Discovery of a potential source of cement stone in the Percé area

Charles Gosselin
Géologie Québec

A large limestone deposit, considered to be a promising resource of cement stone, has been discovered in the Percé area. This deposit was found during work on industrial minerals and construction materials carried out by the Ministère des Ressources naturelles, de la Faune et des Parcs. The results were revealed during Québec Exploration 2004, held in Québec from November 22 to 25, 2004.

A summary evaluation of the limestone indicates grades of CaO (48–50%), Na₂O+K₂O (< 0.6%), MgO (< 2.5%), S (< 0.2%), and Cl (< 30 ppm) that satisfy the requirements of the cement industry. Easily accessible resources are estimated at several hundreds of millions of tonnes. In addition, the potentially exploitable limestone units are located a few kilometers from the coast and near a railway.

Nature of the work

During the summer of 2004, the Ministère des Ressources naturelles, de la Faune et des Parcs updated the inventory of quarries in the Bas-Saint-Laurent and Gaspésie regions. At the same time, a summary evaluation of the composition of White Head Formation limestone was carried out in order to check the potential of the sequence for cement production. The Nouvelle, Chandler, and Percé sectors were chosen because, in these areas, the formation outcrops fairly close to the coast, thereby increasing the likelihood of production (PDF Format, 131 Kb - Available in French). Hand sampling was carried out on a limited number (25) of outcrops. As the White Head limestone sequence is composed of thin limestone beds alternating with mudstone beds, the analyzed samples contain, unless otherwise noted, representative proportions of the two lithologies (PDF Format, 19,3 Kb - Available in French).

Percé area

In the Percé area, the White Head Formation outcrops in a mountainous corridor about 1.5 km wide that crosses the region in a northwest-southeast direction (PDF Format, 587 Kb - Available in French). The formation is divided into four members. The Burmingham, Irlande, and Des Jean members distinguish the formation. They are composed mainly of thin calcilutite beds and friable mudstone interbeds. (photo 1) The Côte de la Surprise Member is a mudstone marker horizon separating the Burmingham and Irlande members.

Distinctive appearance of the White Head Formation, Cap Blanc quarry. Resistant calcilutite beds alternate with friable mudstone interbeds.

Samples from four quarries have been analyzed. The results have been used to estimate the composition of the Irlande and Des Jean members. According to the results, these units have similar chemical compositions, with a CaO grade of about 50% (PDF Format, 19,3 Kb - Available in French). In addition, the alkali-element, magnesium, sulfur, and chlorine concentrations are suitable for the cement industry. It is noteworthy that the two units constitute a limestone sequence whose stratigraphic thickness is estimated at more than 600 m (Kirkwood, 1989). The Burmingham Member, located at the base of the White Head and about 140 m thick, was not analyzed. However, it compares lithologically to the upper limestone units, and it is likely that its composition is also suitable.

Chandler and Nouvelle areas

In the Chandler and Nouvelle areas, the White Head Formation appears to be distinctly less calcareous than at Percé. Most commonly, the formation is banded and composed of limestone beds and argillaceous interbeds, which are welded together producing a massive sequence. The analytical results show that the CaO grade is generally less than 40% (PDF Format, 19,3 Kb - Available in French). In the Nouvelle area, a grab sample from a calcilutite bed gave a CaO grade of 44.9%.

Banded facies of the White Head Formation in the Chandler region.

An adequate evaluation of the potential of these areas would require more detailed work. Stratigraphic horizons richer in carbonate should be sought.

Reference

Kirkwood, D., 1989. Géologie de la région de Percé. Ministère de l’Énergie et des Ressources, Québec; ET 87-17, 33 pages.