Overview

Spain:

  Salamanca I
  Salamanca II
  Caceres I
  Caceres II
  Caceres III
  Caceres VI
  Guadalajara I

Australia:

  Miriam Bouchers

This area is situated in the Argañán district of western Salamanca Province, between Ciudad Rodrigo and the Portuguese border. It is limited to the north and west by the Hercynian granitic intrusives that form the Guarda Batholith. Numerous uranium occurrences and deposits are located in the meta-sedimentary strata that form a southeastern embayment to this batholith.

Uranium was first located in this area by the JEN in 1957. Their exploration activity continued until 1974, when their interests were ceded to ENUSA. In the meantime, they had located the "Fe", "Esperanza" and "Alameda" deposits. ENUSA was principally involved with the development of the Fe Mine and also the evaluation of the Alameda de Gardón Deposit. The Fe mine was in production from 1974 to 2000, and produced an estimated 5,000t of U₃O₈.

Geology

The area is underlain by components of the ‘Schist-Greywacke Complex’ of late Precambrian to early Cambrian age. Martin Izard & Arribas (1984) have established a detailed stratigraphic sequence, which essentially consist of fine-grain detrital sediments that are frequently carbonaceous and pyritic, with occasional limestone, sandstone and conglomerate markers. The total thickness of the sequence appears to be well in excess of a thousand metres.

The sedimentary sequence has experienced intense deformation, principally during the Hercynian Orogeny. There are at least 2 phases of penetrative schistosity, followed by a further two phases of folding. The regional metamorphism corresponds to the greenschist facies, with both chlorite and biotite sub-zones being observed.

Granites of Hercynian age intrude along both the northern and western borders. These are coarse-grained, porphyritic biotite adamellites. At times a microgranitic facies is developed along the border. A thermal aureole is produced in the country rocks. There is a small granitic intrusion located between Gallegos de Argañán and Carpio de Azaba.

Following the main phases of deformation and igneous intrusion, there have been several episodes of fracturing extending from the late Hercynian to the end of the Alpine Orogeny.

Since the Hercynian Orogeny, the area has experienced an extensive period of erosion and peneplanation. During the Oligocene and Miocene, thin sheets of fluvial sands were deposited. These outcrop both to the south and east of the area of interest.

An initial nine hole drilling program confirmed the geological setting and, combined with a trial helicopter airborne magnetic and radiometric survey has highlighted several new target areas.

Uranium Occurrences

Numerous occurrences of mineralisation are concentrated in the following zones:

• the ‘Fe’ & ‘D’ deposits (already partially mined),
• Alameda de Gardón
• Sageras (west of Fe)
• Rio Azaba
• Villar de Yegua
• South of Gallegos de Argañán
• West of Carpio de Azaba

The primary mineralisation consists of pitchblende and coffinite associated with carbonates, adularia and iron sulphides that fill fractures and breccias in finely-laminated sediments. Several phases can be recognised.

Berkeley Resources Ltd.
Level 9, BGC Centre, 28 The Esplanade Perth,
Western Australia 6000