STABLE ISOTOPE RECORD OF SOIL CARBONATES FROM

THE EOCENE-OLIGOCENE TRANSITION, BADLANDS NATIONAL PARK, SOUTH

DAKOTA, USAMichelle R.D. Mullin, MS Candidate

Richard H. Fluegeman, PhDBall State University Department of Geological

Sciences

Greenhouse to Icehouse

Global Mean Annual Temperature Decreased

Changing oceanic circulation patterns

Marine extinctions

Development of large ice sheet on Antarctica

Zachos et al., 2001

Eocene-Oligocene Tectonics

Drake Passage Tasman Passage

38 Myr = pole of rotation 38 Myr = pole of rotation changes, affecting globalchanges, affecting global tectonicstectonics

Cause of Global Climate Change?

• Atmospheric decrease in CO2

OR

• Thermal isolation of Antarctica

Gulf Coast Not In Sync With Global Record

Eocene–Oligocene global climate and sea-level changes: St. Stephens Quarry, AlabamaKenneth G. Miller*,1, James V. Browning1, Marie-Pierre Aubry1, Bridget S. Wade ,1, Miriam E. Katz ,1, Andrew A. Kulpecz1 and James D. Wright1

GSA Bulletin; January 2008; v. 120; no. 1-2; p. 34-53; DOI: 10.1130/B26105.1

Miller et al., 2008

Goal of Research:• Does North American terrestrial climate

record exhibit the same pattern as the regional Gulf Coast record or the global record?– Can the mid-continent record help decipher the

cause of global climate change?

• How does the changing mid-continent climate relate to the White River faunal extinctions?

Badlands Paleosol Isotope Study

Badlands National ParkTertiary Stratigraphy

Field MethodsConata 1 Conata 2 Dillon Pass

Chamberlain Pass

• Collection Permit obtained from park• Locations chosen for extensive previous

sediment characterization, biostratigraphy and magnetostratigraphy

• Hand specimens collected at every calcareous layer, and some non-calcareous

• Surface material scraped away, sample collected at depth

• “Lower Nodule” (LN) layer identified presence of Brule Formation, and correlated to Magnetostratigraphy

Conata Picnic Area -1Conata 1

Eocene-Oligocene Contact

MM-21

MM-20

MM-17

MM-15

Conata Picnic Area -2Conata 2

LN Zone

Eocene-Oligocene Contact

MM-13

MM-22

MM-2

MM-14

MM-5

MM-7

MM-9

Chamberlain Pass

Top of Section

LN Zone

Top of Chadron

Eocene-Oligocene Boundary

MM-25MM-27

MM-32MM-51MM-54

Chamberlain Pass Continued

MM-65

MM-68

MM-71

MM-69

MM-67

MM-64

MM-57

MM-59, MM-60

27

Dillon PassDillon Pass

Eocene-Oligocene Contact

SILCRETE

MM-47

MM-49

MM-42

MM-34MM-36

MM-39MM-42

Chalcedony ledge, top of Chadron

Stable Isotope Crash Course• Carbonate precipitates either biogenically or chemically in paleosols/sediments

via the following equation:Ca2+ + 2 HCO3

- → CaCO3 + CO2 + H2O. • δ18O is the deviation of the oxygen isotope ratio (R=18O/16O) of a sample from

that of a standard, typically Pee Dee Belemnite (V-PDB). This is calculated as:δ18O = 1000 x (Rsample-Rstandard)/Rstandard

• 18O is heavier than 16O, evaporation would thus enrich oceans in 18O– More so as temperatures drop and ice volume expands– Enrichment in 18O is described as “heavier”, δ18O becomes larger

• δ13C is the deviation of the carbon isotope ratio (R=13C/12C ) of a sample from that of a standard:

δ13C = 1000 x (Rsample-Rstandard)/Rstandard

• δ13C is used as a proxy for water chemistry: sea level change, ventilation, nutrient influx, plant root respiration, atmospheric CO2

Results

E-O Boundary (2.95m)

E-O Boundary (4.5m)

Key Findings

•Large variability in δ18O and δ13C in late Eocene and into the early Oligocene

•Positive shift in δ18O (Oi-1) occurs after the E-O boundary•Indicates temperature decrease in the Badlands•Supports large drop in atmospheric CO2

•Positive shift in δ13C indicates increasing aridity

Magnetostratigraphy1998

=Chamberlain Pass

=Dillon Pass =Conata Picnic Area

Comparison to Global Climate

RESEARCH QUESTION #1:

• Does North American terrestrial climate record exhibit the same pattern as the global record?– What are the implications regarding the cause

of climate change?

