Crossland Uranium Mines Ltd

SUMMARY:  

•  Crossland has been able to secure a totally owned contiguous holding of prime prospectivity for URD that has fewer access issues than those that commonly burden explorers on ground of similar prospectivity for URD in the Northern Territory
•  Crossland will explore the tenements systematically and thoroughly utilising the latest methods.  Some of the contact sediments in the Project area are carbonaceous shales having high background radioactivity and elevated uranium contents that could act as an intermediate source of uranium. 

Source of uranium

• In the case of the Chilling project, the district is located in a zone of high uranium background, in both granites and metasediments and volcanics.
• The ultimate source of these high uranium background values is the Proterozoic granite basement, which is likely a re-crystallised Archaean basement similar to which is exposed in the Rum Jungle and Waterhouse granites, 20 km to the NNE of the project area.
• These rocks probably exist at depth through the project area, and in gneiss belts around the western side of the project area. Some phases of the intrusive granites in the south of the project area in the Buchanan Window may be recrystallised Archaean basement granites.  

Transport mechanism

• Basin- forming structures, the Giants Reef and Adelaide River Faults, traverse the project area. It seems likely that the latter may have been active at the appropriate time for related structures to provide channelways for uranium-bearing fluids, and Crossland's holdings give priority to securing this. Generally, mineralisation will be in subsidiary structures rather than major faults.

Site for deposition

• The classic site for deposition of URD is the unconformity surface between (older) metasediments and overlying (younger) sandstones.
• The project area contains about 130km of strike length of this unconformity, over the structures most likely in Crossland's view to provide suitable channelways for uraniferous fluids. These could also control the structures that host mineralisation.
• Almost all of the important Australian examples of these deposits lie below the unconformity surface, while those in the similar Athabasca Basin setting in Canada occur both above and below the unconformity surface, and some of the largest and richest deposits occur in fault structures within the upper sandstone.
• The more spectacular Canadian discoveries have been made in the last few decades, and are probably a function of the much longer period of active exploration through the cover rocks that has been enjoyed by the uranium exploration industry in the Athabasca Basin relative to the equally prospective districts of the Northern Territory.
• By definition, deposits in and below the cover rocks will be more difficult to locate quickly than those exposed where the cover is removed, as is the case in most discoveries in the ARUF, with the exception of the largest discovery, Jabiluka II, and the most recent to be announced, Ranger 68.

Looking east to the plateau formed by Depot Creek Sandstone of the Tolmer Group, across the granite and metasediments below the escarpment, in the Allia Creek Window.	The MEMA Prospect in Allia Creek Window has outcropping secondary uranium mineral.

• The Depot Creek Sandstone of the Tolmer Group is equivalent in age to the Kombolgie Sandstone in the ARUF. Both these sandstone units are older than most of the mineralisation in ARUF and Rum Jungle, and structures that control the deposition of ore cut the sandstones. There are many potential sites for uranium deposition throughout the Depot Creek Sandstone, and probably below it, within the Chilling Project Area, and it is Crossland's intention to locate and test them. 
• The Uranium Expert's Report for the prospectus points out that alteration similar to that associated with URD in ARUF has already been identified in the project area, and that there are several known uranium occurrences, including secondary uranium mineralisation with values up to 0.395% U3O8. Crossland expects that thorough exploration will find more.

Progress at Chilling

Since Crossland listed on ASX, major progress has been made at Chilling, and the project has evolved as several prospect areas have been identified.

Buchanan Sub-Basin [part of EL22738]

Granted in early 2009, Crossland have extensively explored this tenement, located 65km SSW of Tipperary Cattle Station, for 3 field seasons and now have a comprehensive geological model. Originally believed to be a “window” of Lower-Proterozoic sediment within Low to Mid-Proterozoic granite, metasediments and sandstone is now, after a comprehensive Diamond Drilling program in 2011 (10 holes and 2291m), known to be an elongate 2x15km basinal succession of Cambrian basalt and carbonates situated within the Low to Mid-Proterozoic granite, metasediments and sandstone.

