Intergranular pressure solution and cementation of the tuscarora orthoquartzite
. Journal of Sedimentary Research, 4, 881-896.
The age of orthoquartzite and quartzose sandstone in the Matthews Lake Formation, the lower unit of the Ellsworth Group in the NRB, is constrained by earliest Cambrian detrital zircon in the basal beds (Fyffe et al.
On the Snider Mountain Road the formation is composed of white to grey orthoquartzite and intraformational quartzite-pebble-rich conglomerate that appears to be concordantly underlain by pink feldspathic sandstone and pink to reddish arkosic pebble conglomerate of the Grant Brook Formation.
Here it is composed of thick-bedded (65-70 cm), white, granular orthoquartzite (Fig.
The Clinch Sandstone is a mature quartz arenlte or orthoquartzite
of Early Silurian age (also referred to as "Clinch Mountain Sandstone") that is recognized in northeastern Tennessee (Driese, 1988), eastern Kentucky (Englund and others, 1963), and southwestern Virginia (Miller and Fuller, 1947) (Figure 13) (Plate 1).
Prior to this, silcrete artefacts were often identified as silicified sediment, orthoquartzite
or quartzite (see discussions in Hughes et al.
Artifacts of opalescent and common orthoquartzite
, as well as chert, were also associated with this outcrop.
The Chimu, about 80-600 m thick, consists of generally medium-bedded, medium-grained to pebbly, pure quartz sandstone or orthoquartzite with local interbeds of pebble conglomerate.
Faults and fractures normal to the trend of the Algamarca anticline cut orthoquartzite of the Chimu Formation and a K-silicate-altered porphyry stock.
Material from a range of sources was present, including metasomatised argillite, chert, greywacke, obsidian, orthoquartzite
Hughes (1963) studied orthoquartzite boulders along the Coal Bluff outcrop in southwestern Union County, Mississippi, which he recognized as weathered remnants resting on unconsolidated "Wilcox" sands.
The Catahoula Formation contains generally light-colored sands and clays as well as sandstones and opal-cemented orthoquartzites derived diagenetically from volcanic ash.