Quartz Hill Project
Summary | Location and tenure | Geology | Exploration | Mineralisation | Geophysics
Summary
The Quartz Hill Project contains uranium-REO rich pegmatites, brecciated pegmatites, tension gash mineralisation, strong “bullseye” magnetic highs and strong regional sodic/pottasic alteration within the Arunta Province in the Harts Ranges, 160 km ENE of Alice Springs, Northern Territory.
The region is highly prospective for uranium mineralisation in a number of different orebody types, with several uranium anomalies identified in the general area, including Yambla. The immediate target within the project is granitic pegmatite with uraniferous rare-earth minerals, which occur in several places identified to date.
The presence of three “bullseye” magnetic anomalies within the tenements in the vicinity of mixed magma types (mafic and felsic) related to the Hukitta dome granites and a major deep-crustal structure to the north are also targets of significant interest.
Location and Tenure
The Quartz Hill project lies 150km west-northwest of Alice Springs as the crow flies, centred around Ambalindum Station. All tenements lie within the Eastern Arunta block, in the Harts Ranges.
Figure 1: Quartz Hill regional location diagram
The project consists of six leases, two of which are in the Cazaly JV (granted) and four of which are in Newera’s own name (one granted and three in application)
Most of the leases are contiguous. The granted leases E24838 and E25296 are in the Cazaly option agreement and E25647 granted is in Newera’s name. The three applications lie in the immediate vicinity of the granted leases where they are not actually contiguous.
Figure 2: Quartz Hill location diagram, based on 1:250,000 topographical mapping. E24838, E25296 and E25674 are granted, the others are in application.
Geology
The Quartz Hill Project is situated within the SE corner of the Arunta Inlier. The Arunta comprises a sequence of sedimentary, igneous and high grade metamorphic rocks transected by a network of regional and local scale EW and NW–SE anastomosing faults. The uranium/yttrium/tantalite-niobium/rare earth element (REE) rich pegmatites at Quartz Hill are thought to have a metamorphic source, derived from partial melting during the Alice Springs Orogeny.
Figure 3: NTGS 1:250K geology of the Quartz Hill project.
Figure 3a: Legend to the NTGS 1:250K geology.
The dominant feature in the Qtz Hill region is the granites of the Entia (and the inset Huckitta) Dome, which intrude and deform dominantly felsic gneisses with small amounts of mafic and ultramafic volcanics. Fractionated, garnet bearing pegmatites and small mafic lenses intrude the gneisses, and a dominantly ?sodic alteration pervades and degrades the mafic intrusions.
A major structural suture (palaeo-subduction) zone exists to the north of the project (see fig. 5, in Geophysics), and the rim of the Entia dome is interpreted to be a major deep-crustal feature.
Exploration History
Pacific Nuclear Corporation (PNC) explored Quartz Hill in 1992. Prior work to that had been poorly recorded mica mining from the depression era, with re-opening of the mica mines allegedly using POW labour during the war. Many of the Italians who had worked here during the war may have returned in the post-war era, as the anecdotal evidence from prospectors and station managers in the area is that much of the post-war work in what would have been very isolated, primitive and remote camps was carried out by the newly immigrated Italian community.
Some geological work had been done on the mica mines however, as PNC report that one of the mica mines on the Qtz Hill project was known to contain uraniferous minerals. This was probably related to the burst of exploration for uranium that occurred shortly after the war in the 1950’s.
PNC initially flew airborne radiometrics, and followed up the data in 1993-4. This resulted in the discovery of what is now known as Quartz Hill and Spartacus.
Quartz Hill was a priority 1 anomaly on the “quartz blow” outcrop known as Quartz Hill. Ground checks located hotspots within soil and quartz scree and on the pegmatite vein near the spur of the ridge, and a small hole was blasted on the pegmatite. Copper has been indicated on the Geol Survey map at Quartz Hill but PNC found none, whereas they located uranium rich samarskite intergrown with uraninite and coffinite, with some alteration to uraniferous tanteuxenite. Samples were in what they reported as “brecciated pegmatite”.
Felspar (part of the Spartacus area) was a strong anomaly caused by float of a uranium rich mineral associated with a large E-W pegmatite. The mineral was massive, black, glassy, had a conchoidal fracture and didn’t show weathering. It was identified as a Y-Nb>U mineral of the fergusonite series plus alteration products.
PNC mention a small number of “low order” anomalies they traversed, including a possible allanite occurrence in an aplite vein in gneiss to the north of Quartz Hill. In this second rank of anomalies they include “Lone Pine” AKA “Cone Hill”, which Newera have re-named True Grit since pine trees now cover the hill. True Grit lies to the northwest of Quartz Hill in a series of large pegmatites that host an abandoned mica mine, which PNC state had known uraniferous minerals. They found “numerous fragments of a black glassy mineral” later identified as “a member of the fergusonite -samarskite series” in the scree as well as several hot spots on the working face.
