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  • ELSEVIER SCIENCE BV  (3)
  • ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD  (1)
  • AMER GEOPHYSICAL UNION  (1)
  • Kiel  (1)
Publikationsart
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  • 1
    Online-Ressource
    Online-Ressource
    The Holocene Sapropel S1 in the Ionian Sea : paleoceanography and geochemistry : (Teil B: Laborarbeit) (1998)
    Kiel
    Details Verfügbarkeit
    Schlagwort(e): Hochschulschrift
    Materialart: Online-Ressource
    Seiten: 1 Online-Ressource (108 Seiten = 5 MB) , Graphen, Karte
    Ausgabe: Online-Ausgabe 2023
    URL: https://oceanrep.geomar.de/id/eprint/50862/
    Sprache: Englisch
    Anmerkung: Zusammenfassung in deutscher und englischer Sprache
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
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    Investigation of organic matter and biomarkers from Diepkloof Rock Shelter, South Africa: Insights into Middle Stone Age site usage and palaeoclimate (2017)
    ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
    In:  EPIC3Journal of Archaeological Science, ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 85, pp. 51-65, ISSN: 0305-4403
    Details
    Publikationsdatum: 2018-01-02
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , peerRev
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
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    ARTIKEL (OA)
  • 3
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    Origin and fate of sedimentary organic matter in the northern Bay of Bengal during the last 18 ka (2016)
    ELSEVIER SCIENCE BV
    In:  EPIC3Global and Planetary Change, ELSEVIER SCIENCE BV, 146, pp. 53-66, ISSN: 0921-8181
    Details
    Publikationsdatum: 2016-10-19
    Beschreibung: The Northern Bay of Bengal (NBoB) is a globally important region for deep-sea organic matter (OM) deposition due to massive fluvial discharge from the Ganges-Brahmaputra-Meghna (G-B-M) rivers and moderate to high surface productivity. Previous studies have focused on carbon burial in turbiditic sediments of the Bengal Fan. However, little is known about the storage of carbon in pelagic and hemipelagic sediments of the Bay of Bengal over millennial time scales. This study presents a comprehensive history of OM origin and fate as well as a quantification of carbon sediment storage in the Eastern Bengal Slope (EBS) during the last 18 ka. Bulk organic proxies (TOC, TIC, TN, δ13CTOC, δ15NTN) and content and composition of total hydrolysable amino acids (THAA) in a sediment core (SO188-342KL) from the EBS were analyzed. Three periods of high OM accumulation were identified: the Late Glacial (LG), the Bölling/Alleröd (B/A), and the Early Holocene Climatic Optimum (EHCO). Lower eustatic sea level before 15 ka BP allowed a closer connection between the EBS and the fluvial debouch, favoring high terrestrial OM input to the core site. This connection was progressively lost between 15 and 7 ka BP as sea level rose to its present height and terrestrial OM input decreased considerably. Export and preservation of marine OM was stimulated during periods of summer monsoon intensification (B/A and EHCO) as a consequence of higher surface productivity enhanced by cyclonic-eddy nutrient pumping and fluvial nutrient delivery into the photic zone. Changes in the THAA composition indicate that the marine plankton community structure shifted from calcareous-dominated before 13 ka BP to siliceous-dominated afterwards. They also indicate that the relative proportion of marine versus terrestrial OM deposited at site 342KL was primarily driven by relative sea level and enlarged during the Holocene. The ballasting effect of lithogenic particles during periods of high coastal proximity and/or enhanced fluvial discharge promoted the export and preservation of OM. The high organic carbon accumulation rates in the EBS during the LG (18–17 ka BP) were 5-fold higher than at present and comparable to those of glacial upwelling areas. Despite the differences in sediment and OM transport and storage among the Western and Eastern sectors of the NBoB, this region remains important for global carbon sequestration during sea level low-stands. In addition, the summer monsoon was a key promotor of terrestrial and marine OM export to the deep-ocean, highlighting its relevance as regulator of the global carbon budget.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Standort Signatur Einschränkungen Verfügbarkeit
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    ARTIKEL (OA)
  • 4
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    Miocene to Pliocene development of surface and subsurface temperatures in the Benguela Current system (2011)
    AMER GEOPHYSICAL UNION
    In:  EPIC3Paleoceanography, AMER GEOPHYSICAL UNION, 26, ISSN: 0883-8305
    Details
    Publikationsdatum: 2019-07-17
    Beschreibung: The initiation of the Benguela upwelling has been dated to the late Miocene, but estimates of its sea surface temperature evolution are not available. This study presents data from Ocean Drilling Program (ODP) Site 1085 recovered from the southern Cape Basin. Samples of the middle Miocene to Pliocene were analyzed for alkenone-based (U37 K", SSTUK) and glycerol dialkyl glycerol tetraether (GDGT) based (TEX86, TempTEX) water temperature proxies. In concordance with global cooling during the Miocene, SSTUK and TempTEX exhibit a decline of about 8°C and 16°C, respectively. The temperature trends suggest an inflow of cold Antarctic waters triggered by Antarctic ice sheet expansion and intensification of Southern Hemisphere southeasterly winds. A temperature offset between both proxies developed with the onset of upwelling, which can be explained by differences