Archean Greenstone Granite Belts

These so called greenstone belts are the remnants of large volcano sedimentary complexes of archean and proterozoic age.

Archean greenstone granite belts.

Other rocks that occur in granulite gneiss belts zones of. Other articles where greenstone granite belt is discussed. Full text access chapter 10 origin and evolution of archean granite greenstone terranes pages 313 381 download pdf. The archean superior province of canada contains the abitibi greenstone belt which contains some of the world s largest gold and copper zinc deposits with significant amounts of nickel copper platinum group element pge mineralization too.

They are characterized by abundant volcanic rocks that include pillowed subaqueous basalt flows and subaerial and subaqueous volcaniclastic rocks. Greenstone granite belts such as those of the archean continued to form in the proterozoic albeit in greatly reduced amounts. The volcanic rocks range in composition from komatiites and low k tholeiites to dacites and rhyolites and consist of lava flows sills and stratified tuffs. The typical green minerals are chlorite actinolite and other green.

Archean rocks that occur in greenstone granite belts zones rich in volcanic rocks that are primitive types of oceanic crust and island arcs formed on or near the surface of earth and thus preserve evidence of the early atmosphere oceans and life forms. Greenstone belts are zones of variably metamorphosed mafic to ultramafic volcanic sequences with associated sedimentary rocks that occur within archaean and proterozoic cratons between granite and gneiss bodies. Discovered in 1909 the abitibi has generated over 160 million ounces of gold. Magnesian komatiites are for the most part absent however.

Precambrian precambrian greenstones and granites. The name comes from the green hue imparted by the colour of the metamorphic minerals within the mafic rocks. Introduction it is thought that mantle potential temperatures were higher in the archean although how much higher than the present day and whether the mantle was warming during the eoarchean mesoarchean to a high. The abitibi belt canada.

Greenstone belts are generally elongate archean to proterozoic terrains comprising intrusive and extrusive mafic to ultramafic igneous rocks felsic volcanics and inter flow or cover sedimentary rocks.