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  • Journal of Quaternary Science
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  • Abstract: The palaeoclimatic conditions during the Last Glacial Maximum (LGM) of southern South America and especially latitudinal shifts of the southern westerly wind belt are still discussed controversially. Longer palaeoclimatic records covering the Late Quaternary are rare. A particularly sensitive area to Late Quaternary climatic changes is the Norte Chico, northern Chile, because of its extreme climatic gradients. Small shifts of the present climatic zonation could cause significant variations of the terrestrial sedimentary environment which would be recorded in marine terrigenous sediments. To unveil the history of shifting climatic zones in northern Chile, we present a sedimentological study of a marine sediment core (GeoB 3375-1) from the continental slope off the Norte Chico (27.5°S). Sedimentological investigations include bulk- and silt grain-size determinations by sieving, Atterberg separation, and detailed SediGraph analyses. Additionally, clay mineralogical parameters were obtained by X-ray diffraction methods. The 14C-dated core, covering the time span from approximately 10,000 to 120,000 cal. yr B.P., consists of hemipelagic sediments. Terrigenous sedimentological parameters reveal a strong cyclicity, which is interpreted in terms of variations of sediment provenance, modifications of the terrestrial weathering regimes, and modes of sediment input to the ocean. These interpretations imply cyclic variations between comparatively arid climates and more humid conditions with seasonal precipitation for northern Chile (27.5°S) through the Late Quaternary. The cyclicity of the terrigenous sediment parameters is strongly dominated by precessional cycles. For the palaeoclimatic signal, this means that more humid conditions coincide with maxima of the precession index, as e.g. during the LGM. Higher seasonal precipitation for this part of Chile is most likely derived from frontal winter rain of the Southern Westerlies. Thus, the data presented here favour not only an equatorward shift of this atmospheric circulation system during the LGM, but also precession-controlled latitudinal movements throughout the Late Quaternary. Precessional forcing of latitudinal movements of the westerly atmospheric circulation system may be conceivable through teleconnections to the Northern Hemisphere monsoonal system in the Atlantic Ocean region. Category: geoscientificInformation Source: Supplement to: Lamy, Frank; Hebbeln, Dierk; Wefer, Gerold (1998): Late Quaternary precessional cycles of terrigenous sediment input off the Norte Chico, Chile (27.5°S) and paleoclimatic implications. Palaeogeography, Palaeoclimatology, Palaeoecology, 141(3-4), 233-251, https://doi.org/10.1016/S0031-0182(98)90052-9 Supplemental Information: Not Availble Coverage: EVENT LABEL: * LATITUDE: -27.466667 * LONGITUDE: -71.251667 * DATE/TIME: 1995-06-07T00:00:00 * ELEVATION: -1947.0 m * Recovery: 4.89 m * LOCATION: South-East Pacific * CAMPAIGN: SO102/2 * BASIS: Sonne * METHOD|DEVICE: Gravity corer (Kiel type)
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  • Tab11 PS1524-2 sediment... Tab11 PS1527-12 sediment... Tab11 PS1528-3 sediment... Tab11 PS1526-12 sediment... Paleoenvironmental Reconstructions from Marine Sediments @ AWI... Tab11 PS1525-7 sediment... Radioisotopenstratigraphie, Sedimentologie und Geochemie jungquartärer Sedimente des östlichen Arktischen Ozeans (Radioisotope Stratigraphy, Sedimentology and Geochemistry of Late Quaternary Sediments from the Eastern Arctic Ocean)
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  • Abstract: Diatoms were studied quantitatively in six latest Quaternary (~70 kyr B.P. to Recent) piston cores from the westernmost Mediterranean, the Alboran Basin, and the Atlantic region immediately to the west of the Straits of Gibraltar. The Atlantic cores completely lack diatoms. In the Alboran Basin, diatoms are common from late Stage 3 (~27.5 kyr B.P.) to Termination lb (9 kyr B.P.) and in Recent core tops, but are absent in the other latest Quaternary intervals. Maximum accumulation of diatoms and highest abundance of species normally in sediments associated with increased productivity occurred during the latest Quaternary