matter. This is why black shales and source rocks tend
to have rather high radioactivy.
Weathering of phosphate sediments will initially
cause solution of carbonate and carbonate-containing
apatite so that the sediments become enriched in
fluorapatite. As calcium is removed through solution
of calcite by rainwater, the sediment will become
richer in iron and aluminium, and iron and aluminium
phosphates will form. Phosphate deposits are also
formed through weathering of phosphate-bearing
igneous rocks. Carbonatites from the East African
rift system contain a high percentage of apatite, and
when carbonate is dissolved during weathering, apatite becomes concentrated and forms phosphate
deposits which are also rich in iron minerals. There
are many types of apatite deposits and even if there is a
high demand for phosphate in fertilizers it is unlikely
that they would be exhausted in the next few centuries.
Further Reading
Abtew, W. and Melesse, A. 2013. Evaporation and Evaoptranspiration. Meaurements and Estimations. Springer Verlag,
206 pp.
Aplin, A.C., Fleet, A.J. and Macquaker, J.H.S. 1999. Muds and
mudstones: Physical and fluid-flow properties. Geological
Society Special Publication 158, 190 pp.
Bjørlykke, K. 2011. Open-system chemical behaviour of Wilcox
Group mudstones. How is large scale mass transfer at great
burial depth in sedimentary basins possible? A discussion.
Marine and Petroleum Geology 28, 1381–1382.
Bjørlykke, K. 2014. Relationships between depositional
environments, burial history and rock properties. Some principal aspects of diagenetic processes in sedimentary basins.
Sedimentary Geology 301, 1–14.
Chamley, H. 1989. Clay Sedimentology. Springer, New York,
623 pp.
Day-Stirrat, R.J., Flemming, P.B., You, Y., Aplin, A.C. and
Pluijm, van der, B.A. 2013. Modification of mudstone fabric
and pore structure as a result of slope failure; Ursa Basin,
Gulf of Mexico. Marine Geology v 341, 56–67.
Day-Stirrat, R.J., Flemming, P.B., You, Y., Aplin, A.C. and
Pluijm, van der, B.A. 2012. The fabric of consolidation in
the Gulf of Mexico mudstones. Marine Geology. v. 295–298,
77–85.
Delisle, G., Teschner, E., Faber, E., Panahi, B., Guliev, I. and
Alliev, C. 2010. First approach in quantifying fluctuating
gas emission and methane and radon from mud volcanoes
in Azerbaijan. In: Wood, L.J. (ed.), Shale Tectonics. AAPG
Memoir 93, pp. 211–224.
Schieber, J., Eier, W. and Sethi, P. 1998. Shales and Mudstones.
Schweizerbartsche Verlagsbuchhandlung, Stuttgart, 384 pp.
Thyberg, B.I., Stabell, B., Faleide, J.I. and Bjørlykke, K. 1999.
Upper Oligocene diatomaceous deposits in the northern
North Sea – Silica diagenesis and paleogeographic
implications. Norsk Geologisk Tidskrift 79, 3–18.
Thyberg, B., Jahren, J., Winje, T., Bjørlykke, K., Faleide, J.I.
and Marcussen, Ø. 2010. Quartz cementation in Late
Cretatceous mudstones, northern North Sea. Changes in
rock properties due to dissolution of smectite and precipitation of micro-quartz crystals. Marine and Petroleum Geology 27, 1752–1764.
Weaver, C.E. 1989. Clays, Mudrocks and Shales. Developments
in Sedimentology 44, 818 pp.
Wood, L.J. 2010. Shale Tectonics. AAPG Memoir 93, 238 pp.
Yang, Y. and Aplin, A.C. 2010. Permeability-porosity relationships for mudstones. Marine and Petroleum Geology
25, 1692–1696.
6 Mudrocks, Shales, Silica Deposits and Evaporites
229
to have rather high radioactivy.
Weathering of phosphate sediments will initially
cause solution of carbonate and carbonate-containing
apatite so that the sediments become enriched in
fluorapatite. As calcium is removed through solution
of calcite by rainwater, the sediment will become
richer in iron and aluminium, and iron and aluminium
phosphates will form. Phosphate deposits are also
formed through weathering of phosphate-bearing
igneous rocks. Carbonatites from the East African
rift system contain a high percentage of apatite, and
when carbonate is dissolved during weathering, apatite becomes concentrated and forms phosphate
deposits which are also rich in iron minerals. There
are many types of apatite deposits and even if there is a
high demand for phosphate in fertilizers it is unlikely
that they would be exhausted in the next few centuries.
Further Reading
Abtew, W. and Melesse, A. 2013. Evaporation and Evaoptranspiration. Meaurements and Estimations. Springer Verlag,
206 pp.
Aplin, A.C., Fleet, A.J. and Macquaker, J.H.S. 1999. Muds and
mudstones: Physical and fluid-flow properties. Geological
Society Special Publication 158, 190 pp.
Bjørlykke, K. 2011. Open-system chemical behaviour of Wilcox
Group mudstones. How is large scale mass transfer at great
burial depth in sedimentary basins possible? A discussion.
Marine and Petroleum Geology 28, 1381–1382.
Bjørlykke, K. 2014. Relationships between depositional
environments, burial history and rock properties. Some principal aspects of diagenetic processes in sedimentary basins.
Sedimentary Geology 301, 1–14.
Chamley, H. 1989. Clay Sedimentology. Springer, New York,
623 pp.
Day-Stirrat, R.J., Flemming, P.B., You, Y., Aplin, A.C. and
Pluijm, van der, B.A. 2013. Modification of mudstone fabric
and pore structure as a result of slope failure; Ursa Basin,
Gulf of Mexico. Marine Geology v 341, 56–67.
Day-Stirrat, R.J., Flemming, P.B., You, Y., Aplin, A.C. and
Pluijm, van der, B.A. 2012. The fabric of consolidation in
the Gulf of Mexico mudstones. Marine Geology. v. 295–298,
77–85.
Delisle, G., Teschner, E., Faber, E., Panahi, B., Guliev, I. and
Alliev, C. 2010. First approach in quantifying fluctuating
gas emission and methane and radon from mud volcanoes
in Azerbaijan. In: Wood, L.J. (ed.), Shale Tectonics. AAPG
Memoir 93, pp. 211–224.
Schieber, J., Eier, W. and Sethi, P. 1998. Shales and Mudstones.
Schweizerbartsche Verlagsbuchhandlung, Stuttgart, 384 pp.
Thyberg, B.I., Stabell, B., Faleide, J.I. and Bjørlykke, K. 1999.
Upper Oligocene diatomaceous deposits in the northern
North Sea – Silica diagenesis and paleogeographic
implications. Norsk Geologisk Tidskrift 79, 3–18.
Thyberg, B., Jahren, J., Winje, T., Bjørlykke, K., Faleide, J.I.
and Marcussen, Ø. 2010. Quartz cementation in Late
Cretatceous mudstones, northern North Sea. Changes in
rock properties due to dissolution of smectite and precipitation of micro-quartz crystals. Marine and Petroleum Geology 27, 1752–1764.
Weaver, C.E. 1989. Clays, Mudrocks and Shales. Developments
in Sedimentology 44, 818 pp.
Wood, L.J. 2010. Shale Tectonics. AAPG Memoir 93, 238 pp.
Yang, Y. and Aplin, A.C. 2010. Permeability-porosity relationships for mudstones. Marine and Petroleum Geology
25, 1692–1696.
6 Mudrocks, Shales, Silica Deposits and Evaporites
229