INFORMATION COMING SOON
|OWNERSHIP:||Kidman Resources Ltd|
|LOCATION:||Proximal towns to Esmeralda include Croydon (58 km to the northwest) and Forsayth (106 km to the east).|
The Esmeralda EPM18050 covers a series of historical gold workings developed on quartz vein reefs hosted within the Esmeralda Granite of adamellite composition. The workings follow a number of sub-parallel narrow high grade quartz veins and shear zones that are concentrated in an 800 by 500m area. In the period 1894 to 1899, historical records report a total of 5,746.5 tonnes of ore was mined at Esmeralda for a return of 3,189 oz of gold at an average grade of 17.29 g/t Au.
Esmeralda lies within the Georgetown Inlier, a suite of Precambrian metamorphic rocks and granites. Younger felsic intrusions (including adamellite, granite and granodiorite) of Permo-Carboniferous age occur, along with extrusive rhyodacite and tuff of the same age.
Esmeralda occurs on a dissected plateau. The plateau comprises a thin layer of Cretaceous sediments sitting above mainly Croydon Felsite with intrusions of Esmeralda Granite. The overlying sediments form a low angle contact with the underlying felsite in a number of areas where this contact is exposed.
Regional faulting is common with near-vertical, normal faults identified. Regional northeast trending faults are clearly observed on satellite imagery and in some cases, appear to form the boundaries of what has been termed the “Croydon Cauldron”. This is a fault-bounded area of subsidence with several bounding faults being identified for more than 80 km in length.
The Esmeralda Granite is a medium-grained, largely equigranular, grey, biotite adamellite of probable Permo-Carboniferous age. Esmeralda Granite occupies a majority of the tenements two separate area retained post reduction (see Figure 2 below). The granite dominates the Northern block which contains an abandoned area of gold workings. The Southern block of EPM18050 covers the Esmeralda Prospect hosted within the granite, however the southern contact is partly obscured by overlapping younger sediments. In places, the adamellite appears to grade into granodiorite composition. Classic graphic textures in the adamellite are common however patches of fine-grained adamellite have also been observed.
In places, a dark component of the Esmeralda Granite occurs, which is thought to be derived from partly-melted and recrystallised Precambrian-age carbonaceous siltstone. This composition and geological feature is unique to the Esmeralda Granite in this region.
The Esmeralda Granite is well-jointed and north-northeasterly trending faults reflect the regional trend on a prospect scale. Three sets of jointing have been recorded; a NNE, an ESE and a sub-horizontal set. The southern margin of the Esmeralda granite trends in a northwesterly direction (perpendicular to the main fault/joint orientation) and appears to be truncated by a fault. This faulted boundary has not been observed but coincides with a stream aligned in the same direction. It is postulated that the stream outlines the faulted granite southern contact.
Localised kaolinite development immediately adjacent to faults and veins is the only alteration observed within the Esmeralda Granite itself. No significant alteration has been observed elsewhere.
Immediately overlying the Esmeralda Granite unconformably is the Gilbert River Formation. These series of sediments include interbedded conglomerate, quartz greywacke, quartz sandstone, siltstone and shale. The arkose (coarser material) including the greywacke and sandstone is thought to be derived from erosion of the surrounding Palaeozoic granite (providing abundant detrital quartz). The sandy units tend to form resistive hillocks which can assist with topographic field orientation.
Cenozoic alluvium and Quaternary sands covers the younger rocks in places up to 15m thick. This cover consists of clayey sands, sandy clays, conglomerate and sand. These sediments are loosely cemented and lateritised to some extent. The Quaternary material is usually restricted to water courses.
Gold was first discovered at Esmeralda in 1892 and the results of hand pickings were so good that a 5-head stamp battery was installed at Rifle Creek (in the northern part of the tenement) soon after the initial discovery. Early records of gold, tin, silver, lead and copper were identified as being derived from the Esmeralda Granite.
In the five years from 1894 to 1899, records demonstrate that 3,189 oz of gold were derived from 5,746.5t of ore (with an average grade of 17.29 g/t gold).
The Queensland Government funded a geophysical survey and diamond drilling campaign between 1936 and 1939. This pre-war work was aimed at stimulating mineral exploration towards the end of The Great Depression but failed to encourage further exploration at the time.
Exploration since the 1980s had considerable success in identifying Esmeralda’s potential. This includes:
- Rock sampling with gold values up to 59.2 g/t.
- Costeaning uncovered zones varying from 1m at 36.8 g/t Au to 9m at 2.0 g/t Au.
- Soil sampling located anomalous values to 12 g/t Au and a broad 2 g/t zone in the northern part of the historic workings.
- RC drilling. 13 initial shallow holes were drilled in 1983, 11 of which intercepted intervals of 1 to 6m and grades from 1.6 g/t to 5.9 g/t and averaging around 3 g/t Au. Seven follow-up holes in 1994 with one hole returning 4m at 8.09 g/t.