deglaciation, in the first phase of Termination I (~14.8 kyr B.P.). In the modern Alboran Basin, a region of high biological productivity occurs immediately east of the Gibraltar Straits. This high productivity results from upwelling associated with the interaction between the Atlantic inflow and the bottom topography near the Spanish coast. The upwelled nutrient-rich waters are then advected to the east and southeast by the surficial anticyclonic gyral circulation. Late Quaternary variations in diatom abundance are considered to reflect changes in this upwelling intensity with highest diatom abundances inferred to result from increased upwelling associated with an intensification of the anticyclonic gyral circulation. Highest inferred upwelling rates occurred during the first phase of latest Quaternary deglaciation. It is possible that an intensification of circulation within the Mediterranean Basin as a whole occurred from late Stage 3 to mid Termination I because widespread hiatus formation has been reported at this time in the Straits of Sicily due to an increase in the formation of intermediate waters. Diatoms were not preserved in other latest Quaternary intervals due to insufficient productivity to counterbalance their dissolution. Category: geoscientificInformation Source: Supplement to: Abrantes, Fatima F (1988): Diatom productivity peak and increased circulation during latest Quaternary: Alboran Basin (Western Mediterranean). Marine Micropaleontology, 13(1), 79-96, https://doi.org/10.1016/0377-8398(88)90013-8 Supplemental Information: Not Availble Coverage: Not Available
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  • Late-Quaternary stratigraphic interpretation of the profiles A–C in Fig. 1 (modified from Lantzsch et al., 2009b). B=basement; EU=erosional unconformity; U1, U2, U3=main stratigraphic units; R1, R2: seismic reflectors separating the units. Magnification of profile A displays an internal reflector within U2 (marked by dashed line). Sediment core positions are indicated by black arrows. Depth on y-axis is given in m below modern sea level (mbsl). ... Shelf sedimentation... Shelf evolution model showing the distribution and origin of the classified facies types. A=river incision on exposed parts of the shelf, preferential export of fines, and deposition of Gravel Facies (gF) and Mixed-Sand Facies (sFmixed) on the outer shelf during the last-glacial sea-level lowstand; B=large-scale sediment recycling of older deposits, emplacement of the Glaucony-Sand Facies (sFglauc), and landward shift of gF and sFmixed during deglacial sea-level rise; and C=further time-transgressive shift of gF and sFmixed, decreased off-shelf export of fines, and initial deposition of mud depocentres during the Holocene sea-level highstand. Real thickness of the units and supply of sediments by biogenic production are not displayed. ... Core pictures and microscopic photos of the classified facies types. Pictures A–D: core pictures displaying the typical appearance of muddy and sandy facies types; A=Mixed-Sand Facies (Core 11012-2, 119–131cm depth); B=Glaucony-Sand Facies (11004-2, 51–63cm); C=Mud Facies (11030-2, 69.5–81.5cm); and D=Gravel Facies (left: Core 11003-3, 367–379cm depth; right: Core 11014-2, 236–248cm depth). Pictures E–G: Microscopic photos displaying the typical composition of grain-size fraction 250–500μm as described in Section 4.3; E=Mixed-Sand Facies (Core 11012-2, sample depth 120 cm); F=Glaucony-Sand Facies (11004-2, 60cm); and G=Mud Facies (11030-2, 80cm). ... Late Quaternary... Sediment core columns of the respective Boomer profiles in Fig. 2. Lithology is indicated by the width of the core columns. Greyscale fills of the core columns display the stratigraphic classification based on Lantzsch et al. (2009b). Samples for microscopic component counting are marked by circles with cluster numbers which were derived from fuzzy c-means cluster analysis. Facies types are displayed by background colours. The time-slices pre-Last Glacial Maximum (>25ka BP), Last Glacial Maximum (25–18ka BP), early deglaciation (18–15ka BP), late deglaciation (15–10ka BP), early Holocene (10–6ka BP), and late Holocene (6–0ka BP) are marked by dashed lines. A topview of the individual time slices is displayed in Fig. 7. ... Location of sediment vibrocores and surface samples of this study.
