Geology Of The Oaks Belt

1580 Words Aug 14th, 2015 7 Pages
Geology of the Oaks Belt
The Oaks Belt is composed of mafic to felsic volcanic and volcaniclastic rocks, clastic sedimentary rocks, iron formation and several types of intrusive rocks. Mafic volcanic rocks constitute the bulk of the stratigraphy in the OB and occur as both pillowed basalts and massive flows. They are aphanitic to fine-grained and dark green to black (Frey and Venzke 1991). Mafic volcaniclastic rocks are more common lower in the stratigraphy. Intermediate volcanic rocks occur almost exclusively as tuffs, are feldspar-phyric and contain 20-30% mica and amphibole. Felsic volcaniclastic rocks vary from rhyolites to dacites and occur mainly near the stratigraphic top of the volcanic pile where they directly underlie massive sulfide and iron formation deposits. These highly siliceous rocks are mica and amphibole-poor, and occur as both quartzphyric fragments and tuffs. Felsic agglomerate rocks transition from dacite to rhyolite down stratigraphy (Frey and Venzke 1991).
Clastic rocks are most common in the central part of the study area and display graded beds as well as slumping and soft-sediment deformation (Frey and Venzke 1991).Chemical sedimentary rocks in the OB include iron formation and chert. The tendency of massive sulfide deposits to occur in brecciated piles of tuff fragments with associated footwall alteration indicates they are not seawater precipitates. Chert is typically sulfidic, with pyrite and pyrrhotite as the main sulfide minerals. Graphite…

More about Geology Of The Oaks Belt

Open Document