Llanoria Quartzite

Llanoria Quartzite
State Texas
Name Llanoria Quartzite
Geologic age preCambrian (Proterozoic); Grenville Series
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > Quartzite (Granulite)quartzite in middle part and, together with sandstone, in lower part: white, fine-grained, brown-weathering near middle of the unit forms conspicuous bluffs, thick-bedded, cross-bedded, 600-800 ft thick
Sedimentary > Clastic > Mixed-clastic > Sandstone-mudstone (Bed)Gray fine-grained sandstone weathers brown; siltstone thin bedded; and shale, metamorphism slight, thickness 550-700 ft. Upper half of lower part of Lanoria Quartzite is baked sandstone, siltstone, and shale, thin bedded, forms moderate slope; lower half of this lower part is quartzite, medium-grained, cross-bedded, thickness of Lanoria Qtzite is about 1,000 ft
Comments (Franklin Mtns.) Sandstone,quartzite, siltstone, and shale. Upper part--ss. fine=grained, thin bedded, gray, weathers brown; siltst. thin bedded; and shale; metamorphism slight; thickness 550-700 ft. Middle part--quartzite, fine grained, thick bedded, cross-bedded, white; brown-weathering zone near middle, forms conspicuous bluffs; thickness 500-800 ft. Lower part--upper half, baked ss., siltst., and sh., thin bedded, forms moderate slope; lower half, quartzite, medium grained, cross-bedded; thickness 1,000+- ft.
References

Bureau of Economic Geology, 1968, Van Horn-El Paso Sheet, Geologic Atlas of Texas: Bureau of Economic Geology, The University of Texas at Austin, scale 1:250,000.

Thomann, W.F., 1981, Ignimbrites, trachytes, and sedimentary rocks of the Precambrain Thunderbird Group, Franklin Mountains, El Paso, Texas: Geological Socity of America Bulletin, Part 1, v. 92, p. 94-100.

Bureau of Economic Geology, 1992, Geologic Map of Texas: University of Texas at Austin, Virgil E. Barnes, project supervisor, Hartmann, B.M. and Scranton, D.F., cartography, scale 1:500,000.

NGMDB product
Counties El Paso