GEO 1111 Lecture Notes - Lecture 11: Continental Crust, Igneous Rock, Oceanic Crust

• School: University of Ottawa
• Department: Geology
• Course: GEO 1111
• Professor: Robert Jack Cornett

Document Summary

Volcanic activity along plate margins: spreading centres --- ex = mid atlanic spreading center, greatest volume of volcanic rock is produced along the oceanic ridge system (divergence, mechanism of decompression melting. Rising magma can form either: an island arc if in the ocean, both are andesitic (intermediate) composition. A volcanic arc if on a continental margin. Intraplate volcanism: a(cid:272)ti(cid:448)it(cid:455) (cid:449)ithi(cid:374) a te(cid:272)to(cid:374)i(cid:272) plate, asso(cid:272)iated (cid:449)ith plu(cid:373)es of heat i(cid:374) the (cid:373)a(cid:374)tle, for(cid:373) lo(cid:272)alized (cid:448)ol(cid:272)a(cid:374)i(cid:272) regio(cid:374)s i(cid:374) the o(cid:448)erridi(cid:374)g plate (cid:272)alled a hot spot. Produces basaltic magma sources in oceanic crust (e. g. , hawaii and iceland) Produces granitic magma sources in continental crust (e. g. , yellowstone park) A volcanic hotspot is an area in the mantle from which heat rises as a thermal plume from deep in the earth. As the tectonic plate moves over the stationaryhot spot, the volcanoes are rafted away and new ones form in their place. This results in chains of volcanoes, such as the hawaiian islands.