Supplementary Data for "Accumulation of radiocarbon in ancient terrestrial landscapes: A small but significant input of unknown origin"
This study examined the organic carbon content of ~28-33 Ma paleosols. The files in this data set include the raw TG-DSC-EGA data generated with a laboratory instrument, and serve as supplemental materials to the corresponding manuscript. Thermal and Evolved Gas Analysis raw data for two paleosol samples (Luca and Kskus pedotypes from Retallack et al. 2000) are reported here. A Setaram Labsys Evo differential scanning calorimeter (DSC) / thermal gravimeter (TG) connected to a Pfeiffer Omnistar quadrupole mass spectrometer (QMS) was configured to operate similarly to the SAM evolved gas analyzer. The SAM instrument does not have TG/DSC capabilities, but these components permit a better understanding of phase transitions and chemical reactions in laboratory experiments. Approximately 50 mg ± 3 mg of ground paleosol sample were placed in an Al2O3 sample crucible. The sample crucible and an identical empty reference crucible were placed in the furnace and then the system was purged twice with helium gas and set to a pressure of 30 mbar. Helium was chosen as a carrier gas because it is inert and because it used as a carrier gas in the SAM instrument. The crucibles were heated from approximately 35 °C to 1000 °C at a heating rate of 35°C/min and at a flow rate of 10 sccm. Volatiles ranging from mass/charge (m/z) 1 - 100 were measured Retallack, G.J., Bestland, E.., and Fremd, T.., 2000, Eocene and Oligocene Paleosols of Central Oregon: Geological Society of America Special Paper, v. 344, p. 1–192, doi:10.1046/j.1365-3091.2001.0394c.x.
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Data were imported into Igor Pro 7.0 and background-corrected to account for atmospheric composition. All EGA plots were generated in Igor. CO2 peak area was calculated by importing data into Origin Pro. Total organic carbon was quantified by deconvolving CO2 peaks if a carbonate-C peak was present. This was done by determining the relative percentage of peak area from inorganic carbon-evolved CO2 (~700-900° C) then subtracting this value from total carbon-evolved CO2 peak area to solve for TOC.