Minera Gold Ltd.

January 28, 2014 08:00 ET

Minera Gold Ltd.: Ground Magnetic Survey and 3D Model Increases Size and Enhances Prospectivity of 100% Owned Tumi Au/Cu Project

PERTH, AUSTRALIA--(Marketwired - Jan. 28, 2014) - 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: http://media3.marketwire.com/docs/924260_1.png

Material findings from the survey and 3D model interpretation are summarised below:

  • 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 at depth.
  • 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 added.


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: http://media3.marketwire.com/docs/924260_2.png

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 survey results.

Forty-seven (47) NE striking (N45°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: http://media3.marketwire.com/docs/924260_3.png

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 of interest.

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: http://media3.marketwire.com/docs/924260_4.png

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: http://media3.marketwire.com/docs/924260_5.png

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 be present.

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 < 0.001 SI and red > 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: http://media3.marketwire.com/docs/924260_6.png

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: http://media3.marketwire.com/docs/924260_7.png

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: http://media3.marketwire.com/docs/924260_8.png

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.

Geological interpretation

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 targets.

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 appears.

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