re: croupier... For those interested, the following describes...

re: croupier... For those interested, the following describes the various Geologies of Olympic Dam, Prominent Hill and Marathon South...

Make your own minds up…

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***Prominent Hill***

The Prominent Hill iron oxide copper gold (IOCG) deposit is located at the southern margin of the Proterozoic aged Mt Woods Inlier under approximately 100 metres of sedimentary cover. Copper-gold and gold only mineralisation hosted in a large hematite breccia complex has been defined over 1 kilometre of strike to a depth of 500 metres to date. Mineralisation remains open to the east and at depth. Ongoing drilling and associated geological studies continues to improve understanding of the deposit and enhance predictability of drill targeting. Copper mineralisation within the breccia complex grades from a chalcopyrite dominant assemblage at depth, up through bornite-chalcopyrite to chalcocite in the upper parts of the system. Gold occurs co-incident with copper throughout the deposit and also as gold only mineralisation hosted in crackle veined sediments and siliceous hematite breccias enveloping the copper - gold mineralised breccias. Overall uranium concentrations at 103ppm are relatively low for the deposit style. Uranium distribution in the system appears to follow copper minerals with less than 100ppm in the upper chalcocite dominant parts and around 120ppm in the deeper chalcopyrite dominant parts. District wide potential for additional IOCG discoveries within the 3,700 square kilometres of JV tenements is considered high with a large number of untested geophysical anomalies and targets where follow up drilling is justified

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***Olympic Dam***

The deposit, which contains 2.1 billion tonnes at 1.4% copper extends for 5 kilometres in a northwest-southeast orientation and is 2 kilometres wide. Olympic Dam is the world’s sixth largest copper resource and the world’s largest uranium deposit. The deposit is hosted by the Olympic Dam Breccia Complex, a large hydrothermal breccia system wholly contained within the Roxby Downs Granite, a Proterozoic age granitoid interpreted to be part of the Hiltaba Suite. Initial hydrothermal activity within the Olympic Dam Breccia Complex was probably localised by structures in a dextral fault jog environment. Subsequent development of the complex involved repetitive and overprinting physical, chemical and volcanic brecciation mechanisms, resulting in a highly variable array of irregularly shaped and distributed breccia zones with widely differing and gradational lithologies. A complex pattern of hydrothermal alteration dominated by hematite and sericite, with lesser chlorite, siderite and quartz is associated with the breccia zones.

Mineralisation within the deposit is intimately associated with iron-oxide alteration of the granitoid, which dominantly occurs as hematite, with lesser magnetite at depth and on the periphery of the breccia complex. The principal copper minerals within the deposit show a broad lateral and vertical, hypogene zonation pattern grading from chalcopyrite on the margins to bornite, then chalcocite adjacent to a central barren core. Gold and silver are mainly associated with the copper sulfides, while uranium dominantly occurs in pitchblende disseminated throughout the hematitic breccia zones. Overall, mineralisation grade generally correlates with the degree of hematite alteration and is largely dependent on copper sulfide tenor.

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***Marathon South***

Marathon South – Drillhole MS 1 Hematitic Breccias Intersected Tasman Resources NL’s (“Tasman”) drillhole MS 1 at its 100% owned previously undrilled Marathon South prospect, located approximately 24 km north east of WMC’s major Olympic Dam Cu-U-Au-Ag deposit in South Australia, has intersected a thick zone (at least 150m) of hematitealtered breccias very similar in style to those in the Olympic Dam deposit, within the basement, from 558m to 710m depth (the current depth of the hole) (see figure 3).
These are the types of rocks which were targeted (refer our ASX announcement of 20 July 2004) by
MS 1 which is being drilled in an area previously unexplored prior to Tasman’s recent involvement.
The breccias consist of a variety of matrix and clast support styles, with clasts of metasedimentary and igneous rocks within a hematite-dominated matrix. Some breccias contain a variety of clast types, with evidence of more complex rebrecciation. Variable amounts of sericite and silica (quartz) alteration also occur throughout. The thickness and areal extent of the breccias is not known, but the gravity anomaly being targeted is a complex feature, about 4km by 6km in size, and MS 1 has intersected the extreme southwest margin of it.

Weak sulphide mineralisation, consisting of pyrite and lesser chalcopyrite (overall estimated at less than one percent sulphides) was intersected between 558m and 587m, and 689m and 710m depth and is currently continuing. At this stage the grade and thickness of the mineralisation is not known, nor is the overall economic significance of this result. Tasman believes however it may have located a new large iron-oxide system, potentially mineralised and a relatively short distance from Olympic Dam.

Drillhole MS 1 is part of an aggressive Fe-oxide Cu-Au exploration program being conducted by Tasman over a large area north of Olympic Dam. The Marathon South area was selected for drill testing based on geological modelling of Fe-oxide associated Cu-Au deposits, and geophysical anomalies, in this case a significant, but subtle gravity anomaly coincident with a strong (AMT) electrical anomaly, consistent with conductive basement rocks (refer figures 1 and 2). Tasman resolved to drill MS 1 after agreement by the South Australian Government to contribute to the cost of the drillhole under its program to encourage exploration in South Australia. Drilling is continuing to a planned initial depth of approximately 800m which is the current limit of capacity of the drill rig. Further information will be released as it becomes available.

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Cheers!