Archean Greenstone Granite Belts

Discovered in 1909 the abitibi has generated over 160 million ounces of gold.

Archean greenstone granite belts.

Archean granite greenstone belts are important components of ancient cratons and are composed of elongate slivers of volcano sedimentary sequences and tonalite trondhjemite granodiorite ttg suites ranging in age from eoarchean 3 6 ga to end of neoarchean 2 5 ga anhaeusser 2014 furnes et al 2014 manikyamba et al 2015. The abitibi belt canada. The name comes from the green hue imparted by the colour of the metamorphic minerals within the mafic rocks. Other rocks that occur in granulite gneiss belts zones of.

Magnesian komatiites are for the most part absent however. These so called greenstone belts are the remnants of large volcano sedimentary complexes of archean and proterozoic age. Archean dome and keel structure granite greenstone belts metamorphism p t t paths vertical and horizontal tectonics 1. 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.

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 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. Precambrian precambrian greenstones and granites. The typical green minerals are chlorite actinolite and other green.

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. They are characterized by abundant volcanic rocks that include pillowed subaqueous basalt flows and subaerial and subaqueous volcaniclastic rocks. 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. 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 occur sandwiched between regions dominated by granitoids and gneiss greenstones are generally of low to moderate metamorphic grade.