Minera Gold Ltd.: Ground Magnetic Survey and 3D Model Increases Size and
Enhances Prospectivity of 100% Owned Tumi Au/Cu Project
PERTH, AUSTRALIA -- (Marketwired) -- 01/28/14 -- Minera Gold Ltd.
(ASX: MIZ) -
-- The potential of the Tumi breccia is materially enhanced by the
discovery of a magnetic low feature that can be clearly identified from
the magnetic survey up to 400m vertical depth.
-- Magnetic anomalies point to a much wider hydrothermal system related to
gold and copper disseminated mineralisation hosted in numerous breccia
outcrops surrounding a new magnetic high anomaly measuring 600m x 800m.
The Directors of Minera Gold Ltd. ("Minera Gold" or the "Company") are
pleased to announce the results of the ground magnetic geophysical
studies conducted at our Tumi disseminated gold and copper project,
in southern Peru. The magnetic survey results are a follow up to the
maiden trenching, sampling and drilling exploration results contained
in our ASX release dated 19 July 2013.
The work conducted at the end of the December 2013 and in early
January 2014 confirmed the presence of extensive mineralization at
the main Tumi breccia target in the known outcrops and also
identified a separate large anomaly immediately to the north of the
Tumi breccia as shown in Figure 1.
To view Figure 1 please visit the following link:
Material findings from the survey and 3D model interpretation are
-- The main Tumi breccia, being the initial priority target, clearly
appears as a magnetic low feature in the data products and the model
results, suggesting magnetite destruction/depletion in the mineralised
breccia. The results of surface sampling carried out on the breccia were
released in an announcement dated 19 July 2013. Importantly, the
geophysics has proven the that two larger breccia outcrops within the
400m x 400m breccia target area are connected, and measure 200m x 250m
on surface and approximately 400m deep. Further work is required to
confirm that all four known breccia outcrops located within the target
area are connected as one system. It should also be noted also the
absence of high susceptibilities in the 3D model below the Tumi breccia
indicates that there is potential for the breccia to continue to extend
-- The most prominent magnetic feature detected during the survey is a
separate magnetic high anomaly interpreted to be caused by intrusive
rocks to the immediate north of the Tumi breccia. The causative magnetic
body is a new anomaly measuring approximately 600m x 800m in size. The
preliminary interpretation considers this feature to be associated with
the main Tumi breccia.
-- A further material implication of this geophysical study is that the
hydrothermal system, due to its intrusive phase, is much wider than
previously thought based upon the scarcity of previously known outcrops.
Four new outcrop areas have now been identified and are currently being
sampled to confirm the potential limits of the mineralised system.
-- In particular, field work carried out over the weekend on one newly
identified breccia located in the middle of the magnetic high anomaly
that contains visible copper oxides and quartz veinlets and geologically
has very close similarities to the main Tumi breccia target. This new
target is currently being sampled with samples to be sent for assaying
in the coming weeks.
Dr. Alex Losada-Calderon, Chairman of Minera Gold, commented, "These
results enhance the prospectivity of our Tumi project to host
significant disseminated gold and copper mineralisation. The
potential of the main Tumi breccia has now been verified following
the release of the surface results in July 2013 which included 27
trench samples that returned an average grade of 2.16g/t Au, 0.6g/t
Ag and 0.1% Cu. The excitement around the result of the geophysics
work is also attributable to the identification of four new breccia
outcrops surrounding the new large prominent magnetic feature that
all warrant future exploration that will allow us to better interpret
the geological model at Tumi and define a JORC compliant exploration
target for the project this quarter."
"We are now planning a RC drill program to test the outcropping
breccia targets in the coming months. In order to better define the
drill locations for the numerous targets that were identified by the
magnetic survey and are under cover, we are commencing mapping and
sampling programs together with further geophysical studies," he
The Tumi project is located approximately 35km from our flagship
asset, the Torrecillas Gold Project and is approximately 6 km inland
from the Pan American Highway and Pacific Ocean at an altitude of
between 200m and 1200m (Figure 2).