Two RAB programs during 2009 and 2011 completed a total of 2581m and 2837m respectively. The 217 holes were located mainly on the margins of the syncline, aimed at covering the contact between the granite at the edge and sediments within them. Mapping and backpack spectrometer work had highlighted these areas with elevated decay counts per second (CPS) of uranium located on and near the outcropping chert ridges and surface leached “gossanous” zone close by. Results contained high uranium and base metal assay results on both programs.

 

 

The Diamond Drill program gave us a detailed geologic picture of the sub-basin, contained high base metal assays in locations similar to RAB holes but also provided features that allow for development of a supergene base metal model within the depths of the basin. Unconformity related Uranium deposits are common in both the Pine Creek Geo-syncline (Ranger 68, Jabiluka II) and the Athabaska Basin, Canada. The unconformity’s at Buchanan seen between the granite and Tolmer sandstone/Cambrian sediments provides a likely comparison. Mobility of metals in solution is key and is a feature of the basin confirmed during 2011 drilling.

Allia Creek Window [part of EL25076]

The Allia Creek Window in EL25076 is the site of the MEMA prospect, discovered in the 1980s by Mobil Energy Minerals. There are several outcropping occurrences of secondary uranium minerals at MEMA, as illustrated in the photos here. The MEMA structure is strongly developed, and seems to be associated with a strong linear response that can be mapped with magnetics and is also associted with and Airborne EM response from a survey completed for Geoscience Australia with Crossland’s participation.

In 2009, 2010 and 2011 an intensive geochemical and ground radiometric survey commenced at Allia Creek to prepare it for drill testing in the 2012 field season with multiple targets having been established.

 Marchfly Prospect [part of EL24557]

Additional prospective ground was acquired at Mount Thomas, where the Marchfly prospect, discovered in the 1980s and tested by Mobil Energy Minerals and the French energy company, Total, was acquired from Aldershot Resources Limited.   Their work identified high grade shoots of pitchblende that extend from outcrops of secondary uranium minerals.  Crossland’s target at Marchfly is a modest high grade open pit resource that might provide feed to an existing mill.  A second target is better developed structures along the Marchfly mineralized trend.  Crossland has completed detailed radiometric surveys and has so far drilled 11 core holes to test the Marchfly zone.

• Assay highlights of various drill programs are summarised in the table below.

 Eccles Prospect [part of EL25077]

The northernmost area of Crossland’s Chilling Project overlaps with the NT’s Litchfield Park. Exploration on carefully controlled conditions is permitted in NT Parks, and Crossland works with NT Parks and Wildlife Service to ensure that our impact on park values is minimized. There are some historic prospects within the park boundaries, including some that have been drilled in the past for uranium. Crossland is working towards follow up programs on some of these.

Previous work carried out at Eccles and an area extending NW was undertaken by Total/PNC from 1988-90, with 70 percussion holes drilled and 4 diamond drill holes drilled. All previous work existed in either hard copy or as scans of the originals. All of the handwritten drill litho logs and CPS Scintillometer data have been compiled into an Access database for ease of use and manipulation.

Using the aforementioned database, analysis of the data was done in Microlynx producing cross sections with assay data, CPS data and lithology data to highlight areas of significant interest. Four holes stand out with anomalous highs in U-CPS and 3 have the following assay sample results:

• Assay highlights found within the TOTAL drill program at Eccles in the table below 

The general consensus is that the anomalous mineralisation is found within a sequence of schists and carbonaceous shales.

Chlorite and Serecite alteration are common in the basement rocks of Eccles. Any Tolmer lying unconformably above tends to be (relatively) unaltered and have low Uranium counts. This is evidence that the top of the Burrell-Creek greywacke could be a palaeo-regolith, being chemically different to the Middle-Proterozoic rocks above. In addition, almost all holes show evidence of a rise in background Uranium counts going from the Middle-Proterozoic rocks above the unconformity to the Lower-Proterozoic rocks below the unconformity, showing that mineralisation is either older than the Tolmer sequence or the unconformity is a controlling factor in the movement of mobile Uranium.

Colour geological map of Eccles showing multiple drill locations and lithology, EL25077.

Progress at Chilling:

 Marchfly's radiometric survey zone: