Quartz arenites

Johnsson, M. J., Stallard, R. F., and Meade, R. H. (1988). First-cycle quartz arenites in the Orinoco River basin, Venezuela and Colombia. /. Geol. 96, 263-277. 

Improved magnetotelluric methods have detected deep conductors and shallow alteration zones in the search for deep unconformity-related deposits (Farqu-harson Craven 2008). Clay-rich, quartz-corroded quartz-arenite has relatively low resistivity, whereas quartz-rich silicified zones are characterized by high resistivity. Although expensive, 3D seismic has been used to image details of basement topology and more favourable areas for drilling. 

These unconformity-type deposits are located around the unconformity between the Helikian Athabasca Group sandstones and underlying Archean to early Proterozoic metamorphic basement (Hoeve Sibbald 1978 Hoeve Quirt 1984). The present sandstone cover ranges from 0 to 1500 m in thickness and is dominantly composed of mature coarse-grained quartz arenite with a kaolin-illite clay matrix. 

The McArthur River Uranium Deposit lies in the eastern portion of the Athabasca Basin and within the Churchill Structural Province of the Canadian Shield. The deposit straddles the unconformity between the quartz arenite - rich Late Paleoproterozoic Athabasca Group and... 

De Ros L. F. (1998) Heterogeneous generation and evolution of diagenetic quartz arenites in the Silurian-Devonian Furnas Formation of the Parana Basin, southern Brazil. Sediment. Geol. 116, 99-128. 

Harris N. B. (1990) Diagenetic quartz arenite and destruction of secondary porosity an example from the Middle Jurassic... 

Makowitz A. and Sibley D. F. (2001) Crystal growth mechanisms of quartz overgrowths in a Cambrian quartz arenite. J. Sedim. Res. 71, 809-816. 

Donaldson, J. A. de Kemp, E. A. 1998. Archaean quartz arenites in the Canadian Shield examples from the Superior and Churchill provinces. Sedimentary Geology, 120, 153-176. 

In the Upper Namur Sandstone the poikilotopic calcite cement is absent in moderately to poorly sorted quartz arenites and feldspathic quartz aren-ites that contain abundant primary porosity and some secondary porosity. Only minor patches of siderite micrite and microspar are observed in these elastics, where euhedral quartz overgrowths are well developed, albeit not volumetrically significant (< 5-10%) (Fig. 14D). The detrital grains are dominated by tangential and long contacts, with rare sutured contacts. 

Based on Folk s (1974) classification scheme, the average sandstone of the Hibernia Field is a sublith-arenite (Qgv 9 F3 g Rg.s). Individual samples are either quartz-arenitic or sublitharenitic, and some are subarkoses (Fig. 7 Table 1). If shale clasts, which are probably predominantly rip-up clasts of intrabasinal origin and do not carry provenance information with respect to terrigenous source areas, are excluded, then the majority of the samples would be classified as quartz arenites. 

Fig. 7. QFR triangular diagram of sandstone petrography of Folk (1974). Q, quartz F, feldspar R, rock fragments. 1, quartz arenite 2, subarkose 3, sublitharenite 4,5, arkose 6,7, litharenite.

O kane, A., Onasch, C.M Farver, J.R. (2007). The role of fluids in low temperature, fault-related deformation of quartz arenite. Journal of Structural Geology, Vol. 29, p>p. 819-836... 

In other words, those sandstones with more than 15% matrix were termed wackes. The chief type of wacke is greywacke, which can be subdivided into lithic and feldspathic varieties. Those sandstones with less than 15% matrix were divided into three families. The orthoquartzites or quartz arenites contain 95% or more of quartz 25% or more of the detrital material in arkoses consists of feldspar and in lithic sandstones, 25% or more of the detrital material consists of rock fragments (Fig. 1.20). 

Thin section of Fell Sandstone (a quartz arenite), Lower Carboniferous, Northumberland, England. 

Sandstone Grains are mainly mineral fragments Quartz arenite 95% quartz, voids empty or cemented Arkose 75% quartz, up to 25% feldspar voids empty or cemented... 

The degree of resistance that sandstone offers to weathering depends on its mineraiogicai composition, texture, porosity, amount and type of cement/matrix, and the presence of any planes of weakness. Accordingly, the best type of sandstone for external use for building purposes is a quartz arenite that is well bonded with siliceous cement, has a low porosity and... 

Unconformity-related U,Ni,Co,As,Au Developed within palaeosol at unconformity between mid-Proterozoic quartz arenite and lower Proterozoic metasedimentary rocks mineralization closely associated with graphitic zones, clay-rich fault breccias epigenetic, disconformable Athabasca Region, Canada East Alligator River, Australia... 

Middle Proterozoic rocks of 1800 to 900m.y. in age are characterized by thick marine biogenic and chemical carbonate strata, evaporites, fine-grained clastic sedimentary rocks, and extensive, thick subaerial tholeiitic basalts, and quartz arenite and conglomerate. Ophiolitic and calc-alkaline volcanic rocks are absent in sequences of this age. ... 

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