Foraminifera, Isotopes and
Paleoclimate Signals
Shannon Valley
EAS 4480
April 23, 2015
What are foraminifera?
…and what can they tell us?
Isotope Ratios
δ18O in forams: #T, $δ18O
δ13C in forams: #productivity, $δ13C
Data and Methods
Core KNR 166-2 JPC 26 from the Florida Straits
3 benthic foram species:
Cibicidoides pachyderma Planulina ariminesis
Cibicides mollis
Data include depth/age model, δ18O and δ13C
Analyses: Linear Regression
Correlation Coefficient
Residual Analysis
Polynomial Fits
Time Series Analysis
Isthere a relationship between temperature and productivity evident in these species?
Can we
see evidence of past glaciations?
Linear Regressions with Error Bounds
P ariminesis
2.2
C mollis
1.8
1.6
2
1.4
1.8
1.2
1.6
1
1.4
0.8
1.2
0.6
1
0.4
0.8
0.6
0.8
0.2
1
1.2
1.4
1.6
1.8
2
2.2
2.4
0
1.3
2.6
1.4
1.5
1.6
1.7
C pachyderma
2
1.5
1
0.5
0
-0.5
0.5
1
1.5
2
2.5
1.8
1.9
2
2.1
2.2
2.3
Correlating productivity and
temperature
1.8
1.7
Species
Corr. Coef.
P. ariminesis
0.6272
1.5
C. mollis
0.4918
1.4
C. pachyderma 0.5742
1.3
1.6
1.2
1.1
1
0.9
0.8
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
Residual Analysis
1st Degree Residual Analysis, P ariminensis
1st order– P ariminensis
1.8
Critical value Χ2 value
1.6
1.4
21.03
173.2
1.2
1
0.8
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
P arimenisis Regression Residual Distribution
70
0.8
0.6
60
Residual
0.4
50
0.2
0
40
-0.2
-0.4
-0.6
0.8
30
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
20
10
0
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
nd
2
Degree Polynomial Fits
P ariminesis
2
P ariminesis
0.8
1.8
0.6
1.6
0.4
1.4
0.2
1.2
1
0
0.8
-0.2
0.6
-0.4
0.4
0.2
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
C mollis
1.8
-0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
C mollis
0.6
1.6
0.4
1.4
0.2
1.2
1
0
0.8
-0.2
0.6
0.4
-0.4
0.2
-0.6
0
-0.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2
2.1
2.2
2.3
-0.8
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2
2.1
2.2
2.3
nd
2
Degree Polynomial Fits C pachyderma
2
C pachyderma
0.8
1.8
0.6
1.6
0.4
1.4
0.2
1.2
0
1
0.8
-0.2
0.6
-0.4
0.4
-0.6
0.2
0
0.5
1
1.5
2
2.5
-0.8
0.5
1
1.5
2
2.5
P ariminesis Time Series
2.6
1.8
2.4
1.6
2.2
2
1.4
1.8
1.2
1.6
1.4
1
1.2
0.8
1
0.8
0
0.5
1
1.5
2
Age (yr BP)
2.5
3
0.6
3.5
4
#10
0
0.5
1
1.5
2
Age (yr BP)
2.5
3
3.5
4
#10
Power Spectrum for #; hifac=2; ofac=4.
20
18
16
14
Significant Periodicities (Yrs)
p = 0.001
12
Power
p = 0.005
p = 0.01
10
δ18O 17,173 4293 3523
δ13C 22,898 10,568 4432
p = 0.05
p = 0.1
8
p = 0.5
6
4
2
0
0
1
2
3
4
Frequency (Hz)
5
6
7
8
#10
-3
C mollis Time Series
2.3
1.6
2.2
1.4
2.1
2
1.2
?13C?
?18O?
1.9
1.8
1
1.7
0.8
1.6
1.5
0.6
1.4
1.3
1
1.5
2
2.5
3
0.4
3.5
#10 4
Age (yr BP)
1
1.5
2
2.5
3
Age (yr BP)
3.5
#10 4
p = 0.1
Power Spectrum for #; hifac=2; ofac=4.
6
p = 0.5
5
4
Power
Significant Periodicities (Yrs)
3
-
-
δ18O
δ13C 29,623 9875
2
1
0
0
0.5
1
1.5
Frequency (Hz)
2
2.5
#10-3
-
6348
C Pachyderma Time Series
2.5
1.8
1.6
1.4
2
?13C?
?18O?
1.2
1.5
1
0.8
0.6
1
0.4
0.2
0.5
0
0.5
1
1.5
2
2.5
3
Age (yr BP)
0
3.5
#10 4
0
0.5
1
1.5
2
2.5
Age (yr BP)
3
3.5
#10 4
Power Spectrum for #; hifac=2; ofac=4.
Significant Periodicities (Yrs)
50
δ18O 27,459 11,441 7268
δ13C 27,459 7226
5492
Power
40
5492
4291
3520
2214
1807
2921
-
-
-
-
30
20
p = 0.001
p = 0.005
p = 0.01
10
p = 0.05
p = 0.1
p = 0.5
0
0
0.001
0.002
0.003
0.004
0.005
Frequency (Hz)
0.006
0.007
0.008
0.009
0.01
Conclusions, Questions
Temperature is not shown to be an indicator of productivity
using these isotopes for these species. Why?
Time series analyses using these methods are inconclusive.
Records are too short for known periodicities.
Are the three species saying the same thing? Interpolation
for cpsd / cross spectral analysis may cause aliasing/ spectral
leakage.