depth of about 40–50 km where the rock composition
changes from quartzo-feldspathic rocks to olivinedominated peridotite (Figure 3).
Lithospheric rocks are considered elastic, but not viscous, and exhibit at least a minimum of strength. At some
depth the temperature reaches a critical point when rocks
start behaving like a viscous fluid. That depth is treated
as the boundary between lithosphere and asthenosphere.
The asthenosphere is viscous because partial melting
occurs in the order of 1–5 %, which allows for the movement of lithospheric plates relative to each other. This process is known as plate tectonics.
Bibliography
Albarède, F., 1998. The growth of continental crust.
Tectonophysics, 296, 1–14.
Condie, K., 2000. Episodic continental growth models: afterthoughts and extensions. Tectonophysics, 322, 153–162.
Kearey, P., Klepeis, K. A., and Vine, F., 2009. Global Tectonics,
3rd edn. London: Wiley-Blackwell, 496 pp.
Kirby, S. H., 1983. Rheology of the lithosphere. Reviews Geophysical Space Physics, 21, 1458–1487.
Müller, R. D., Sdrolias, M., Gaina, C., and Roest, W. R., 2008. Age,
spreading rates and spreading symmetry of the world’s ocean
crust. Geochemistry, Geophysics, Geosystems, 9, Q04006,
doi:10.1029/2007GC001743.
Ranalli, G., 1995. Rheology of the Earth, 2nd edn. London: Chapman & Hall, 413 pp.
Ringwood, A. E., 1962. A model for the upper mantle. Journal of
Geophysical Research, 67, 857–867.
Schubert, G., Turcotte, D. L., and Olson, P., 2001. Mantle Convection in the Earth and Planets. Cambridge: Cambridge University
Press, 940 pp.
Skinner, B. J., Porter, S. C., and Park, J., 2003. The Dynamic Earth:
An Introduction to Physical Geology. London: Wiley, 648 pp.
Turcotte, D. L., and Schubert, G., 2002. Geodynamics, 2nd edn.
Cambridge: Cambridge University Press, 456 pp.
Cross-references
Gabbro
High-pressure, Low-temperature Metamorphism
Mid-ocean Ridge Magmatism and Volcanism
Mohorovičić Discontinuity (Moho)
Oceanic Spreading Centers
Ophiolites
Peridotites
Silica
Subduction
LITHOSTRATIGRAPHY
Rüdiger Henrich
Department of Geosciences, University of Bremen,
Bremen, Germany
Lithostratigraphy comprises the categorization of sediment/rock strata based on lithology (e.g., color, texture,
grain size, and composition), physical properties
(seismic character, nature of well log response, magnetic
susceptibility), and structural sedimentary inventory.
A broad spectrum of methods is applied to describe and
correlate marine lithostratigraphic units. This includes
visual core description, smear slide analysis, digital imaging, diffuse color reflectance spectrophotometry, magnetic
susceptibility, physical properties (gamma ray attenuation,
moisture, density, sonic), grain size analysis, and geochemical analysis (e.g., CaCO 3 , TOC, element composition measured with an XRF sediment scanner).
Fundamental unit of lithostratigraphy is the formation
comprising beds as subunits that may reveal similar lithologies or were deposited in a certain environment. The
higher hierarchy of classification terms includes groups
and supergroups. Sediments deposited under similar conditions revealing distinct lithological, structural, and paleontological characteristics are summarized as facies.
Walther's law, the most important principle concerning
lateral variation and vertical stacking of facies, implies
that facies that occur in conformable vertical succession
of strata also occur in laterally adjacent environments.
Also, it is essential to realize that the extension of facies
bodies is always limited. They laterally and vertically
pinch out and/or transit into another facies. Hence, the spatial arrangement of facies is in the form of more or less
elongated lens-shaped bodies that are vertically stacked
on top of each other. In the marine realm, pelagic facies
often develops far extending flat lens-shaped units,
whereas continental margin and shelf settings comprise
less-extensive and complex-shaped facies bodies often
interfingering in complex manner. These aspects bear
essential implications when applying lithostratigraphic
correlations. The use of bed and facies boundaries as
chronostratigraphic time lines is limited and thus should
always be calibrated with chrono- and biostratigraphic
methods. In open ocean settings, different surface water
masses are characterized by typical pelagic communities
with distinct feed webs and production patterns (see
Hüneke and Henrich (2011) for review). In addition,
changes in surface water mass configurations and their
properties, in particular their pelagic production rate, often
correspond with climate shifts and thus represent time
lines that can be traced over far distances. Hence, certain
pelagic parameter records, for example, carbonate records,
have been successfully applied as stratigraphic tools.
However, due to variable lateral advection of terrigenous
material (see Henrich and Hüneke 2011), the applicability
of carbonate records as stratigraphic tools is rather limited
in continental margin and shelf settings. On the other
hand, distinct short-term sedimentation events like volcanic eruptions (e.g., volcanic ash layers) or glaciomarine
diamictons and IRD layers (i.e., Heinrich events) deposited during the rapid decay of the marine-based parts of
huge ice sheets (see review by Henrich and Hüneke
(2011)) provide excellent time lines for lithostratigraphic
correlations.
