readme

(Magma Classification Major-element based System)

README A computer program MagClaMSys available from http://tlaloc.ier.unam.mx/hmgclamsys for the classification of igneous rocks in terms of four magma types:

ultrabasic, basic, intermediate, and acid. Simulation modelling confirmed the

robustness of our classification with respect to analytical errors and post-emplacement compositional changes. From robustness considerations, our proposal for the nomenclature of altered igneous rocks is shown superior to the IUGS scheme which was recommended for the classification of relatively fresh rocks only.

The interested person is invited to enter the web server http://tlaloc.ier.unam.mx (see Fig. 1a). If you are a new user, you must register and provide the information requested: first name, last name, institutional email address and affiliation as shown in Fig. 1b. If you do not have an institutional email account, you must provide all institutional details. Afterwords, the user will then receive an e-mail message with a temporary password, which can be changed. If you are a registered user, you must sign in using your email address and password (see Fig. 1c).

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Fig. 1 Welcome screen of web server and user authentication. (a) Welcome screen of web server; (b) The screen to create a new account; and (c) The screen to user authentication.

As a registered user, you may use the “MagClaMSys_ilr” option of “Online program” menu as shown in Fig. S2.

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Fig. 2 “HMgClaMSys_ilr” options of “Online program” menu.

Once you access the online program MagClaMSys_ilr, you can open an input file, for which there are three options as shown in Fig. 3a: (i) Magma Type; (ii) Sensitivity analysis; and (iii) Analytical errrors_Uncertainty Propagation. The literature sources of the igneous rocks are summarized in pdf file available (link identified by a blue rectangle: “Download MagClaMSys DatabaseInfo”; see Fig. 3a). You can download each of several input file folders available from web server (see Fig. 3b): “InputFile_MagClaMSys.xls”, “PropUcM_Format”, “Sensitivity_Ultrabasic”. These templates are required for testing the different processing options. At least the user must download the input file “InputFile_MagClaMSys.xls” as shown in Fig. 3b (link identified by a blue circle and an arrow).

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(b) Fig. 3 Menu options and input files available. (a) Three options of “Open file” menu; and (b) Input files available for download.

Optionally you can download the file “Applications” (Fig. 4a; ten files) and “Sediments” (Fig. 4b; five files) and “Test” (Fig. 4c; five files) folders. Altogether, twenty documents are available in these folders (Fig. 4a-c).

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Fig. 4 Input files available for download from web server. (a) “Applications” folder; (b) “Sediments” folder; and (c) “Test” folder.

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New multidimensional magma type classification scheme based on major elements

MagClaMSys offers a set of 10 discriminant functions and 5 diagrams to facilitate magma type classification. The user must download the input file “InputFile_MagClaMSys.xls” as shown in Fig. 3b (link identified by a blue circle and an arrow). If you downloaded this file click on the “Download (30k)” hyperlink to download the input file as shown in Fig. 5a (identified by a red circle). Once the download is successfully completed, click on the downloaded file (identified by a blue circle in Fig. 5a) to open it as shown in Fig 5b. MagClaMSys requires 10 oxides from SiO2 to P2O5 (see Fig 5b). It is important to note that the measured data are input with total Fe as Fe2O3T. If you do not have Fe2O3T values, please calculate it as follows (it is immaterial if you have either FeOT or separately FeO and Fe2O3, the equation will give you the Fe2O3T value; * means multiplication): Fe2O3T = Fe2O3 + (FeO * 159.6882 / (2 * 71.8444) ) From the measured major element compositions, MagClaMSys efficiently calculates the adjusted values on an anhydrous 100% basis.

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(b) Fig. 5 Download of input file “InputFile_MagClaMSys.xls”. (a) Hyperlink to download the file; and (b) View the contents of the file in Excel.

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In this case, we will use “T1_Honolulu_Clague.xls” test file (see Fig. 6a-b) to explain how the program works. This file is available in “Test” folder. The user can download this file from web server (see Fig. 6a).

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(b) Fig. 6 Download of test file “T1_Honolulu_Clague.xls”. (a) Hyperlink to download the file; and (b View the contents of the file in Excel.

After saving the download file to a location on your computer, you must open the “T1_Honolulu_Clague.xls” file as shown in Fig. 7.

Fig. 7 Open file option of MagClaMSys.

If everything is fine, the file will open as shown in Fig. 8.

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Fig. 8 Input data file already open and validated in MagClaMSys.

Once the Excel input data file is correctly loaded without errors, the user can process the data using “Process Magma-Type” as shown in Fig. 9a. After the job is done, the user can download the general report (Fig. 9b).

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(b) Fig. 9 Process Magma-Type option to be chosen.

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The general report contains: 

Classification summary, adjusted major element concentrations and Log-transformed ratios of individual samples (see Fig 10a).

