Geoscience Reference
In-Depth Information
Fig. 3.3 Cross Section of the Escondida Lithology model, October 2001, N108400, looking north. Corresponds to the section line shown in Fig. 3.2
a
b
c
d
e
f
Pyrite shell. d ) The Top of Primary Mineralization (TPr) is interpreted
next. Three main sulphide volumes are thus generated e ) The Top of
Bornite (TBn) is interpreted next. f ) Additional “patches” are added
on, including above-TDS mineralization, Leached and Oxide remnants
within the enrichment blanket, and other isolated volumes
Fig. 3.4 Steps used in developing the Escondida Norte geologic
model. Courtesy of Minera Escondida Ltda. a ) Topography and the
interpretation of the Top of Dominant Sulfides (TDS) using prior min-
eralization models, an alteration model, and structural interpretations.
b ) The Top of Dominant Chalcopyrite (TDCpy) is interpreted next. c )
The Lateral Limits of the TDCpy establish the inner limit of the outer
mining engineers will usually plan the operation based on
benches. For vein-type deposits, it is likely that the most
important view will be cross sectional, although sometimes
along longitudinal views. A simplified interpretation would
skip one of the two sectional views, for example, the longitu-
dinal section. This may be acceptable for deposits in an early
stage of exploration.
An example of surface and volume modeling as done
for the Escondida Norte deposit is reproduced here with
permission from Minera Escondida Ltda and BHP Billiton.
Figure 3.4a - f shows the sequence of steps involved in pro-
ducing the mineralization model. A combination of surfaces
and three-dimensional shapes are used to define the different
volumes representing mineralization zones, including patch-
es and remnants of one type of mineralization within other.
Although only one set of sections is shown, this process is
repeated for orthogonal sections.
The minerals shown in these figures are OxCu (Copper
Oxides), Cup (Cuprite), OxFe (Iron Oxides), Chalcosite
(Cc), Covelite (Cv), Chalcopyrite (Cpy), Pyrite (Py), and
Bornite (Bn). The surfaces shown are Topography; TDS (Top
of Dominant Sulfides); TDCpy (Top of Dominant Chalcopy-
rite), TPr (Top of Primary Mineralization); and TBn (Top of
Bornite).
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