, floodplain and gallery forests characterize the interval between 15,500 and 11,800 14 C yr BP as the wettest recorded period in NE Brazil, which allowed floristic exchanges between Atlantic rain forest and Amazonian rain forest, and vice versa. The paleodata from core GeoB 3104-1 confirm the, in general, dry pre-Last Glacial Maximum (LGM) and LGM conditions and the change to wet Lateglacial environments in tropical South America. The annual movement of the intertropical convergence zone over NE Brazil, the strong influence of the Antarctic cold fronts and changes of the high-pressure cell over the southern Atlantic, may explain the very wet Lateglacial period in NE Brazil. The documented NE Brazilian short-term signals correlate with the documented Dansgaard-Oeschger cycles and Heinrich events from the northern Hemisphere and suggest strong teleconnections.

The western South Atlantic boundary currents represent a sensitive system within the global thermohaline circulation (THC). We investigated the impact of deglacial THC changes on the western tropical Atlantic studied in six high resolution sediment cores from the upper continental slope of Brazil. The stratigraphy of the cores is mainly based on 14C AMS dating of monospecific foraminiferal samples. Changes in the upper layer tropical ocean during the deglaciation are inferred from stable oxygen isotope measurements on planktic and benthic foraminifera. Variations in the δ18O residuals are assumed to be mainly temperature related. During the Oldest and Younger Dryas cooling periods, two major deglacial THC disturbances are reported from North Atlantic sediment cores. Concomitant to the repeated THC slowdown, we observe an upper layer warming in the tropical ocean. A reduced northward heat export from the tropical areas during these periods (weak North Brazil Current) is additionally reflected by low meridional gradients in the stable oxygen records. This generally agrees with results from coupled ocean atmosphere models.

The stable isotope composition of planktonic foraminifera correlates with evidence for pulses of terrigenous sediment in a sediment core from the upper continental slope off northeastern Brazil. Stable oxygen isotope records of the planktonic foraminiferal species Globigerinoides sacculiferand Globigerinoides ruber(pink) reveal sub-Milankovitch changes in sea-surface hydrography during the last 85,000 yr. Warming of the surface water coincided with terrigenous sedimentation pulses that are inferred from high XRF intensities of Ti and Fe, and which suggest humid conditions in northeast Brazil. These tropical signals correlate with climatic oscillations recorded in Greenland ice cores (Dansgaard-Oeschger cycles) and in sediment cores from the North Atlantic (Heinrich events). Trade winds may have caused changes in the North Brazil Current that altered heat and salt flux into the North Atlantic, thus affecting the growth and decay of the large glacial ice sheets.

Sediments from the Black Sea, a region historically dominated by forests and steppe landscapes, are a valuable source of detailed information on the changes in regional terrestrial and aquatic environments at decadal to millennial scales. Here we present multi-proxy environmental records (pollen, dinoflagellate cysts, Ca, Ti and oxygen isotope data) from the uppermost 305 cm of the core 22-GC3 (42°13.53′N, 36°29.55′E) collected from a water depth of 838 m in the southern part of the Black Sea in 2007. The records span the last ~ 18 kyr (all ages are given in cal kyr BP). The pollen data reveal the dominance of the Artemisia-steppe in the region, suggesting rather dry/cold environments ~ 18–14.5 kyr BP. Warming/humidity increase during melt-water pulses (~ 16.1–14.5 kyr BP), indicated by δ18O records from the 22-GC3 core sediment and from the Sofular Cave stalagmite, is expressed in more negative δ13C values from the Sofular Cave, usually interpreted as the spreading of C3 plants. The records representing the interstadial complex (~ 14.5–12.9 kyr BP) show an increase in temperature and moisture, indicated by forest development, increased primary productivity and reduced surface run-off, whereas the switch from primary terrigenous to primary authigenic Ca origin occurs ~ 500 yr later. The Younger Dryas cooling is clearly demonstrated by more negative δ13C values from the Sofular Cave and a reduction of pines. The early Holocene (11.7–8.5 kyr BP) interval reveals relatively dry conditions compared to the mostly moist and warm middle Holocene (8.5–5 kyr BP), which is characterized by the establishment of the species-rich warm mixed and temperate deciduous forests in the low elevation belt, temperate deciduous beech-hornbeam forests in the middle and cool conifer forest in upper mountain belt. The border between the early and middle Holocene in the vegetation records coincides with the opening of the Mediterranean corridor at ~ 8.3 kyr BP, as indicated by a marked change in the dinocyst assemblages and in the sediment lithology. Changes in the pollen assemblages indicate a reduction in forest cover after ~ 5 kyr BP, which was likely caused by increased anthropogenic pressure on the regional vegetation.

[1] Glacial millennial-scale paleoceanographic changes in the Southeast Pacific and the adjacent Southern Ocean are poorly known due to the scarcity of well-dated and high resolution sediment records. Here we present new surface water records from sediment core MD07-3128 recovered at 53°S off the Pacific entrance of the Strait of Magellan. The alkenone-derived sea surface temperature (SST) record reveals a very strong warming of ca. 8°C over the last Termination and substantial millennial-scale variability in the glacial section largely consistent with our planktonic foraminifera oxygen isotope (δ18O) record of Neogloboquadrina pachyderma (sin.). The timing and structure of the Termination and some of the millennial-scale SST fluctuations are very similar to those observed in the well-dated SST record from ODP Site 1233 (41°S) and the temperature record from Drowning Maud Land Antarctic ice core supporting the hemispheric-wide Antarctic timing of SST changes. However, differences in our new SST record are also found including a long-term warming trend over Marine Isotope Stage (MIS) 3 followed by a cooling toward the Last Glacial Maximum (LGM). We suggest that these differences reflect regional cooling related to the proximal location of the southern Patagonian Ice Sheet and related meltwater supply at least during the LGM consistent with the fact that no longer SST cooling trend is observed in ODP Site 1233 or any SST Chilean record. This proximal ice sheet location is documented by generally higher contents of ice rafted debris (IRD) and tetra-unsaturated alkenones, and a slight trend toward lighter planktonic δ18O during late MIS 3 and MIS 2.

