by Harold L. Levin
Chapter 5 - page 1
The Sedimentary Archives
Pamela J. W. Gore
Georgia Perimeter College
The characteristics of sedimentary rock deposited in an area depend on:
- Tectonic setting.
- Physical, chemical, and biological processes in the depositional environment.
- Method of sediment transport.
- Rocks in source area from which sediment is derived.
- Climate (and its effect on weathering).
- Post-depositional processes of lithification (cementation, compaction).
The forces controlling deformation or structural behavior of a large area of the Earth's
crust over a long period of time.
An area may be:
- Tectonically stable - like the midwestern US.
- Subsiding (sinking) - like New Orleans or Mexico City.
- Rising gently - like New England and parts of Canada after glacier retreat.
- Rising actively to produce mountains and plateaus - like parts of Oregon in the Cascade Mountains .
Tectonics influences the grain size and thickness of sedimentary deposits.
Recent uplift of the source area leads to rapid erosion of coarse-grained sediment.
Subsidence in the depositional basin leads to the accumulation of great thicknesses of sediment.
Note thick accumulations of shallow water sediment in the Appalachians.
Principle tectonic elements of a continent
Craton - Stable interior of a continent, undisturbed by mountain-building events
since the Precambrian.
Orogenic belts - Elongated regions bordering the craton which have been deformed by
compression since the Precambrian Mountain belts.
- Shields - Large areas of exposed crystalline rocks.
- Platforms - Ancient crystalline rocks are covered by flat-lying or gently
warped sedimentary rocks.
The craton and orogenic belts of North America.
Next Page | Back to Index
Document created by: Pamela J. W. Gore
Georgia Perimeter College, Clarkston, GA
September 14, 2005