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  • South Atlantic in Late Quaternary: Reconstruction of Budget and Currents
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  • Abstract: High-resolution percent Corg and delta18Oforam records obtained from Panama Basin core Atlantis II 54-25PC and additional data from nearby core P7 show that enhanced burial of organic carbon has characterized every major glacial period for the last 500 kyr in that area. Both Corg concentration and mass accumulation rate profiles exhibit a sawtooth pattern with maxima occurring typically in the later stages of glacial periods. Comparison with dust records suggests that the carbon accumulation rate profile reflects both the upwelling history and a variable rate of iron input during the late Quaternary. The sawtooth character may derive from increased wind velocities and rates of upwelling during glacials which are indirectly related to ice volume (Sarnthein et al., 1988). The rapid decline in export production at the end of glacials in the equatorial Pacific may be attributed to the retreat of ice sheets (thus reduced wind velocities and upwelling) coupled with a coincident decline in atmospheric dust load and/or delivery rate. The Corg accumulation rate profiles do not correlate well with atmospheric CO2 records. For example, atmospheric CO2 was already at a minimum 40 kyr ago when production in the Panama Basin began increasing dramatically, commensurate with an increase in global dust levels. Using the relationship between the degree of photosynthetic fractionation and the concentration of free CO2 in the surface ocean postulated by Popp et al. (1989), delta13Corg measurements made on core P7 show that Panama Basin surface waters have been supplying CO2 to the atmosphere continually for at least the last 50 kyr. There is no evidence for a flux of CO2 into the surface ocean in this area at any time during this period despite the higher production. If the Panama Basin cores are representative of the eastern and central equatorial Pacific, then these observations weaken the influence on CO2 drawdown postulated for increased glacial productivity at low latitudes. Category: geoscientificInformation Source: Supplement to: Pedersen, Thomas F; Nielsen, B; Pickering, Mark (1991): Timing of Late Quaternary productivity pulses in the Panama Basin and implications for atmospheric CO2. Paleoceanography, 6(6), 657-677, https://doi.org/10.1029/91PA02532 Supplemental Information: Not Availble Coverage: EVENT LABEL: * LATITUDE: -4.270000 * LONGITUDE: -85.897000 * ELEVATION: -3225.0 m * CAMPAIGN: ATII_USA * BASIS: Atlantis II (1963) * METHOD|DEVICE: Piston corer EVENT LABEL: * LATITUDE: 2.604333 * LONGITUDE: -83.986333 * ELEVATION: -3085.0 m * LOCATION: Panama Margin * METHOD|DEVICE: Core
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  • Abstract: Piston cores from fiords, shelf troughs, and the deep-sea off eastern Baffin Island, N.W.T., Canada, have been sampled for texture and detrital carbonate in the <2 mm fraction. The sediments consist primarily of silty clays usually containing <5% sand. Estimates are made for sediment accumulation (kg/m**2/ka) over the last ca. 10 ka. Three sets, of two cores each, lie on a fiord-shelf transect and thus define variations in sediment accumulation gradients. These continental margin data are compared with cruder estimates of Holocene sediment accumulation at three sites farther offshore in Baffin Bay, Davis Strait and the northern Labrador Sea. Minimum accumulation in a 2 ka interval was 200 kg/m2 with a maximum estimate of 8,800 kg/m2. Detrital carbonate accumulation varies between 0 and 1,300 kg/m**2. Median accumulation for a typical fiord-shelf-deep-sea transect over the last 10 ka have been 10,340, 3493 and 820 kg/m**2. At DSDP Leg, site 645 in central Baffin Bay, the sedimentation rate ranged between 40 and 130 m/Ma (ca. 400 and 1200 kg/m**2/2ka); that is, comparable with the Late Quaternary input into Baffin Bay. Category: geoscientificInformation Source: Supplement to: Andrews, John T (1987): Late Quaternary marine sediment accumulation in fjord-shelf-deep-sea transects, Baffin Island to Baffin Bay. Quaternary Science Reviews, 6(3-4), 231-243, https://doi.org/10.1016/0277-3791(87)90006-0 Supplemental Information: Not Availble Coverage: EVENT LABEL: * LATITUDE: 62.766667 * LONGITUDE: -59.366667 * ELEVATION: -1057.0 m * Recovery: 7 m * LOCATION: Baffin Bay * METHOD|DEVICE: Piston corer EVENT LABEL: * LATITUDE: 70.706667 * LONGITUDE: -64.978333 * ELEVATION: -2041.0 m * Recovery: 7.03 m * LOCATION: Baffin Bay * METHOD|DEVICE: Piston corer EVENT LABEL: * LATITUDE: 61.850833 * LONGITUDE: -64.200500 * ELEVATION: -487.0 m * Recovery: 3.15 m * LOCATION: Baffin Shelf * METHOD|DEVICE: Piston corer EVENT LABEL: * LATITUDE: 62.834167 * LONGITUDE: -67.034000 * ELEVATION: -570.0 m * Recovery: 9.69 m * LOCATION: Baffin Bay * METHOD|DEVICE: Piston corer EVENT LABEL: * LATITUDE: 71.217000 * LONGITUDE: -71.484667 * ELEVATION: -832.0 m * Recovery: 5.81 m * LOCATION: Baffin Bay * METHOD|DEVICE: Piston corer EVENT LABEL: * LATITUDE: 68.250833 * LONGITUDE: -65.201500 * ELEVATION: -457.0 m * Recovery: 5.93 m * LOCATION: Baffin Bay * METHOD|DEVICE: Piston corer EVENT LABEL: * LATITUDE: 71.083330 * LONGITUDE: -71.883330 * ELEVATION: -683.0 m * Recovery: 10.16 m * LOCATION: Baffin Bay * METHOD|DEVICE: Piston corer EVENT LABEL: * LATITUDE: 69.191667 * LONGITUDE: -68.391667 * ELEVATION: -487.0 m * Recovery: 11.41 m * LOCATION: Baffin Bay * METHOD|DEVICE: Piston corer EVENT LABEL: * LATITUDE: 66.555000 * LONGITUDE: -61.710000 * ELEVATION: -146.0 m * Recovery: 7.7 m * LOCATION: Baffin Bay
