Ilo Norte, Peru
The Ilo Norte Project located in the Arequipa Region consists of four contiguous concessions covering 3,300 ha located in southern Peru’s costal copper belt. The large alteration system is-10km long and several hundred metres thick and hosts IOGC and Skarn Replacement style mineralisation in a package of Jurassic Volcano-sedimentary rocks. The claim block is located 5 km from the road, 10 km from a copper smelter and 29 km from deep ocean Port of Ilo.
Map of Westminster’s Ilo projects
The Ilo Norte deposit shares many mineralogical and textural characteristics with other major exocontact Andean Cu-rich IOCG deposits, e.g. Raul-Condestable (Peru), Mantoverde and La Candelaria in the Punta del Cobre District (Chile) The Ilo Norte project is also considered to be an IOGC type gold-base metal deposit due to the recognition of widespread albite – chlorite alteration throughout the area. Mineralisation apart from skarn type deposits coincident with the recognized skarn mineralisation. Also identified from mapping is the presence of hydrothermal breccias which can be a differentiating factor from pure skarn deposits. There is potential for massive banded sulfide horizons to be present.
Iron oxide-copper-gold (IOCG) deposits are a diverse family of mineral deposits unified by a number of common geological features, including the presence of abundant iron oxides, extensive hydrothermal alteration and strong structural controls. As well as copper and gold, a suite of other commodities such as uranium and rare earth elements may also be present. Deposits can have very high tonnages and an extensive geological footprint, creating favorable targets for mineral exploration.
Over 10,000m of historical diamond drilling has been completed with drill results improving towards the North East of the project area; Best intersections from the drill campaign are as follows:
Accessibility & Location:
The Ilo Norte and Ilo Este projects can be accessed initially via Arequipa, Peru’s second largest city that is 760km south-east of the capital Lima with a population of approximately 890,000 people. Arequipa has most products and services available for operating an exploration project. It is serviced by many daily flights from Lima as well as major highways and a railroad. From Arequipa, it is an approximately 220km, four-hour car journey to the port town of Ilo which acts as the base point for operations for both the Ilo projects.
Although the Ilo Norte concessions are approximately 22km north along the coastal highway to gain access to the higher and most prospective part of the concessions, it is necessary to travel northeast initially on the Pan American highway 78km to the Department capital Moquegua and continuing 32km to the small village of Cruz Misionera. From there its necessary to travel to the south-west on gravel tracks approximately 26km to the project site.
The Department of Moquegua has four broad physiographic features which are more or less parallel to the coast:
- a narrow coastal strip that comprises the lowlands.
- a string of hills with altitudes over 1,000 meters above sea level and form the Cordillera de la Costa.
- a pampa/plain that is dissected by steep ravines/valleys. Where there are rivers the alluvial terraces at the base of these valleys contains intense agriculture.
- the beginnings of the Western Andes foothills.
The Ilo Projects are both located within the Cordillera de la Costa which is a chain of low hills along the coast extending nearly the entire length of the southern Peru region. The elevation of these hills is between 200m to 1,600m with mostly quite rugged and some gently rolling topography
Both Ilo Norte and Ilo Este contain sufficient space to locate infrastructure such as tailings storage facilities, waste storage areas, heap/dump leach pads and large mineral processing facilities.
Activity Previous to Peruvian Latin Resources (<2009)
2000 – Southern Peru Copper Company carried out mapping and sampling of the broad Ilo area between the smelter and the town of Cerrillos. There are no reports or data available for this work.
May 2003 – Teck flew airborne magnetic and radiometric surveys and completed stream sediment and rock chip sampling surveys.
Peruvian Latin Resources Activity (2009 – Present)
Access to exposed outcrop at Ilo Norte is severely limited in places due to the steep, cliffforming terrain in the area caused by rapid up-lift of the coastal block. The same process has caused a significant portion of the area to be covered by scree debris which masks outcrop geology. At the top of the plain, there is also little exposure and the geology is obscured by recent eluvial sand cover.
Detailed 1:5000 scale geological mapping of the available exposure was carried out in 2011 – 2012. This campaign particular focused on identifying the alteration.