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The discriminant function (DF1-DF2) values for five diagrams for the classification of magma type as ultrabasic, basic, intermediate, and acid; see Fig 10b.

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The probability values for the four magma types (1—ultrabasic; 2—basic; 3—intermediate; 4—acid); see Fig 10c.

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(c) Fig. 10 The Excel output file contains: (a) Classification summary, adjusted major element concentrations and log-transformed ratios of individual samples; (b) The detailed results of discriminant function (DF1-DF2) for five diagrams; and (c) The probability values for the four magma types (1—ultrabasic; 2—basic; 3—intermediate; 4—acid).

2. Robustness of the new multidimensional classification scheme based on major elements with respect to post-emplacement compositional changes The maximum loss or gain (% m/m) of an element in the centroid composition is estimated as the value that will still give the same magma or rock type as determined from our multidimensional diagrams. However, the minimum and maximum changes possible for any given element are also automatically set for that particular element to show final concentrations between 0% (no concentration can become negative) and 100% (no concentration can be >100% m/m). Therefore, our sensitivity analysis was carried out within these two limits for the final composition, although more stringent conditions could be used in future. To try this option, the user must download the “Sensitivity_Ultrabasic.xls” file (Fig. 11a). This template contains the composition (Fig. 11b) of the centroid of all 1671 ultrabasic rocks to estimate the post-emplacement compositional changes of SiO2 at a time in the classification of magma type as ultrabasic, basic, intermediate, and acid

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(a) Fig. 11 Template available for sensitivity analysis.

If you downloaded successfully the template “Sensitivity_Format.xls”, you can click on “Sensitivity analysis” option of “File Open” menu (see Fig. 12).

Fig. 12 “Sensitivity analysis” option of “File Open” menu.

Once the Excel input data file is correctly loaded without errors, the user can proceed to run the sensitivity analysis. MagClaMSys provides two options in the “Process File” menu as in Fig. 13. “Sensitivity Magma Type” option performs sensitivity analysis of MagClaMSys.

Fig. 13 “Sensitivity Magma Type” option of “Process File” menu.

After the job is done, the user can download (click on link identified with blue circle in Fig. 14a) and open the sensibility report (see Fig. 14b).

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(a) Fig. 14 Sensibility report. (a) The sensibility process is done; (b) Sensibility report opened.

Thus, you are free to input your own sample replacing the concentration values in the example file (Fig. 10b). You can similarly choose any element(s) for loss, gain or no change by simply inputting -1, 1 or 0 for that element(s).

3. Robustness of the new multidimensional classification scheme based on major elements with respect to analytical errors To illustrate the robustness of MagClaMSys, we used major element compositions of three reference materials (basalt JB-1, basalt JB-1a, and andesite JA-3). These files are available in “Reference Material PropuC” folder (see Fig. 15a). You can download these three files (“Andesite JA-3.xls”, “Basalt JB-1a.xls” and “Basalt JB-1.xls”; see Fig. 15b) to use this simulation module.

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Fig. 15 Selected samples for sensitivity analysis with respect to analytical errors. (a-b) Templates of 3 selected samples.

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In this case, we will use “Andesite JA-3.xls” file (see Fig. 16) to explain how this module program works. The mean and total uncertainty values for this geological material were used to simulate a large number of analyses (2200 + 1 initial analysis) from the Monte Carlo simulation procedure. The 2201 analyses from the initial inter-laboratory data were processed from our new multidimensional procedure (MagClaMSys_ilr) and compared with the conventional IUGS approach. “Andesite JA-3.xls” file contains the mean and total uncertainty values for JA-3 geological material (see Fig. 16).

Fig. 16 View the contents of the “Andesite JA-3.xls” file in Excel.

In order to simulate this sample (Fig. 16), you must download the ““Andesite JA-3.xls”.xls” file. After, you must open this file as shown in Fig. 17a (click on the option identified with red circle). Once the Excel input data file is correctly loaded without errors, the user can proceed to simulate the sample as a shown in Fig. 17b (click on the option identified with red circle). After the process is done, the user can download the general report as a shown in Fig. 17c (click on the output file identified with blue circle).

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(c) Fig. 17 Process “Sensitivity Uncertainty Propagation” option to be chosen.

The Excel output file contains: classification summary, initial concentration and adjusted concentrations (see Fig 18a), logtransformed ratios of individual samples, detailed results of discriminant function DF1-DF2 (see Fig 18b), and probability values for the four magma types (1—ultrabasic; 2—basic; 3—intermediate; 4—acid) (see Fig 18c). MagClaMSys showed that the inferred magma type is consistent with the rock name (intermediate for andesite JA-3; see 18a) for all 2200 simulated analyses.

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Fig. 18 The Excel output file contains: (a) first section; (b) second section; and (c) third section.

You are free to input your own sample replacing the concentration values in the example file and changing the uncertainty or %RSD values (see Fig. 16).

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