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  • Documentation of sediment core PS1789-1... Alfred Wegener Institute - Polarstern core repository... Documentation of sediment core PS1599-3... Documentation of sediment core PS1790-1... Paleoenvironmental Reconstructions from Marine Sediments @ AWI
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  • Long and short cores obtained in both, the deep and shallow subbasins of the Lake El Tobar. Composite sedimentary sequence resulted from the correlation of short core TOB07-1A-1G (red), the section 2 from thelong core TOB04-1D-1K-2 (green) and the sections 2 to 6 from the long core TOB04-1B-1K (blue). Cores were correlated by using the magnetic susceptibility (MS) and visual comparison of the sediment. Sedimentary events (inlight brown) can be easily traced along the long cores in both subbasins, thus they affect the whole lake. ... A) Left: Iberian Peninsula and main Iberian Range geological units. Right: Subdivision of the Iberian Range in the study area: Serranía Alta, Media and Baja. Green dots represent the locations of main regional records in the Eastern Iberian Peninsula discussed in text: Pyrenees (1, Estaña, 2, Montcortès), South (3, Zoñar) and Iberian Range (4, Taravilla, 5, Cañada del Hoyo). C) Bathymetric map of El Tobar Lake showing the main water inlets and outlets and the geometry of the small meromictic sub-basin and the large holomictic sub-basin. Number indicates the depth of the isobaths in meters. Yellow stars indicate the position of the recovered long-cores, while white star mark the collected 210Pb-137Cs short-core. Green and red dashed lines indicate the trace of the seismic survey in the deep and shallow basins respectively. D) Seismic lines from the deep sub-basin (green dashed line) and from the shallow sub-basin (red dashed line) and the location of coring sites. ... El Tobar Lake depositional evolution during the last 1000years. Main sedimentary (S1, S2, S3 and S4, brown-shaded) and changes in sediment delivery to the lake (PC1) and sediment organic content (PC2). The El Tobar record is compared with main regional flooding periods reconstructed from Taravilla Lake (Moreno et al., 2008) and Tagus River (Benito et al., 2003) records; and with available regional sequences from the nearby Lake La Parra (sediment delivery, Barreiro-Lostres et al., 2014) and Lake La Cruz (pollen record, Julià et al., 1998) in the Torcas karstic lake complex (see Fig. 1 for location). Crops pollen percentage includes Cerealia, Secale, Cannabacea and Vitis. Anthropogenic pollen taxa include Artemisia, Plantado, Chenopodia, Brassicace, Urticaceae, Rumex, Centaurea and Asteraceae. Main historical events with large landscape impacts in the study area are also shown. The global North Hemisphere ‘Medieval Climate Anomaly’ and the ‘Little Ice Age’ are represented following the chronology of Mann et al. (2009). Chronology for Iberian Peninsula climatic periods is based on Moreno et al. (2012) and Morellón et al. (2011). ... Left: Correlation using TOC (%) standardized values between the short core with 137Cs dates (red line, gray dotted line represents the smoothed curve) and the long-core (black line) with 14C dates. Right: Age-Depth model of El Tobar sequence based on four AMS 14C dates from the TOB04-1B-1K long core (blue horizontal lines) and 137Cs essays (topmost green points) from the short-core TOB07-1A-1G using a weighted spline regression (Blaauw, 2010). Red crossed dates have not been included in the model. Black line represents the age-depth function framed by error lines (gray shaded area). ... A) Composite sedimentary sequence from El Tobar. From left to right: units, core image, sediment stratigraphy, facies with sedimentary evolution organized in fining-upward sequences and sedimentary events, Lightness (L*), magnetic susceptibility (MS [SI]), density (ρ [g/cm3]), basic geochemistry TIC (%), TOC (%), TOC/TN (atomic) and TS (%), and PC1 and PC2 eigenvectors (plotted in red) summarizing geochemical XRF stratigraphy. B) Left: Principal Component Analysis (PCA) of El Tobar composite record using main geochemical XRF elements, elemental composition (TOC, TIC, TS), incoherence/coherence ratio (IC). The first eigenvector (PC1) highlights the detrital inputs, whereas the second eigenvector (PC2) is interpreted as changes in organic content. Right: Map of the facies distribution. ... Sediment delivery... Late Quaternary
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