Algoman orogeny geophysical measurements on the greenstone belts in Canada, suggest the metavolcanic and metasedimentary rocks of the belts project downward at least a few kilometers. The action of metamorphism on the border between granite and gneiss bodies produces a succession of metamorphosed volcanic and sedimentary rocks called greenstone belts. Most Archean volcanic rocks are concentrated within greenstone belts; the green color comes from minerals, such as chlorite, epidote and actinolite that formed during metamorphism. After metamorphism occurred, these rocks were folded and faulted into a system of mountains by the Algoman orogeny. The volcanic beds are thick. About the greenstone belt
Malagasy orogeny Malagasy orogeny Malagasy orogeny is the name given to the Ediacaran to Cambrian orogeny that resulted as India collided with the already amalgamated African continent that consisted of Azania and the Congo-Tanzania-Bangweulu Block. The orogeny affected the parts of the East African Orogen that are now found in southern India, Madagascar and central Arabia. The term "Malagasy orogeny" was introduced by for the orogenisis between India and a series of Gondwanan cratonic blocks in present-day Africa (Congo/Tanzania/Bangweulu/Azania). In their reconstruction, India collided with Australia/Mawson in the Kuunga orogeny before the formation of Gondwana. They identified the Betsimisaraka suture in eastern