Chemistry Reference
In-Depth Information
a) homogeneous trapping
b) heterogeneous trapping
cogenetic inclusions
shrinkage
immiscible
liquids
L
1
L
2
L
1
L
2
L
1
L
V
L
2
saturation
L
1
L
2
L
1
L
2
L
1
V
V
S
S
L
V
L
1
L
2
L
2
L
1
S
unmixing
boiling solution
L
1
L
2
L
unmixing &
saturation &
shrinkage
L
V
L
V
L
unmixing &
saturation
unmixing &
shrinkage
saturated solution, suspended solids
S
2
S
1
L
1
S
V
L
2
S
L
1
L
2
L
1
V
L
2
S
1
S
2
S
1
L
V
L
V
ii In these samples, identify the different inclusion-containing minerals.
If the rock contains quartz, this mineral will in principle contain most
inclusions. This gives a first indication (if quartz does not contain work-
able inclusions, better do something else. But quartz traps easily many
inclusion generations, which might be quite difficult to study properly.
If inclusions are found in other minerals (apatite, garnet, pyroxenes,
feldspars), then their study might be much more simple and rewarding.
iii Experiences shows that, in most rocks, the apparent complexity of mil-
lions of inclusions resolves in a small number (typically less than 5, most
commonly 1 or 2) of fluid types, a fluid type being defined by a rela-
tively constant chemical composition and a limited variation in density
(for details, see the fluid inclusion literature).
iv Once a fluid type has been identified, most important is to evaluate
its homogeneity or heterogeneity (described in the inclusion literature
as homogeneous
versus
heterogeneous trapping, see Table below (from
Van den Kerkhof & Hein, 2010). For aqueous fluids, the only ones
which can be studied for this purpose without specialized equipment,
homogeneity is immediately indicated by a constant volume ratio of
the different phases: degree of fill (Liquid/total) (for pure water giving
immediately the density), solid/liquid, etc… If the timing of the fluid
trapping is known, then the interpretation of homogeneous fluid system
is immediate, in first approximation (homogenization temperature for
H
2
O evaluated from the degree of fill).
