• Noel Ong

Good Geology Never Disappoints - Los Cerros Limited (ASX: LCL) Colombian Style

With every company and thought leader I listen to, I am learning more and more about what makes a good mineral province. It is amazing what you learn when you start listening to the stories of people in different industries sharing their knowledge and experiences. Definitely one of the big perks of growing older - we gain experience and insights. We are like wine, the older it is, the more interesting the depth of flavours.


In geology, especially mineral geology, I have learned that finding great deposits is all about understanding the regional geology. Once you have understood the provincial aspects, the local geology specifications become clearer. What this means is, investors who want to know the likelihood of discovery, the likelihood of mineral exploration success and hence the probability of investment success should just stop and look at the bigger picture first.


I know there are other non-geological aspects that are equally or more important, but one has to recognise that science and facts do not allow the truth to be stretched.


The Colombian Story


I first came across the Colombian story almost 5 years ago when I came to know about Andes Resources Limited. Andes was unlisted at that time and has now resurfaced with a new name as Los Cerros Limited (ASX: LCL). Prior to this, I have never looked at Colombia as a resource jurisdiction. I suspect this is due mainly to the lack of visibility in the ASX.


I was privileged enough to have Jason Stirbinskis on Coffee with Samso - Los Cerros Limited (ASX: LCL) - A High-Grade Gold Porphyry Story in Colombia to talk about the project.


While researching for our conversation on Coffee with Samso, I learnt about the prospectivity of this little part of the South American continent. I dare say that I am not the only one who does not know much about the prospectivity of Colombia.


What is so Interesting about Colombian Geology ?


As we have discussed in a previous Samso Insight - New England Fold Belt - Critical Resources Limited (ASX: CRR) - the importance of understanding the potential of a project/deposit is underlined by the understanding of the tectonic history/controls. What I mean is, do the potential geological controls allow the story to be achievable? Does the stated resource potential have any chance of being attained?


The Andes can be divided into the Northern Central and Southern. The Colombian story is in the Northern Andes and it consists of three cordilleras ( Western, Central and Eastern), which are themselves internally complex as well (Figure 1A and 1 B).


Figure 1: A: Tectonic scheme of northern South America and the Caribbean (Gómez et al., 2015a, 2015b). [1]. B: Lithotectonic map of the Northern Andes showing the location of the Miocene Buriticá, Quinchía, Marmato, and La Colosa gold deposits (modified from Cediel et al., 2003). [5]

This region is complicated in the sense that there are subducting plates and then there is lateral movement of plates as well. As you read, I will try and explain in layman´s terms what it means when I say that the mineralisation can be directly related to the level of magmatism. To put it simply, it appears that certain types of subduction activities do not create volcanic activities and hence, a lack of mineralisation (Figure 1B).



Tectonic Activity

According to [1], the tectonic framework of Colombia (Figure 1A) is influenced by the interaction between the Caribbean and Nazca oceanic plates, and the South American continental plate, with ocean ridges, oceanic trenches, subduction zones, accretionary prisms,formation belts, transform faults, and several other structural elements, as defined by [2] and [3] based on the findings of numerous researchers (Figure 1A, 3A and 3B).


To say this is an oyster of structural complexity would be an understatement. The more I read about the geology, the more it starts to make sense to me. What is obvious is that we are looking at a serious subduction zone - the Northern Andes is a series of plate consumption and plate creation.


What this means for the average investor is that the structural component of the cooking mechanism means the mineralisation process is in place. Like all scientific explanations, there are a lot of variables that create outliers, so I will try to stay as basic as I can.


Geology and Magmatism

It is obvious then, that the rocks (Figure 2) in this area is the product of the subduction zones and the collision of the three plates and the segmentation of plates. Looking at the geological map, you can make a safe assumption that the majority of magmatism is concentrated with the three structural corridors of Western, Central and Eastern Cordillera.


Figure 2: Geological map of Colombia. After Gómez et al. (2019).[1]

What is interesting is that [4] talked about how the level of volcanism is restricted to the central region, between the eastern portion of the Western Cordillera and the Central Cordillerra. You can see the the results of that paper in Figure 3B below.

Figure 3: A: Main geological structures of Colombia. After Gómez et al. (2019). [1]
B Seismicity and volcanism of NW South America. Black arrows indicate plate velocity relative to stable South America [Trenkampet al., 2002], red triangles indicate volcanoes. Coloured circles indicate earthquakes recorded during 1993–2009. Earthquake data are downloaded from National Earthquake Information Center website (NEIC, ttp://earthquake.usgs.gov/regional/neic/). [4]

It is not surprising then that Epithermal and Porphyry style deposits dominate this province. Tectonic settings like this discussion is the prime candidate for creating a recipe for large high grade deposits that are being discovered in the last decades.


That line of red triangles in Figure 3A is also consistent with the known giant deposits that are in Colombia. There is a glimpse of that in Figure 1B where the massive Buritica Gold Deposit headlines that northern trend and the recent discovery of the Alpala (Cascabel) discovery by SolGold sits at the bottom end of that trend in Ecuador (See Figure 4A and 4B).



Figure 4: A The summary of the Buritica Gold Mine [6]. B The overview of the Alpala deposit by SolGold. [7]

Magmatic Belts and Ore Deposits

[5] talks about six magmatic belts with ages from Triassic to Neogene. I won´t bore you with what they mean but it is sufficient to say that they are very young and are forming geologically even as you read these words. In fact, this is not far from the truth as magmatic activities are brewing literally today.


As I mentioned earlier, the main type deposits are Porphyry Cu- (Au-Mo) and Epithermal Au-Ag deposits. In the above section, I have listed two known giant deposits. There are still relatively few discoveries and that may be solely due to the geopolitical issues in the past.


