Alkali Lake North
Big Smoky South
Columbus Salt Marsh


The Nevada Lithium Brine projects comprise Placer Mining Claims over three prospects in large basins (ground water catchment areas) located in Nevada, USA (refer to ASX release 30 January 2017).

The projects are within 10 to 50 kilometres of the Silver Peak lithium production operation of Albemarle Corp, in Clayton Valley. Silver Peak is the only lithium brine operation, and one of only a handful of lithium mines, in North America. The Tesla Gigafactory 1 - a lithium-ion battery factory - is only 250 kilometres northwest of RLC's lithium projects (Figure 1).

The three projects cover a combined area of 4,580 hectares (11,323 acres) under 534 placer claims. All the placer claims are 100% owned.

Figure 1. Nevada Lithium Brine Project location.

Figure 2. Nevada Lithium Brine Projects, Google Earth image.

Figure 3. Nevada Lithium Brine Projects, USGS gravity (Bouguer anomaly) image. The areas where lower density is indicated (mostly green here) are interpreted to be basins with thick accumulations of younger sediments.

Figures 2 and 3 (above) show the topography (satellite image) and gravity for the same area, covering RLC's projects and the Silver Peak lithium operation. The areas of low gravity response (less dense - mostly green here) are areas where there has been significant subsidence caused by the development of deep grabens (fault-bounded basins) and infilling by younger sediments. The areas of high gravity response (more dense - mostly red to purple) are associated with uplifted areas of relatively dense basement rocks. It should be noted that the scale of this gravity survey is too coarse to show areas where there are localised sub-basins that are the preferred trap sites for lithium-rich ground waters. Geophysical surveys carried out by RLC have been successful in demonstrating the presence of these sub-basins in all three of the Company's prospects (refer to ASX releases 5 May 2017, 26 May 2017, 29 May 2017, 30 May 2017).

Brine targets (salty water potentially containing lithium) have been identified at each of the projects in geophysical surveys conducted in April / May 2017. Drilling is planned for September 2017 with permitting being arranged for 6 drill sites to investigate multiple aquifer targets.


Big Smoky South Project is located 10 kilometres northwest of the Silver Peak lithium operation where the southern end of Big Smoky Valley meets the western side of Clayton Valley. This northwest striking valley is defined by a series of major northwest and north east faults. Based on USGS open file gravity data there is a discrete sub-basin in the centre of the valley with more than 2.4 kilometres of subsidence. In addition to the extensive Tertiary volcanic deposits in the area there are significant deposits of volcanic ash in the valley that in places are more than 30 metres thick. The ash deposits are capped by very recent basalt lava flows and cinder cones. The presence of recent volcanism is considered to be an important heat source for driving geothermal activity which can dissolve lithium from the tuffa beds and circulate it in ground water convection cells.


Figure 4. Big Smoky South. Google Earth image showing the location of RLC's placer mining claims, with the evaporation ponds of Albemarle Corporation's Silver Peak Lithium Operation to the lower right.

 

Brine targets identified for drill testing       (refer to ASX release 26 May 2017).

Strong brine targets have been identified in MT geophysical surveys.

  • The targets are identified within two sub-basins located within the project area.
  • Drill permitting commenced in May 2017.
  • Drill rig available in Q3 CY2017.

Geophysical Survey Results

The geophysical survey method used is known as a magneto-telluric survey (MT survey), selected because it has the capacity to resolve multiple conductors at varying depths within a basin. Resistivities of one ohm-metre or less are considered indicative of brines. The results clearly indicate brine targets within two basins that are associated with the development of an overall half-graben structure (Figure 5). This half-graben is the structural feature that defines the valley and we believe controls the location of the most prospective brine accumulations and any associated lithium.


Figure 5. Big Smoky South project. MT survey line showing brine targets (<1.0 ohm-metre resistivity - coloured deep blue on this image) and basin structure, and proposed drill holes (DH1, DH2).

 

Brine targets are observed in the MT survey as follows:

In addition to the above targets there is evidence of a shallow aquifer system at a depth of 150m which could represent a buried playa lake surface. This will also be tested by both drill holes.
 


The Columbus Salt Marsh project is located 45 kilometres northwest of Clayton Valley (Figure 2). The Columbus Salt Marsh valley represents a closed basin with extensive Tertiary volcanic deposits in the surrounding hills. USGS open file gravity data (Figure 3) indicates that the centre of the valley has subsided up to 3.5km. The valley is fault bounded and several geothermal springs discharge alkali salts onto the lake surface. These alkali deposits have in the past been mined for borax.


Figure 6. Columbus Salt Marsh Project. Google Earth image showing the location of RLC's placer mining claims.

 

Brine targets identified for drill testing       (refer to ASX release 30 May 2017).

Very strong brine targets have been identified in MT geophysical surveys.

  • Multiple brine targets are identified within the project area located in a broad structurally controlled basin.
  • Drill permitting commenced in May 2017.
  • Drill rig available in Q3 CY2017.

Geophysical Survey Results

The geophysical survey method used is known as a magneto-telluric survey (MT survey), selected because it has the capacity to resolve multiple conductors at varying depths within a basin. Resistivities of one ohm-metre or less are considered indicative of brines. The results clearly indicate a broad, structurally defined basin with multiple, sub one ohm-metre, brine targets associated with individual sub-basins.


Figure 7. Columbus Salt Marsh project. MT survey line showing brine targets (<1.0 ohm-metre resistivity - coloured deep blue on this image) and basin structure, and three proposed drill holes.

 

Brine targets are observed in the MT survey as follows:

The area encompassed by the Company's tenements is located on the southern margin of the Columbus Marsh structural depression. Regional geophysical data indicates that the centre of the basin is very deep and this has been an impediment to exploration in this particular basin in the past. RLC acquired its tenements on the margin of the basin based on a concept that shallow sub-basins should be present on the basin margins. The results of the MT survey fully support this concept.
 


The Alkali Lake North Project covers part of a discrete sub basin located 30 kilometres northeast of Silver Peak and it occurs within an extensive 30 kilometres long, northwest trending basin that drains to the south towards Alkali Lake. The Google Earth image together with the gravity image (Figure 3) suggests that a deep basin is masked by recent alluvium. Several hot springs discharge alkaline salts onto the surface of the playa lake.


Figure 8. Alkali Lake North. Google Earth image showing the location of RLC's placer mining claims, with the evaporation ponds of Albemarle Corporation's Silver Peak Lithium Operation to the lower left.

 

Brine targets identified for drill testing       (refer to ASX release 29 May 2017).

A strong brine target is identified in MT geophysical survey.

  • The target is spatially associated with a discrete sub-basin approximately 1200m wide.
  • Drill permitting commenced in May 2017.
  • Drill rig available in Q3 CY2017.

Geophysical Survey Results

The geophysical survey method used is known as a magneto-telluric survey (MT survey), selected because it has the capacity to resolve multiple conductors at varying depths within a basin. Resistivities of one ohm-metre or less are considered indicative of brines. The results clearly indicate a broad, structurally defined basin that contains a brine target associated with a discrete fault bounded sub-basin.


Figure 9. Alkali Lake North project. MT survey line showing brine targets (<1.0 ohm-metre resistivity - coloured deep blue on this image) and basin structure, and proposed drill hole.

 

Brine targets are observed in the MT survey as follows:


 

 

11 August 2017