Archean Greenstone Granite Belts

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Archean greenstone granite belts.

The abitibi belt canada. These so called greenstone belts are the remnants of large volcano sedimentary complexes of archean and proterozoic age. Precambrian precambrian greenstones and granites. 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.

Greenstone granite belts such as those of the archean continued to form in the proterozoic albeit in greatly reduced amounts. The typical green minerals are chlorite actinolite and other green. 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. 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.

Greenstone belts occur sandwiched between regions dominated by granitoids and gneiss greenstones are generally of low to moderate metamorphic grade. The name comes from the green hue imparted by the colour of the metamorphic minerals within the mafic rocks. 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 dome and keel structure granite greenstone belts metamorphism p t t paths vertical and horizontal tectonics 1. Discovered in 1909 the abitibi has generated over 160 million ounces of gold. Full text access chapter 10 origin and evolution of archean granite greenstone terranes pages 313 381 download pdf. Other rocks that occur in granulite gneiss belts zones of.

Magnesian komatiites are for the most part absent however.