Swinden reported in 2011 that Namibia Rare Earths Inc. (“NRE”) had conducted an exploration program for rare earth elements on its Lofdal property in north-western Namibia. The property has widespread occurrences of REE hosted by the Lofdal carbonatite complex, a ca 750 Ma silicate/carbonatite intrusive suite. The Lofdal rare earth element property is held under Exclusive Prospecting Licence (EPL) 3400 by Namibia Rare Earths (Pty) Ltd (formerly Etruscan Resources Namibia (Pty) Ltd), which is 100% owned by NRE through its subsidiary Cayman Namibia Rare Earths Ltd. The company name was officially changed from Etruscan Resources Namibia (Pty) Ltd to Namibia Rare Earths (Pty) Ltd (“NRE (Pty)”) and entered into the Namibian Register of Companies on February 15, 2011. NRE (Pty) is the operating entity in Namibia.
Swinden Geoscience Consultants Ltd. was commissioned by Namibia Rare Earths Inc. to prepare an independent technical report (ITR) on the rare earth mineralization and exploration potential on the Lofdal property in north-western Namibia, in compliance with disclosure and reporting requirements set forth in National Instrument 43-101, Standards of Disclosure for Mineral Projects and the companion policy 43-101CP, and in accordance with Ontario Securities Commission Form 43-101F1. The Lofdal property is a new district scale greenfields exploration project for rare earth elements associated with alkali syenite and carbonatite intrusions which has a relatively limited exploration history dating back to only 2008.
The Lofdal property is underlain by Paleoproterozoic metamorphic rocks of the Huab Metamorphic Complex, which outcrop as an inlier of the Congo Craton surrounded by stratified rocks of the Damaran Orogen. The metamorphic basement was intruded at ca 750 Ma by alkaline silicate rocks and carbonatites of the Lofdal carbonatite complex. The complex comprises an early silicate intrusive assemblage of dominantly nepheline syenite, and a later carbonatite intrusive assemblage ranging from sovite through dolomitic and ankeritie carbonatite. The entire complex, as it is presently understood, comprises a central intrusive core characterized by a number of plugs of nepheline syenite and carbonatite with associated diatreme breccias, surrounded by a wide area of dyking and associated hydrothermal alteration, in which phonolite and carbonatite dykes related to the intrusive plugs have exploited pre-existing structures in the basement that were re-activated during Neoproterozoic tectonism.
The carbonatite dykes are widely mineralized with rare earth elements. The total area affected by carbonatitic dykes and associated alteration and mineralization is more than 200 km2. Rare earth element mineralization in the Lofdal carbonatite complex is closely associated with the carbonatite dykes and related hydrothermal alteration. A high quality lithogeochemical database demonstrates that significant numbers of the dykes are geochemically anomalous in the rare earth elements and yttrium with a significant population being of economic interest.
Almost 40% of the 3,764 grab samples taken to date contain more than 0.25% total rare earths+yttrium (TREE+Y) and almost 15% carry greater than 1% TREE+Y. Of particular significance and exploration interest is the frequent enrichment of heavy rare earths in the dykes. The rare earth mineralization in the Lofdal carbonatite complex is extremely variable. It includes both light rare earth- and heavy rare earth-enriched varieties that appear to have been introduced in separate mineralizing events. Evidence suggests that the heavy rare earth-rich mineralization is dominantly a hydrothermal event, that occurred relatively late in the history of the complex. Mineralogically, the heavy rare earth-enriched mineralization is dominated by xenotime, which is commonly associated with apatite and/or thorite. The mineralization is, in many areas, associated with wide zones over 10’s of meters of carbonatite intrusion and related hydrothermal alteration. The alteration systems are robust, continuous both along
strike and at depth and produce clear geological, geochemical and radiometric signatures that are easily recognized, particularly in drill core that can be utilized for exploration.
The author concluded that The Lofdal property is a high quality, greenfield exploration project that warrants comprehensive exploration for rare earth elements. The Lofdal carbonatite complex is a diverse and robust igneous-hydrothermal system that from all present data exhibits significant potential to host deposits of rare earth elements. Exploration to date has not defined a mineralized zone of economic size and grade but has identified significant areas of heavy rare earth enrichment and a significant number of high quality targets for further exploration on a district scale. The association of rare earths with carbonatites is well known and there are many advanced
exploration projects targeting this deposit type. The large majority of these are LREE-enriched, with limited potential for production of HREE. What is unique at Lofdal is the significant enrichment in heavy rare earths associated with the carbonatites, and the dominance of xenotime as one of the principal REE-bearing minerals. This presents a significant opportunity to discover a deposit of economic significance.
