Sequence Stratigraphy

Seismic sequence stratigraphy contains a set of manually or automated horizons, which need calibration. The calibration is generally done by taking the simple measurements from logs and assigning them to a fixed event on seismic. Such an event is generally labelled as a horizon. Since each seismic horizon can be treated as a timelines, going back to Peter Vail's assertion, one can establish a linear time scale and assign it to a set of seismic horizons. In addition to this, we also have relative time units such as geochronologic (Jurassic, Cretacous, Tertiary). So, we are dealing with three time scales to be calibrated: An arbitrary time series established by counting seismic horizons, either manually mapped or automatically extracted. Geochronologic units Absolute time scale. To construct a time scale, that matches all time series, one really need to implement or draw a nomogram as proposed by Qayyum et al. (2017). It may look like this: Tripple nature...

A short note for beginners/students One of fundamental problems in our stratigraphic understanding is that we consider a stratigraphic unit as layers that may continue over a part of basin and may also correlate within and across the basin. This leads us to a troublesome procedure of correlation to build a sequence stratigraphic framework. This post is a brief review on the correlation concept within a sequence stratigraphic perspective. I would like to cover briefly one point here that a sequence stratigraphic unit is spatially a limited unit. A stratigraphic unit is always formed within a specific space (or accommodation space; do not want to complicate with terms). Within such a space, it may be altered or modified by post-depositional sedimentary and structural processes. Despite the fact of its origin; the unit would remain within the same space and may be reduced in volume (if eroded). Such a space would always be geographically restricted suggesting that a unit woul...

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 ...