Opening the gateways for diatoms primes Earth for Antarctic glaciation
The abrupt onset of Antarctic glaciation during the Eocene–Oligocene Transition (?33.7 Ma, Oi1) is linked to declining atmospheric pCO2 levels, yet the mechanisms that forced pCO2 decline remain elusive. Biogenic silicon cycling is inextricably linked to both long and short term carbon cycling throu...
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ftsouthampton:oai:eprints.soton.ac.uk:359551 2023-07-30T03:59:23+02:00 Opening the gateways for diatoms primes Earth for Antarctic glaciation Egan, Katherine E. Rickaby, Rosalind E.M. Hendry, Katharine R. Halliday, Alex N. 2013-08-01 https://eprints.soton.ac.uk/359551/ English eng Egan, Katherine E., Rickaby, Rosalind E.M., Hendry, Katharine R. and Halliday, Alex N. (2013) Opening the gateways for diatoms primes Earth for Antarctic glaciation. Earth and Planetary Science Letters, 375, 34-43. (doi:10.1016/j.epsl.2013.04.030 <http://dx.doi.org/10.1016/j.epsl.2013.04.030>). Article PeerReviewed 2013 ftsouthampton https://doi.org/10.1016/j.epsl.2013.04.030 2023-07-09T21:50:06Z The abrupt onset of Antarctic glaciation during the Eocene–Oligocene Transition (?33.7 Ma, Oi1) is linked to declining atmospheric pCO2 levels, yet the mechanisms that forced pCO2 decline remain elusive. Biogenic silicon cycling is inextricably linked to both long and short term carbon cycling through the diatoms, siliceous walled autotrophs which today account for up to 40% of primary production. It is hypothesised that during the Late Eocene a sharp rise in diatom abundance could have contributed to pCO2 drawdown and global cooling by increasing the proportion of organic carbon buried in marine sediment. Diatom and sponge silicon isotope ratios (?30Si) are here combined for the first time to reconstruct the late Eocene–early Oligocene ocean silicon cycle and provide new insight into the role of diatom productivity in Antarctic glaciation. At ODP site 1090 in the Southern Ocean, a 0.6‰ rise in diatom ?30Si through the late Eocene documents increasing diatom silicic acid utilisation with high, near modern values attained by the earliest Oligocene. A concomitant 1.5‰ decline in sponge ?30Si at ODP site 689 on the Maud Rise tracks an approximate doubling of intermediate depth silicic acid concentration in the high southern latitudes. Intermediate depth silicic acid concentration peaked at ?31.5 Ma, coincident with the final establishment of a deepwater pathway through the Tasman Gateway and Drake Passage. These results suggest that upwelling intensification related to the spin-up of a circum-Antarctic current may have driven late Eocene diatom proliferation. Organic carbon burial associated with higher diatom abundance and export provides a mechanism that can account for pCO2 drawdown not only at, but also prior to, Antarctic glaciation as required by a pCO2 ‘threshold’ mechanism for ice sheet growth. Article in Journal/Newspaper Antarc* Antarctic Drake Passage Ice Sheet Southern Ocean University of Southampton: e-Prints Soton Antarctic Drake Passage Maud Rise ENVELOPE(3.000,3.000,-66.000,-66.000) Southern Ocean Earth and Planetary Science Letters 375 34 43 |
institution |
Open Polar |
collection |
University of Southampton: e-Prints Soton |
op_collection_id |
ftsouthampton |
language |
English |
description |
The abrupt onset of Antarctic glaciation during the Eocene–Oligocene Transition (?33.7 Ma, Oi1) is linked to declining atmospheric pCO2 levels, yet the mechanisms that forced pCO2 decline remain elusive. Biogenic silicon cycling is inextricably linked to both long and short term carbon cycling through the diatoms, siliceous walled autotrophs which today account for up to 40% of primary production. It is hypothesised that during the Late Eocene a sharp rise in diatom abundance could have contributed to pCO2 drawdown and global cooling by increasing the proportion of organic carbon buried in marine sediment. Diatom and sponge silicon isotope ratios (?30Si) are here combined for the first time to reconstruct the late Eocene–early Oligocene ocean silicon cycle and provide new insight into the role of diatom productivity in Antarctic glaciation. At ODP site 1090 in the Southern Ocean, a 0.6‰ rise in diatom ?30Si through the late Eocene documents increasing diatom silicic acid utilisation with high, near modern values attained by the earliest Oligocene. A concomitant 1.5‰ decline in sponge ?30Si at ODP site 689 on the Maud Rise tracks an approximate doubling of intermediate depth silicic acid concentration in the high southern latitudes. Intermediate depth silicic acid concentration peaked at ?31.5 Ma, coincident with the final establishment of a deepwater pathway through the Tasman Gateway and Drake Passage. These results suggest that upwelling intensification related to the spin-up of a circum-Antarctic current may have driven late Eocene diatom proliferation. Organic carbon burial associated with higher diatom abundance and export provides a mechanism that can account for pCO2 drawdown not only at, but also prior to, Antarctic glaciation as required by a pCO2 ‘threshold’ mechanism for ice sheet growth. |
format |
Article in Journal/Newspaper |
author |
Egan, Katherine E. Rickaby, Rosalind E.M. Hendry, Katharine R. Halliday, Alex N. |
spellingShingle |
Egan, Katherine E. Rickaby, Rosalind E.M. Hendry, Katharine R. Halliday, Alex N. Opening the gateways for diatoms primes Earth for Antarctic glaciation |
author_facet |
Egan, Katherine E. Rickaby, Rosalind E.M. Hendry, Katharine R. Halliday, Alex N. |
author_sort |
Egan, Katherine E. |
title |
Opening the gateways for diatoms primes Earth for Antarctic glaciation |
title_short |
Opening the gateways for diatoms primes Earth for Antarctic glaciation |
title_full |
Opening the gateways for diatoms primes Earth for Antarctic glaciation |
title_fullStr |
Opening the gateways for diatoms primes Earth for Antarctic glaciation |
title_full_unstemmed |
Opening the gateways for diatoms primes Earth for Antarctic glaciation |
title_sort |
opening the gateways for diatoms primes earth for antarctic glaciation |
publishDate |
2013 |
url |
https://eprints.soton.ac.uk/359551/ |
long_lat |
ENVELOPE(3.000,3.000,-66.000,-66.000) |
geographic |
Antarctic Drake Passage Maud Rise Southern Ocean |
geographic_facet |
Antarctic Drake Passage Maud Rise Southern Ocean |
genre |
Antarc* Antarctic Drake Passage Ice Sheet Southern Ocean |
genre_facet |
Antarc* Antarctic Drake Passage Ice Sheet Southern Ocean |
op_relation |
Egan, Katherine E., Rickaby, Rosalind E.M., Hendry, Katharine R. and Halliday, Alex N. (2013) Opening the gateways for diatoms primes Earth for Antarctic glaciation. Earth and Planetary Science Letters, 375, 34-43. (doi:10.1016/j.epsl.2013.04.030 <http://dx.doi.org/10.1016/j.epsl.2013.04.030>). |
op_doi |
https://doi.org/10.1016/j.epsl.2013.04.030 |
container_title |
Earth and Planetary Science Letters |
container_volume |
375 |
container_start_page |
34 |
op_container_end_page |
43 |
_version_ |
1772810175893209088 |