At the outset on my personal behalf and on
behalf of the team I welcome you to this introductory
session of the lecture series on fluid inclusions
in minerals.
This is a little different type of lecture
series in the sense that it will not be based
on any particular subject, but it actually
be based on methodology technique that is
adopted by researchers in Geology.
So this lecture series essentially meant for
popularizing this technique and methodology
amongst undergraduate, graduate students,
and researchers, and professional geologists
in different organizations.
Like geological surveys other explorations
of agencies and this technique that we will
be discussing about is mostly more than about
accentuated half old and it has evolved into
a fair level of sophistication and with development
of the analytical facilities.
So we will be discussing about the fluid inclusions
that we see in minerals, the tiny objects,
but as it happens in many of the methodologies
that we adopt for studying rocks formed and
diverse geological settings.
We actually mean to address broader problems
of geological processes and this particular
technique also is helpful in terms of the
data that we generate in addressing issues
of broader processes, several outstanding
problems of formation of rocks, crustal evolution
and in particular that has been happening
in the geological past.
So we will essentially be describing these
tiny objects.
That you see in different minerals ores that
could be any mineral that forms in the earth
crust constituting rocks, quartz, calcite,
fluorite, apatite, feldspar, then metamorphic
minerals like garnet, cordierite, ore minerals
like the sulphites which can be observed in
a different technique.
So these are the tiny objects that will be
describing and discussing through these lecture
series and would actually be discussing as
to what kind of information.
We could retrieve from them and in what way
so essentially this lecture would be having
the 4 parts that we have mentioned: Its principals,
the methodology, the practice and the applications
to different areas of Geology.
So now before we go to study this fluid inclusion
we ask ourselves that why do we study fluid
inclusions are essentially why do we so let
us concerned about fluid because we know that
they are major substantial part of the earth
is constituting of fluids.
And there is fluid on the surface of atmosphere,
fluid is in the hydrosphere, rivers, and stagnant
water and in shallow ground water, in deeper
ground water and even up to extending up to
much greater depths in the mantle.
They are responsible in processes of metamorphism,
melting, deformation of rocks, and even has
very interesting surficial processes, formation
of the evaporites and even sometimes we also
do address the issues of the paleo atmosphere.
And study the fluid inclusion even in ice
cyrstals which formed in the addition geological
past.
So the techniques that we have employed to
study fluids that we could do it by an indirect
technique by studying the different minerals
in rocks and then try to indirectly approximate
or try to find, try to estimate the compositional
characteristics of the fluid that were there
during the formations of the rocks.
And the technique that we will employing here
essentially is the direct method of studying
the fluid, the paleo fluid by looking at the
inclusions in minerals in rocks which form
in several millions 100s or 1000s million
years ago in the geological past.
So this is a means by which we can directly
sample the fluid that we are interested in.
So then we will talk about what principal
that will be essentially be applying employing.
So we here we are more interested in studying
the behaviour of this fluids or the fluid
mixtures because we know that the fluid that
we are talking about dominantly constituted
of water, but has substantial amount of dissolved
non electrolytes and electrolyte species and
we need to understand the behaviour of this
complex fluids in different geological conditions
where pressure and temperature.
And other compositional characteristics like
fugacity of oxygen, fugacity of sulphur so
these are the compositional variables which
dictate the compositions of the fluid . So
we have to understand the basic we have to
employ very simple principals of chemical
thermodynamics or even more specifically the
principals of phase rules and the phase behaviour
of this fluid multi component multiphase fluid
and essentially.
What we essentially were to do is to understand
the pressure volume, temperature, composition
relationships of this complex fluid mixtures
and see that how we correlate them to the
occurrence of this fluid inclusions in minerals
and when we do this some experiments and then
the type of data that we retrieve how we are
going to correlate and how we use them in
understanding the broader processes.
So the methodology that we employ here is
to determine the fluid how what kind of experiments
that we do to understand the fluid characteristics
and the different thermal and chemical attributes
and so we do that by observing the response
of these tiny inclusions that we see in minerals
to heating and freezing experiments on what
we essentially called as microthermometry
and microanalysis of this fluid inclusions
to understand them.
To characterize them and to see what results
we get from them so that we can apply them
to understand broader processes.
So when we talk about practice means the very
simple very beginning that the way we will
sample the rock from the field of a any kind
of a rock that we have studying in a ore body
or a metamorphic rock so we discuss about
how to prepare the samples and then look at
this inclusions under microscope.\
Because they are tiny objects and we need
to study them in high magnification in normal
polarizing microscopes.
Sometimes we use specialized microscopes like
infrared microscopes and even techniques like
the scanning electromicroscope also is used
to characterize the fluid inclusions in the
totality and then how to plan, how to organize
the experiments like the heating treating
experiments of the micro thermometric experiments.
Then the data that we generate how we present
the data and then comes the applications that
we can apply to the problem that we have addressing.
It could be an ore body how it formed the
nature it could be the metamorphic rock of
any particular way in any crystal segment,
how the metamorphism took place or it evolved
under different changing conditions of physiochemical
conditions under what conditions the rocks
deformed.
And sometimes we are also interested in the
study of the ancient sediments of the basins,
the sedimentary involvements and even you
can apply this technique to see the hydrocarbon
which fluid in petroliferous basins and the
maturation of the ore compounds and also it
has been used in exploration for hydrocarbon
in petroliferous basins and also it is used
in exploration for it can be used in exploration
for mineral deposits.
And as I told sometimes even we can sample
this fluid inclusions in ice crystals which
form several hundreds of thousands years ago
and can talk about the change in conditions
of the atmosphere so that is how it makes
an interesting and very exciting technique
of methodology that is applied to across all
the almost many disciplines in geology and
I sincerely hope that the outcome of this
course will be very helpful and useful to
you.
Thank you very much.