E-O Boundary (4.5m)

E-O Boundary (2.95m)

Key Findings

•Variability of the paleosol late Eocene record does not match the global record

•Indicates that decreasing atmospheric CO2 levels are not the only controlling factor on terrestrial climate

•Positive shift in δ18O (Oi-1) occurs in both records•Indicates decreased temperatures•Supports large drop in atmospheric CO2

•Terrestrial Oi-1 lags the marine Oi-1•Decoupling of terrestrial and marine responses

RESEARCH QUESTION #1:

• Does North American terrestrial climate record exhibit the same pattern as the Gulf Coast record?– What are the implications regarding the cause

of climate change?

Regional Comparison: Gulf Coast

Eocene–Oligocene global climate and sea-level changes: St. Stephens Quarry, AlabamaKenneth G. Miller*,1, James V. Browning1, Marie-Pierre Aubry1, Bridget S. Wade ,1, Miriam E. Katz ,1, Andrew A. Kulpecz1 and James D. Wright1

GSA Bulletin; January 2008; v. 120; no. 1-2; p. 34-53; DOI: 10.1130/B26105.1

E-O Boundary (4.5m)

E-O Boundary (2.95m)

•Fish otolith isotopes•Summer temps~ 20°C, winter temps down to 13.5°C•Increased aridity

•Ice volume influences

Key Findings

•Variability in δ18O and δ13C of both records•Indicates that decreasing atmospheric CO2 levels are not the only controlling factor on terrestrial climate

•Positive shift in δ18O and δ13C occurs in both records•Supports large drop in atmospheric CO2

•Indicates increasing aridity

•Terrestrial Oi-1 lags the marine Oi-1•Decoupling of terrestrial and deep marine responses

Badlands Fossil Tooth Isotopes• Zanazzi et al. 2007 examined stable isotopes

from fossil teeth• Large drop in MAT (8.2°C +/- 3.1°C) over

400,000 years• Only small changes in increased temperature

seasonality, no change in aridity.

•Positive shift in δ18O (Oi-1) agrees with paleosol and Gulf Coast

•Supports large drop in atmospheric CO2

•Terrestrial Oi-1 lags the marine Oi-1•Decoupling of terrestrial and deep marine responses

•Disagrees with paleosol and Gulf Coast in terms of aridity

•Variability in the δ18O = decreasing atmospheric CO2 was not the onlyInfluencing factor on terrestrial climate

•Paleotopography may have had a significant role.•Ice volume increases probably led to increasing aridity

•Positive shift in δ18O does indicate a significant drop in temperature•Supports large drop in atmospheric CO2

•Does North American terrestrial climate record exhibit the same pattern as the regional Gulf Coast record or the global record?

•Can the mid-continent record help decipher the cause of global climate change?

Conclusions to Question 1

•Paleosol record matches the global record in magnitude and direction of the δ18O shift

•Paleosol record matches the Gulf Coast record in the variabilty through the late Eocene,the magnitude and direction of the δ18O shift, and the lag in regional response

Badlands Chadronian NALMA

Allen Debus•Savannah adapted mammal migration, largely from Asia•Included dogs, camels, rhinos, pocket gophers, •beavers, squirrels, rabbits, and shrews

•Chadronian NALMA saw few extinctions, but many immigrations

Allen Debus

Question 2: How does the changing mid-continent climate relate to the White River faunal extinctions?

•Native groups that existed were horses and oreodonts

•All make up the White River Chronofauna

•Cold blooded fauna were preferably selected against

•Fish kill horizons•Ostracode death horizons

Badlands Orellan NALMA•Orellan NALMA, defined by FAD of Hypertragulus calcaratus

•No major faunal break, though Archaic groups such as brontothere, camel-like oromerycids and some rodents died out

Allen Debus

Allen Debus

•First appearance of Leptomeryx eransi (deer-like), Palaeolagus intermedius (lagomorph)and Miniochoerus chadronensis (oreodont)•Most mammals typical of the Chadronian persisted with minor changes in abundance, such as the subhyracodon

•Selection pressures favored teeth appropriate for chewing grasses

•New appearances of mammals had high-crowned teeth for eating tough vegetation

Conclusions to Question 2

•Savannah adapted immigrants arrived in the Eocene•Added to climatic variability pressures

•The terrestrial Oi-1 event occurs after the Chadronian-Orellan NALMA

Answer: Moderately

•Long term variability in temperatures and aridity likely increased selection pressures throughout the Eocene

How does the changing mid-continent climate relate to the White River faunal extinctions?

Summary•Variability in the δ18O = decreasing atmospheric CO2 was not the onlyInfluencing factor on terrestrial climate

•Paleotopography may have had a significant role.•Ice volume increases probably led to increasing aridity

•Positive Shift in δ18O does indicate a significant drop in temperature•Supports large drop in atmospheric CO2

•The terrestrial Oi-1 record lags the marine Oi-1 global record•Decoupling of marine and terrestrial records

•The Chadronian-Orellan NALMA occurs before the terrestrial climate shift

•Long term variability in temperatures and aridity likely increased selection pressures throughout the Eocene

Acknowledgements