Carbonate isotope geochemistry • isogeochem

isogeochem makes working with stable oxygen, carbon, and clumped isotope data straightforward and reproducible. It offers tools to quickly calculate:

carbonate δ¹⁸O, δ¹⁷O, ∆₄₇, and ∆₄₈ values at a given temperature
carbonate growth temperatures from δ¹⁸O, ∆₄₇, and ∆₄₈ values
isotope fractionation factors, e.g., carbonate/water, quartz/water
model DIC speciation as a function of temperature, pH, and salinity
convert between the VSMOW and VPDB scales

The list of available proxy–temperature calibrations is growing with each new released version. Please get in touch if you have suggestions to include!

Getting started

Installation

Install the released version of isogeochem from CRAN.

install.packages("isogeochem")

Install the development version of isogeochem from GitHub.

if (!require("devtools")) install.packages("devtools")
if (!require("rmarkdown")) install.packages("rmarkdown")
devtools::install_github("davidbajnai/isogeochem", build_vignettes = TRUE)

Vignettes

Case studies demonstrating the use and scope of the functions in isogeochem are available as vignettes.

browseVignettes("isogeochem")

Dual clumped isotope thermometry

Use D47() and D48() to calculate equilibrium carbonate clumped isotope values (∆₄₇, ∆₄₈) for a given temperature. temp_D47() calculates carbonate growth temperatures from ∆₄₇ values, while temp_D48() calculates growth temperature corrected for kinetic effects considering both the ∆₄₇ and the ∆₄₈ value.

if (!require("shades")) install.packages("shades")

# Model equilibrium carbonate ∆47 and ∆48 values
temp  = seq(0, 100, 10) # temperature range: 0—100 °C
D47eq = D47(temp, eq = "Fiebig21")
D48eq = D48(temp, eq = "Fiebig21")

# Sample data
D47_coral  = 0.617; D47_coral_err  = 0.006
D48_coral  = 0.139; D48_coral_err  = 0.022
D47_speleo = 0.546; D47_speleo_err  = 0.007
D48_speleo = 0.277; D48_speleo_err  = 0.029

## Plot in ∆47 vs ∆48 space ##
plot(0, type = "l", axes = TRUE, ylim = c(0.4, 0.7), xlim = c(0.1, 0.3),
     ylab = expression(Delta[47] * " (CDES90, ‰)"),
     xlab = expression(Delta[48] * " (CDES90, ‰)"),
     lty = 0, font = 1, cex.lab = 1, las = 1)

# Plot the equilibrium curve and points
lines (D48eq, D47eq, col = "purple", lwd = 2)
points(D48eq, D47eq, col = shades::gradient(c("blue", "red"), length(temp)),
       pch = 19, cex = 1.2)

# Plot the sample data,
# ... the kinetic slopes,
# ... and calculate growth temperatures corrected for kinetic effects
# ... using a single function!
temp_D48(D47_coral, D48_coral, D47_coral_err, D48_coral_err, ks = -0.6,
         add = TRUE, col = "seagreen", pch = 15)
#>   temp temp_err
#> 1   38        6
temp_D48(D47_speleo, D48_speleo, D47_speleo_err, D48_speleo_err, ks = -1,
         add = TRUE, col = "darkorange", pch = 17)
#>   temp temp_err
#> 1   30        9

# Add labels to the plot
text(D48(temp, eq = "Fiebig21"), D47(temp, eq = "Fiebig21"), paste(temp, "°C"),
     col = shades::gradient(c("blue", "red"), length(temp)), pos = 4, cex = 0.8)

Triple oxygen isotopes

d17O_c() calculates equilibrium carbonate oxygen isotope values (δ¹⁸O, δ¹⁷O, ∆¹⁷O) for a given temperature and ambient water composition. Use the mix_d17O() function to calculate mixing curves in triple oxygen isotope space, e.g., for modeling diagenesis.

if (!require("shades")) install.packages("shades")

# Model equilibrium *calcite* precipitating from seawater
temp_sw  = seq(0, 50, 10) # temperature range: 0—50 °C
d18O_sw = 0 # d18O value of seawater
D17O_sw = -0.004 # D17O value of seawater
d18Op = prime(d17O_c(temp_sw, d18O_sw, D17O_sw, eq18 = "Daeron19")[, 1])
D17O  = d17O_c(temp_sw, d18O_sw, D17O_sw, eq17 = "Wostbrock20", eq18 = "Daeron19")[, 3]

# Model progressing meteoric diagenetic alteration
d18O_ds = -8 # d18O value of diagenetic fluid
D17O_ds = 0.020 # D17O value of diagenetic fluid
em_equi = d17O_c(temp = 10, d18O_H2O = d18O_sw, D17O_H2O = D17O_sw,
                 eq17 = "Wostbrock20", eq18 = "Daeron19") # equilibrium endmember
em_diag = d17O_c(temp = 80, d18O_H2O = d18O_ds, D17O_H2O = D17O_ds,
                 eq17 = "Wostbrock20", eq18 = "Daeron19") # diagenetic endmember
mix = mix_d17O(d18O_A = em_equi[1], d17O_A = em_equi[2],
               d18O_B = em_diag[1], d17O_B = em_diag[2], step = 25)

## Plot in ∆17O vs d'18O space ##
plot(0, type = "l", ylim = c(-0.1, 0.05), xlim = c(-10, 40), 
     xlab = expression(delta * "'" ^ 18 * "O (‰, VSMOW)"),
     ylab = expression(Delta ^ 17 * "O (‰, VSMOW)"),
     lty = 0, font = 1, cex.lab = 1, las = 1)

# Plot meteoric waters from the build-in dataset
points(prime(meteoric_water$d18O), D17O(meteoric_water$d18O, meteoric_water$d17O),
       col = "lightblue1", pch = 20)
text(-4, 0.05, "meteoric water", pos = 4, col = "lightblue1")

# Plot the composition of the fluids
points(prime(d18O_sw), D17O_sw, col = "darkmagenta", pch = 8) # seawater
text(prime(d18O_sw), D17O_sw, "seawater", pos = 4, col = "darkmagenta")
points(prime(d18O_ds), D17O_ds, col = "deeppink", pch = 8) # diagenetic fluid
text(prime(d18O_ds), D17O_ds, "diagenetic fluid", pos = 4, col = "deeppink")

# Plot the equilibrium curve and points
lines(d18Op, D17O, col = "darkmagenta", lwd = 2)
points(d18Op, D17O, pch = 19, cex = 1.2, 
       col = shades::gradient(c("blue", "red"), length(temp_sw)))
text(d18Op, D17O, paste(temp_sw, "°C"), pos = 4, cex = 0.8, 
     col = shades::gradient(c("blue", "red"), length(temp_sw)))
text(30, -0.05, paste("equilibrium calcite \nfrom seawater"),
     pos = 3, col = "darkmagenta")

# Plot the mixing model between the equilibrium and diagenetic endmembers
lines(prime(mix[, 1]), mix[, 2], col = "deeppink", lty = 3, lwd = 2)
points(prime(mix[, 1]), mix[, 2], pch = 18, cex = 1.5, 
       col = shades::gradient(c("#3300CC", "deeppink"), length(mix[, 2])))
text(prime(mix[, 1]), mix[, 2], paste(mix[, 3], "%", sep = ""), pos = 2, cex = 0.8, 
     col = shades::gradient(c("#3300CC", "deeppink"), length(mix[, 3])))
text(22, -0.09, paste("progressing", "\ndiagenetic alteration", "\n(recrystallisation) at 80°C", sep =""),
     pos = 2, col = "deeppink")

Thermometry

Use isogeochem to calculate crystallization temperatures from carbonate δ¹⁸O and ∆₄₇ values.

