Exploration Licenses 1947 (Druid Range) and 1948 (Kanyaka) are in the western central part of the Proterozoic to Cambrian Adelaide Geosyncline approximately 70 – 110 km north-east of Port Augusta, close to the town of Hawker. In a regional...
Exploration Licenses 1947 (Druid Range) and 1948 (Kanyaka) are in the western central part of the Proterozoic to Cambrian Adelaide Geosyncline approximately 70 – 110 km north-east of Port Augusta, close to the town of Hawker. In a regional context, the South Flinders Ranges have been the focus of sustained diamond exploration interest since Stockdale Prospecting Limited discovered the Eurelia kimberlite dyke swarm during the period between the late 1960s and late 1970s. The Eurelia dykes are located 65 to 75 kilometres south-southeast of Hawker and comprise thirteen Jurassic micaceous kimberlite dykes which trend in a north-westerly direction. During the initial 6 months of tenure, exploration activities over the tenements included a detailed desktop review of existing open-file company reports and historical exploration data, a structural study of the project area, field reconnaissance/mapping and bulk stream sediment sampling. In total 5 bulk stream sediment samples were collected in and marginal to the tenement boundaries, to verify the results of earlier explorers, and to test the effectiveness of sampling techniques and to identify indicator trails that would indicate shedding from within the tenements. The recent structural interpretation of the project has highlighted extensional faults associated in part with kimberlite indicator mineral occurrence in nearby active drainage. These fault zones have not formed the basis of previous exploration philosophy and have therefore not been adequately tested for intrusions related to possible kimberlite emplacement. On the basis of previous survey work any primary source is unlikely to possess a discernible magnetic signature and therefore future exploration will probably rely on detailed mineral-graphic surveys guided by structural and geomorphological analysis. Exploration work in the 6-month period to 14th July 1996 exploration activities on EL 1948 Kanyaka saw Amity International Ltd the collection and processing of 75 stream sediment samples and 3 bulk loam samples to produce a heavy mineral concentrate. The concentrates produced underwent analysis that included stereo-microscope analysis and semi-quantitative SEM work. Several identified indicator minerals underwent microprobing including comparative probing of picroilmenite from the Springfield Basin. One rock sample was collected for petrographic analysis. Results conformed the results of earlier exploration in the Calabrinda Creek drainage, with the indicator mineral trails refined upstream. Four further areas (Hunt Hill, CC050, CC053 & Wilson Valley) were highlighted for diamond exploration. An area of ~20 square-km was also identified at Kanyaka Hill for base metal prospectivity. During the same reporting period on Druid Range no work was undertaken, with the focus being on proofing the earlier completed structural study within Kanyaka along Calabrinda Creek before moving into the more rugged Druid Range EL 1947. In the reporting period to 14th July 1997, comprehensive stream gravel (71), grid loam (49) and rock chip (6) sampling was carried out around the previously identified anomalies, plus the acquisition and interpretation of aerial photography. Processing and detailed analysis of these samples, including heavy mineral analysis and microprobing was undertaken. Detailed and general geological mapping was undertaken. Stream sediment samples were collected at 50 m interval upstream of previous positive sample sites, and at 100 m spacing along the eastern (negative) branch of the creek. Work to date has resulted in the discovery of a very decomposed, kimberlite indicator bearing rock in the upper Calabrinda drainage, with a similar situation thought likely to exist at the Hut Hill anomaly. Ground work during sampling has revealed that remnants of ancient land surfaces which Amity believe may have played a role in preserving the source of the indicators, and restricting the amount shed into the catchment. A number of samples returned minerals of interest in respect to base metals. In the 6 months to 14th July 1998 for EL 1948 and EL 2050 Amity undertook detailed griding, ground magnetics and geological mapping over the Calabrinda, Hut Hill and Pine Flat Swamp anomalies. They collected 1800 kg of a bulk sample from Calabrinda. A further 47 stream sediments, 1 loam and 10 decomposed rock samples were collected from across the anomalies. Ground magnetic surveys were completed over 3 anomalies along with geological mapping, at 25 m x 10 m intervals (Calabrinda), 25 m x 100 m (Hut Hill) and 50 m x 100 m (Pine Flat Swamp). Work to date has resulted in the delineation of a weathered and oxidised polymictic breccia at the Calabrinda Anomaly, possibly related to diatreme development. A single micro diamond measuring 0.3 x 0.18 x 0.125 mm was recovered from the Calabrinda breccia and is considered diamondiferous. This breccia has close textural similarities to the Argyle Lamproite, (“sandy tuff”, Western Australia), the Bakwanga Kimberlite (“polymictic kimberlite tuff”, Zaire), and the Camatue Kimberlite (“polymictic kimberlite tuff”, Angola). The survey showed that the Calabrinda breccia is marked by a 40 gamma “low” within the area of no outcrop. In the 6 months to March 1999 for EL 1948, Tiger International signed a JV agreement with Amity, and the reporting covers the work completed by Tiger. Fifteen gravel/loam/rock samples from across all the prospects for indicator mineral sampling, while geological mapping at Calabrinda and Hut Hill was undertaken at the 1:2500 scale [results included in the report]. A total of 45 aircore/RAB bedrock exploratory holes for a total of 1040 m were completed in in December 1998, with 38 holes for 798 m at Hut Hill (20 m spacing extended out to 40 and 80 m), 4 holes for 117 m at Calabrinda, and 3 holes for 125 m at the Wilson Valley prospect. Mineral processing and mineralogical observations of drill samples (26) and the assaying of 155 samples for incompatible trace elements (Nb, La, Ce, Zr, Ni, Ba, Sr and Rb) was also completed. A single costean 100 m long by 5 m deep was constructed at Calabrinda to cut the topographic low/anomaly, however the walls collapsed rendering it too unsafe for detailed investigations. Four rock samples were sent for petrological analysis. Drilling at Calabrinda Prospect has proven that the topographic low is not a large kimberlitic intrusive, but a karstic micro-basin filled with fluvial and lacustrine sediments of possibly Pleistocene age, intermixed with kimberlitic indicator minerals. In the reporting period to 13th October 2000, for EL 2656, Flinders Diamonds Ltd commissioned an independent geological review by Ms Maureen Muggeridge of all its holdings including EL2656. The review resulted in confirmation of the potential of the Hut Hill prospect near where some kimberlitic indicators have been located and drill testing is recommended. In the reporting period to 13th October 2001, no new technical work was carried out while Flinders Diamonds was preoccupied with its share market float.
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