GDGT and alkenone flux in the northern Gulf of Mexico : implications for the TEX86 and UK'37 paleothermometers
MetadataShow full item record
The TEX86 and UKˈ37 molecular biomarker proxies have been broadly applied in downcore marine sediments to reconstruct past sea surface temperature (SST). Although both TEX86 and UKˈ37 have been interpreted as proxies for mean annual SST throughout the global ocean, regional studies of glycerol dibiphytanyl glycerol tetraethers (GDGTs) and alkenones in sinking particles are required to understand the influence of seasonality, depth distribution, and diagenesis on downcore variability. We measure GDGT and alkenone flux, as well as the TEX86 and UKˈ 37 indices in a 4 year sediment trap time series (2010–2014) in the northern Gulf of Mexico (nGoM), and compare these data with core-top sediments at the same location. GDGT and alkenone fluxes do not show a consistent seasonal cycle; however, the largest flux peaks for both occurs in winter. UKˈ 37 covaries with SST over the 4 year sampling interval, but the UKˈ 37-SST relationship in this data set implies a smaller slope or nonlinearity at high temperatures when compared with existing calibrations. Furthermore, the flux-weightedUKˈ 37 value from sinking particles is significantly lower than that of underlying core-top sediments, suggesting preferential diagenetic loss of the tri-unsaturated alkenone in sediments. TEX86 does not covary with SST, suggesting production in the subsurface upper water column. The flux-weighted mean TEX86 matches that of core-top sediments, confirming that TEX86 in the nGoM reflects local planktonic production rather than allochthonous or in situ sedimentary production. We explore potential sources of uncertainty in both proxies in the nGoM but demonstrate that they show nearly identical trends in twentieth century SST, despite these factors.
Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 31 (2016): 1547–1561, doi:10.1002/2016PA003032.
The publisher requires that this item be embargoed until 2017-06-19. Please check back after 2017-06-19.
Showing items related by title, author, creator and subject.
The sediments of the western Gulf of Mexico. I. The continental terrace of the western Gulf of Mexico : its surface sediments, origin, and development. II. Chemical studies of sediments of the western Gulf of Mexico Stetson, Henry C.; Trask, Parker D. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1953-05)In 1947 the Woods Hole Oceanographic Institution organized an expedition to investigate the bottom sediments and oceanography of the northwest Gulf of Mexico. The Geological Society of America contributed to the support ...
An evaluation of 14C age relationships between co-occurring foraminifera, alkenones, and total organic carbon in continental margin sediments Mollenhauer, Gesine; Kienast, Markus; Lamy, Frank; Meggers, Helge; Schneider, Ralph R.; Hayes, John M.; Eglinton, Timothy I. (American Geophysical Union, 2005-01-25)Radiocarbon age relationships between co-occurring planktic foraminifera, alkenones and total organic carbon in sediments from the continental margins of Southern Chile, Northwest Africa and the South China Sea were ...
Eastern tropical Pacific hydrologic changes during the past 27,000 years from D/H ratios in alkenones Pahnke, Katharina; Sachs, Julian P.; Keigwin, Lloyd D.; Timmermann, Axel; Xie, Shang-Ping (American Geophysical Union, 2007-12-18)The tropical Pacific plays a central role in the climate system by providing large diabatic heating that drives the global atmospheric circulation. Quantifying the role of the tropics in late Pleistocene climate change has ...