# Temperature from D47 with or without errors
temp_D47(D47_CDES90 = 0.601, eq = "Petersen19")
#> [1] 24.9
temp_D47(D47_CDES90 = 0.601,
         D47_error = 0.008 ,
         eq = "Anderson21")
#>   temp temp_err
#> 1 22.6      2.7

# Temperature from d18O
temp_d18O(
  d18O_c_VSMOW = 30,
  d18O_H2O_VSMOW = 0,
  min = "calcite",
  eq = "Watkins13")
#> [1] 25.9

Fractionation factors

Use isogeochem to calculate ¹⁶O/¹⁸O fractionation factors at given temperatures.

if (!require("viridisLite")) install.packages("viridisLite")

plot(0, type = "l", las = 1, yaxt = "n", 
     xlim = c(10, 30), ylim = c(-30, 50),
     xlab = "Temperature (°C)",
     ylab = expression("Equilibrium enrichment in "^18*"O relative to H"[2]*"O (‰)"))
axis(2, seq(-30, 50, 10), las = 1)

temps = seq(10, 30, 1)
d18O_H2O_VSMOW = 0
cols = viridisLite::viridis(7, option = "C")

text(10, 45, expression("CO"[2]*" (aq)"), col = cols[1], adj = c(0, 0))
lines(temps, A_from_a(a18_CO2aq_H2O(temps), d18O_H2O_VSMOW),
      lwd = 2, lty = 2, col = cols[1])
text(10, 35, expression("HCO"[3]^"–"), col = cols[2], adj = c(0, 0))
lines(temps, A_from_a(a18_HCO3_H2O(temps), d18O_H2O_VSMOW),
      lwd = 2, lty = 2, col = cols[2])
text(10, 30, "calcite", col = cols[3], adj = c(0, 0))
lines(temps, A_from_a(a18_c_H2O(temps, "calcite", "Daeron19"), d18O_H2O_VSMOW),
  lwd = 2, lty = 1, col = cols[3])
text(10, 21, expression("CO"[3]^"2–"), col = cols[4], adj = c(0, 0))
lines(temps, A_from_a(a18_CO3_H2O(temps), d18O_H2O_VSMOW),
  lwd = 2, lty = 2, col = cols[4])
text(10, 1, expression("H"[2]*"O"), col = cols[5], adj = c(0, 0))
lines(temps, rep(d18O_H2O_VSMOW, length(temps)),
      lwd = 3, lty = 1, col = cols[5])
text(10, -23, expression("OH"^"–"), col = cols[6], adj = c(0, 0))
lines(temps, B_from_a(a18_H2O_OH(temps, eq = "Z20-X3LYP"), d18O_H2O_VSMOW),
  lwd = 2, lty = 1, col = cols[6])

Utility functions

# Convert between the VSMOW and VPDB scales:
to_VPDB(32)
#> [1] 1.05032
to_VSMOW(1)
#> [1] 31.95092

# Convert between classical delta and delta prime values:
prime(10)
#> [1] 9.950331
unprime(9.95)
#> [1] 9.999666

# Calculate isotope fractionation factors:
a_A_B(A = 30.40, B = 0.15)
#> [1] 1.030245
epsilon(a_A_B(A = 30.40, B = 0.15))
#> [1] 30.24546

Datasets

Within isogeochem you have quick access to important datasets.

Name	Description	Reference
`devilshole`	The original Devils Hole carbonate δ¹⁸O time series	Winograd et al. (2006)
`LR04`	A benthic foraminifera δ¹⁸O stack	Lisiecki & Raymo (2005)
`GTS2020`	An abridged version of the GTS2020 oxygen isotope stack	Grossman & Joachimski (2020)
`meteoric_water`	A compilation of meteoric water δ¹⁸O and δ¹⁷O values	Barkan & Luz (2010), Aron et al. (2021)

For more information on the datasets please have a look at the corresponding documentation, e.g., ?devilshole

License and citation

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License version 3, or (at your option) any later version. This program is distributed in the hope that it will be useful, but without any warranty.

Follow the citation format provided in CITATION when referencing isogeochem.

isogeochem:
Tools for Stable Isotope Geochemistry

Getting started

Installation

Vignettes

Dual clumped isotope thermometry

Triple oxygen isotopes

Thermometry

Fractionation factors

Utility functions

Datasets

License and citation

See also

isogeochem: Tools for Stable Isotope Geochemistry

Getting started

Installation

Vignettes

Dual clumped isotope thermometry

Triple oxygen isotopes

Thermometry

Fractionation factors

Utility functions

Datasets

License and citation

See also

isogeochem:
Tools for Stable Isotope Geochemistry