To view Figure 2 please visit the following link:
Zissou Peru SAC completed a ground magnetic survey over part of the
Tumi Project in December 2013. Lubbe Geophysics Inc. from Florida,
USA, was contracted to process, model and interpret the geophysical
Forty-seven (47) NE striking (N45 degrees E) traverses were completed
for approximately 67 line kilometres. Original line spacing was
designated to be 60 metres, however the extreme topography present in
portions of the area made maintaining straight survey lines difficult
and resulted in varying line spacing across the survey area (Figure
3). Geophysical equipment and procedures are given in Appendix 1 and
in further detail in Appendix 2.
To view Figure 3 please visit the following link:
The Coastal Batholith rocks (monzonite and monzogranites) have
intruded Jurassic sediments consisting of continental sediments and
conglomerates, which in turn are overlain by a sequence of andesite
and breccias. The above mentioned units are covered by eluvium and
alluvial sand and conglomerate deposits for the majority of the area
Mineralisation occurs in a cluster of four outcropping hydrothermal
breccia's containing Au with Cu and Ag. These breccia outcrops are
located with a 400m x 400m perimeter, with the principal zone of the
Tumi breccia outcrops being traced over an area of 70m x 60m;, and a
second zone measuring 20m x 10m meter (located about 400m west and
250m below the principal zone). Two short diamond drill holes (90m
and 72.5m lengths) were completed in the Tumi breccia in 2007 with
re-assayed results reported in July 2013.
Mineralisation also occurs in narrow high grade gold veins. Informal
miners at the project are currently extracting gold from a vein (the
Tumi 1 Vein) that has been traced for a strike length of about 700m.
Geophysical survey results:
The total range of the magnetic amplitude in the survey area is
approximately 500 nT. NW striking (Andean) linear features are
visible in the data with less clear NE striking lineaments
interrupting the Andean parallel trends (Figure 4). Delineating NE
striking features with this survey is problematic since the survey
lines are in this direction.
To view Figure 4 please visit the following link:
A magnetic anomaly that appears to have a remnant magnetisation
component is located in the NW quadrant of the survey area. The
anomaly has an amplitude of approximately 400 nT and is the only
robust, magnetic feature in the survey area. The varying nature and
amplitude of magnetic responses seen elsewhere in the survey area are
common in both intrusive and volcanic rocks.
The 3D analytic signal calculation (Figure 5) is quite useful at low
magnetic latitudes since the magnitude or amplitude of the analytic
signal is nearly independent of the magnetization direction. This
derivative result is good at mapping the limits of magnetic bodies -
the main magnetic anomaly is well defined by the analytic signal.
The larger portion of the main magnetic anomaly is located within a
valley and has been correlated with some outcrops of oxidized and
hydrothermally altered monzogranite - monzodiorite rocks.
To view Figure 5 please visit the following link:
A case can be made that the subdued magnetic values associated with
the Tumi breccia (drill holes are marked in grey in Figure 5) are
indicative of magnetite depletion. However, similar low magnetic
amplitude responses are common in the survey area. The signature is
therefore of doubtful use for targeting other breccia bodies that may
Magnetic model results:
Magnetic vector intensity (MVI) and susceptibility inversions were
both done. Database line data as well as gridded data were used as
source data for the inversions. When using the gridded data as a
source, the models are generally 'smoother' than when the line data
is used as a source, as can be expected (Figure 6). The latter
therefore is more detailed than the former, however both model
inversion approaches resulted in the same general characteristics.
The mesh cell sizes for the models are 25m x 25m x 12.5m (X by Y by
Z) and provides a measure of the spatial resolution of the model. The
MVI model based on the database line data is the result chosen to be
shown in this report. It should be kept in mind that potential field
solutions are not unique.
In the following images the vertical extent of the sections is 600m.
The images are coloured linearly with dark blue less than 0.001 SI
and red greater than 0.025 SI units. All discussion is based on the
magnetic vector intensity (MVI) inversion results.
To view Figure 6 please visit the following link:
There is a spatial relationship between subdued magnetic responses
and the mineralized Tumi breccia. In Figure 7 the very low
susceptibility values are coloured in dark blue. The model results
support the interpretation that there is a measurable susceptibility
contrast between the mineralised breccia and the host rocks.
To view Figure 7 please visit the following link:
A cut-away view of the model (Figure 8) better shows the attitude of
the main magnetic high anomaly. The general shapes that were
calculated suggest the causative source for the anomaly to be
intrusive rather than volcanic rocks, since it is expected that the
volcanic rocks would have a more horizontal orientation.
To view Figure 8 please visit the following link:
The model as presented has a lower depth limit of 600m below surface.
