Sedimentary Petrology
Sedimentary petrology studies the composition, classification, and origin of sedimentary rocks formed at or near the Earth's surface.
Definition
The branch of petrology concerned with the description, classification, and origin of sedimentary rocks and the processes of weathering, transport, deposition, and diagenesis that form them.
Scope
This area covers the formation of sedimentary rocks from weathering, transport, deposition, and lithification; the classification of clastic, carbonate, and chemical-biochemical rocks; the post-depositional processes of diagenesis; and the use of composition and texture to infer source areas and depositional environments. It links surface processes to the rock record.
Sub-topics
Core questions
- How are sedimentary rocks classified by composition and texture?
- What distinguishes clastic, carbonate, and chemical sedimentary rocks?
- How does diagenesis convert loose sediment into rock?
- How do composition and texture record provenance and environment?
Key theories
- Textural and compositional maturity
- The degree of sorting, rounding, and removal of unstable grains in a clastic sediment, its maturity, reflects the intensity and duration of weathering and transport, providing a framework for interpreting sediment history.
- Sediment cycle and provenance
- Sedimentary rocks record a cycle of erosion, transport, deposition, and lithification; their mineral and clast composition fingerprints the source rocks and tectonic setting from which the detritus was derived.
Clinical relevance
Sedimentary petrology underpins the exploration for hydrocarbons, groundwater, and many mineral resources, the reconstruction of past environments and climates, and the interpretation of basin evolution and stratigraphy.
History
Sedimentary petrology matured in the twentieth century through the descriptive frameworks of Pettijohn and the classification schemes of Folk, which standardized the naming of clastic and carbonate rocks and tied composition and texture to depositional and provenance interpretation.
Key figures
- Francis J. Pettijohn
- Robert L. Folk
- Maurice E. Tucker
Related topics
Seminal works
- boggs2009
- folk1980
- pettijohn1987
Frequently asked questions
- What are the main types of sedimentary rocks?
- Clastic rocks made of transported grains (such as sandstone and shale), carbonate rocks (limestone and dolostone), and other chemical or biochemical rocks (such as evaporites and chert).
- Why are sedimentary rocks important for resources?
- They host most of the world's oil, gas, coal, and groundwater, and many ores, because their porosity, organic content, and layering create reservoirs and traps.