Figure 5 below is a good depiction of the type of ore deposits in Colombia based on the ages and the structural constraints and the volcanic activity shown in Figure 3B.

Figure 5: Gold metallogenic belts and major Mesozoic and Cenozoic intrusive rocks of Colombia (modified from [8], and [9]) [5]

There is this consistent reference to that region where we see the most volcanic activity.


Conclusion

Whenever I do my research when preparing for a Samso Insights, there are always lots to learn. In January 2020, I published Copper Porphyry Districts - Chile & Associates which was a pretty long blog. It was a 12 minute read, and in terms of attention span, it really tested readers. But that Insight was a real eye opener for me.


As I mentioned, the Colombian mineralisation story was only something on my radar screen after I did the Coffee with Samso with Los Cerros Limited. I must say that I did not know that there was such a a thing as a high grade porphyry gold deposit.


What is interesting is that even today, investors in the Australian Stock Exchange (ASX) are not fully well-versed in the potential of Porphyries and Epithermal deposits as being a giant target. There aren´t too many stories in the market place now that are in the same league as the Los Cerros of the market.


Just look at Cadia-Ridgeway (NSW, Australia), Ok Tedi (Papua New Guinea), Bougainville Copper (Bougainville), Batu Hijau (Indonesia), Grasberg (West Papua, Indonesia), Tujuh Bukit (Indonesia), Bingham Canyon Mine (USA), Escondida (Chile)...etc these are mines that go for generations.


When I look at what Los Cerros have and the results they are releasing lately, I can´t help but think that the limiting factor for the company is funding. The Quinchia deposit is a well-known Colombian deposit and when you look closer, there are satellite deposits as well.


I came across [10] and wanted to share this (Figure 6) as it shows that the Los Cerros project is not some unknown topic. The whole Colombian story is a revelation for me. At this time with the geopolitical situation and the onset of rising interest rates, having a large high-grade gold deposit will be a good story.

Figure 6: Location maps of the study areas. A) Middle Cauca Au-Cu belt in northwest Colombia within the Northern Andes. Western Colombia geologic terranes including the Cajamarca-Valdivia para-autochthonous terrane (hatched), the Romeral mélange terrane (black) and western allochthonous terranes (gray) are shown (Cediel et al., 2003). B) Location of principal porphyry and epithermal deposits within the Middle Cauca Au-Cu belt, including the Quinchía district and the El Poma prospect. Occurrences of garnets in late Miocene porphyries and the Colombia Formation mentioned in the text are also indicated.
The geologic terranes of western Colombia (see also A) and their major bounding fault systems are labeled. C) and D) Simplified geologic maps of the Quinchía district and El Poma prospect, respectively. Principal porphyry and epithermal deposits within the Quinchía district, as well as garnet-bearing porphyry occurrences at Tesorito and El Poma prospects are indicated.

Reference


1. Gómez, J., Núñez–Tello. A., Mateus–Zabala, D., Alcárcel–Gutiérrez, F.A., Lasso–Muñoz, R.M., Marín–Rincón, E. & Marroquín–Gómez, M.P. 2020. Physiographic and geological setting of the Colombian territory. In: Gómez, J. & Mateus–Zabala, D. (editors), The Geology of Colombia, Volume 1 Proterozoic – Paleozoic. Servicio Geológico Colombiano, Publicaciones Geológicas Especiales 35, p. 1–16. Bogotá.


2. Gómez, J., Montes, N.E., Nivia, Á. & Diederix, H., compilers. 2015. Geological Map of Colombia 2015. Scale 1:1 000 000. Servicio Geológico Colombiano, 2 sheets. Bogotá. https://doi. org/10.32685/10.143.2015.936


3. Gómez, J., Nivia, Á., Montes, N.E., Diederix, H., Almanza, M.F., Alcárcel, F.A. & Madrid, C.A. 2015b. Explanatory notes: Geological Map of Colombia. In: Gómez, J. & Almanza, M.F. (editors), Compilando la geología de Colombia: Una visión a 2015. Servicio Geológico Colombiano, Publicaciones Geológicas Especiales 33, p. 35–60. Bogotá


4. Claudio Chiarabba, Pasquale De Gori, Claudio Faccenna, Fabio Speranza, Danilo Seccia, Viviana Dionicio, and German A. Prieto  2015. Subduction system and flat slab beneath the Eastern Cordillera of Colombia. Geochem. Geophys. Geosyst., 17, pp16-27.


5. Guillaume Lesage, Jeremy P. Richards, Karlis Muehlenbachs, Terry L. Spell, 2013. Geochronology, Geochemistry, and Fluid Characterization of the Late Miocene Buriticá Gold Deposit, Antioquia Department, Colombia. Economic Geology; 108 (5): pp1067–1097.


6. https://www.zijinmining.com/


7. https://www.solgold.com.au/


8. Aspden, J.A., McCourt, W.J., and Brook, M., 1987, Geometrical control of

subduction-related magmatism: The Mesozoic and Cenozoic plutonic history of western Colombia: Journal of the Geological Society of London, v.144, pp. 893–905.


9. Sillitoe, R.H., 2008, Major gold deposits and belts of the North and South American Cordillera: Distribution, tectonomagmatic settings, and metallogenic considerations: ECONOMIC GEOLOGY, v. 103, pp. 663–687


10. Thomas Bissig, Hildebrando Leal-Mejía, Roger B. Stevens, and Craig J.R. Hart, 2017. High Sr/Y Magma Petrogenesis and the Link to Porphyry Mineralization as Revealed by Garnet-Bearing I-Type Granodiorite Porphyries of the Middle Cauca Au-Cu Belt, Colombia. Economic Geology, Vol 112, pp 551-568.



 

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