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3b. Calculate fO2 from melt ST for analyses from a csv file using default options

This time, instead of creating a dataframe in a cell for the analysis, we’ll read it in from a spreadsheet.

Python set-up

You need to install VolFe once on your machine, if you haven’t yet. Then we need to import a few Python packages (including VolFe)

# Install VolFe on your machine. Don't remove the # from this line!
# pip install VolFe # Remove the first # in this line if you have not installed VolFe on your machine before.

# import python packages
import pandas as pd
import matplotlib.pyplot as plt
import VolFe as vf

Import data

We’ll use the examples_marianas_wT csv in files and use all the default options again and we’ll do the calculation at Pvsat (i.e., we don’t know the pressure).

The data in this file are from Brounce et al. (2014) and Kelley & Cottrell (2012).

# Read csv to define melt composition
my_analyses = pd.read_csv("../files/example_marianas_wT.csv")

Run the calculation

Calculate only for the first row

There are a few analyses in the csv. First, we will tell the function to stop after the first analysis by saying last_row=1:

# runs the calculation
vf.calc_melt_S_oxybarometer(my_analyses,last_row=1)

	sample	T ('C)	H2OT-eq_wtpc	CO2T-eq_ppmw	ST_ppmw	X_ppmw	P (bar) sulf	S2- SCSS	sulfide saturated?	DFMQ-sulfide	...	KHOSg opt	KOSg opt	KOSg2 opt	KCOg opt	KCOHg opt	KOCSg opt	KCOs opt	carbonylsulfide opt	density opt	Date
0	TN273-01D-01-01	1200	1.88	13	362.83	0		422.089182	no		...	Ohmoto97	Ohmoto97	ONeill22	Ohmoto97	Ohmoto97	Moussallam19	Holloway92	COS	DensityX	2024-07-13 18:12:06.185911

1 rows × 67 columns

Calculate for all rows

To run all the analyses, simply don’t tell it the last row you want to run.

All analyses must be in consequitive rows for this to work!

At the end it will show the dataframe of the full results.

# runs the calculation
results = vf.calc_melt_S_oxybarometer(my_analyses)

Calculate for particular rows

If we only want to run row 4 (Agr07-4) through 18 (AGR19-02-16) in that spreadsheet, we simply specify the first and last rows we want to run (remembering that row 2 in a spreadsheet - i.e., the first analysis under the headings - is actually row 0 in the dataframe).

results2 = vf.calc_melt_S_oxybarometer(my_analyses,first_row=2, last_row=17)

Plotting

We can plot Pvsat vs. fO2 for all the analyses

fig, (ax1) = plt.subplots(1, 1, figsize=(4,4))

# Plotting data

data1 = results[results['DFMQ-sulfide'] != ""] # all calculations
data2 = results2[results2['DFMQ-sulfide'] != ""] # 4 to 18

ax1.plot(data1['DFMQ-sulfide'],data1['P (bar) sulf'], 'ok', mfc='blue')
ax1.plot(data2['DFMQ-sulfide'],data2['P (bar) sulf'], 'ok', mfc='red')

ax1.set_xlabel('DFMQ')
ax1.set_ylabel('P (bar)')
ax1.set_ylim([4500, 0])

(4500.0, 0.0)