Deep ocean carbonate ion increase during mid Miocene CO2 decline
Characterised by long term cooling and abrupt ice sheet expansion on Antarctica ~14 Ma ago, the mid Miocene marked the beginning of the modern ice-house world, yet there is still little consensus on its causes, in part because carbon cycle dynamics are not well constrained. In particular, changes in...
| Published in: | Scientific Reports |
|---|---|
| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | unknown |
| Published: |
Nature Publishing Group
|
| Subjects: | |
| Online Access: | http://hdl.handle.net/1885/57446 https://doi.org/10.1038/srep04187 https://openresearch-repository.anu.edu.au/bitstream/1885/57446/5/Yu_2014_Deep_ocean.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/57446/7/01_Kender_Deep_ocean_carbonate_ion_2014.pdf.jpg |
| Summary: | Characterised by long term cooling and abrupt ice sheet expansion on Antarctica ~14 Ma ago, the mid Miocene marked the beginning of the modern ice-house world, yet there is still little consensus on its causes, in part because carbon cycle dynamics are not well constrained. In particular, changes in carbonate ion concentration ([CO3(2-)]) in the ocean, the largest carbon reservoir of the ocean-land-atmosphere system, are poorly resolved. We use benthic foraminiferal B/Ca ratios to reconstruct relative changes in [CO3(2-)] from the South Atlantic, East Pacific, and Southern Oceans. Our results suggest an increase of perhaps ~40 μmol/kg may have occurred between ~15 and 14 Ma in intermediate to deep waters in each basin. This long-term increase suggests elevated alkalinity input, perhaps from the Himalaya, rather than other shorter-term mechanisms such as ocean circulation or ecological changes, and may account for some of the proposed atmospheric CO2 decline before ~14 Ma. |
|---|