However the deeper levels (i.e. deeper than 400m) are not totally
reliable representations of the geological environment and less
confidence should be placed on the shapes and susceptibilities of the
model at these depths.
The most prominent magnetic feature defined by the survey is a
magnetic high anomaly, covering an area of roughly 600m x 800m in the
north-western quadrant of the survey area. The anomaly exhibits a
remnant magnetic component and is interpreted to be caused by
intrusive rocks. Part of the causative source is located in the
higher lying elevations but a substantial portion is positioned at
lower altitudes. This magnetic high anomaly, although it is mostly
under cover, it is thought to be related with some small outcrops of
monzodiorite and monzogranite rocks of the Coastal batholith, that
are moderately K-feldspar hydrothermally altered in some areas. Minor
magnetite is observed, although it is been altered to hematite.
The focus of the magnetic survey was on the main Tumi breccia, which
contains four known mineralized outcrops covering a surface area of
approximately 1.6 km2 (400 m in strike and 400 m wide). Modeling of
the magnetics data suggests that there is a measurable magnetic low
anomaly associated with the Tumi hydrothermal breccia. If true
(magnetic low features like the one over the breccia are common in
the data set), the size of the Tumi breccia and its associated
alteration is approximately 200m x 250m. This area needs to be drill
tested, to better correlate the surface mapping results with the
magnetic interpretation. One plausible explanation for the differing
target size may be the fact that the exploratory shallow diamond
holes, as well as trenches and channel sampling previously reported
in July 2013 on the breccia target, have returned Au values in the
host rocks as well as the mineralised structure.
The postulated size based on the magnetic model results, is not a
confident estimation due to the low susceptibility contrast between
breccia and host rock, and the true extend of the breccia under cover
cannot be defined entirely on ground magnetic studies. However,
ground magnetic has shown other areas that are under cover or with
scarce outcrops; where first recognition work has identified more
breccia outcrops with Cu-oxide and carbonates that were not mapped or
sampled before. These new areas are currently the focus of a new
mapping, channel/trench sampling work (as shown in Figure 1).
The position of the Tumi breccia immediately adjacent to the main
magnetic high anomaly suggests that there is an association between
the breccia and the interpreted intrusive. This is highly possible,
since the nature of the crackle breccia suggest the proximity to an
intrusive body. Also, it can be seen the pervasive nature of the
K-feldspar alteration and total replacement of magnetite by hematite
in the breccia, thus explaining the low magnetic signature of the
breccia. It should be noted that the both the exploratory shallow
diamond drilling, as well as trenches and channel sampling, have
returned Au values in the hosting rocks, as previously reported.
The absence of high susceptibilities below the Tumi breccia indicates
that there is potential for the breccia to exist at depth, however as
mentioned above this geophysical technique does not allow to confirm
below the 400 m.
Currently a mapping program with trenching/channel sampling is been
done in areas that had low magnetic signatures and can be accessed
easily. These works will be followed up by an IP/resistivity survey
that will help to map the distribution of sulfides and alteration
successfully, and should also provide reliable and easily
interpretable resistivity data. This data will generate drilling
There are no well-defined linear magnetic features present in the
data set that can be interpreted to be associated with the known high
grade veins on the project, since these veins are just narrow (less
than 0.50 m) and would not provide any signature.
For and on behalf of the Board,
Ashley Pattison, Managing Director
28 January 2014
Competent Person's Statement
The information in this report that relates to Exploration Results
and Mineral Resources is based on information reviewed by Dr. Alex
Losada-Calderon who is a Member of the Australasian Institute of
Mining and Metallurgy. Dr. Losada-Calderon is the Non-Executive
Chairman of Minera Gold Ltd. and is employed by TAE Resources Pty
Ltd., who acts as consulting geologist to Minera Gold Limited. Dr.
Losada-Calderon has sufficient experience which is relevant to the
style of mineralisation and the type of deposits under consideration
and to the activity which he is undertaking to qualify as a Competent
Person as defined in the 2012 Edition of the "Australasian Code for
Reporting of Exploration Results, Mineral Resources and Ore Reserves.
Dr. Losada-Calderon consents to the inclusion in the report of the
matters based on his information in the form and context in which it
Minera Gold Ltd.
Mr. Ashley Pattison
+1 (212) 521-4493
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