Publication Date:
2022-05-26
Description:
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.
Description:
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.
Description:
USGS Climate and Land Use Research and Development Program
Description:
2017-06-19
Keywords:
TEX86
;
UKˈ37
;
Alkenone
;
GDGT
;
Sediment trap
;
Gulf of Mexico
;
Biomarkers
Repository Name:
Woods Hole Open Access Server
Type:
Article
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