Introduction
The Bondaye Project is located 265km west of Accra, centred about 12km south of the Prestea mine-site and 75km northwest of Takoradi, the capital of the Western Region. The project lies within the Wassa West and Nzima East Districts of the Western Region. The project consists of one Reconnaissance Licence under Application that covers about 44km².
Project Geology
The area covers part of the south-western portion of the Ashanti Belt, just south of its change in strike from northeast, between Prestea and Obuasi, to north-south on the southernmost section, from Prestea to Axim. This southern portion is frequently referred to as the Ankobra Lineament. From west to east within the southern part of the concession area, the stratigraphy changes from meta-sedimentary rocks of the Kumasi Basin, to meta-volcanoclastic rocks and graphitic phyllites with thrust-slices of andesitic to mafic volcanic rocks of the Ashanti Belt, followed by Tarkwaian clastic sedimentary rocks to the east. Slices of Tarkwaian units are incorporated within the main Tarkwaian/Birimian contact area, suggesting superimposed thrust slices. The more or less north-south oriented eastern section of the proposed concession roughly follows the Ankobra River and the Tarkwaian/Birimian boundary, and includes a number of prospective fault contacts. Airborne geophysical and topographic data show strong north-south striking structures sub-parallel to the stratigraphy. These are cross-cut locally by northeast-striking faults.
Weathering has resulted in the formation of a mature lateritic profile which has commonly partly degenerated to a latisol, and has been eroded and incised.
Exploration History
The Bondaye Project has been the subject of only very limited exploration.
In past centuries the region was the site of substantial artisanal gold production. The first direct involvement by Europeans in the area was in 1654 when the Dutch built a fort in the southern part of the project area as a trading centre. Active prospecting and mining in the region by the British commenced in the 1880s.
One minor hard rock gold occurrence, at Bippokil, is noted in the southern part of the project area. The prospect is indicated on very old maps, close to the site of a Dutch Fort, but the nature of the prospect not known. Its structural location is, however, near the fault that hosts the Bonza and Tintinah prospects in Takoradi Gold’s licence to the north. The Bonza Prospect is described as a number of colonial workings, including small shafts and trenches, on a meta-sedimentary/meta-volcanic contact, comprising a quartz vein 0.2m to 2.5m wide, located just north of the licence boundary. The Tintinah Prospect, 7km along strike to the north, consists of extensive artisanal open cut pits, underlain by Birimian meta-sedimentary rocks that have been intruded by granitoids. The best gold mineralisation is hosted by fine quartz stockworks in the granitoid.
The licence area borders that of Takoradi Gold to the north, where the main hard rock target lies 4km west of the Tintinah-Bonza trend at Insamankaw, just south of Kutukrom village. Colonial workings are scattered along a 3km length of a north-south striking structure that is interpreted to be a splay off the main north-easterly striking Ashanti structure at Prestea to the north. A four-stamp battery was operating at Insamankaw prior to the World War I. Operations included underground workings on at least two levels, however there is no record of any gold production.
The southern and western part of the proposed licence was previously held by Takoradi Gold, which carried out systematic soil sampling and testing of alluvial prospects. The eastern side was held by Gold Coast Mining and Development, but little work was undertaken.
The Ankobra River has long been a significant source of alluvial gold for local inhabitants. Portions of the river continue to be worked by artisanal miners in the dry season, when the river gravels can be more easily accessed. In addition, many of the riverbank areas and older terraces have also been worked in the past.
Europeans showed interest in the alluvial potential at the end of the 1800s. Various groups tried to establish dredging operations. Numerous small dredges were sited along various sections of the river between the Bonsa and the Awudua tributaries, within the proposed licence area, in the period 1904 to 1919. Production of 41,500oz of gold is recorded. In addition, dredging was carried out along the lower reaches of the Fure River, also partly within in the licence area, where 456oz was produced. Dredging was mostly confined to the area between the Bonsa and Huni Rivers.
A quite extensive Banka drilling program was carried out in 1975 to 1976. Most of this work was completed on the western bank of the Ankobra River. The work indicated substantial low grade resources potentially suitable for large scale dredging.
Exploration Potential
The Bondaye Licence, is situated in a structural and geological domain with potential for the following types of deposits:-
- Recent unconsolidated placers; substantial low grade alluvial resources are indicated in the Ankobra and Fure Rivers, however these are considered uneconomic at current gold prices.
- Palaeo-placer gold mineralisation in Tarkwaian Banket Series conglomerates.
- Mineralisation associated with quartz vein and stockwork systems hosted in Tarkwaian rocks (Damang type). This style of mineralisation appears to be related to major fault systems that crosscut earlier structures, often in the vicinity of Tarkwaian Banket Series conglomerates. Significant structures are evident in the Tarkwaian units on the eastern side of the concession.
- Orogenic vein-dominant deposits hosted primarily in Birimian meta-sedimentary and meta-volcanic rocks, and associated with major regional structures.
- Orogenic deposits hosted in granitoid and felsic porphyry intrusions; mineralisation associated with alteration zones and quartz stockworks in granitoids occurs at Tintinah to the north.