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STABLE ISOTOPE RECORD OF SOIL CARBONATES FROM THE EOCENE-OLIGOCENE TRANSITION, BADLANDS NATIONAL PARK, SOUTH DAKOTA, USA M...
Eocene-Oligocene Tectonics Drake Passage Tasman Passage Tethys Sea 38 Myr = pole of rotation  changes, affecting global te...
Eocene-Oligocene Climate Global Mean Annual Temperature Dropped 5  0 C  Atmospheric CO 2  decreased substantially Marine e...
Goal of Research: <ul><li>Does North American terrestrial climate exhibit the same pattern as the global record? </li></ul...
Stable Isotope Crash Course <ul><li>Carbonate precipitates either biogenically or chemically in paleosols/sediments via th...
Zachos et al., 2001
Current Research Aims to answer question 1: Does North American terrestrial climate exhibit the same pattern as the global...
Field Methods <ul><li>Collection Permit obtained from park </li></ul><ul><li>Locations chosen for extensive previous sedim...
Results
Comparison to Global Climate
Key Findings <ul><li>Large variability in δ 18 O and δ 13 C in late Eocene and into the early Oligocene </li></ul><ul><li>...
Regional Comparison: Gulf Coast <ul><li>Different from Global Record </li></ul><ul><li>Fish otolith isotopes </li></ul><ul...
Key Findings <ul><li>Large variability in δ 18 O and δ 13 C in late Eocene and into the early Oligocene </li></ul><ul><li>...
Badlands Fossil Tooth Isotopes <ul><li>Zanazzi et al. 2007 examined stable isotopes from fossil teeth </li></ul><ul><li>La...
Badlands Chadronian NALMA <ul><li>Large, drab-haloed root traces </li></ul><ul><li>Thin Paleosols with fine root traces </...
Badlands Orellan NALMA <ul><li>Vegetation similar to Chadron </li></ul><ul><li>Hackberry endocarps </li></ul><ul><li>Large...
Conclusions <ul><li>Badlands National Park Paleosol carbonates bridge the gap between stable isotopic data from the Gulf C...
Conclusions <ul><li>Increased aridity and decreasing temperatures led to </li></ul><ul><ul><li>Breakup of canopy structure...
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Global Climate Change Effects on the Mid-Continent

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A Stable Isotopic Record for the Badlands National Park was obtained across the Eocene-Oligocene Transition (Greenhouse to Icehouse global climate change). The isotopic record indicates changes in temperature and aridity and allows for direct comparision of a local continental climate response to a global climate change event. Effect on regional biota are also described. This presentation was given at the GSA North-Central/South-Central Combined Meeting 2010.

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Global Climate Change Effects on the Mid-Continent

  1. 1. STABLE ISOTOPE RECORD OF SOIL CARBONATES FROM THE EOCENE-OLIGOCENE TRANSITION, BADLANDS NATIONAL PARK, SOUTH DAKOTA, USA Michelle R.D. Mullin, MS Candidate Richard H. Fluegeman, PhD Ball State University Department of Geological Sciences
  2. 2. Eocene-Oligocene Tectonics Drake Passage Tasman Passage Tethys Sea 38 Myr = pole of rotation changes, affecting global tectonics
  3. 3. Eocene-Oligocene Climate Global Mean Annual Temperature Dropped 5 0 C Atmospheric CO 2 decreased substantially Marine extinctions Development of large ice sheet on Antarctica
  4. 4. Goal of Research: <ul><li>Does North American terrestrial climate exhibit the same pattern as the global record? </li></ul><ul><li>How does the changing regional climate affect terrestrial biota? </li></ul>
  5. 5. Stable Isotope Crash Course <ul><li>Carbonate precipitates either biogenically or chemically in paleosols/sediments via the following equation: </li></ul><ul><li>Ca 2+ + 2 HCO 3 - -> CaCO 3 + CO 2 + H 2 O. </li></ul><ul><li>δ 18 O is the deviation of the oxygen isotope ratio (R= 18 O/ 16 O) of a sample from that for a standard, typically Pee Dee Belemnite (V-PDB). This is calculated as: </li></ul><ul><li>δ 18 O = 1000 x (R sample -R standard )/R standard </li></ul><ul><li>18 O is heavier than 16 O, evaporation would thus enrich oceans in 18 O </li></ul><ul><ul><li>More so as temperatures drop and ice volume expands </li></ul></ul><ul><ul><li>Enrichment in 18 O is described as “heavier”, δ 18 O becomes larger </li></ul></ul><ul><li>δ 13 C is the deviation of the carbon isotope ratio (R= 13 C/ 12 C ) of a sample from that of a standard: </li></ul><ul><li>δ 13 C = 1000 x (R sample -R standard )/R standard </li></ul><ul><li>δ 13 C is used as a proxy for water chemistry: sea level change, ventilation, nutrient influx, plant root respiration, atmospheric CO 2 </li></ul>
  6. 6. Zachos et al., 2001
  7. 7. Current Research Aims to answer question 1: Does North American terrestrial climate exhibit the same pattern as the global record?