Several other mica mines in the area were checked for uranium minerals, and uranium proved to be present in small concentrations in some, with associated high rare earths.
Mineralisation
Previous work in the project has identified uranium and Rare Earth Element (REE) mineralisation within a series of radioactive pegmatites and associated quartz veins which have been intruded along NW-SE trending structures.
These fractionated pegmatites and more importantly the minerals within them, are a prime target at Quartz Hill. The garnets contain Samarskite and Euxenite. These minerals occur as garnet-shaped crystals in the pegmatites, and as inclusions within garnets themselves.
Garnet aggregates are known to grow to very large sizes in the Harts Ranges, with a reserve to the north of the project said to contain a specimen over 10m in size.
Newera has identified uraniferous Samarskite and Euxenite, grading to in excess of 1000ppm U, within the Spartacus pegmatite system on E25296 with a strike extent of over 1300m. The host pegmatites outcrop as a pair of overlapping, sub-parallel units each in excess of 650m long and with a lateral extent of in excess of 100m. Smaller parallel external units surround the main pegmatites and they contain internal rafts of the host granitoid gneiss.
The volume at Spartacus gives ample scope for scale. Concentrations have yet to be determined, but mapping evidence suggests the minerals occur throughout the pegmatites with higher density clusters or patches.
Rare Earths
Rare earth designated minerals consist of the 15 elements between atomic numbers 58 and 71. Today the metal derivatives of rare earths are essential components to products relating to the electronics and technology industries, energy efficiency and greenhouse gas reduction.
The Samarskite and Euxenite found at Quartz Hill are highly radioactive minerals forming a solid solution, and contain significant amounts of Niobium, Tantalum and other REEs in an iron oxide matrix which also contain up to 38% U. Both massive and crystalline forms are present on the project and specimens found to date are up to 55mm in diameter.
Markets for rare earth metals and/or their alloys have enormous future world wide growth potential. Production of REEs is currently dominated (97%) by China, and currently China controls 100% of the refining of these strategic metals.
Reflecting rising demand, prices of rare earth elements have continued to rise over the past several years and of late have increased strongly.
Geophysics
Regional aeromagnetic data, combined with newer research on deep-crustal structures from the University of Adelaide, shows a major deep-crustal suture zone to the north of the Harts Ranges (fig. 5), associated with the Alice Springs Orogeny. This is possibly a palaeo-subduction zone, as evidenced by TEM cross-sectioning (Maidment, 2005, as presented at the 2007 AGES conference in Alice Springs).
Figure 5: Regional TMI aeromagnetics and interpreted structures.
This data gives an indication of just how prospective the Harts Range area is. It indicates that the entire province is part of a very good area for mineralisation of many different sorts, and the fact that it is so under-explored means Newera is very well placed for major discoveries.
Radiometrics
Radiometric data is limited at Quartz Hill by the line spacing of current and historic data, which is a little more critical for radiometrics than for aeromagnetics. Newera has commissioned a new, tighter spaced survey to give better resolution of the imagery.
Imaging of the Uranium signal divided by the Thorium signal (U/Th) gives the best indication of enrichment in uranium. The U/Th image for the project (fig. 6) shows significant anomalism in the lease, and compares the positions of the two main pegmatite targets at True Grit and Spartacus.
Figure 6: U/Th image of the Quartz Hill project with main pegmatite targets.
Aeromagnetics
As expected, the aeromagnetic signature of the felsic gneisses in the project is very subdued. There are two areas of exception to this however, with “bullseye” magnetic highs coming through (fig. 7). The main bullseye target is under a granite intrusion, with a lesser one to the north and another on the application to the west of the Spartacus pegmatite. This latter has some mafic (more magnetic) material to help explain it, but they are highly unusual anomalies in felsic or granitic terrain.
Figure 7: Reduced To Pole aeromagnetic image of the Quartz Hill project. Note “bullseye” magnetic highs. These highs have been the subject of a recently completed VTEM aerial geophysical survey.
EM
Newera believes the presence of pegmatites containing magnetite in the vicinity of copper mineralisation within the Harts Range region suggests the two large “bulls-eye” magnetic highs on the edge of the dome within Newera’s leases are significant exploration targets for Iron-Oxide-Copper-Gold (IOCG) mineralisation.
Granites do not normally have high magnetism, and the bullseye shape of these targets has led to Newera conducting a VTEM aerial electromagnetic (EM) survey in late September 2007 to test the possibility.
Copper is known to occur in other places within the Harts Range, and has been reported at Quartz Hill in the past. With the presence of mixed magma types (mafic and felsic), alteration fluids and magnetite in the pegmatites, this is the correct environment for IOCG mineralisation.
With the surrounding granites and gneisses being strongly anomalous in uranium, any such mineralisation would undoubtedly be uraniferous.