PACE Theme 2 (drilling partnerships with PIRSA and industry): Year 6 partnership DPY6-33 - Mount Hope district, south-western Eyre Peninsula, Archaean iron ore mineral prospects. Drilling project final report.
Published: 11 Nov 1911 Created: 12 Nov 2024 Revised: 12 Nov 2024

The south-western Eyre Peninsula regional iron ore targeting project has recently been initiated due to the success of Lynch Mining’s previous, in part PACE Initiative - subsidised, exploratory drilling programmes (DPY2-38, January-March 2006 and...

The south-western Eyre Peninsula regional iron ore targeting project has recently been initiated due to the success of Lynch Mining’s previous, in part PACE Initiative - subsidised, exploratory drilling programmes (DPY2-38, January-March 2006 and DPY4-52, January-May 2007), which identified significant iron mineralisation at the Bramfield prospect and found indications of substantial magnetite-bearing iron formations at the Trikera prospect. As part of this new project, a total of five prospects were initially selected by Lynch Mining for inclusion in an approved PACE Year 6 drilling subsidy proposal, but because of the paucity of information on the complex basement geology in the Mount Hope region, the numbers of drillholes planned for each prospect were later varied during the course of the actual drilling programme; consequently, two of the nominated prospects have not as yet been drilled. Instead, aircore drilling was carried out at just three prospects, Trikera, Mount Cora and Hillsea, during May-July 2011, aimed at testing known strong magnetic features. At Trikera prospect on EL 4172, a very strong linear magnetic anomaly (in excess of 13 km long) was already known to be produced by an iron formation, by evidence gained from Lynch Mining's earlier drillhole BRDD01. This hole had intersected magnetite-bearing gneiss and BIF which are cut by extensive late pegmatite swarms. Lynch Mining had determined that additional aircore drilling of at least 9 holes was required to the north and south of BRDD01 to ascertain the precise location of the iron formation, to guide planning of the sites of additional appraisal diamond drilling. For the PACE Year 6 drilling project, 45 aircore holes with a total penetration of 2407.6 m were completed along a number of drill traverses across this anomaly, which successfully further defined the iron formation. The dominant basement lithologies encountered are amphibolite, granites and various gneisses, as well as magnetite- bearing gneisses. These units are similar to those encountered in hole BRDD01 drilled earlier on the southern part of the anomaly. Some iron intercepts of interest were recorded from within them, e.g. 39 m @ 14.79% Fe in hole BRAC025, although a number of the holes bottomed in magnetite-bearing lithologies which did not assay above economic threshold levels. It is thought that this may be due to only a small interval of the magnetite-rich lithology having been penetrated by the aircore drill method. At Mount Cora prospect on EL 4537, very widely spaced aircore drilling previously carried out by BHP had indicated the presence of probable haematitic iron formation (12 m @ 35.95% Fe in hole BLAC1035). Lynch Mining decided that closer spaced aircore drilling, involving at least 6 additional holes, would be required to allow for a better interpretation of this iron occurrence. Accordingly, as part of the PACE Year 6 programme, a single aircore drilling traverse of 15 holes for 1056 m total penetration was completed across the target anomaly, at approximately 40 m hole spacing, approximately 100 m to the south of BHP's drill site. However, no significant iron intersections were recorded on this traverse, and the nature of the earlier intersection remains uncertain. Weak base metal mineralisation recorded in holes BLAC008 and BLAC010 appears to be similar to the Malache / Oakdale style mineralisation discovered further to the north by Lynch Mining early in 2006, and may reflect a further local development of this mineralisation. This view is supported by the presence of graphite rich schists in hole BLAC011. At the Hillsea magnetic anomaly located on EL 4442, the results of detailed ground magnetic surveying led Lynch Mining to interpret that it represents a folded iron formation, similar to that hosting the Bramfield iron deposit. The main Hillsea anomaly had not then been drilled, although Stockdale had previously reported encountering "ferruginous schist" in one of its diamond exploration aircore holes drilled on the flank of a weaker, north-western subanomaly. Accordingly, for the PACE Year 6 programme, 13 aircore holes with a total penetration of 787 m were drilled by Lynch Mining along two traverses across this anomaly. All of holes successfully reached basement, with 2 holes intersecting significant iron mineralisation. The iron formation encountered in hole MHAC085 consists predominantly of magnetite plus subordinate haematite, with the intersection commencing at the top of the basement profile. Elevated nickel (0.12% Ni) from this hole suggests a possible mafic affinity for the mineralisation (?skarn related). The iron in the other drillhole, MHAC093, was encountered at the base of the hole and proved too hard for the aircore drilling method to penetrate. This formation also contains elevated nickel, and is probably the same unit as that encountered in hole MHAC085. The intersection made in MHAC082 is non magnetic and may represent a weathered sulphide horizon, as it also contains anomalous uranium (48 ppm U) and elevated zinc values. Units surrounding the iron formation(s) include mica schists and sillimanite-rich gneisses. Follow-up drilling is still required in the Mount Hope region to test the encouraging indications of iron mineralisation found by both the subject PACE - assisted drilling and Lynch Mining's earlier wide-spaced reconnaissance drilling. Due to time constraints on conducting the iron ore search, the aircore phase of the proposed Pace Year 6 programme was expanded as described, and planned diamond drilling of the prospects will be completed at a later date after carrying out further geophysical interpretation.

