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Showing 1 to 9 of 9 for “"Alkenone"”.
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Alkenone-based evidence of Holocene slopewater cooling in the northwest Atlantic
Alkenone-based estimates of sea surface temperature (SST) in the northwest Atlantic during the last 10,000 years are presented and used to assess scenarios for Holocene climate variability. Alkenone concentration and unsaturation records are presented from cores KNR140-39GGC, KNR140-51GGC, …
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Sedimentary lipids as indicators of depositional conditions in the coastal Peruvian upwelling regime
… A variety of lipids (n-alkanes, n-alkanols, C37 alkenones, hopanoids, keto-ols, lycopane, phytol, stenols, stanols, sterenes, and tetrahymanol) were quantified in Peru margin sediments from both the oxygen minimum zone (OMZ) and several near-shore locations. I discuss the utility of the lipid …
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Middle Miocene carbon cycle dynamics: A multi-proxy approach
… expansion (“E3”; Miller et al. 1993). Combined alkenone unsaturation index (U<sup>K'</sup><sub>37</sub> ) and <i>G. trilobus</i> Mg/Ca ratios were used to reconstruct sea surface temperature. Over CM6 temperatures dropped by ~5°C as the ice sheet expanded, and the temperature contribution to the …
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Determination of sediment provenance at drift sites using hydrogen isotopes in lipids
… We hypothesize that hydrogen isotope ratios of alkenones, a class of lipids from phytoplankton, may provide insight into the source of fine fraction sediment. Because of their restricted sources, broad geographic distribution, and excellent preservation properties, alkenones are of particular …
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Palaeoceanographic conditions and palaeoproductivity changes from the sub-Antarctic island South Georgia since the late deglacial, using marine micropalaeontology and geochemistry
… assemblage analysis, XRF elemental analysis, and alkenone-derived sea-surface temperatures (SST). The base of GC666 contains laminated sediments (ca. 15.2 to 14.7 cal. kyr BP) interpreted as seasonal alternations between Chaetoceros-dominated biogenic laminae formed during the spring/early summer …
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Orbital and Suborbital Climate Variability during the Pliocene Intensification of Northern Hemisphere Glaciation
… export<br/>productivity. Results suggest that alkenone accumulation may be a useful indicator of export<br/>productivity and that the late Pliocene biological pump was stronger during glacials than<br/>interglacials.<br/>In Chapter 4, an inferred secular productivity shift is investigated using …
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Palaeoenvironmental reconstruction of late Holocene climate dynamics in Southwest Africa using a multi-proxy characterization of Namaqualand mudbelt sediments
… the production of an uninterrupted age model. Alkenone and isotopic analyses were conducted at a multi-decadal resolution to assist in the reconstruction of sea-surface tem- perature (SST) in the St. Helena Bay region, and hydrological variation in the WRZ. Changes in moisture availability were …
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Refinement and application of a new paleotemperature estimation technique
… the unsaturation ratio of long chain C37 methyl alkenones (Uk37) produced by Prymnesiophyceae phytoplankton, has been applied to late Quaternary sediment cores. Previous studies have shown that the Uk37 ratio of these alkenones is linearly proportional to the sea-water temperature in which the …
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Investigations on rainfall variability during the late Quaternary based on geochemical analyses of lake sediments from tropical and subtropical southern Africa
This thesis presents investigations on sediments from two African lakes which have been recording changes in their surrounding environmental and climate conditions since more than 200,000 years. Focus of this work is the time of the last Glacial and the Holocene (the last ~100,000 years before …