2011 Group technical report GR213/11 ELR 28161 and ELR 28162

Abstract

Groote Eylandt is Aboriginal-owned land, as granted under the Aboriginal Land Rights (NT) Act 1976 (ALRA). The Groote Eylandt Mining Company Pty Ltd (GEMCO) has its obligations defined in various lease documents including Mineral Leases, Exploration Retention Leases (ERLs) and Special Purpose Leases (SPLs), a Letter of Understanding dated 13 May 1965 and an Agreement dated 16 September 2006. Groote Eylandt is predominantly composed of a stable basement of Proterozoic quartz sandstones and quartzites. The overlying manganese deposits are part of a blanket of Cretaceous sediments lapping onto the western margin of the Proterozoic basement sandstones and quartzites of the McArthur Basin. The manganese orebody is a sedimentary layer, consisting of manganese strata occurring between clay and sand beds and gently undulates beneath the western plains of the island. It extends over an area of about 50 square kilometres as an almost continuous horizon ranging in thickness up to 11 metres. The ore body is thus essentially stratabound and strataform in character. This report covers what is commonly referred to as the 'Eastern Leases', the two Exploration Retention Licences (ERL 28161 and 28162) east of the main mining leases. Granted in November 2010, these licences cover the areas previously held by GEMCO under Exploration Licence EL 10115 and 10108 respectively. During the reporting period (December 1 2010 to November 30 2011), analytical results from the 2010 drill program returned and the remaining infill drillholes were completed in September/October 2011. The recent campaign included 110 holes for a total of 2,416m and included 1,498 samples for analysis. In addition, an aerial photography fly-over was completed.