Stable carbon isotope ratios of n-alkane in ODP Hole 175-1083A in the South Atlantic Ocean (Table 1)

The intensification of Northern Hemisphere Glaciation (iNHG) is one of the critical climate thresholds in the Cenozoic. This study focuses on marine sediments recovered from Marine Isotope Stages 101/100 at the Ocean Drilling Program Site 1083 to assesses the impact of the iNHG on continental southe...

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Bibliographic Details
Main Authors: Denison, S M, Maslin, Mark, Boot, C, Pancost, Richard D, Ettwein, V J
Format: Dataset
Language:English
Published: PANGAEA 2005
Subjects:
175-1083A
Amplitude
Benguela Current
South Atlantic Ocean
DEPTH
sediment/rock
DRILL
Drilling/drill rig
DSDP/ODP/IODP sample designation
Isotope ratio mass spectrometry
Joides Resolution
Leg175
n-Alkane C27
δ13C
n-Alkane C29
n-Alkane C31
n-Alkane C33
Ocean Drilling Program
ODP
Sample code/label
Online Access:https://doi.pangaea.de/10.1594/PANGAEA.694036
https://doi.org/10.1594/PANGAEA.694036
Description
Summary:The intensification of Northern Hemisphere Glaciation (iNHG) is one of the critical climate thresholds in the Cenozoic. This study focuses on marine sediments recovered from Marine Isotope Stages 101/100 at the Ocean Drilling Program Site 1083 to assesses the impact of the iNHG on continental southern African vegetation through n-alkane (straight-chain hydrocarbon) abundance and delta13C values. The n-alkane abundance data yield a convoluted signal due to the number of controlling factors such as the source area, transportation routes and vegetation type. The C31 n-alkane delta13C values, however, exhibit a cyclic pattern with a periodicity of c. 20 ka, and are not correlated to the abundance data. It is inferred that the signal does not represent a change in the geographical source of n-alkanes. Instead, we suggest that the variations are caused by water-stress-induced changes in either carbon isotope fractionation during C3 photosynthesis or subtle changes in the proportion of C3 and C4 plants. These changes, unlike variations in oceanographic proxies, closely track precessional forcing factors and are independent of the prevailing obliquity-forced glacial/interglacial cycles. We conclude that the varying monsoon strength, rather than pCO2 or temperature change, forced changes in southern African vegetation during this period.

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