Evolution of sequence stratigraphy

Evolution of sequence stratigraphy

The sequence stratigraphy and depositional environments of outcrops are examined, including stratigraphic sections measured in the field. These accumulated during the latest Pennsylvanian to early Permian in the Paradox foreland basin of southeast Utah. In contrast to Muto et al. This is an important piece of work, not least because sequence stratigraphic interpretations of outcrop that fully consider sediment routing and the possible contribution of autogenic processes are still relatively rare Burgess , so demonstrating how this can be done well is useful. The Geological Society William Smith meeting in Burlington House in September considered the current state and future developments in sequence stratigraphy, and focused particularly on how the subject should progress, either by evolution or by revolution. The mixed nonmarine and shallow marine nature of the inferred paleoenvironments of the lower Cutler beds is significant because the preserved expression of the nonmarine eolian and fluvial units in each cycle demonstrates an external climatic control on system development, whereas the marine units in each cycle together with associated transgressive and regressive surfaces demonstrate repeated episodes of relative sea-level change. Key stratigraphic surfaces have been traced from the continentally dominated northeastern portion of the basin into apparently contemporaneous, shallow-marine dominated sections in the southwest of the basin. The preserved thickness and number of high-frequency cycles, together with their relation to the long-term subsidence trend of the Paradox Basin, records a periodic switching of both climate and relative sea level, the temporally linked nature of which demonstrates that glacio-eustasy exerted a dominant control on the origin of the preserved succession. When the world's sea level was at this "low stand", former sea bed sediments were subjected to subaerial weathering erosion by rain, frost, rivers, etc. The autogenic processes they consider include delta lobe switching, channel avulsion, auto-retreat and variations in sediment supply that control stacking patterns.

These lateral shifts in deposition create alternating layers of good reservoir quality rock porous and permeable sands and poorer-quality mudstones capable of providing a reservoir "seal" to prevent the leakage of any accumulated hydrocarbons that may have migrated into the sandstones.

In contrast to Muto et al. Advanced Search Abstract Sequence stratigraphy was first developed as concepts and methods from the late 19th to mid 20th century by geologists such as Barrell and Sloss.

types of sequence stratigraphy

For example, one of the major hindrances to progress has been the interweaving of description and interpretation, mixing method with model. The final paper in the set has a rather different focus. The next larger cycle '4th order' is about 40, years and approximately matches the rate at which the Earth's inclination to the Sun varies again explained by Milankovitch.

It is now at the forefront of how sedimentary geologists observe, record, model and predict strata. The mixed nonmarine and shallow marine nature of the inferred paleoenvironments of the lower Cutler beds is significant because the preserved expression of the nonmarine eolian and fluvial units in each cycle demonstrates an external climatic control on system development, whereas the marine units in each cycle together with associated transgressive and regressive surfaces demonstrate repeated episodes of relative sea-level change.

sepm sequence stratigraphy

Thus we encourage some standardization of method but not of interpretation. This is an important piece of work, not least because sequence stratigraphic interpretations of outcrop that fully consider sediment routing and the possible contribution of autogenic processes are still relatively rare Burgessso demonstrating how this can be done well is useful.

Sequence stratigraphy basics

The lower Cutler beds preserve evidence for the linkage and feedback between combined climatic and eustatic allogenic controls on sedimentation, and their role in generating high-frequency Milankovitch-style cycles in mixed clastic—carbonate successions. Challenges arising in how to apply the method to new types of data Turner et al. New observations and understanding from experiments are challenging even basic concepts such as accommodation by providing examples where original definitions do not work well. A key focus of the method is to keep observations of sedimentary facies, stratal stacking and terminations as objective as possible and distinct from interpretations of driving mechanisms. In contrast to Muto et al. You do not currently have access to this article. In the distant past, sea level has been significantly higher than today. Later transgression culminated in marine incursion over the former low-relief floodplain. We would also like to thank all the Geological Society staff who hosted and facilitated the meeting. The ancient shoreline of the last glacial period is now under approximately feet meters of water.

Relative sea-level lowstand was coincident with climatic aridity at which time exposure of a broad, low-relief coastal plain enabled the generation of a substantial eolian sediment supply that was available for transport by a paleowind aligned parallel to the trend of the paleocoastline, resulting in dune-field construction and accumulation along a coastal belt.

Key stratigraphic surfaces have been traced from the continentally dominated northeastern portion of the basin into apparently contemporaneous, shallow-marine dominated sections in the southwest of the basin.

sequence geology

The extent to which such subdivisions actually relate to accommodation perhaps requires independent evidence to demonstrate, but this work is a good example of the potential and the challenges in applying the sequence stratigraphic method to less frequently studied datasets.

Rated 6/10 based on 65 review
Download
History of Stratigraphy