Norfolk Metals (ASX:NFL) (Norfolk or the Firm) is happy to current the next Orroroo Undertaking replace.
- Norfolk engaged Pacific Consultants to construct a knowledge base offering for a extra mannequin pushed method to additional exploration within the expanded tenement package deal.
- Beforehand recognized gamma anomalies at round 120m depth confirmed diminished sediments (redox surroundings) developed round this goal horizon.
- Structural reinterpretation of the gravity knowledge and phreatic uranium circulation mannequin generates new targets.
- Norfolk progressing exploration in direction of regional method with concentrate on broad spaced drilling over potential controlling constructions.
Determine 1: Orroroo Undertaking Location Plan
Commenting on Norfolk Metals, Government Chairman, Ben Phillips, states:
“Norfolk is extraordinarily happy with the outcomes of Pacific Consultants and our technical group growing our understanding on the regional prospectivity of the Orroroo Undertaking. The Firm expects to conduct a subsequent drilling marketing campaign which should think about all of the structurally hosted contributions together with any low value pre-drilling concentrating on methods to be accomplished prior. We now have further info to proceed ahead with stakeholder engagements and required contractors”
Drill core and drill chips Investigation
Drill core, drill cuttings and muds from holes drilled within the Walloway Basin to the north of Orroroo had been not too long ago reviewed on the South Australian (SA) Authorities core facility in Adelaide.
Determine 2: Spectrometer 153 cps Orroroo 2A diminished sediment margin.
Pacific Consulting was engaged to construct a knowledge base offering for a extra mannequin pushed method to additional exploration throughout the tenement package deal. Knowledge incudes drill knowledge from Linc Power drilling in addition to quite a few water bores within the district.
A digital knowledge base has been inbuilt Micromine utilizing open file knowledge from the SA Authorities. Numerous water bores and coal exploration holes are positioned inside the Norfolk tenement package deal. Radiometric logs present a large unfold anomaly within the higher Tertiary at ~ 120m beneath present floor. The Walloway Coal (lignite) Seam happens within the decrease Tertiary stratigraphy of the basin and is related to low radiometric anomalism marginal to the lignite.
In borehole Orroroo 2A (Determine 2), the carbonaceous silty clay at ~ 112-114m has an elevated radiometric studying on the margin with oxidized sediments above and beneath. A transparent demonstration that, not less than regionally, diminished sediments had been developed at this goal sedimentary horizon and that uranium was deposited on the redox margin. The drill core typically exhibits massive intervals of silt / clayey silt with medium to coarse sand bands now silted up. The present drainage exhibits the same and anticipated sample in cross part with slender cobble strewn excessive power channels and silty alluvial followers with sandy beds.
The Walloway Basin comprises sediment on the base which incorporates fine-grained sands, clayey sands and clays with minor lignite, of center to late Eocene age. The overlying sediments embody as much as 70m of clays with coarse gravel beds, usually lenticular. These overlying sediments vary in age from mid-Tertiary to Quaternary. Obscuring the Quaternary are older deposits of latest alluvium and outwash materials, derived from the encircling Pre- Cambrian rocks.
Whereas the paleoenvironment has not been reconstructed it may be anticipated that oxidized groundwater has percolated down gradient into the Walloway Basin carrying uranium which has interacted with both diminished sediments or sediments bearing diminished fluids. The supply of the uranium stays unsure (presumably from the west/northwest), however the coarse (sandy) beds on the goal horizon are the clear exploration targets.
Seismic Knowledge
In March 1980, the Division of Mines and Power South Australia (DME SA) performed a number of seismic traces over the Walloway Basin, particularly across the central portion of EL 6552 (Orroroo Undertaking) and the northern portion of EL 6814 (Black Rock Undertaking) (Determine 3).
The aim of the research was to establish the depth and lithological layers of the Walloway Basin and establish potential structural options which will affect the water consumption/circulation of the basin.
The outcomes of the seismic survey confirmed that the Walloway Basin might be divided into completely different layers primarily based on the completely different seismic velocities. The layers had been then correlated with the lithological items recognized within the NFL and Linc Power drill holes (Determine 4): –
- Quaternary to Current – Layers 2, 2A and three
- Higher Tertiary – Layer 3
- Decrease Tertiary – Layer 4
- Basement – Layer 5
As confirmed within the drill core and drill chips investigation, Layer 4 (Decrease Tertiary unit) consists of interbedded sand, silt and clay which is overlain by Layer 3 (Higher Tertiary), typically thick clay unit. The Decrease Tertiary unit predominates and thickens alongside the deeper troughs of the basin and its sandy nature counsel deposition in a fluviatile surroundings. The overlying Higher Tertiary unit is a extra intensive and steady unit of gray, brown and black clay, with kaolinite bands indicating deposition in a lacustrine surroundings.
The final form of the valley is asymmetrical with western margins steeper than east and bedrock depth as much as 350m deep on the noticed deepest level on line WB-79-1.
A number of sections had been constructed from the seismic survey however the two foremost seismic part traces WB-79-1 and WB-79-2 coincides with the drilling performed by NFL alongside the Walloway Creek and Rankin Rd Targets respectively (see ASX announcement: 7 February 2024).
Determine 3: Seismic Survey DME SA March 1980
It was additionally famous from the seismic research that structurally, the Walloway Basin is fault managed to the west and the main northwest-southeast fault recognized to the east could also be a zone of diapiric exercise. These faults have additionally been noticed within the interpretation of the regional gravity knowledge.
You will need to word that historic water nicely drill holes have been included within the seismic sections however no knowledge has been sighted on the general public area database of the DME SA.
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