in habitat: alkenone!producing phytoplankton live in the euphotic zone and record sea surface temperatures, while GDGT!producing Thaumarchaeota are displaced to colder subsurface waters in upwelling!influenced areas and record subsurface water temperatures. We suggest that variations in subsurface water temperatures were driven by advection of cold Antarctic waters and thermocline adjustments that were due to changes in North Atlantic deep water formation. A decline in surface temperatures, an increased offset between temperature proxies, and an increase in primary productivity suggest the establishment of the Benguela upwelling at 10 Ma. During the Messinian Salinity Crisis, between 7 and 5 Ma, surface and subsurface temperature estimates became similar, likely because of a strong reduction in Atlantic overturning circulation, while high total organic carbon contents suggest a “biogenic bloom.” In the Pliocene the offset between the temperature estimates and the cooling trend was reestablished.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
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    ARTIKEL (OA)
  • 5
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    Long chain 1,13- and 1,15-diols as a potential proxy for palaeotemperature reconstruction (2012)
    ELSEVIER SCIENCE BV
    In:  EPIC3Geochimica et Cosmochimica Acta, ELSEVIER SCIENCE BV, 84, pp. 204-216, ISSN: 00167037
    Details
    Publikationsdatum: 2019-07-17
    Beschreibung: Although commonly reported in marine and freshwater environments, little is known about the biological sources of long chain alkyl 1,13- and 1,15-diols, and factors controlling their distributions. Here we analyzed the occurrence and distribution of these lipids in a comprehensive set of marine surface sediments and compare their distributions with environmental conditions like sea surface temperature (SST), salinity and nutrient concentrations. Fractional abundances of the C28 1,13-, C30 1,13- and C30 1,15-diols show a strong correlation with SST and based on these results, we propose the Long chain Diol Index (LDI), which expresses the C30 1,15-diol abundance relative to those of C28 1,13-, C30 1,13- and C30 1,15-diols. The LDI shows a strong linear correlation with SST (LDI = 0.033 � SST + 0.095; R2 = 0.969, n = 162) over a temperature range of �3 to 27 �C. Long chain diol distributions in sediments from the South Atlantic close to the Congo River outflow (West Africa) provided a 43 kyr LDI SST record. This record reflects several known climatic events and shows similarities with an alkenone- derived SST record obtained using the same suite of sediments, both in trend and in terms of absolute SST. This confirms the potential of the LDI as a proxy for palaeo-SST reconstruction.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Standort Signatur Einschränkungen Verfügbarkeit
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    ARTIKEL (OA)
  • 6
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    Controls on the distributions of GDGTs and n-alkane isotopic compositions in sediments of the Amazon River Basin (2022)
    ELSEVIER SCIENCE BV
    In:  EPIC3Chemical Geology, ELSEVIER SCIENCE BV, 594, pp. 120777, ISSN: 0009-2541
    Details
    Publikationsdatum: 2022-02-26
    Beschreibung: ARTICLE INFO Keywords: Amazonia GDGT Amazon River Biomarkers Compound-specific isotopes N-Alkanes Paleoclimate proxies Plant waxes ABSTRACT Lipid biomarker proxies from terrigenous sediments have been extensively used to understand variations in paleoenvironmental conditions, but many of the mechanisms affecting these proxies during riverine transport are still poorly understood. Here, we analyze glycerol dialkyl glycerol tetraether (GDGT) distributions and n-alkane isotopic compositions of soils and sediments from the Amazon River Basin. Our dataset includes suspended sediments of the Amazon River and its main tributaries, as well as soils and sediments of the Xingu River, a large clearwater tributary draining the easternmost part of the Amazon River Basin. Our sampling design aimed at understanding the processes behind spatially distinct GDGT distributions and n-alkane isotopic signatures across lowland Amazonia. Gradual changes in the fractional abundances of isoprenoid GDGTs and in 5- and 6- methyl branched GDGT ratios in suspended sediments of the Amazon River towards its mouth suggest that riverine production is an increasingly important control on the distribution of GDGTs in the lower parts of the system, while values from the western parts are more in line with a dominant soil sourcing. In the Xingu River, indices based on the fractional abundances of branched GDGTs and long-chain n-alkanes demonstrate a strong contri- bution of terrestrial organic material during the high-water season and an important aquatic component during low-water season. Meanwhile, average stable carbon (δ13C) and hydrogen (δD) isotopic signatures of long-chain n-alkanes in soils, riverbed and suspended sediments of the Xingu River are similar and reinforce the relatively conservative behaviour of these proxies within large river systems. The average compound-specific δ13C signa- tures of sediments in the Xingu River are within the expected range for C3 vegetation and do not seem to capture the signals from the nearby deforested areas. n-Alkanes δD signals in the Xingu Basin are similar to values ob- tained in the Amazon River mouth and indicate that n-alkanes sourced from easternmost Amazonian lowlands may predominate over signals from western areas.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Standort Signatur Einschränkungen Verfügbarkeit
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    ARTIKEL (OA)
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