Summary:
The structural setting, host lithologies, and mineralization observed on the Tonopah Lithium Claims (TLC) Property is similar to the lithium in smectite clay model proposed by Asher-Bolinder (1991).
Local Geology
Surficial geology within the Property boundary is mapped as a Quaternary-aged flat alluvial outwash plane. The outwash plane is interspersed with shallow washes draining towards the west. The shallow washes partially expose underlying fines-dominant sediments and lithic tuffs of the Tertiary Miocene-age Siebert Formation. Exploration drilling on the Property shows the outwash plane surface alluvium to have an average thickness of 22 feet (ft) (6.7 metres (m)). Bordering the Property are rhyolite intrusions in the east and andesite in the north that are exposed on the high ground.
Alluvium ranges from 3 to 157 ft, with the thicker alluvium in the north regions of the property. Bordering the Property along the east-central edge is a predominant rhyolite intrusion, other volcanics occur at the southeast, northeast, and northwest Property edges.
The dominant lithology below the alluvial cap varies throughout the Property. Below the alluvial cap, lithology as observed from drill hole records, are finely laminated claystone beds with lenses of sandstone and conglomerate with occasional volcanic tuff and ash layers. Collectively, this mixed unit of lacustrine sedimentary beds and minor volcanics is referred to as claystone or “upper claystone”. Underlying the upper claystone are tuffaceous sandstones and conglomerates collectively referred to as the basal tuff marker beds, which are grouped with additional lower claystone units. The basal tuff marker beds are more pronounced in the east and southeast areas of the Property. New drilling to the west and northwest demonstrated a continuation of the alternating clays and tuffs with additional claystone below the basal tuff marker bed. These claystone’s below and including the basal tuff marker beds are collectively referred to as “lower claystone”. The lower claystone’s suggests a deepening of a paleo basin westward. Below the lower claystone (basal tuff marker bed and deeper claystone) drilling has intercepted both tuffaceous crystalline basement and limestone (referred to as basement).
Ten (10) significant regional fault blocks were interpreted from the exploration data on the Property. Blocks 1 through 5 (southern blocks) are at the south end of the property, 6 and 7 (central blocks) at the center, and 8 through 10 (northern blocks) at the north. Regional blocks are more complex (additional smaller structural faults and/or features exist) and further review and studies are needed to better define the Property. The stratigraphy is additionally complex with Tertiary volcanic intrusions and tuffs occurring simultaneously with clastic paleo basin deposition within a region of ongoing typical Basin and Range faulting.
The northern blocks are divided from the central blocks by a normal fault (F2) with possible eastwest strike-slip displacement. The northern blocks are further separated by two normal high angle (northeast-southwest trending) faults that envelope a central downthrown block (block 9) that is interpreted as a paleo sub basin with a thickening of clay deposits.
South of the F2 fault, the central and southern regional blocks are separated by sets of both north- south and east-west trending high angle faults. The central and southern blocks are divided east to west by a dominant north-south trending fault (F1) with an average displacement of approximately 500 ft (152.4 m) of displacement in the south. Here the F1 fault separates shallower higher grade (greater than 500 ppm Li) lithium claystone in the east from same high grade lithium claystone in the west.
Eastern blocks (central block 7 and southern block 2) have elevated lithium concentrations occurring in the surficial alluvial, underlying claystone (upper claystone), and the basal tuff conglomerate units (grouped with lower claystone’s for modeling purpose). Here lithium grades are highest and most consistent in the upper claystone beds. In the western blocks (central block 6 and south block 1) there are additional elevated lithium concentrations at depth in lower claystone. The southern block 3 is a horst type block of volcanics interpreted as containing no claystone. Southern block 5 contains a shallow basal tuff conglomerate and block 4 appears to be a down dropped graben.
The claystone and basal tuff conglomerate units are interpreted to be generally flat lying with a southwest dip. In surficial outcrops dips ranged from 29° southeast, 10° south, and 5° southwest with the variation interpreted as soft sediment deformation and local fault flexure. Cross Section A-A’ is oriented looking northeast, and Cross Section B-B’ is oriented looking towards the north-northwest. The cross sections have a vertical exaggeration of 2:1.
Fault displacement on the property is estimated using bedding trends from available drill holes and displacement can vary up to hundreds of feet on the same fault plane for some. The northern interpreted graben (block 9) has an average displacement of approximately 300 ft (91.4 m) on the east and approximately 75 ft (22.9 m) on the west. The F1 fault separating the central and southern blocks from east to west varies in displacement from only 10 ft (3.0 m) of displacement in the central block to approximately 500 ft (152.4 m) in the south.
Mineralization
Elevated lithium concentrations occur in eastern regional blocks on the property in the surface alluvial, underlying claystone (upper claystone), and basal tuff unit. Elevated lithium concentrations also occur within deeper clay units (lower claystone) in the western blocks 1 and 6 and northern block 9. The highest and most consistent lithium grades occur in the upper claystone beds that are located east of the F1 fault. Samples taken from the claystone at similar depths located west of the F1 Fault contain significantly less lithium (less than 400 ppm). East of the F1 fault, the lithium concentration is highest in a zone of about 150 ft (45.7 m) above the basal tuff; the lithium concentration tends to decrease higher in the sequence to the base of the alluvium. The overall footprint of mineralized clays, with lithium concentrations greater than 500 ppm, is 7,500 acres (3,035 hectares) extending from just below surface weathering to a depth of approximately 1,000 ft (304.8 m) below surface.