  8. 8. Field Methods <ul><li>Collection Permit obtained from park </li></ul><ul><li>Locations chosen for extensive previous sediment characterization, biostratigraphy and magnetostratigraphy </li></ul><ul><li>Hand specimens collected at every calcareous layer, and some non-calcareous </li></ul><ul><li>Surface material scraped away, sample collected at depth </li></ul><ul><li>“ Lower Nodule” (LN) layer identified presence of Brule Formation </li></ul>Conata 1 Conata 2 Dillon Pass Chamberlain Pass
  9. 9. Results
  10. 10. Comparison to Global Climate
  11. 11. Key Findings <ul><li>Large variability in δ 18 O and δ 13 C in late Eocene and into the early Oligocene </li></ul><ul><li>Large shift in δ 18 O occurs </li></ul><ul><ul><li>Supports large drop in atmospheric CO 2 </li></ul></ul><ul><ul><li>Indicates temperature decrease in the Badlands </li></ul></ul><ul><li>Changes lag the marine record </li></ul><ul><ul><li>Decoupling of terrestrial and marine responses </li></ul></ul><ul><li>Increase in δ 13 C indicates increasing aridity </li></ul>
  12. 12. Regional Comparison: Gulf Coast <ul><li>Different from Global Record </li></ul><ul><li>Fish otolith isotopes </li></ul><ul><ul><li>Eocene summer temps~ 20°C, winter temps down to 13.5°C </li></ul></ul><ul><ul><li>Oligocene summer temps same winter temps dropped 4°C </li></ul></ul><ul><li>Ice volume influences </li></ul><ul><ul><li>Inverse P:B to d18O </li></ul></ul>
  13. 13. Key Findings <ul><li>Large variability in δ 18 O and δ 13 C in late Eocene and into the early Oligocene </li></ul><ul><li>Large shift in δ 18 O occurs </li></ul><ul><ul><li>Supports large drop in atmospheric CO 2 </li></ul></ul><ul><ul><li>Indicates temperature decrease in Gulf Coast </li></ul></ul><ul><li>Changes lag the marine record </li></ul><ul><ul><li>Decoupling of terrestrial and deep marine responses </li></ul></ul><ul><li>Increase in δ 13 C indicates increasing seasonality </li></ul><ul><li>Ice Volume played a significant role leading up to the E-O </li></ul>
  14. 14. Badlands Fossil Tooth Isotopes <ul><li>Zanazzi et al. 2007 examined stable isotopes from fossil teeth </li></ul><ul><li>Large drop in MAT (8.2°C +/- 3.1°C) over 400,000 years </li></ul><ul><li>Only small changes in increased temperature seasonality, no change in aridity. </li></ul><ul><li>Large shift in δ 18 O occurs </li></ul><ul><ul><li>Supports large drop in atmospheric CO 2 </li></ul></ul><ul><ul><li>Indicates temperature decrease in Gulf Coast </li></ul></ul><ul><li>Changes lag the marine record </li></ul><ul><ul><li>Decoupling of terrestrial and deep marine responses </li></ul></ul>
  15. 15. Badlands Chadronian NALMA <ul><li>Large, drab-haloed root traces </li></ul><ul><li>Thin Paleosols with fine root traces </li></ul><ul><li>Hackberry endocarps </li></ul><ul><li>Depth to calcic horizon = </li></ul><ul><li>500-1,000mm annual rain fall </li></ul><ul><li>Lacustrine Limestones </li></ul><ul><li>Savannah adapted mammal migration, largely from Asia </li></ul><ul><ul><li>Included dogs, camels, rhinos, pocket gophers, </li></ul></ul><ul><ul><li>beavers, squirrels, rabbits, and shrews </li></ul></ul><ul><li>Chadronian NALMA saw few extinctions, </li></ul><ul><li>but many immigrations </li></ul>Question 2: How does the changing regional climate affect terrestrial biota? <ul><li>Native groups that existed were horses and oreodonts </li></ul><ul><li>All make up the White River Chronofauna </li></ul>Allen Debus Allen Debus