The Lofdal carbonatite complex is a large intrusive system with a significant component of hydrothermal alteration and mineralization. The intrusive center for the system seems to be in the area of the Main intrusion, which is exposed over an area of about 2,000 m x 800 m and may be considerably larger, according to preliminary gravimetric data. The carbonatites in this area are grey to white, and although exhibiting typical carbonatite LREE-enriched chondrite normalized patterns, the absolute concentrations of the REE are sub-economic. The other intrusive plug that has been identified is the Emanya intrusion, which by its composition, associated minerals, and rare earth contents, appears to have more of a hydrothermal component. It is also a LREE-rich body, but has absolute concentrations that are significantly higher than the Main intrusion and a more fractionated REE distribution. Although not an initial priority, the Emanya intrusion presents a prospective drill target because of the locally high
concentrations of REE and the size of the body. The corridor between the Main and Emanya intrusions is about 3.5 km long and characterized by a number of small nepheline syenite bodies that appear to be related to, but intruded earlier than, the carbonatites. Coarse diatreme breccias are widespread and are apparently related to
the intrusion of the syenite. The intrusive centre of the complex was a dynamic system. The abundance of breccias suggests that it was also explosive and the widespread hydrothermal alteration indicates that it was volatile-rich. The syenites are typically closely associated with the carbonatite intrusions suggesting that they utilized the same pathways during ascent. The corridor between the two intrusions is, therefore, considered to be highly prospective.
The emplacement of the nepheline syenites was associated with regional fracturing of the metamorphic basement rocks, mainly along NNE/SSW to NE/SW structures that may locally result from reactivation of older basement structures, and a suite of phonolite dykes was emplaced in these fractures. These fracture systems remained active during subsequent emplacement of the carbonatites which were sometimes emplaced in and/or adjacent to the phonolites in the same system and sometimes in nearby parallel fractures. The intrusion of these carbonatite dykes was accompanied by significant brecciation and alteration of both preexisting silicate intrusives and the adjacent metamorphic wall rocks, producing sometimes wide zones of variable carbonatite and silicate intrusion accompanied by carbonatized, altered rocks and breccia. Some of the carbonatites, and some of the hydrothermally-altered rocks, were mineralized with significant quantities of rare earths. The intrusion and the REE mineralization was accompanied by variable fenetisation of the wall rocks, now manifested in phlogopite-rich intervals near the margins of the altered zones.
The carbonatite/carbonatized alteration zones are locally very extensive along strike and can be traced over 100’s of metres. The 2B zone, the only zone to date that has been investigated in 3 dimensions, is part of a dyke system that can be traced along strike for more than three km. Similar dykes with regional extent are found elsewhere on the property and most have segments where sampling has identified anomalous proportions of HREE-rich samples. One very significant outcome of the 2010 diamond drilling program is the recognition and characterization of hydrothermal alteration and structural controls associated with the mineralizing event. All observations and information in the 2B zone drill core suggests that the hydrothermal alteration zones are characterized by both a geochemical signature of elevated REE’s, Y, and Th, and by radiometric anomalies. Although the zones locally are very wide, the most intense REE mineralization appears to have been introduced late in the hydrothermal sequence, and to date has been observed to occupy relatively narrow, late hydrothermal corridors within the larger alteration systems. This being said, the 2B zone is exposed on surface over widths ranging from 15 to more than 120 m. The most intense alteration zone at its widest point measures up to 27 m in drill core. These are attractive exploration targets and the focus must be to identify zones with consistently high HREE values over economic widths. Although not the focus of this report, the author is aware of ongoing geological mapping and sampling that is confirming the association of discrete carbonatite dykes or dyke swarms with broad
alteration haloes in a number of areas on the property.
Observations in the 2B zone trenches, and particularly in the 2B zone diamond drill holes, suggest that the HREE-enrichment is controlled by hydrothermal activity related to carbonatite emplacement. This being the case, there would seem to be significant opportunity for HREE mineralization to occur both in the carbonatites and in the related hydrothermally-altered silicate rocks. This has not been tested by sampling on a regional scale.
To this point in time, only the 2B zone has been substantially tested. The testing of this target has yielded much valuable information about the nature of the intrusions and related alteration, and the nature of the mineralization. The zone remains robust and open at depth and should be further tested below the current level of exploration. There are many other targets of similar potential in the area of the property that have been identified by regional lithogeochemical sampling that have the potential to host significant HREE mineralization. There is also a large area outside of the present target area, but within the regional Th anomaly that defines the prospective area, that has significant potential for further discoveries.
The nature of the HREE-mineralizing event remains elusive and, in particular, its timing with respect to the intrusion of the carbonatite plugs. There remains the possibility of a magmatic episode that is contemporaneous with (and perhaps the source of) the HREE-enriched hydrothermal fluids. Exploration on the property must be carried out with the possibility of a HREE-enriched primary intrusive body in mind.
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