Sedimentary basins are areas of crustal subsidence where sediments accumulate by deposition in environments such as rivers, lakes, alluvial plains, coastal areas, deltas, continental shelves, and deep oceans. Whenever we see a thick (> ~100 meters) succession of sedimentary rocks in outcrop or in the subsurface, the basin analyst will ask: why did this pile of sediment accumulate here, how fast did the basin subside through time, where did the sediment come from, what types of environments and climate existed here during deposition, and what were the driving structural, tectonic and geophysical forces that created the basin? Through integrative analysis that includes stratigraphy, sedimentology, paleocurrents, structure, regional tectonics, and physical modeling, we often are able to answer these questions and thereby gain a good understanding of the geologic, climatic, and tectonic evolution of a region.
We can understand how basins form by considering different tectonic settings, the main geologic processes active in those regions, and the related physical mechanisms that cause subsidence. The following table provides a summary of the main processes that create sedimentary basins, provided in the context of common tectonic settings found on Earth today and in the past. Of the following tectonic settings, we discussed (1) continental rift zones, (2) how they evolve to become passive continental margins, and (3) foreland basins produced by lithospheric flexure due to crustal loading in a thrust belt. Thust loading and foreland basins can be found in both "Andean-type" margins, and zones of contintental collision. You want to think about what the term "collision" means in geology (hint: it is not like a car accident on the highway).
| Plate-Tectonic Setting |
Geologic Process |
Subsidence Mechanisms |
Basin Name |
| Continental Rift Zones |
Extension, Crustal Thinning |
Isostatic Subsidence |
Rift Basin |
| Passive Continental Margins |
Lithospheric Cooling |
Thermal Subsidence |
Miogeocline |
| Convergent Margins: Orogenic Fold-Thrust Belts, Continental Collision Zones |
Crustal Thickening, Loading |
Flexural Subsidence |
Foreland Basin |
| Subduction Zones, Volc. Arcs |
Possible Lithosph. Cooling |
Possible Thermal Subs. |
Forearc Basin; Trench, Trench-Slope Basins |
| Strike-Slip Fault Zones: |
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| Transtensional |
Oblique Extension |
Isostatic Subsidence |
Pull-Apart Basin |
| Transpressional |
Oblique Contraction |
Flexural Subsidence |
Foreland-type |
| Stable Plate Interiors |
Slow Cooling |
Slow Thermal Subsidence |
Intracratonic Basin |