Situational Analysis Paper

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System tracts are areas of the lithosphere which have multiple interacting depositional systems. These system tracts are the arrangement of layers in a depositional sequence. The structure of a depositional sequence begins with a sequence boundary, followed by a lowstand systems tract, then a transgressive systems tract, a highstand systems tract, and a falling-stage systems tract, before finally reaching another sequence boundary. These strata were deposited at different points of transgressions and regressions, during eustatic sea level change or relative sea level change.
Each system tract is bound by a surface, between the lowstand and transgressive systems tract we find the transgressive surface. The transgressive and highstand systems tracts end and begin respectively by the the maximum flooding surface. The highstand and falling-stage systems tracts are separated by the basal surface of forced regression. …show more content…

Sequence boundaries are the beginning and the end of a depositional sequence, and are formed by erosional unconformities. This happens when the shoreline migrates seaward during a regression. The drop in sea level leads to erosion on the shelf from waves, the exposing of sediments to the air allows them to erode as well. These occur at the beginning and end of every cratonic sequence (Sauk, Tippecanoe, Kaskaskia, Absaroka, Zuni, and Tejas). Catuneanu (2002) described sequence boundaries as “diachronous, capping the previous highstand systems tract and eroding the surface of the down-stepping sediments deposited during accompanying forced regression associated with sea level

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