49 6.3 Depositional Environments and Sedimentary Basins — Physical Geology – 2nd Edition

6.3 Depositional Environments and Sedimentary Basins

Sediments accumulate in a wide variety of environments, both on the continents and in the oceans. Some of the more important of these environments are illustrated in Figure 6.3.1.

Figure 6.3.1 Some of the important depositional environments for sediments and sedimentary rocks.

Table 6.4 provides a summary of the processes and sediment types that pertain to the various depositional environments illustrated in Figure 6.3.1. We’ll look more closely at the types of sediments that accumulate in these environments in the last section of this chapter. The characteristics of these various environments, and the processes that take place within them, are also discussed in later chapters on glaciation, mass wasting, streams, coasts, and the sea floor.

Table 6.4 The important terrestrial depositional environments and their characteristics
Environment Important transport processes Depositional environments Typical sediment types
Glacial gravity, moving ice, moving water valleys, plains, streams, lakes glacial till, gravel, sand, silt, and clay
Alluvial gravity steep-sided valleys coarse angular fragments
Fluvial moving water streams gravel, sand, silt, and organic matter (in swampy parts only)
Aeolian wind deserts and coastal regions sand, silt
Lacustrine moving water (flowing into a lake) lakes sand (near the edges only), silt, clay, and organic matter
Evaporite moving water (flowing into a lake) lakes in arid regions salts, clay
Table 6.5 The important marine depositional environments and their characteristics
Environment Important Transport Processes Depositional Environments Typical Sediment Types
Deltaic moving water deltas sand, silt, clay, and organic matter (in swampy parts only)
Beach waves, longshore currents beaches, spits, sand bars gravel, sand
Tidal tidal currents tidal flats silt, clay
Reefs waves and tidal currents reefs and adjacent basins carbonates
Shallow water marine waves and tidal currents shelves and slopes, lagoons carbonates in tropical climates,  sand/silt/clay elsewhere
Lagoonal little transportation lagoon bottom carbonates in tropical climates
Submarine fan underwater gravity flows continental slopes and abyssal plains gravel, sand, mud
Deep water marine ocean currents deep-ocean abyssal plains clay, carbonate mud, silica mud

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ACC Physical Geology by Mark Leatherman is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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