LITHOSTRATIGRAPHY
397
changes from quartzo-feldspathic rocks to olivinedominated peridotite (Figure 3).
Lithospheric rocks are considered elastic, but not viscous, and exhibit at least a minimum of strength. At some
depth the temperature reaches a critical point when rocks
start behaving like a viscous fluid. That depth is treated
as the boundary between lithosphere and asthenosphere.
The asthenosphere is viscous because partial melting
occurs in the order of 1–5 %, which allows for the movement of lithospheric plates relative to each other. This process is known as plate tectonics.
Bibliography
Albarède, F., 1998. The growth of continental crust.
Tectonophysics, 296, 1–14.
Condie, K., 2000. Episodic continental growth models: afterthoughts and extensions. Tectonophysics, 322, 153–162.
Kearey, P., Klepeis, K. A., and Vine, F., 2009. Global Tectonics,
3rd edn. London: Wiley-Blackwell, 496 pp.
Kirby, S. H., 1983. Rheology of the lithosphere. Reviews Geophysical Space Physics, 21, 1458–1487.
Müller, R. D., Sdrolias, M., Gaina, C., and Roest, W. R., 2008. Age,
spreading rates and spreading symmetry of the world’s ocean
crust. Geochemistry, Geophysics, Geosystems, 9, Q04006,
doi:10.1029/2007GC001743.
Ranalli, G., 1995. Rheology of the Earth, 2nd edn. London: Chapman & Hall, 413 pp.
Ringwood, A. E., 1962. A model for the upper mantle. Journal of
Geophysical Research, 67, 857–867.
Schubert, G., Turcotte, D. L., and Olson, P., 2001. Mantle Convection in the Earth and Planets. Cambridge: Cambridge University
Press, 940 pp.
Skinner, B. J., Porter, S. C., and Park, J., 2003. The Dynamic Earth:
An Introduction to Physical Geology. London: Wiley, 648 pp.
Turcotte, D. L., and Schubert, G., 2002. Geodynamics, 2nd edn.
Cambridge: Cambridge University Press, 456 pp.
Cross-references
Gabbro
High-pressure, Low-temperature Metamorphism
Mid-ocean Ridge Magmatism and Volcanism
Mohorovičić Discontinuity (Moho)
Oceanic Spreading Centers
Ophiolites
Peridotites
Silica
Subduction
LITHOSTRATIGRAPHY
Rüdiger Henrich
Department of Geosciences, University of Bremen,
Bremen, Germany
Lithostratigraphy comprises the categorization of sediment/rock strata based on lithology (e.g., color, texture,
grain size, and composition), physical properties
(seismic character, nature of well log response, magnetic
susceptibility), and structural sedimentary inventory.
A broad spectrum of methods is applied to describe and
correlate marine lithostratigraphic units. This includes
visual core description, smear slide analysis, digital imaging, diffuse color reflectance spectrophotometry, magnetic
susceptibility, physical properties (gamma ray attenuation,
moisture, density, sonic), grain size analysis, and geochemical analysis (e.g., CaCO 3 , TOC, element composition measured with an XRF sediment scanner).
Fundamental unit of lithostratigraphy is the formation
comprising beds as subunits that may reveal similar lithologies or were deposited in a certain environment. The
higher hierarchy of classification terms includes groups
and supergroups. Sediments deposited under similar conditions revealing distinct lithological, structural, and paleontological characteristics are summarized as facies.
Walther's law, the most important principle concerning
lateral variation and vertical stacking of facies, implies
that facies that occur in conformable vertical succession
of strata also occur in laterally adjacent environments.
Also, it is essential to realize that the extension of facies
bodies is always limited. They laterally and vertically
pinch out and/or transit into another facies. Hence, the spatial arrangement of facies is in the form of more or less
elongated lens-shaped bodies that are vertically stacked
on top of each other. In the marine realm, pelagic facies
often develops far extending flat lens-shaped units,
whereas continental margin and shelf settings comprise
less-extensive and complex-shaped facies bodies often
interfingering in complex manner. These aspects bear
essential implications when applying lithostratigraphic
correlations. The use of bed and facies boundaries as
chronostratigraphic time lines is limited and thus should
always be calibrated with chrono- and biostratigraphic
methods. In open ocean settings, different surface water
masses are characterized by typical pelagic communities
with distinct feed webs and production patterns (see
Hüneke and Henrich (2011) for review). In addition,
changes in surface water mass configurations and their
properties, in particular their pelagic production rate, often
correspond with climate shifts and thus represent time
lines that can be traced over far distances. Hence, certain
pelagic parameter records, for example, carbonate records,
have been successfully applied as stratigraphic tools.
However, due to variable lateral advection of terrigenous
material (see Henrich and Hüneke 2011), the applicability
of carbonate records as stratigraphic tools is rather limited
in continental margin and shelf settings. On the other
hand, distinct short-term sedimentation events like volcanic eruptions (e.g., volcanic ash layers) or glaciomarine
diamictons and IRD layers (i.e., Heinrich events) deposited during the rapid decay of the marine-based parts of
huge ice sheets (see review by Henrich and Hüneke
(2011)) provide excellent time lines for lithostratigraphic
correlations.
LITHOSTRATIGRAPHY
397