GOLD ORE DEPOSITS IN NEWFOUNDLAND

J.M. Healey B.A., M.B.A.

The principal types of gold mineralization found in Newfoundland are:

1. orogenic (or mesothermal) gold ore deposits;

2. epithermal gold ore deposits;

3. volcanogenic massive sulphide gold ore deposits;

The most common type of gold ore found in Newfoundland and Labrador is  orogenic gold ore and it is the primary target of gold exploration in the Province.

Orogenic (Mesothermal) Deposits

Orogenic gold deposits share the common attributes of being vein-hosted and are typically found in quartz-sulfide veins within fault zones and shear zones.  These lode gold deposits, formed during mountain-building periods (orogeny), are the most significant type of gold ore deposits in Newfoundland. Where companies are exploring for gold-only deposits, orogenic gold ore occurrences are the favoured exploration targets.

Successful exploration has centred within what is referred to as the Central Newfoundland Gold Belt (CNGB). The area spans most of  central Newfoundland, with major activity near Gander. The belt hosts orogenic gold systems concentrated in fault zones. Recent exploration has produced consistent, high-grade drilling success along the Appleton and JBP fault zones.The region is considered to have a massive metal endowment, with exploration continuing to identify new, multi-kilometer-scale targets.

Locations of Current and Past Producing Orogenic Gold Mines

Valentine Gold Mine      Point Rousse            Stog’erTight           Pine Cove           Nugget Pond           Hammerdown           Hope Brook

Some Locations of Advanced Orogenic Gold Projects with Resource Estimates

Cape Ray      Valentine Lake      Green Bay      Glover Island       Viking       Great Northern       Point Rousse       Golden Promise

Some Representative Orogenic Gold Ore Occurrences With Drill Data

Moosehead          Queensway        Wilding Lake            Staghorn          Titan           Golden Rose

Epithermal gold deposits

Epithermal gold deposits form near the Earth’s surface from hot, circulating fluids, that flow upwards during volcanic activity. These deposits are classified into two types: 

  • Low-sulphidation: These are characterized by quartz veins with minerals like sericite and calcite, and are typically sulfide-poor but rich in gold and silver.

  • High-sulphidation: These form when highly acidic magmatic fluids dissolve surrounding rock, leaving behind silica. The former Hope Brook Mine in southwestern Newfoundland is a high-sulphidation epithermal gold system. 

Most examples of epithermal mineralization in Newfoundland are found in the Avalon Zone on the south coast of Newfoundland. Epithermal deposits in the Avalon Zone are found principally on the Burin and eastern Avalon peninsulas. There are some deposits found in the Dunnage Zone, notably in and around the Botwood basin.

The Hope Brook Mine  of the western Avalon Zone is the only example of production from this deposit class. This was the largest deposit ever mined in the Canadian Appalachians and was the Province’s second largest gold producer after Buchans. The deposit contained 41 tonnes (not all of which was recovered) of gold in a resource of 10.2 million tonnes grading 4.54 g/t and had a copper content of 12 224 tonnes. It is one of best examples of an epithermal high-sulphidation gold deposit in Canada.

Epithermal Gold Occurrences With Drill Data

Big Easy          Heritage          Clarks Brook          Mustang

Volcanogenic massive sulfide ore deposits

Volcanogenic massive sulfide ore deposits are usually referred to as VMS ore deposits. These deposits are also, but less frequently, called volcanic-hosted massive sulfide (VHMS) deposits.

.VMS ore deposits were formed on the seafloor around undersea volcanoes. As hot, hydrothermal fluids flowed upward through the fault systems within the volcanoes, they leached various metals and sulphur from sub-seafloor rock systems. After the hydrothermal fluids were vented from the volcanoes onto the sea floor, the fluids cooled into solid rock and were deposited on the surrounding sea floor.

Later movements and collisions of tectonic plates transported the VMS ore deposits to where they are found today.

VMS ore deposits represent a significant source of the world’s copper, zinc, lead, gold and silver ores. Metals that are also extracted from these deposits as by-products of the mining process are cobalt, tin, antimony, barium, sulfur, selenium manganese cadmium indium, bismuth, tellurium, gallium and germanium.