Rock Chip Samples
A total of 235 rock chip samples have been collected across the Ilo Note concessions over the course of all exploration mapping programs. Typically these samples were taken representively by hand using a rock hammer. Average weight was approximately 2kg. The samples were submitted to the independent SGS laboratory in Lima and the results of these samples were imported into a dedicated MS-Access database.
QAQC samples were also submitted and the results of these reported as satisfactory. Soil Geochemical Sampling
A total of 137 soils geochemical samples have been collected across the Ilo Note concessions over the course of all exploration mapping programs. Typically these samples were taken by hand using a small shovel from holes dug to the C soil horizon. The material was sieved to – 1mm size. Average weight was approximately 1kg. The samples were submitted to the independent SGS laboratory in Lima and the results of these samples are were imported into a dedicated MS-Access database. QAQC samples were also submitted and the results of these reported as satisfactory.
The northern two-thirds of the Ilo Norte concessions are covered by an aeromagnetic survey commissioned by Teck that was flown by the geophysical contracting company Fugro Airborne Surveys from May until July 2003. The survey was flown on 400m spaced survey lines with 4000m tie lines from an average height of 120m. In addition to magnetics, the survey also included radiometrics measuring K-Th-U.
Over the Ilo Norte area the survey delineated several magnetic anomalies which could be related to magnetite mineralisation and or structures that maybe prospective for mineralisation of interest.
Ground Magnetic Surveys
A ground magnetic survey was carried out over llo Norte by the geophysical contractors Fugro Ground Geophysics between April and July 2009. In total approximately 300 linear km of survey lines were completed. Magnetic readings were taken every 50m along the survey lines which were spaced 200m apart. In some places the survey was infilled so that the line spacing was 100m.
The magnetics indicates an anomaly of similar size to the surface geological anomaly, with possible deep extensions to the east. The anomaly possibly extends to 300 metres of depth, either extending vertically or possibly to the east down-dip. The measured magnetic response ranges up to 1,000 nanoteslas. The magnetic results strongly suggest both northwest and northeast trending off-sets to the mineralisation, adding to the exploration potential with the possibility of discovering, deeper, down-dropped blocks of mineralisation. Gravity surveying was difficult to correct due to the steep terrain but did produce a separate anomaly 400 meters to the west of the surface skarn, suggesting the potential for finding hematite-rich zones. The surface over the gravity anomaly is covered with fresh to weakly altered andesite, suggesting that the target is within more favourable host rocks deeper in the layered sequence. The magnetic complex in the northern part of the area has the potential for both magnetite and haematite mineralisation. It could represent a substantial, variable magnetite content alteration system.
As a magnetite target, the large (600m x 300m), partially defined, moderately to strongly magnetic body at the central northern edge of the survey area (8074000N 251000E) and tenement may contain a substantial, near surface magnetite concentration. This zone is not closed off to the north. Peak anomaly magnitudes are 1000- 2000nT in these stronger areas. For a significant magnetite body, these intensities are moderate rather than high. This probably indicates that there is significant magnetite within the strongly anomalous areas, but it is more likely to be distributed as a series of small, massive magnetite bodies, a stockworked magnetite vein system or disseminated through the host lithology rather than being a single, largish body of massive magnetite. The available magnetic data does not have sufficient resolution or extent to determine the detailed magnetite distribution within the central anomalous area.
The major magnetic feature and immediate surrounds could also represent a good IOCG style copper-gold target. For this style of alteration, mineralisation could be in either the magnetite or haematite zones. The smaller and weaker magnetic zones within the overall magnetic complex offer similar but smaller scale magnetite mineralisation potential to the significant magnetic zone.
The elongate (1km2 long), north-easterly trending magnetic zone extending NE from the southeastern edge of the magnetic complex is likely to be mapping a narrow magnetite vein or a magnetic andesite dyke. From the profile shape, the depth to the top could be about 20m or so, deepening to the north east. This feature looks fragmented in the images but the profile data indicates that it is probably more or less continuous.
There is a similar, but less well defined, northerly trending vein type magnetic zone immediately to the north east of the main magnetic anomaly.
