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  • 1
    Electronic Resource
    Electronic Resource
    GLACIAL VARVE THICKNESS AND 127 YEARS OF INSTRUMENTAL CLIMATE DATA: A COMPARISON (1997)
    Springer
    Climatic change 36 (1997), S. 391-411 
    Details
    ISSN: 1573-1480
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Annually laminated sediments (glacial varves) from Lake Silvaplauna, a High Alpine proglacial lake in the Central Swiss Alps, were compared with glacier monitoring data and instrumental climate data from 1864 to 1990. Long-term and short-term responses to climatic change as well as anthropogenic influence can be traced separately in the varve succession. Economic development in the lake catchment has resulted in higher autochthonous production in recent years. Autochthonous components contribute around 10% to the total amount of sediment accumulated annually since 1960 but their contribution is negligible before this date. Decadal-scale varve thickness trends correlate with glacier size-variations. A stepwise, running multiple regression analysis demonstrates that interannual changes in varve thickness are strongly correlated with changes in mean summer temperatures, but cannot be sufficiently explained without considering summer precipitation and the number of days with snow per year. The wide range of observed correlation coefficients reveals the sensitivity of the archive to temporal variability of the climatic forcing factors and makes the development of transfer functions ambiguous.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005376913455
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Refining the Late Quaternary tephrochronology for southern South America using the Laguna Potrok Aike sedimentary record (2019)
    PERGAMON-ELSEVIER SCIENCE LTD
    In:  EPIC3Quaternary Science Reviews, PERGAMON-ELSEVIER SCIENCE LTD, 218, pp. 137-156, ISSN: 0277-3791
    Details
    Publication Date: 2019-12-22
    Description: This paper presents a detailed record of volcanism extending back to ~80 kyr BP for southern South America using the sediments of Laguna Potrok Aike (ICDP expedition 5022; Potrok Aike Maar Lake Sediment Archive Drilling Project - PASADO). Our analysis of tephra includes the morphology of glass, the mineral componentry, the abundance of glass-shards, lithics and minerals, and the composition of glass- shards in relation to the stratigraphy. Firstly, a reference database of glass compositions of known eruptions in the region was created to enable robust tephra correlations. This includes data published elsewhere, in addition to new glass-shard analyses of proximal tephra deposits from Hudson (eruption units H1 and H2), Aguilera (A1), Reclus (R1, R2-3), Mt Burney (MB1, MB2, MBx, MB1910) and historical Lautaro/Viedma deposits. The analysis of the ninety-four tephra layers observed in the Laguna Potrok Aike sedimentary sequence reveals that twenty-five tephra deposits in the record are the result of pri- mary fallout and are sourced from at least three different volcanoes in the Austral Andean Volcanic Zone (Mt Burney, Reclus, Lautaro/Viedma) and one in the southernmost Southern Volcanic Zone (Hudson). One new correlation to the widespread H1 eruption from Hudson volcano at 8.7 (8.6e9.0) cal ka BP during the Quaternary is identified. The identification of sixty-five discrete deposits that were pre- dominantly volcanic ashes (glass and minerals) with subtle characteristics of reworking (in addition to three likely reworked tephra, and one unknown layer) indicates that care must be taken in the analysis of both visible and invisible tephra layers to decipher their emplacement mechanisms.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 3
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    Periodic 1.5 ka climate variations during MIS 2 in the belt of Southern Hemispheric westerlies (2017)
    In:  EPIC3Quaternary Research, 88(1), pp. 110-120, ISSN: 0033-5894
    Details
    Publication Date: 2020-06-01
    Description: Lacustrine sediments retrieved from Laguna Potrok Aike in the framework of the Potrok Aike Maar Lake Sediment Archive Drilling Project (PASADO) offer the possibility to investigate climate variations of the past ~51 cal ka BP in Southern Hemispheric midlatitudes, Argentinean Patagonia. This study focuses on short-term cyclicities in the Ca and magnetic susceptibility data sets between 51 and 15 cal ka BP. The record yields a climate pattern with a periodicity of 1.5 ka during Marine Oxygen Isotope Stage 2 (MIS 2) detected in the Southern Hemisphere from 31 to 17 cal ka BP for the first time. MIS 2 is known for constantly cold temperatures, whereas prominent climate variations paced by a 1.5 ka periodicity occurred during MIS 3. Our study documents that minor latitudinal oscillations of the Southern Hemispheric westerlies and the polar easterlies with a 1.5 ka periodicity also took place during MIS 2. However, we assume that because of a major northward displacement of the Southern Hemispheric westerlies, these oscillations did not sufficiently affect the zone of Circumpolar Deep Waters and an increased greenhouse effect by upwelling of CO2-rich deep waters did not occur. This mechanism illustrates why prominent climate events fail to appear during MIS 2.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 4
