COMPUTER APPLICATION IN SOLVING PETROLOGICAL PROBLEMS

1. COMPUTER APPLICATION IN SOLVING
PETROLOGICAL PROBLEMS

2. CONTENTS:
 Introduction
 Instruments used for Petrological analyses
 Solving problems using MS Excel
 Software used in Geology
 Conclusion
 Reference

3. INTRODUCTION

4. COMPUTER APPLICATION IN
GEOLOGY
 It is used to make the problems easier
 Four major computer –oriented techniques are used -
*Statistics
*correlation and classification
*Trend analysis
*Simulation
Computers made the analyses much more rapid and
complete than work done by the physical model.
The techniques were also known from before but they
were too complicated before computers became readily
available.

5.  Some of the instruments which are used are:
1. Electron Probe Micro Analyzer(EPMA)
2. X-ray Fluorescence Spectrophotometer (XRF)
3. Atomic Absorption Spectroscopy (AAS)
4. Fourier Transform Infrared Spectroscopy (FTIR)
5. X-ray Diffraction Spectrophotometer (XRD)
Instruments used for
petrological analyses

6. EPMA:
 EPMA is a micro beam instrument used primarily to non-
destructively determine the chemical composition of minute
solid samples.
 Primary importance of an EPMA is the ability to acquire
precise, quantitative elemental analysis at very small spot
sizes, primarily by wavelength-dispersive spectroscopy
(WDS)

7. APPLICATION OF EPMA
 Quantitative EPMA analysis is the most commonly used
method for chemical analysis of geological materials at small
scales.(10-30 cubic micrometer)
 It gives history of the crystal’s formation
 EPMA is chosen in cases where individual phases need to be
analysed e.g., igneous or metamorphic minerals.
 Used in Elemental mapping to find out the concentration of
various element in minerals.
 Chemical age dating of minerals to determine the age of
crystallisation & later deformation.

8. CONT…..
 Significance of mineral analysis-
a) to obtain the wt% of different oxides in minerals
thereby calculating the structural formula of
minerals
b) to know the mineral chemistry
c) to estimate the P-T conditions of metamorphism

9. XRF(X-RAY FLUORESCENCE
SPECTROPHOTOMETER):
 X-ray is absorbed by the atom or scattered through the
material when it hits a sample.The process is known as
“Photoelectric effect”
 Measurement of heavy metals in soils,sedimemts,water and
aerosols. Qualitative and quantitative analysis of
soil,minerals and rock.

10. AAS(ATOMIC ABSORPTION
SPECTROSCOPY):
 AAS is a technique for determining the
concentration of a particular metal element present
in a sample.
FTIR(FOURIER TRANSFORM
INFRARED SPECTROSCOPY ):
 Experimental technique for determining
qualitative mineral identification.

11. XRD(X-RAY DIFFRACTION
SPECTROPHOTOMETER):
 It is used for the identification of crystalline minerals.
 Analysis is accomplished by determining the inter
atomic spacing.
 It is the definitive test in the detection and
quantification of silica and its polymorphs.

12.  Results obtained from the mineral analyses using the
analytical instruments are Stored and processed using various
computer softwares.
 Out of these, I am dealing mainly with the application of
Microsoft Excel in solving petrological problems.
Excel is applied mainly for :
2. Structural formula calculations
3. Norm calculations
5. Plottings
Application of Softwares
1. Mineral analyses (results)
4. P-T calculations

13. Mineral analyses (results) for different
minerals
plag- plagioclase
ortho-orthoclase
bioti-biotite
garnet
amphi-amphibole
Analyses results are
stored in an excel file

14. Major elemental analyses (results) for different
rocks
Analyses results are stored in an excel file

15. Structural formula calculation using MS-
Excel
Here structural formula calculation is done for plagioclase

16. Calculated structural formula of various minerals
using MS-Excel

17. INPUT OUTPUTCIPW NORM
calculations

18. Mineral chemistry diagrams plotted using
computer softwares (Excel, Tridraw)

19. Variation diagrams using MS-
Excel

20. Triangular Plottings using MS-
Excel helps in demarcating the
different environments of rock
formation.
Plottings using MS-Excel, there
by determining the actual
composition of the analysed rock

21. Plottings and calculations using MS-Excel
worksheet

22. P-T calculations (using MS-Excel
programmes)
 Pressure-Temperature of metamorphism are determined with
the help of various P-T models using Microsoft excel.
 Excel programme calibrated by different authors for various
thermobarometric models are used to determine the P-T.
 Some of the P-T models are:
e.g: Garnet-Biotite thermometric model (T)
Hornblende-plagioclase thermobarometry (P-T), etc.

23.  Here we are giving the input (respective cations) for the garnet and biotite mineral
assemblage from the analysed rock sample.
Garnet-Biotite thermometry using Ms
Excel

24.  Here we will get the result (temperature) of equilibrium between garnet and
biotite i.e. Metamorphic temperature.
Rs-112, etc are the sample name
B92-HW,Dasg91 etc are the thermometric models by different authors.
Cont..... Garnet-Biotite thermometry using
Ms Excel

25. BELOW ARE A FEW GEOLOGY RELATED
COMPUTER PROGRAMS
 CSpace - graphical and algebraic analysis of data representing
compositional coordinates
 Domino-Theriak - calculate and plot thermodynamic functions,
equilibrium assemblages and assemblage diagrams
 DRAWxtl - display crystal structures
 EQS4WIN- chemical equilibrium solver
 FABRIC7- analysis of structural and strain data
 GeoOrient -structural geology, stereograms, rose diagrams
 Geo Chemical Data Toolkit -a system for handling and
recalculation of whole-rock data
 JCcrystalsoft-Crystallographic software for educational and
research purposes

26. CONT……..
 PHREEQC - latest version of USGS aqueous geochemical
modeling program
 SIGEOL - GIS tool
 SinCris - Crystallographic Software Database
 SOLVCALC - ternary feldspar solvus and two-feldspar
geothermometry
 AMP-TB - amphibole thermobarometry for calc-alkaline
magmas
 Petro.calc.plot
 Petrograph
 Tridraw – plotting ternary diagrams
 Origin – plotting variation diagrams, ternary diagrams,etc.

27. CONT….
 BLF and MIXNFRAC -Roger Nielsen's magmatic
differentiation programs
 NIH Image - Image Analysis
 Eridas Imagine- For GIS related work.
 AX-Win- Structural formula calculations
 Arc View- GIS software
 Thermocalc- P-T plottings, preparing Pseudosections,
etc.
 Noddy - 3D Structural Modeling
 Ortep - crystal structure visualization
 Paleomag - paleomagnetic plotting
 Poly3D - Structural Geology and Geomechanics
Simulation

28. CONCLUSION
 Computer is an electronic device that receive input
from the user and processed it in a fashion and
displays the result on the screen.
 Different softwares are installed for solving specific
problems.
 Computers are used in all fields in geology
 MS EXCEL is a software which uses spreadsheet for
calculation.It features graphing tools and pivot
tables.

29. REFERENCE
 http://en.wikipedia.org/wiki/MS Excel
 http://serc.carleton.edu/research_education/geochemsheets/techn
 http://www.newport.com/Introduction-to-FT-IR-Spectroscopy/40
 http://en.wikipedia.org/wiki/X-
ray_scattering_techniques