This document discusses fluid inclusions, which are microscopic bubbles of liquid and gas trapped in minerals during their formation. Fluid inclusions can provide important information about the temperature, pressure, composition and other characteristics of the fluids present during mineral growth. The main types of fluid inclusions are primary, which formed during mineral crystallization, and secondary, which formed later in fractures. Studying fluid inclusions using petrography and microthermometry can help understand a rock's geologic history and aid mineral exploration.

1. Priya Verma
2nd semester
Msc Geology

2.  Fluid inclusion is a microscopic bubble of liquid &gases that is trappedin mineral .
 Range in size : 0.1- 1mm
 Visible in microscopic study
 Formed from defects in crystals during their growth which lead to the entrapment of
fluid in their surrounding.
 Trapped fluid maybe : liquid, vapour, or supercritical fluids.
 Host minerals are: Sphalerite, Cassiterite, Quartz,Calcite, Dolomite, fluorite , topaz
etc
 Somefeldspar in granite also contain fluid inclusion

4.  Vapour contains or liquid phase : H2O
 Gas phase: CO2,CH2,H2S,Cl,etc
 Solid phase: Na, K, Ca, Mg, Fe and their salt.
 E.g: NaCl

5. Classification of Fluid Inclusions:
It relates the timing of formation of the inclusion relative to that of the
host mineral (Bodnar, 2003). Based on their origin, fluid inclusions
are of following types:
• Primary
Secondary
• Pseudo secondary

6.  It is formed during the formation of the
enclosing crystal are primary in origin.
 Trapped along the growth zones and crystal
faces.
 Very good indicators of the condition of
crystallization.

7.  Trapped in the fractures which are developed after
the formation of host mineral.
 At the time of healing.
 Occur as trails or clusters
 Often cut across the grain boundaries.
 They can reveal the evolution of pressure,
temperature and chemistry of fluids.

10.  Trapped during formation of the host minerals.
 Occur along trails

11.  Commonly identified as primary or secondary on
the basis of detailed petrological study.
Single Crystal

12. Zoned crystal
• It provides important guides for identifying primary fluid
inclusion

13.  They are of 3 types:
Isolated,
Clustered,
Trail-Bound inclusion
• Isolated: Basically primary but additional criteria
are required to know about its principle nature.

14.  Clustered: typically comprised of a group of 10-20
neighbouring inclusions.
: may have quite different origins such as neighbouring
isolated cavities.
 Trail bound: It either remain confined to a single
mineral or cut across different grains or phases.

16.  Trapped fluid inclusions are sometimes modified because
of several processes subsequent to their trapping.
 It cause reduction in their volume, change in morphology
and often loss of originally trapped fluid.
 Some mechanisms are: Recrystallization
Stretching and Necking-down
Explosion Decrepitation
Leakage

17.  Sample Preparation
 Fluid Inclusion Petrography
 Microthermometry
 Raman Microprobe

19. Fluid inclusions provide a wealth of information on the
geofluids that influenced the petrogenesis of rocks.
Such inclusions provide important information:
Temperature of Entrapment of Fluid
Pressure of the Fluid System
Density of Fluids
Salinity of Fluids
Composition of Fluids
P-T History of the Sample
Gas Composition of the Inclusions

20.  The more direct uses of fluid inclusions in exploration
mainly rely on defining an empirical relationship between
some inclusion characteristic and mineralization.
 It is used for mineral exploration : for hydrothermal
deposits like, copper , gold, silver etc.

21.  If the hydrothermal fluid is highly saline, above
23% NaCl. Halite can crystallise upon cooling
with solid crystals present.
 Such fluids usually occur in porphyry copper
deposits or the core of igneous intrusion
derived fluid systems.
* Saline inclusions are less common.

22.  https://www.slideshare.net/VishakhaNathani
/fluid-inclusion-in-ores?qid=48e6bea9-
daff-4ddb-a8ff-
37262bdbceb0&v=&b=&from_search=2
 https://www.researchgate.net/profile/Kirtiku
mar_Randive/publication/275337661_Study_
of_Fluid_Inclusions_Methods_Techniques_and
_Applications