Sequence Stratigraphy

Maximum Regressive Surface (MRS) Other Synonyms: Transgressive Surface (TS) This is a short post about the MRS that is considered as an easy to identify on outcrops and well data because of some reasons. This post would covers the fundamentals of placing a MRS in a stratigraphic unit and how to avoid pitfalls in its interpretation. Definition It is a surface that marks the start of shoreline regression towards basin. It suggests a base level fall and subsequent marine regression. Recognition In the outcrop and wireline logs it is mostly recognized as a surface separating a coarsening upward succession from the overlying fining upward succession. This suggests that the underlying succession is a regressive unit and the overlying sequence is a transgressive unit. In the above seismic data, you may notice a distinct MRS separating the underlying regressive unit (RST) from the overlying transgressive unit (TST). This surface forms a healing phase wedge above that i...

Maximum Flooding Surface (MFS) By F. Qayyum This is a short post about the MFS that is considered as an easy to identify on outcrops and well data because of some reasons. This post would covers the fundamentals of placing a MFS in a stratigraphic unit and how to avoid pitfalls in its interpretation. Definition It is a surface that marks the end of shoreline transgression towards land or coastal plain. It suggests a base level rise and subsequent marine transgression onto the shelf or coastal plain. Recognition It can be treated as a downlap surface because overlying strata may prograde and downlap on it. This is a typical case for a normal regressive deltaic progradation or simply siliciclastic system reaching the shoreface and basin. The overlying system could either be a HST or LST depending on the location. On the well logs, it is marked by a deepening up-ward GR trend. This means that one is going to mostly define a massive shale as a MFS marker at a shelf lo...

H.E. Wheeler's Innovation A short note for those who are innovative and do not bother about making patents. By F. Qayyum Wheeler spent his time with Sloss and finally got succeeded in presenting a stratigraphic unit within a spatio-temporal framework. When he proposed the idea to the scientific community, he probably did not think that his innovation would be commercialize in such a way that at present days people will earn money. He proposed an idea  voluntarily just like other geologists such as Steno, Lyell, William Smith etc. No one would have ever thought that their principles (non patented) would   be used everyday. They actually benefited the entire mankind and thanks to them that we are using them to explore for the energy resources. In any case, we started using those concepts and put patents on top of each others. If you scroll through the historical development of Wheeler diagrams, you would be fully surprised that why are we doing this. We inven...