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    Rock-magnetic proxies of wind intensity and dust since 51,200 cal BP from lacustrine sediments of Laguna Potrok Aike, southeastern Patagonia (2015)
    In:  EPIC3Earth and Planetary Science Letters, 411, pp. 72-86, ISSN: 0012821X
    Details
    Publication Date: 2017-01-27
    Description: The sedimentary archive from Laguna Potrok Aike is the only continuous record reaching back to the last Glacial period in continental southeastern Patagonia. Located in the path of the Southern Hemisphere westerly winds and in the source region of dust deposited in Antarctica during Glacial periods, southern Patagonia is a vantage point to reconstruct past changes in aeolian activity. Here we use high-resolution rock-magnetic and physical grain size data from site 2 of the International Continental scientific Drilling Program (ICDP) Potrok Aike maar lake Sediment Archive Drilling prOject (PASADO) in order to develop magnetic proxies of dust and wind intensity at 52◦S since 51,200 cal BP. Rock-magnetic analysis indicates the magnetic mineral assemblage is dominated by detrital magnetite. Based on the estimated flux of magnetite to the lake and comparison with distal dust records from the Southern Ocean and Antarctica, kLF is interpreted as a dust indicator in the dust source of southern Patagonia at the millennial time scale, when ferrimagnetic grain size and coercivity influence are minimal. Comparison to physical grain- size data indicates that the median destructive field of isothermal remanent magnetization (MDFIRM) mostly reflects medium to coarse magnetite bearing silts typically transported by winds for short-term suspension. Comparison with wind-intensity proxies from the Southern Hemisphere during the last Glacial period and with regional records from Patagonia since the last deglaciation including marine, lacustrine and peat bog sediments as well as speleothems reveals similar variability with MDFIRM up to the centennial time scale. MDFIRM is interpreted as a wind-intensity proxy independent of moisture changes for southeastern Patagonia, with stronger winds capable of transporting coarser magnetite bearing silts to the lake.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
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    Using distributions and stable isotopes of n-alkanes to disentangle organic matter contributions to sediments of Laguna Potrok Aike, Argentina (2016)
    In:  EPIC3Organic Geochemistry, 102, pp. 110-119, ISSN: 01466380
    Details
    Publication Date: 2016-12-01
    Description: When using biomarkers such as n-alkanes as tools for paleo-environmental reconstructions, it is imperative to determine their specific sources for each setting. Towards that goal, we analysed a set of various potential organic matter (OM) sources such as aquatic and terrestrial plants, dust, and soils from Laguna Potrok Aike (LPA) and surrounding areas in Southern Patagonia. We determined chain length distributions and hydrogen (δD) and carbon (δ13C) isotopic compositions of n-alkanes of different OM sources in order to quantify their relative contributions to lake sediments. Our results reveal that mid-chain n-alkane, n-C23, is predominantly produced by submerged aquatic plants, whereas long-chain n-alkanes (n-C29 to n-C31) are derived from various terrestrial sources. We estimated their relative contributions to the sediment using two approaches, i.e. based on the n-alkane distributions and their δD and δ13C values. Both approaches result in similar estimates of aquatic and terrestrial contributions for mid- and long-chain n-alkanes to the sediment. 62-73% of the mid-chain n-C23 alkanes originate from aquatic sources while 66-77% of the long-chain n-alkanes originate from dust and 14-30% from terrestrial plants. Our study shows that mid-chain n-alkanes such as n-C23 alkane in LPA are derived mainly from aquatic macrophytes and thus have the potential to record changes in lake-water isotopic composition. In contrast, the n-C29 alkane reflects the isotopic signal of various terrestrial sources from Southern Patagonia.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 6
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    Lateglacial and Holocene wet--dry cycles in southern Patagonia: chronology, sedimentology and geochemistry of a lacustrine record from Laguna Potrok Aike, Argentina (2018)
    Sage Publications | London
    Details
    Publication Date: 2021-03-29
    Description: A high-resolution multiproxy geochemical approach was applied to the sediments of Laguna Potrok Aike in an attempt to reconstruct moist and dry periods during the past 16 000 years in southeastern Patagonia. The age–depth model is inferred from AMS 14C dates and tephrochronology, and suggests moist conditions during the Lateglacial and early Holocene (16 000–8700 cal. BP) interrupted by drier conditions before the beginning of the Holocene (13 200–11 400 cal. BP). Data also imply that this period was a major warm phase in southeastern Patagonia and was approximately contemporaneous with the Younger Dryas chronozone in the Northern Hemisphere (12 700–11 500 cal. BP). After 8650 cal. BP a major drought may have caused the lowest lake level of the record. Since 7300 cal. BP, the lake level rose and was variable until the ‘Little Ice Age’, which was the dominant humid period after 8650 cal. BP.
