Abstract
Antarctic palaeoclimate evolution and vegetation history after the formation of a continent-scale
15 cryosphere at the Eocene/Oligocene boundary, 33.9 million years ago, has remained a matter of controversy. In
particular, the reconstruction of terrestrial climate and vegetation has been strongly hampered by uncertainties in
unambiguously identifying in situ as opposed to reworked sporomorphs that have been transported into Antarctic
marine sedimentary records by waxing and waning ice sheets. Whereas reworked sporomorph grains over longer
non-successive geological time scales are easily identifiable within younger sporomorph assemblages (e.g., Permian
20 sporomorphs in Pliocene sediments), distinguishing in situ from reworked material in palynological assemblages
over successive geological time periods (e.g., Eocene sporomorphs in Oligocene sediments) has remained
problematic. This study presents a new quantitative approach to identifying in situ grains from a marine sediment
core from circum-Antarctic waters. We measured the fluorescence signature and mean red, green and blue,
brightness, intensity and saturation values of selected pollen and spore taxa from Eocene, Oligocene and Miocene
25 sediments from the Wilkes Land margin Site U1356 (East Antarctica) recovered during Integrated Ocean Drilling
Program (IODP) Expedition 318. Our study identified statistically significant differences in mean red fluorescence
values of in situ sporomorph taxa against age. We conclude that red fluorescence is a reliable parameter to identify
the presence of in situ pollen and spores in Antarctic marine sediment records from the circum-Antarctic realm that
are influenced by glaciation and extensive reworking. Our study provides an essential new tool required to
30 accurately reconstruct Cenozoic terrestrial climate change on Antarctica using fossil pollen and spores.
15 cryosphere at the Eocene/Oligocene boundary, 33.9 million years ago, has remained a matter of controversy. In
particular, the reconstruction of terrestrial climate and vegetation has been strongly hampered by uncertainties in
unambiguously identifying in situ as opposed to reworked sporomorphs that have been transported into Antarctic
marine sedimentary records by waxing and waning ice sheets. Whereas reworked sporomorph grains over longer
non-successive geological time scales are easily identifiable within younger sporomorph assemblages (e.g., Permian
20 sporomorphs in Pliocene sediments), distinguishing in situ from reworked material in palynological assemblages
over successive geological time periods (e.g., Eocene sporomorphs in Oligocene sediments) has remained
problematic. This study presents a new quantitative approach to identifying in situ grains from a marine sediment
core from circum-Antarctic waters. We measured the fluorescence signature and mean red, green and blue,
brightness, intensity and saturation values of selected pollen and spore taxa from Eocene, Oligocene and Miocene
25 sediments from the Wilkes Land margin Site U1356 (East Antarctica) recovered during Integrated Ocean Drilling
Program (IODP) Expedition 318. Our study identified statistically significant differences in mean red fluorescence
values of in situ sporomorph taxa against age. We conclude that red fluorescence is a reliable parameter to identify
the presence of in situ pollen and spores in Antarctic marine sediment records from the circum-Antarctic realm that
are influenced by glaciation and extensive reworking. Our study provides an essential new tool required to
30 accurately reconstruct Cenozoic terrestrial climate change on Antarctica using fossil pollen and spores.
| Original language | English |
|---|---|
| Journal | Biogeosciences |
| DOIs | |
| Publication status | Published - 24 Oct 2016 |
