The advantage of this package is that the plots already have the geotectonic field boundaries on them. The disadvantage is that the plots are not directly linked to a spreadsheet or database; and consequently the spreadsheet data must be converted to an external file (.ROC file) with a special ascii format, and also be reconverted every time the data set is updated. This disadvantage is mitigated by the fact that Newpet will allow you to modify the data file it uses while you are in Newpet. However, if the modifications are permanent, you will need to remember to update your spreadsheet once you have left Newpet.
The authors of NEWPET have provided a data set of major element analyses representing most major rock types. The data is contained in a file called IGNEOUS.ROC. If you have not already done so, please copy this file to your B: drive diskette. It is this file which will be imported into NEWPET for this week's exercise.
The plots that are of interest to us are those contained in the 'X-Y, Ternary plots' menu, viz.:
1) plots of major elements (Majors Discrimination Plots).
2) plots of trace and minor elements (Trace Discrimination Plots).
3) plots useful in discriminating between different types of granites (Granitoid Discrimination Plots).
In a subsequent laboratory exercise we will use the menu 'Normalized REE plots or SPIDERGRAMS'.
The NewPet program and the data files are located in the folder ‘Mapped drive\Public\Es300b\Newpet on Earthnt’. Make a note of the drive letter attributed to the mapped drive. Click the ‘My Computer’ icon (or NT Explorer) and select Public\Es300b on Earthnt, and then the subdirectory (folder) ‘NewPet’. To implement ‘NewPet’ double click the ‘Newpet.exe’ file. The NewPet DOS window will appear. (If Newpet does not appear in a full window, either 1) click the top of the window with the right mouse button; click properties, click screen, and click 'Full Screen' in the Display Options box to have the DOS window displayed as a 'Full Screen'; or 2) create a short cut to Newpet.exe and set the screen properties of the shortcut icon to 'Full Screen'.
When New pet is displayed as a full screen, press any key to continue.
Cursor to the plot option 3 'NewDisc discrimination X-Y, Ternary plots’ and press ENTER. A 'Discrimination Plots' menu will appear. Cursor down to the 'Get a data file' line and press the ENTER key. If the mapped drive letter does not correspond to that shown in the instruction "Press ENTER for default data directory: ?\NEWPET", enter the drive letter e.g. G, and then add the path 'Es300b\Newpet'. In the NewPet folder select ‘igneous.roc’ and press the ENTER key.
You will be returned to the 'Discrimination Plots' menu, on which will be shown a choice of plotting procedures (e.g. Majors Discrimination plots.). Cursor to Majors Discrimination plots, and press ENTER. You will be provided with the following set of plotting possibilities:
SiO2 - Na2O + K2O (rock classification)
SiO2 - K2O (K variation in andesite)
Alkali - FeO - MgO (Tholeiitic, Calc-alkaline)
SiO2 - Alkali (Alkaline, Subalkaline)
Al2O3 - FeO+TiO2 - MgO (PK, BK, CB, CA, CD, CR; TB, TA, TD, TR, HFT, HMT)
SiO2 - FeO/MgO (Tholeiite, Calcalkaline)
FeO/MgO - FeO (Thol, Mac, TH, CA, Am)
FeO/MgO - TiO2 (Thol, Am)
MnO - TiO2/10 - P2O5 (OIA, OIT, MORB, IAT, CAB)
MgO - FeO - Al2O3 (Spreading Centre Island; Orogenic; Ocean Ridge and Floor; Ocean Island; Continental)
If you were to choose the Traces Discrimination plots option, you would be presented with the options:
Zr/4 - Nb*2 - Y (WPA, WPT, PMORB, NMORB, VAB)
log Cr - log Ti (OFB, LKT)
Zr - Ti (OFB, LKT, CAB)
Zr - Ti/100 - Y*3 (WPB, OFB, LKT, CAB)
Zr - Ti/100 - Sr/2 (OFB, IAB, CAB)
log Zr - log Zr/Y (Within Plate, Island arc, Mid-ocean Ridge)
Ti/100 - V (arc, OFB)
Nb/Y - Zr/Ti (rock classification)
log Zr/Ti - SiO2 (rock classification)
and in the 'Granitoid Discrimination Plots' we might use:
Log Y - Log Nb (WPG, ORG, VAG + synCOLG)
In the 'Major Discrimination Plot' menu, first select the plot SiO2 - Na2O + K2O (rock classification) and follow the screen instructions. All the samples in the database igneous.roc will be displayed. Note that the program allows you the option of highlighting the data one sample at a time (the sample symbol flashes and the name of the sample appears in the lower left part of the window).
To plot individual samples or groups of samples according to name or symbol select 'Choose samples to Plot'. The new menu will present you with the option of plotting data by symbol (Set Plot Symbol Flag) and/or by name (Set Plot Sample Name Flag). In the 'Symbol' part of the menu, FIRST select 'Reset all samples' and then enter 'D' (upper case D) in response to the 'Do you wish to [P]lot samples or [D]on't plot' query, in order to negate the previous choice of samples selected for plotting. Next choose 'Individual samples'. A list of the sample records will be shown. Select the samples you want to plot by using the space bar and the cursor down key. Press ESC to exit the menu, and enter '[P]' in response to the 'Do you wish to [P]lot or [D]on’t plot' query that will automatically appear at this point.
Repeat the operation for the 'Set Plot Sample Name Flag' option, if you wish to have the sample name plotted as well as the symbol. (If samples have been grouped by symbol, they can also be plotted as a group by choosing the 'Symbol' option.) Select 'Quit to Main Menu', and choose a plotting option for the data you have chosen, e.g. SiO2 - Na2O + K2O.
Examine other plotting schemes for major elements. In particular look at the distribution of rock types in the TiO2 v FeO/MgO plot. Note that the rock types tend to form two trends, one exhibiting a tendency for TiO2 to decrease with increasing FeO/MgO, the other the converse. Using the option to plot the samples one at a time, list on a piece of paper the rock types that exhibit one or the other tendency, or to be indeterminate. Indicate those rock names you recognise and those that you do not.
Rocks samples in the IGNEOUS.ROC data set:
"Adamellite" "Andesite" "Anorthosite" "Basalt" "Basanite" "Dacite" "Diabase" "Diorite" "Dolerite" "Dunite"
"Gabbro" "Granite" "Granodiorite" "Harzburgite" "Hawaiite"
"Latite" "Monzonite" "Mugearite" "Nepheline syenite" "Nephelinite""Norite"
"Peridotite "Phonolite "Pyroxenite",
"Rhyodacite" "Rhyolite" "Syenite"
"Tephrite" "Tonalite" "Trachy-andesite" "Trachy-basalt" "Trachyte".