Editing Guiana Shield (section)

== Geology ==
The oldest rocks in the shield consist of [[Archean]] Imataca Complex, composed of a [[quartz]]-[[feldspar]] [[gneiss]] and subordinate [[mafic]] gneiss. The Guri [[fault (geology)|Fault]] marks the southern boundary of the complex. South of that fault are Early [[Proterozoic]] rocks consisting of the [[metavolcanic rock|metavolcanic]] Pastora [[geological unit|Supergroup]] and the [[granitic]] [[plutonic]] Supamo Complex. The Cuchivero Group consists of [[ash flow]] [[tuff]] and granitic plutonic rocks. The Early to Middle Proterozoic Roraima Group consists of continental [[clastic sediment]]ary rocks. These [[Precambrian]] sediments include quartz [[sandstones]], [[quartzite]]s, and [[conglomerate (geology)|conglomerates]] presumed to be 1.8 to 1.4 [[Giga annum|Ga]] in age.<ref>{{cite book|title=Geology and Mineral Resource Assessment of the Venezuelan Guayana Shield, USGS Bulletin 2062|date=1993|publisher=US Government Printing Office|pages=10–15}}</ref><ref>{{cite book|last1=Wray|first1=Robert|editor1-last=Migon|editor1-first=Piotr|title=The Gran Sabana: The World's Finest Quartzite Karst?, in Geomorphological Landscapes of the World|date=2010|publisher=Springer|isbn=9789048130542|pages=80–81}}</ref>