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Stratigraphic Base Level Revisited in Deep-water Settings

It has been 100 years since Barrell (1917) solidified the base level concept, which is widely used in sequence stratigraphy. The concept was first introduced by Powel (1875). It is still broadly used in non-marine, near shore and deep-water settings. The problem arrives when the base level concept is applied in deep-water settings. Most of us will consider the sea level/wave base as a base level. However, it is simply not! The magnitude at which sea level or wave base varies is much smaller than the changes that we observe on the modern or ancient sea floor. Recalling, below the base level deposition happens and above it erosion is possible. This original definition gets violated when sea level is chosen as a base level proxy. As annotated in the figure below, the sea level or wave base can not be considered as a proxy for the base level since erosion and deposition happen below this level. To solve such a conceptual problem, we always need to place the base level close to the sea floor topography depending on its gradient much similar to the way we define the base level in a non-marine setting. Obviously, the ultimate reference can be the sea level but the instantaneous variations on the Earth’s surface are controlled by a temporary base level. This was the beginning of our synthesis to compile a document that not only describes the concept but also provides an optimum solution to the problem. The preservation/removal of geologic timelines and time units and their reconstruction based on flattening theory is another thing to look at within the context of the base level. It is the base level oscillation that results in creation/destruction of an accommodation space, which allows the erosional and depositional profiles to re-adjust & produce geologic timelines or time-units. To read more, follow this link.

https://authors.elsevier.com/a/1VVEByDcGAl5h
(free copy valid till Sep 15, 2017)

You can also request for a private copy via my ResearchGate page.



Image taken from Qayyum et al., 2017, The Wheeler diagram, flattening theory, and time, Marine and Petroleum Geology, 86, 1417-1430.


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