Introduction
The Horse Well Project covers 33.65km² in Exploration Licence E08/1557.
Figure 4 Horse Well Project Geology, Uranium Occurrences, Targets
Geological Setting
E08/1557 covers part of a north northwesterly trending elongated syncline of Palaeoproterozoic Bangemall Supergroup sediments in the northeastern portion of the tenement, with Palaeoproterozoic foliated and gneissic granodiorite of the Gascoyne Complex predominant to the west and occupying the majority of the tenement. The Bangemall Supergroup lies unconformably on the granodiorite basement.
Horse Well Project -
Radiometric image showing radiometric anomalies (red stars) and known uranium locations (red dots) (survey 400m line spacing)
Previous Exploration and Mineralisation
The area was initially regionally targeted for uranium mineralisation during reconnaissance by various companies commencing in 1972.
Mapping and radiometric traverses were undertaken within a mineral claim located in the southwest of the tenement. The claim was over a narrow shear zone with copper mineralisation evident in a series of pyritic quartz veins. A grab sample with values of 41.5% Cu and 200ppm U3O8 was obtained. The mineralisation is limited to a small portion of the vein series, and further work was not conducted.
During 1973, Uranerz conducted geological mapping, radiometery, trenching, hand auger drilling and drilling of four shallow diamond drill holes on mineral claims adjacent to the northeast boundary of E08/1557.
Secondary uranium minerals were found in trenches and drill holes. A trench sample assayed 580ppm U3O8 was thought to be surface enrichment, and a drill core intersection over 15cm from 15m assayed 809ppm U3O8. The occurrences are of two types: those associated with a calcareous horizon over the basement, and those related to deep infilled scour channels of pegmatite and granite detritus (source rock) which were later cemented by carbonate.
Further trenching over the unconformity assayed up to 1030ppm U3O8, and a further nine diamond drill holes were drilled. Carbonaceous and pyritized clayey-silt horizons were intersected and a uranium assay up to 539 U3O8 over almost 1m was obtained. Trenching also uncovered oxidized spheres of ex-marcasite indicating reducing conditions once existed in the scour channels. The drilling indicated a moderate thickness of sediments to 80m of predominantly fine to medium grained unconsolidated sands including the minor carbonaceous clayey silt horizons. No mineralisation was observed in the carbonaceous bands with uranium probably bound to the carbonaceous material to provide the anomalous radioactivity.
In 1976, Uranez extended their holding to include the western and eastern synclinal unconformity contacts with the purpose of locating, mapping, drilling and accessing possible channel structures. This holding partially included the northeasten section of E45/1557. Traverses and resulting geological mapping and radiometric readings indicated some 20 areas of interest. The anomalies were drill tested with 88 rotary and percussion drill holes totalling 1965m. The best intersection was in PDH 106 between 18.5m and 25.5m with a weighted average of 700ppm U3O8. All other drill holes had samples which assayed less than 500ppm.
Between 1979 and 1982, exploration at Horse Well followed up the Uranerz effort at the eastern limb of the syncline in the area adjacent to E08/1557. Work initially included a helicopter radiometric survey, geological mapping, geochemical sampling and assaying. Seven anomalies were identified, with follow up drilling limited to a previous Uranerz percussion drill hole site which intersected carbonaceous silts. The hole intersected carbonaceous material from 74m to 78m and from 107m to 109m with negligible uranium mineralisation. Grab samples associated with the anomalous areas showed best results of 590, 540 and 430ppm U3O8.
Discussion
The western and eastern unconformity contacts and anomalies proximal to them have been drilled by previous explorers. The drilling included the Bangemall sequence with associated overlying channels of Cainozoic sediments. The western unconformity lies in the northeastern part of E45/1557.
The granodiorites of the Gascoyne Complex which are predominant within E08/1557 remain largely unexplored. To the north of the tenement at Glenflorrie within the Hooley Project area anomalous uranium mineralisation has been reported in high background uranium granite of the Gascoyne Complex associated with tension fracturing.
There remains potential for primary hydrothermal uranium mineralisation to be present within the granodiorites on E08/1557, associated with tension fracturing and faulting. If such structural features can be identified, further follow-up work would be warranted.
Furthermore, calcrete developed proximal to drainage systems will not be discounted as potential secondary mineralisation hosts.