    Keywords: Holocene ; Younger Dryas ; Lateglacial ; `Little Ice Age' ; lacustrine sediments ; geochemistry ; tephrochronology ; multiproxy approach ; Patagonia ; Argentina. ; 551
    Language: English
    Type: article , publishedVersion
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    CITATION GEO-LEO
  • 7
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    Mechanisms of lake-level change at Laguna Potrok Aike (Argentina) – insights from hydrological balance calculations (2013)
    In:  EPIC3Quaternary Science Reviews, 71, pp. 27-45, ISSN: 02773791
    Details
    Publication Date: 2016-11-19
    Description: Laguna Potrok Aike is an exceptional site in the southern hemisphere’s mid-latitudes because it records changes in the hydrological regime through lake-level variations in a continuous, high-resolution sedi- ment record back into the late Pleistocene. In this study, driving forces of lake-level changes at Laguna Potrok Aike are evaluated by means of process studies using data from an extensive multi-year moni- toring in and around the lake. Lake-volume changes were calculated with an energy-budget/bulk- transfer approach and translated into lake-level variations, which were then compared to pressure sensor data. Calculated lake levels are in broad agreement with measured data. We hypothesize that on short time scales, lake-level fluctuations are mainly driven by the precipitation-to-evaporation ratio. Apart from changing catchment conditions, relative humidity, precipitation, temperature, wind strength and wind direction have the most important influence on the hydrological balance of the lake. Lake level decreases during periods of persistently high wind speeds from westerly directions, whereas, during periods with more frequent occurrences of easterly winds, it increases. These situations are linked to a strengthening of the Southern Hemispheric Westerlies in the first and more frequent blocking situa- tions in the latter case. Although lake-level changes at Laguna Potrok Aike show some degree of simi- larity to variations of the El Niño Southern Oscillation (ENSO) and the Southern Hemisphere Annular Mode (SAM), a persistent correspondence remains to be documented. Water chemistry and sediment-trap data suggest that lake-internal carbonate precipitation is highly sensitive to short-term changes in the lake water volume and, thus, to lake-level variations. However, it becomes obvious that the sedimentary carbonate record, representing changes on longer time scales, is not linearly linked to lake-level changes, hence complicating quantitative lake-level reconstructions back in time. We suggest that short-term changes in authigenic carbonate production are mainly driven by changing precipitation/evaporation ratios probably superimposed on longer-term changes in ground- water input that represent a buffered climate signal. Scenario calculations for a period of 60 years show that changes of the controlling meteorological parameters in the range of 15-17% can lead to lake-level changes with a magnitude comparable to the reconstructed Holocene and Lateglacial extreme situations. In addition, modifications in the water- retaining capacity of the lake can also produce large lake-level changes. It is hypothesized that the development or disappearance of permafrost in the catchment of Laguna Potrok Aike during the Last Glacial/Interglacial transition may have changed the water-retaining capacity tremendously. The lake- level reconstructions for Laguna Potrok Aike might express some of the meridional climate variability observed in coupled general circulation model (CGCM) simulations for southern South America for the Last Glacial Maximum (LGM) and the mid Holocene.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 8
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    Geochemistry, grain size and radiocarbon ages of MIS 3 sediment record from Nesseltalgraben, Germany (2020)
    PANGAEA
    Details
    Publication Date: 2024-02-01
    Description: Continuous sediment profiles were taken from ravine slopes at the Nesseltalgraben site in the Northern Calcareous Alps (SE Germany, 47.6567°N 13.0467°E, 560-582 m a.s.l.) in October 2016. The profile consists of fine-grained lacustrine-palustrine sediments overlain by several metres of glacifluvial gravels and lodgement tills of the Last Glacial Maximum and underlain by a diamicton. High-resolution (2 mm steps) element counts (Ca, S, Si, K, Ti, Mn, Fe, Zn, Rb, Sr, Zr) were obtained with an XRF core scanner (Itrax, Cox Analytical Systems, Sweden). Organic geochemistry (total organic and inorganic carbon, total nitrogen, total sulphur) was analysed with an elemental analyser (Euro EA, Eurovector, Germany), grain size with a laser diffractometer (Beckman-Coulter LS 200). The sediment profiles were compiled to a composite record of 21 m length. The age model bases on 29 radiocarbon analyses of macroscopic terrestrial plant remains (byrophytes, plant debris, monocots, wood, and twigs) and a previously discovered paleomagnetic anomaly assigned to the Laschamp event. The age model covers the period 59 to 29.6 ka cal BP and assigns the record to Marine Isotope Stage (MIS) 3. The sediment record shows rapid changes in lithology, sedimentology, and geochemistry related to Dansgaard-Oeschger climatic events.