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About this record

Record No mesac24560
Topic Geoscientific Information
Type of Resource Document
Category Type
Document Type Mineral Company Report - Mineral Exploration
Contributor
Sponsor
Tenement
Tenement Holder Lynch Mining Pty Ltd;Alphadale Pty Ltd;Lymex Mineral Tenements Pty Ltd
Operator Lynch Mining Pty Ltd
Geological Province
Mine Name Karalee prospect;Mount Cora West prospect;Mount Cora prospect;Trikera prospect;Hillsea prospect
Stratigraphy
Commodity
Notes
Notes: PACE project code DPY6-33 : company final submission includes exploration drilling actual total cost ($69,971.00 excluding Goods and Services Tax), out of which PACE Initiative funds have paid $35,000.00 (excl. GST).
Geographic Locality:...

Notes: PACE project code DPY6-33 : company final submission includes exploration drilling actual total cost ($69,971.00 excluding Goods and Services Tax), out of which PACE Initiative funds have paid $35,000.00 (excl. GST). Geographic Locality: South-western Eyre Peninsula;Mount Cora;Bramfield;1999 TEiSA Area A1 Aerial Magnetic Survey;1999 TEiSA Area A1 Aerial Radioactivity Survey Doc No: Env 12244 Drillhole: BRAC001 - BRAC045;(266559);(266560);(268239 - 268281);BLAC001 - BLAC003;(268282);(268283);(268285);BLAC003a - BLAC014;(266564);(268284);(268286 - 268295);MHAC082 - MHAC094;(268296 - 268307) Drillhole Unit No: 6029 01403;THROUGH;6029 01447;6030 00784;6030 00786;6030 00799;5930 01509;5930 01514;5930 01525

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Language English
Metadata Standard ISO 19115-3

Citations

Use constraints License
License Creative Commons Attribution 4.0
Persistent identifier https://pid.sarig.sa.gov.au/document/mesac24560
Citation Brewer, A.M. 1911. PACE Theme 2 (drilling partnerships with PIRSA and industry): Year 6 partnership DPY6-33 - Mount Hope district, south-western Eyre Peninsula, Archaean iron ore mineral prospects. Drilling project final report. Mineral Company Report - Mineral Exploration
https://pid.sarig.sa.gov.au/document/mesac24560

Technical information

Status
Maintenance and Update Frequency
Geographic Reference GDA2020 (EPSG:7844)
Geo bounding box {"type":"Polygon","coordinates":[[[135,-34.5],[136,-34.5],[136,-33.5],[135,-33.5],[135,-34.5]]]}
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