Petrogenesis of the silicate minerals associated with copper ores, Gaspé, Quebec.

Detailed geological mapping of the interior of the Gaspe peninsula has been carried on only in recent years. Logan (1) as early as 1863, however, correctly interpreted the structure of the peninsula as a great east-west trending synclinorium. When the Federal lead - zinc and the Miller copper prospects were found just after the First World War, detailed mapping of the interior was commenced. The areal geology mapped by I.W. Jones in the district served as a basis for the study of the Miller properties. The mineralisation of the Miller claims is pyrometasamatic but, in certain respects, it differs radically from mineralisation of other deposits of this type in Eastern North America. In Gaspe, the grade of regional alteration of the Devonian rocks is very low, - comparable perhaps to that of the Trenton group in the St. Lawrence Lowlands. Certain rock3 of Lower Devonian age, however, show contact metamorphism of a high grade over restricted areas. Mineralised skarns and porcellanites have been produced. Pyrometasomatic deposits of the skarn type in the Grenville sub-province are characteristically coarse in grain, and this and certain other features suggest that they were formed at great depths under considerable pressure. The skarns of the Miller deposits, on the other hand, are extremely fine in grain, and give evidence of shallow formation without extreme hydrostatic or tangential pressures. [...