Item talk:Q122098

Geology and geochemistry of the Wanamu-Blue Mountains area, Waini SW, Guyana

The Wanamu-Blue Mountains area is situated in the Northwest District of Guyana, about 110 miles northwest of Georgetown. The Blue Mountains are low, but rugged, hills that have developed on mafic metamorphic rocks that occur in an arcuate "mantle" around a granite batholith, the Aranka-Wanamu Granite. The area lies within the Precambrian Guiana Shield and is entirely covered with tropical rain forest. The geology of the area is complex and is made up of an assemblage of metamorphic rocks consisting of phyllites, quartzites, amphibolites, and epidiorites that are intruded by serpentinites. The serpentinites occur as thin, tabular, dike-like bodies that trend northwest across the area. The serpentinites contain abundant magnetite, but very little chromite or sulfide minerals. Lletasomatic reaction zones have developed around the serpentinite bodies at their contacts with country rock. These reaction zones consist of aureoles of actinolite schist, chloritic hornfels, and talcose zones in the phyllites.