VCS Mining
Gold, copper, and silver creation on the Caribbean Plate
Haiti is located on the Caribbean Plate with the North American plate bordering to the north, South American plate to the east and south, the Nazca plate to the south & south-west, and covering a very small margin is the Cocos plate to the west. The Caribbean Plate is one of the smallest plates in the world at only 3.2 million square kilometers or 1.2 square miles in total area and oceanic in nature. Its current border plate tectonic environment has seismic activity including earthquakes, tsunamis, and volcanic eruptions.
The North American plate is a transform fault (two plates shifting side by side creating friction) and is moving north-west. The Coscos Plate is being subducted under the Caribbean Plate from the east and forms the middle America Trench. As the North American and South American plate line is yet not defined, it is unknown which plate, or both, is subducting on the eastern side. The southern boundary of the South American plate is moving nortwest resulting in transform faulting along with thrust faulting and some subduction.
Evolution of the Caribbean plate began 200 million years ago and went through 5 distinct stages. For this purpose, we will focus on the geological history of Northern Haiti as this is the location of the properties in which VCS Mining has interest.
During a time when quarry dinosaurs were wandering the earth in the late Jurassic period up to the beginning of the early Cretaceous, this region was primarily under mafic volcanic conditions. The chemical composition of mafic magma is high in heavy elements such as magnesium and iron which may be relatively enriched in calcium and sodium. Mafic minerals are usually dark in color and have a greater than 3.0 specific gravity.
This occurrence brought about massive flows of andesitic lavas (named after the Andes mountains, it is a dark, fine grained, brown or grayish volcanic rock that is intermediate in composition), basaltic lavas (a dark fine grained volcanic rock that displays a columnar structure), and andesitic tuffs (porous rock formed by consolidation of volcanic ash). As there are no pillow-lavas (extrusion of the lava under water), it is believed the eruptions occurred mostly on land and formed the base of the volcano-sedimentary belt in the area.
138 million years ago, the second stage began with the eruption of felsic rocks. This differs from mafic rock as it is light gray in color and has a lower percentage of the heavier elements. Lighter elements (with specific gravities less than 3.0) in felsic minerals, magmas, and rocks are silica, oxygen, aluminum, and potassium. Rocks produced during this timeframe were dacite, rhyolite, and their tuff. Part of the eruptions occurred under water, favoring the formation of Kuroko type deposits found in Japan. These deposits have yielded ores that contain as much as 20 percent combined copper, lead, and zinc by weight plus important amounts of gold and silver.
It is unknown why it went from mafic rocks to felsic rocks during this time frame. It could be the result of a different magmatic source or the evolution of the first magmatic source due to the continuous assimilation of crust material.
The third main event in the development of this area transpired in the Late Cretaceous Period. This time frame is marked by the intrusion of small bodies of mafic and ultramafic rocks, and relatively larger, but scattered, bodies of tonalites. As there is an absence of micas in these rocks, it indicates formation and deposition in a dry environment therefore low potential of mineralization. More complex folding and faulting of the pre-existing volcano-sedimentary layers, very probably accompanied by a reactivation of hydrothermal fluids, was also a result of this orogenic event. These fluids could have brought or re-mobilized the mineralization from the host rock to the geo-tectonic traps.
Reactivation of the volcanic belt in the fourth event brought about the eruption of felsic and intermediate volcanic rocks again. This formed small lenses inside the older mafic units.
The fifth and final stage of Haiti's geological history unfolds during the rest of the Cenozoic Period. Several million years of marine and lacustrine sediment deposits partially covered the volcano-sedimentary rocks that formed near or under sea level. Much erosion left scattered outcrops of tonalities (felsic rocks), and small amounts of gabbro (mafic rocks). Serpentinization (a hydration and metamorphic transformation of ultramafic rock from the Earth's mantle) brought observable amounts of pyroxenite and peridotites (igneous rocks). This region has tonalitic stocks found in areas which have more association with mafic and ultramafic units creating layers from felsic at the top through intermediate to mafic and ultramafic rocks at the bottom of the cut.
The completion of the fifth stage brings us to the current condition, where there exists much mining interest, not only by mining companies but also by the United Nations Development Program, in the formation of Iron Hats or gossans. A gossan is intensely oxidized, weathered or decomposed rock and is the exposed part of an ore deposit or mineral vein. In northern Haiti, these formations are clues to the deposits of gold, PGM, nickel, cobalt, and copper.
The following is a direct quote from a report presented at the thirty-sixth session June 1989 in New York labeled as item 8 (c) of the provisional agenda by the Governing Council of the United Nations Development Program.
The Fund's project in Haiti was completed in 1988 and the final report submitted to the Government. The report listed gold as a reported mineral in the area known as Faille B. The project involved the drilling of 3,200 meters consisting of 31 boreholes, 97 line kilometers of geophysical surveys and analysis of over 8,300 samples. The reserves discovered amount to approximately 520,000 tonnes with a grade of 14 grams of gold per tonne. The Fund is presently assisting the Government in attracting investment in order to bring the discovery into production.
© Scripps Institute of Oceanography