Page 56 - Sedimentology and Stratigraphy

Further Reading 43

a basaltic composition are dark in colour, whereas FURTHER READING
more rhyolitic deposits are paler. Fine ash and tuff
can be more difficult to identify with certainty in the Adams, A.E. & Mackenzie, W.S. (1998) A Colour Atlas of
field, especially if the material has been weathered. Carbonate Sediments and Rocks under the Microscope. Man-
son Publishing, London.
Brightly coloured green and orange strata sometimes
Braithwaite, C. (2005) Carbonate Sediments and Rocks. Whit-
form as a result of the alteration of ash beds. Char-
tles Publishing, Dunbeath.
acteristic sedimentary structures resulting from the Cas, R.A.F. & Wright, J.V. (1987) Volcanic Successions: Mod-
processes of transport are considered further in Chap- ern and Ancient. Unwin-Hyman, London.
ter 17 along with the environments of deposition of Northolt, A.J.G. & Jarvis, I. (1990) Phosphorite Research and
volcaniclastic sediments. Development. Special Publication 52, Geological Society
Petrographic analysis of volcaniclastic sediments is Publishing House, Bath.
usually required to confirm the composition. In thin- Scholle, P.A. (1978) A Color Illustrated Guide to Carbonate
section the composition of lithic fragments can be deter- Rock Consituents, Textures, Cements and Porosities. Mem-
mined if a high magnification is used to identify the oir 27, American Association of Petroleum Geologists,
minerals that make up the rock fragments. Crystals of Tulsa.
feldspar are usually common, especially if the deposit is Scoffin, T.P. (1987) Carbonate Sediments and Rocks. Blackie,
Glasgow, 274 pp.
a crystal tuff, and other silicate minerals may also be
Stow, D.A. (2005) Sedimentary Rocks in the Field: a Colour
present as euhedral to subhedral crystal grains. Fiamme
Guide. Manson, London.
can be seen as clear, isotropic grains with characteristic Tucker, M.E. (2001) Sedimentary Petrology (3rd edition).
shapes: volcanic glass is not stable, and in older tuffs the Blackwell Science, Oxford.
glass may have a very finely crystalline structure or will Tucker, M.E. & Wright, V.P. (1990) Carbonate Sedimentology,
be altered to clay minerals. Blackwell Scientific Publications, Oxford, 482 pp.