Marqua Phosphate Project, Australia
Project Description
The Marqua Phosphate Project in the Northern Territory is located 300km south of Mount Isa (Figure 1). Rox has applied for two exploration licences at Marqua covering more than 2,400km2. The area is highly prospective, with high grade phosphate drill intersections already encountered and also occurrences of base metals and uranium.
Previous exploration of the area identified five phosphate prospects over a strike length of 20km with outcrops grading up to 39.4% P2O5 along a phosphorite horizon (Figure 2).
The prospects occur near the southern extent of the Georgina Basin, which is rapidly becoming Australia’s major hard-rock phosphate province.
Figure 1: Marqua Phosphate Project Location
Deposits within the Georgina Basin include:
|
Deposit
|
Resource
|
Status
|
|
Phosphate Hill 1
|
1,115 Mt @ 17.2% P2O5
|
Production
|
|
Wonarah 1,2
|
461 Mt @ 18.8% P2O5
|
DFS/Development
|
|
D-Tree 3
|
305 Mt @ 15.0% P2O5
|
BFS/DFS
|
|
Paradise South 3
|
72 Mt @ 17.0% P2O5
|
BFS/DFS
|
|
Paradise North 3
|
15 Mt @ 23.9% P2O5
|
BFS/DFS
|
(Source data: 1 Register of Australian Mining 2010/2011,
2 Minemakers Limited, December 2008 Quarterly Report
3 Legend International Holdings, Investor Presentation, 13 October 2010)
(DFS = Definitive Feasibility Study, BFS = Bankable Feasibility Study)The project area (Figure 3) is located only 250km from the nearest railhead at Phosphate Hill in QLD, and from the Western QLD gas pipeline; comparable distances as the Wonarah project (located further to the north) is to adjacent infrastructure.
Previous drilling has intersected good phosphate mineralisation at Marqua, including:
6m @ 19.9% P2O5 from 32m depth in hole QDA045
5m @ 23.7% P2O5 from 12m depth in hole QDA046
2m @ 45.8% P2O5 from 1m depth in hole QDA003
3m @ 25.1% P2O5 from 9m depth in hole QDA070
5m @ 26.1% P2O5 from 0m depth in hole QDA068
3m @ 21.5% P2O5 from 3m depth in hole QDA002
3m @ 21.0% P2O5 from 21m depth in hole QDA027
3m @ 16.9% P2O5 from 19m depth in hole QDA019
The drilling was, generally, wide-spaced (~ 300m) and as such these are encouraging results. Phosphate deposits in the Georgina Basin (e.g. Wonarah) generally cover large areas along relatively thin horizons (i.e. 1-7 metres thick) with the high grade DSO (direct shipping ore) of >30% P2O5 covering much smaller areas.
Given the results from surface sampling and drilling to date there is potential at Marqua for a substantial phosphate target above a 15% P2O5 cut-off, with zones of high-grade DSO contained within it.
Marqua is well situated to supply phosphate to the growing markets in Asia and North America. Phosphate is an essential component of fertilisers for the agricultural industries around the world. There are currently no substitutes for phosphate, so the demand should keep rising with the expansion of agricultural activities in the developing and developed world.
Previous explorers recognised the potential for phosphate to occur in the Marqua area and conducted surface geochemical sampling and drill testing of several targets.
Drilling conducted in 2003 returned values such as 1m @ 19.9% P2O5 from 5m depth, and surface samples at that time returned up to 32% P2O5.
Follow-up of these results culminated in the recognition of a 20km long phosphorite horizon that returned high grade surface samples at a number of prospects, including Red Heart, White Hill, Foss Hill, Coquina Creek and Library Ridge (Figure 2). This horizon has potential to be extended further along the host Cambrian Thorntonia Limestone unit (Figure 2).
Surface geochemistry was initially by portable Niton XRF analyser, but results were repeated by laboratory analysis, and produced in most cases results higher than the original Niton XRF. A combination of soil and rock chip samples was taken along the outcropping phosphorite zone.
Air core drilling followed, with 69 holes drilled for 1,863 metres in the September 2008 quarter. Selected results have been listed above.
Table 1 below lists the peak P2O5 results from the various prospects for the surface sampling and the drilling (1m samples).
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Figure 2: Tenement Plan Showing Prospect Locations and Geology
Figure 3: Georgina Basin Showing Phosphate Deposits
Table 1: Peak Assay Results
|
Prospect
|
Surface
P2O5 %
|
Drilling
P2O5 %
|
|
Red Heart
|
1.3
|
18.4
|
|
White Hill
|
36.3
|
27.3
|
|
Foss Hill
|
39.4
|
36.5
|
|
Coquina Creek
|
37.0
|
29.8
|
|
Library Ridge
|
38.7
|
15.7
|
For example, at the Foss Hill prospect, drilling has intersected several horizons of phosphorite dipping at about 27o, with good results being returned (Figure 4) indicating potential for extension at depth and along strike.
In addition to the phosphate prospectivity there are known base-metal occurrences and uranium potential which also need to be properly researched and followed up.
Rox is planning to follow-up the drilling conducted so far with confirmatory surface sampling and then further drilling to expand the potential size of the deposit to enable a phosphate resource to be estimated, probably by mid 2011.
The tenement applications will be processed by the NT Department of Resources, and should be granted to Rox in due course.
Figure 4: Foss Hill Surface Sampling Results and Drill Cross-Section