Geology Reference
In-Depth Information
Table 10.5: Mineralogical composition of the crepuscular crust. - continued
from previous page.
Mineral
Formula
mass, %
Polixene/
Tetraferroplat-
inum
PtFe
2.00E-10
Wohlerite
NaCa
2
Zr
0:6
Nb
0:4
Si
2
O
8:4
(OH)
0:3
F
0:3
5.05E-11
End of the table
10.3.3.2 Reliability of the model
As stated in Valero D. et al. (2010a), the composition of the crepuscular crust is
far from certain. However, since the crust will not be empirically explored in such
detail as to provide more accurate experimental data (at least not in the short
to medium term), one can rely on indirect results. Furthermore, if the data of
Rudnick and Gao (2004) is accepted as the most reliable and Grigor'ev's results
adapted accordingly to ensure a satisfactory mass balance between both models,
only three questions remain. One, given that the crepuscular crust is based on the
model of Grigor'ev (2007), did he consider enough samples to form an accurate
depiction of the entire crust? Two, since the authors had the challenge of a sparse
matrix with independent variables differing by more than 12 orders of magnitude,
is the resolution procedure of the Crepuscular Earth Model the most reliable
13
?
And three, is the list of additional geological hypotheses used to make the matrix
squared consistent?
That said, despite the need for further lines of enquiry and the fact that the
results are obtained through a mathematical model rather than experimentally, this
procedure ensures that there is coherence between the results of Grigor'ev (2007)
with those of Rudnick and Gao (2004). Table 10.5 is thus proposed as the model
of Thanatia for the evaluation of the loss of the mineral endowment on Earth for
each of the 78 elements listed. It will no doubt be improved as and when better
earth system models, geochemical and geological information appear, as has already
occurred with the chemical composition of the existing crust models.
10.4 The difference between Thanatia and the reference
environment
The concept of Thanatia could be easily confused and wrongly used as a reference
environment instead of a baseline. Therefore, in this section, the differences between
both approaches and their respective necessity are explained.
The reference environment, the most commonly used of which is that of Szargut
(1989), is well established within the literature as a tool for chemical exergy cal-
13
Note that a 40% error in a very rare mineral is less significant for the bulk composition of the
crust than a 0.001 percent error in a very common one such as quartz.
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