  16. 16. Badlands Orellan NALMA <ul><li>Vegetation similar to Chadron </li></ul><ul><li>Hackberry endocarps </li></ul><ul><li>Large drab-haloed root traces </li></ul><ul><li>Cracked and veined paleosols </li></ul><ul><li>Fine root traces replacing former </li></ul><ul><li>wooded floodplain </li></ul><ul><li>Sub-humid climate </li></ul><ul><li>Calcite depth indicates ppt. was half that of Eocene </li></ul><ul><li>Streams became less frequent and more confined </li></ul><ul><li>Orellan NALMA, defined by FAD of Hypertragulus calcaratus </li></ul><ul><li>No major faunal break, though Archaic groups such as </li></ul><ul><li>brontothere, camel-like oromerycids and some rodents </li></ul><ul><li>died out </li></ul>Question 2: How does the changing regional climate affect terrestrial biota? <ul><li>First appearance of Leptomeryx eransi (deer-like ), </li></ul><ul><li>Palaeolagus intermedius (lagomorph ) and Miniochoerus chadronensis (oreodont) </li></ul><ul><li>Most mammals typical of the Chadronian persisted with minor changes in abundance </li></ul><ul><li>Selection pressures favored animals with teeth appropriate for chewing grasses </li></ul>Allen Debus Allen Debus
  17. 17. Conclusions <ul><li>Badlands National Park Paleosol carbonates bridge the gap between stable isotopic data from the Gulf Coast and fossil teeth of the Badlands. </li></ul><ul><li>Variability in the δ 18 O = decreasing atmospheric CO 2 was not the only </li></ul><ul><li>Influencing factor on terrestrial climate </li></ul><ul><ul><li>Paleotopography may have had a significant role. </li></ul></ul><ul><ul><li>Ice volume increases probably led to increasing aridity </li></ul></ul><ul><li>Large fluctuation in δ 18 O does indicate a significant drop in temperature </li></ul><ul><ul><li>Supports large drop in atmospheric CO 2 </li></ul></ul><ul><li>All three studies show that the δ 18 O shift lags the marine global record </li></ul><ul><ul><li>Decoupling of marine and terrestrial records </li></ul></ul>Question 1: Does North American terrestrial climate exhibit the same pattern as the global record? Answer: Somewhat
  18. 18. Conclusions <ul><li>Increased aridity and decreasing temperatures led to </li></ul><ul><ul><li>Breakup of canopy structure </li></ul></ul><ul><ul><li>Increasing grasslands </li></ul></ul><ul><li>Mammals underwent subtle changes </li></ul><ul><ul><li>Savannah adapted immigrants </li></ul></ul><ul><ul><li>Selection favored teeth appropriate for chewing grasses </li></ul></ul><ul><li>Reptiles and cold-blooded animals affected the most significantly </li></ul><ul><li>Middle Eocene fauna experienced a more dramatic decline </li></ul><ul><ul><li>Perhaps this is when the variability in temperatures began </li></ul></ul>Answer: Moderately Question 2: How does the changing regional climate affect terrestrial biota? <ul><li>Long term variability in temperatures and aridity likely increased selection </li></ul><ul><li>pressures throughout the Eocene- making a mass extinction less likely </li></ul>

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