The ultra-high sedimentation rates at ODP Site 1233, situated at 41°S off Chile, enabled the investigation of the millennial to multi-centennial scale relationship and variability of the Patagonian Ice Sheet (PIS) extent, as indicated by the Fe relative concentration record, and offshore sea surface temperatures (SST) during the last glacial period. The close relationship of the Fe record and the SST pattern as described previously for the 50–19 kyr time-interval extends in the older part of the records (70–50 kyr). During marine isotope stage (MIS) 4, a delay of ∼500 yr of PIS retreats relative to SST increases has been found, similar to that described for the coldest part of MIS 3 and 2. During early MIS 3 (∼60–56 kyr), synchronous variability in both records resembles the deglacial-to-Holocene time-interval, reflecting either a meltwater pulse or a dominant control of the Fe input by rainfall changes related to a rather small PIS. Results of spectral analysis on the detrended records show three main periodicity-bands at ∼4.5–3.1, 2.4–2.2 and 1.2–0.8 kyr. The possible origins of these bands are discussed in terms of stochastic resonance and solar forcing.

High-resolution stable oxygen isotope (d 18 O on ostracod shells), XRF-scanning and bulk grain-size data obtained on a transect of 6 gravity cores from the continental slope in the northwestern Black Sea give new insight into the hydrological evolution of the Black Sea since the Last Glacial Maximum (LGM). Stable climatic conditions during the LGM were followed by a series of meltwater pulses between 18 and 15.5 kyr BP that resulted in temporary isotopic depletion of the Black Sea waters. Subsequently, steadily increasing d 18 O values in all cores are mainly caused by isotopically enriched precipitation at the onset of the Allerod/ Bolling warm period. A comparison of the major trends in d 18 O at different water depths suggests evaporation-driven deep water formation since ~14.5 kyr BP, while the two shallowest cores from 168 and 465 m water depth were under the influence of increased warming in the upper water column since 14.5 and 12.5 kyr BP, respectively. The core from 168 m depth seems to be additionally influenced by freshwater input of the Danube. This core provides a high-resolution record from the Younger Dryas/ Allerod boundary and suggests that a NAO-like climate mode was governing the interannual variability in the run-off of the Danube, which implies that this climate mode has been a persistent climatic feature over central Europe. The inflow of saline Mediterranean waters occurs between 9 and 8 kyr BP, where a merging of all d 18 O records signals an initial homogenisation of the water column.

Gravity cores from the continental slope in the northwestern Black Sea were studied using high-resolution stable isotope, grain size and XRF-scanning data. The measurements provide a 30 000 years AMS 14C-dated record of variations in the hydrological regime of the Black Sea and give insight into changing paleoenvironments in the surrounding areas. Stable climatic conditions during the Last Glacial Maximum were followed by a series of meltwater pulses most likely originating from the Scandinavian ice sheet between 18 000 and 15 500 yr BP. 1 This meltwater input rose the level of the Caspian Sea to a point that Caspian water could spill into the Black Sea via the Manych-depression north of the Caucasian mountains. High-frequency oscillations in the XRF-data during this period suggest a probable link to the arctic climate regime. Later, during the Bolling/Allerod and the early Holocene, prevailing high temperatures led to authigenic calcite precipitation through increased phytoplankton activity, interrupted by the Younger Dryas and the “8200 yr BP cold event” with dominant clastic sedimentation.

[1] We used planktic foraminiferal assemblages in 70 sediment cores from the tropical and subtropical South Atlantic Ocean (10°N-37°S) to estimate annual mean sea surface temperatures (SSTs) and seasonality for the Last Glacial Maximum with a modified version of the Imbrie-Kipp transfer function method (IKTF) that takes into account the abundance of rare but temperature sensitive species. In contrast to CLIMAP Project Members [1981], the reconstructed SSTs indicate cooler glacial SSTs in the entire tropical/subtropical South Atlantic with strongest cooling in the upwelling region off Namibia (7-10°C) and smallest cooling (1-2°C) in the western subtropical gyre. In the western Atlantic, our data support recent temperature estimates from other proxies. In the upwelling regions in the eastern Atlantic, our data conflict with SST reconstructions from alkenones, which may be due to an environmental preference of the alkenone-producing algae or to an underestimation of foraminiferal SSTs due to anomalous high abundances of N. pachyderma (sinistral).

Detailed 14C AMS data and isotope based stratigraphies from high-resolution paleoceanographic records for the last 22 ka of cores from the upper continental slope off NE Brazil reveal sedimentation rates of up to 100 cm per 1000 yr. Variations in the sediment composition relate to changes in the input of terrigenous material. The sedimentation is controlled by sea level and by the climatic regime of the hinterland. Short-term changes in the tropical wind field may act as a climatic trigger. The zonality of the SE trades was probably increased and the monsoonal activity over Africa reduced during the Younger Dryas period.