    Keywords: ALPWÜRM; Central Europe; Dansgaard-Oeschger cycles; Environmental and climatic variability during the Middle Würmian in the northern Alps; Glaciation; Grain-size analyses; Greenland interstadials; Lacustrine-palustrine sediment; Middle Würmian; paleoclimatology; Pleistocene; radiocarbon dating
    Type: Dataset
    Format: application/zip, 4 datasets
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    DATA PANGAEA
  • 9
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    XRF, Carbon and CaCO3 data from the profiles Bok N, Bok O, Bok P on the Island of Susak (2017)
    PANGAEA
    In:  Supplement to: Profe, Jörn; Wacha, Lara; Frechen, Manfred; Ohlendorf, Christian; Zolitschka, Bernd (2018): XRF scanning of discrete samples – A chemostratigraphic approach exemplified for loess-paleosol sequences from the Island of Susak, Croatia. Quaternary International, 494, 34-51, https://doi.org/10.1016/j.quaint.2018.05.006
    Details
    Publication Date: 2024-03-01
    Description: X-ray fluorescence (XRF) scanning of discrete samples provides a time- and cost-efficient alternative to conventional geochemical analyses of discretely sampled paleoenvironmental archives. Loess-paleosol sequences (LPS) as complex terrestrial archives are thus predestinated for benchmarking this new application of the well-established XRF scanning technology. Stratigraphically incomplete outcrops, like those on the Island of Susak (Croatia), are unique paleoenvironmental archives at least for the penultimate and last interglacial/glacial cycles and provide ideal test sites. Available proxy data from previous investigations on Susak ensure validation of conclusions drawn from XRF scanning-derived data. Three representative profiles were studied to examine the potential of XRF scanning-derived element ratios as proxy for environmental processes: (1) Ca/Sr for the strength of ubiquitously present secondary calcification; (2) Rb/K for the intensity of weathering; (3) Ti/Al and Ti/Zr for changes in wind speed with Zr being additionally indicative for sediment recycling; (4) Si/Al for changes in grain-size; and (5) Br and Cl as proxies for sea spray. Furthermore, we established a multivariate statistics-based chemostratigraphy to facilitate profile correlation and to improve lithostratigraphic characterization. In conclusion, this study demonstrates that XRF scanning of discrete samples from LPS is a valuable tool for paleoenvironmental reconstruction.
    Keywords: Aluminium; Barium; Bok_N; Bok_O; Bok_P; Bromine; Calcium; Calcium carbonate; Carbon, inorganic, total; Carbon, organic, total; Carbon, total; Chlorine; Chlorine/Bromine ratio; Coherence; Confidence interval; Event label; Incoherence; Iron; Latitude of event; Lithology/composition/facies; log-Barium/Strontium ratio; log-Calcium/Strontium ratio; log-Iron/Manganese ratio; log-Rubidium/Potassium ratio; log-Rubidium/Strontium ratio; log-Silicon/Aluminium ratio; log-Titanium/Aluminium ratio; log-Titanium/Zirconium ratio; log-Zirconium/Rubidium ratio; Longitude of event; Manganese; Mean squared error; Potassium; Rubidium; SECTION, height; Silicon; Strontium; Titanium; X-ray fluorescence ITRAX core scanner, Cr-tube 30kV 40mA 100s, Bremen; X-ray fluorescence ITRAX core scanner, Mo-tube 30kV 30mA 100s, Bremen; Zirconium
    Type: Dataset
    Format: text/tab-separated-values, 18799 data points
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    DATA PANGAEA
  • 10
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    Isotopic compostion of Laguna Azul sediments (2018)
    PANGAEA
    Details
    Publication Date: 2024-01-27
    Keywords: AGE; Argentina; AZU_03; COMPCORE; Composite Core; Depth, composite; δ13C, organic carbon; δ15N
    Type: Dataset
    Format: text/tab-separated-values, 712 data points
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    DATA PANGAEA
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