An Induced Polarization survey was completed by the geophysical contracting company Val D’or Geofisica S.A.C on Ilo Norte Project on behalf of Peruvian Latin Resources S.A.C. during December 2012 and January 2013. The survey consisted of three parallel survey lines at a spacing of 400 meters, for a total of 11.9 line-km.
The IP survey consisted of a pole-dipole configuration using an expanding potential dipole from 100 to 400 meters allowing a maximum depth of detection of > 600 meters below the surface. The IP transmitter used had a nominal power of 9.0 KW. The receiver setting was Time Domain in Cole-Cole sampling mode. The IP results were processed using a 3D inversion algorithm for both chargeability and resistivity parameters.
The inversion block model outlined a deep chargeability anomaly along the three survey lines.
The chargeability anomaly amplitude is 15 mV/V over a background of 3-5 mV/V, which constitutes a moderate amplitude intensity anomaly.
Although the anomalous chargeability values form a broad zone at depth of approximately 2000 meters in width, it appears that two different mineralized bodies formed it:
- The northern IP anomaly extends at approximately 200-250 meters below the surface, and it is associated with a high resistivity response.
- The southern anomaly extends at approximately 250-300 meters below the surface, and it is also associated with a low resistivity response.
Both anomalies are caused by the presence of disseminated sulphides at depth in the order of approximately 5-10% sulphide content.
2011 Reverse Circulation Drill Program
In April 2011 a reverse circulation drilling program consisting of eight holes for a total of 2,690 meters was completed by the drilling company AK Drilling S.A.C. Two-meter sampling interval was used to produce 1,431 samples including standards and blanks for QAQC.
The program aimed to define the existence or absence of Fe-Cu ± Au mineralisation within the magnetic anomaly targets generated by the ground magnetic survey completed in the July of 2009 and supported by the geological surface mapping including geochemical sampling of soils and outcrops.
The results obtained from the RC program were considered positive as seven of the eight holes intercepted Cu-Au mineralisation and Fe oxides mainly associated with horizons with greater contained magnetite. The best intercepts coincided with volcanic sedimentary (formation Chocolate) metamorphosed to hornfels and skarns that contain magnetite mineralisation as replacement disseminations, veins, veinlets with spots of pyrite, chalcopyrite that in environment supergene occur as hematite, limonite, and secondary Cu. The favorable package of hornfels and skarn with moderate to strong alteration propylitic containing levels of replacement of magnetite ores of Cu ± Au was intercepted with a thickness greater than 250m, a width of 400 meters and an extension of 1 km. The relationship between the sample length and the true thicknesses of the mineralization is greater contained magnetite. The best intercepts coincided with volcanic sedimentary (formation Chocolate) metamorphosed to hornfels and skarns that contain magnetite mineralisation as replacement disseminations, veins, veinlets with spots of pyrite, chalcopyrite that in environment supergene occur as hematite, limonite, and secondary Cu. The favorable package of hornfels and skarn with moderate to strong alteration propylitic containing levels of replacement of magnetite ores of Cu ± Au was intercepted with a thickness greater than 250m, a width of 400 meters and an extension of 1 km.
The relationship between the sample length and the true thicknesses of the mineralization is unknown.
2013 Diamond Drill Program
In January 2014 Peruvian Latin Resources signed an earn in agreement with Compania Minera Zahena SAC. This agreement was subsequently dissolved.
Between April and December of 2014 Zahena completed 16 diamond drill holes for a total of 12,658 meters at Ilo Norte on an approximate 400m grid. Most of the drilling was completed in HQ diameter core.
The drilling intercepted the altered and mineralised volcaniclastic sequences of the Chocolate Formation.
The mineralisation encountered was erratically distributed within the sequence however the mineralised package of the Chocolate Formation has the expected orientation of approximately 30 degree’s dip toward the northeast.
The relationship between the sample length and the true thicknesses of the mineralization is unknown.
Ilo Norte is an Iron Oxide Copper Gold (IOCG) type deposit that presents significant exploration potential. The work to date has concentrated on a relatively small portion of the prospective part of the lease holding. Remote sensing and in field mapping has demonstrated that the silica and potassic alteration halo that exists at the known mineralisation extends across the entire property.