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