1. Reconstructing elevation histories using
13C-18O bonds in soil carbonates
Prosenjit Ghosh (CIT)
Carmala Garzione (Rochester)
John M. Eiler (CIT)

2. Pieces of the Isostatic Puzzle
Uplift
Elevation

3. Paleoaltimetry based on lava vesicle size
(Sahagian, 2002)

4. Botanical Paleoaltimetry
(Wolfe, 1995)
Variants:
• Multi-parametric correlations w/ T
• Multi-parametric correlation w/ enthalpy
• Physiognomic correlation w/ p(CO2)

5. ‘Conventional’ Stable Isotope Paleoaltimetry
(Drummond et al., 1993; Chamberlain et al. 1999; Garzione et al., 2002)
Measure
Derive ?
Guess

6. 13C-18O ‘clumping’ in calcite: Rigorous T measurement using isotopes
40Ca13C16O3 + 40Ca12C18O16O Ca12C16O3 + 40Ca13C18O16O2 .
~1000 (keq-1)
Harmonic, DFT-LDA-NCPP model; Schauble, pers. com.

7. Getting the ‘clumps’ out of the carbonate
CaCO3 + H3PO4 = gaseous CO2 + ‘CaO’ in dilute solution
In the absence of any analytical fractionation, ∆47 of product CO2
Should equal ∆[13C18O16O2-2] in reactant carbonate

8. Calibration using inorganic calcite and biogenic aragonite

9. The Altiplano — a 4 km high plateau in the central Andes
After Jordan et al., 1983

10. Two independent ‘votes’ on altitude
±1se Ma Ma
Today Ma Ma
±1se Ma
Today Ma

11. There must be something more we can do with
two independent constraints…

12. Combined T-d18Owater constraints on altitude of the Altiplano

13. Integrated uplift history of the Altiplano

14. Conclusions Geologic evolution of the Altiplano
• Plateau rose at 1.03 ± 0.12 mm/yr between 10.3 to 6.7 Ma
• This is 3x rate expected for crustal shortening driven by plate motions
• Implies altitude rise occurred in response to de-lamination of dense lower
crust and/or lithospheric mantle (?)
• Timing coincident with change in Nazca—SA convergence, slowing of
shortening across Altiplano, river incision, and other changes
Broader problem of paleoaltimetry
• ‘Clumped isotope’ approach appears capable of reconstructing altitude with
precision of ±200 to 400 m for groups of several samples
• Applicable to soil carbonates; should also be useful for lake sediments
• Should be tried in southern Altiplano, Tibetan plateau, Colorado plateau