Sheila Trampush and Liz Hajek Evaluating the Effect of Autogenic Sedimentation on the Preservation of Climate Proxy Records: Modeling and Examples from the Paleocene Eocene Thermal Maximum Sheila Trampush and Liz Hajek

Global climate vs. local sedimentation Fluvial Coastal Shelf Colorado Wyoming New Jersey Maryland Foreman et al., 2012 Baczynski et al., 2013 Stassen et al, 2015 Self-Trail et al, 2012

Can landscape dynamics be responsible? Constant sedimentation = best preserved? High sedimentation = best preserved? Manners et al. (2013)

Landscape Dynamics High Sedimentation, High variability High Sedimentation, Low variability Fluvial Lacustrine Low Sedimentation, High variability Low Sedimentation, Low variability Coastal Shelf Deep Marine

(Double Pareto distribution) Stochastic Sedimentation Model Sedimentation Bed elevation Proxy signal Record 50 350 350 400 Mean sedimentation High: 30 cm/Kyr Low: 10 cm/Kyr 40 30 Density [%] Total Duration: 200 Kyr 300 250 250 20 10 Time [Kyr] Time [Kyr] Elevation [m] 200 Recovery: 180 Kyr -2 2 Annual event size [m] 150 150 (Double Pareto distribution) 100 year event: +/- 16 cm or 5 cm 1,000 year event: +/- 170 cm or 40 cm 10,000 year event: +/- 360 cm or 140 cm 100 Onset: 20 Kyr 50 50 Total model time: 350 ky 200 400 -6 -4 -2 2 -6 -4 -2 2 Elevation [m] δ13C [‰] δ13C [‰]

Example Synthetic Records Variable Preservation in All Models Proxy Example Synthetic Records 120 80 350 400 150 100 60 300 250 80 100 Time [Kyr] Elevation [m] 200 60 40 150 40 50 100 20 20 50 -6 -4 -2 2 -6 -4 -2 2 -6 -4 -2 2 -6 -4 -2 2 -6 -4 -2 2 δ13C [‰] δ13C [‰] δ13C [‰] δ13C [‰] δ13C [‰]

Variable Preservation in All Models Trampush & Hajek, in prep

Model Summary High Sedimentation, High variability High Sedimentation, Low variability Record Preserved: 88% (53%) Magnitude: -4.6‰ (-5.2 to -2.2‰) Onset: 15 Kyr (2 to 57 Kyr) Recovery: 131 Kyr (51 to 215 Kyr) High probability of modified record Record Preserved: 100% (89%) Magnitude: -5.0‰ (-5.2 to -4.5‰) Onset: 19 Kyr (3 to 46 Kyr) Recovery: 171 Kyr (116 to 215 Kyr) Highest probability of a good record Fluvial Lacustrine Low Sedimentation, High variability Low Sedimentation, Low variability Record Preserved: 69% (44%) Magnitude: -4.1‰ (-5.1 to -1.5‰) Onset: 10 Kyr (2 to 58 Kyr) Recovery: 117 Kyr (40 to 210 Kyr) Lowest probability of a good record Record Preserved: 87% (58%) Magnitude: -4.7‰ (-5.2 to -2.6‰) Onset: 16 Kyr (2 to 53 Kyr) Recovery: 138 Kyr (51 to 224 Kyr) High probability of a modified record Coastal Shelf Deep Marine

Ensemble records are more reliable 300 200 Time [Kyr] 100 -6 -4 -2 2 -6 -4 -2 2 -6 -4 -2 2 -6 -4 -2 2 -6 -4 -2 2 δ13C [‰] δ13C [‰] δ13C [‰] δ13C [‰] δ13C [‰]

Can landscape dynamics be responsible? Fluvial Coastal Shelf Colorado Wyoming New Jersey Maryland Foreman et al., 2012 Baczynski et al., 2013 Stassen et al, 2015 Self-Trail et al, 2012

Wide variety of records in fluvial and shelf environments Trampush & Hajek, in prep

Conclusions Preservation of proxy systems is sensitive to the sedimentation rate and variability Individual records can be very different from actual event, but averages of large numbers of records can recover the true event rates and durations The “body” of the PETM could be entirely an artifact of variable sedimentation (but it’s possible that it’s not)

Ensemble records are more reliable