A Simplified Guide to Sequence Stratigraphy

In the past 3 decades the sequence stratigraphy jargon has proliferated, resulting in multiple definitions of the same surface or new surfaces and units based on drawings of deposition in response to relative changes in sea level. The close association between base-level changes, the formation of surfaces, and specific stratal stacking that define systems tracts are at the heart of the confusion.

It is proposed a back-to-basics approach, emphasizing key observations that can be made from any geologic data: lithofacies, lithofacies association, vertical stacking, stratal geometries, and stratal terminations. Parasequence stacking is a consequence of the interplay of accommodation and sediment supply, which are controlled by eustasy, tectonics, climate, and initial depositional profile.

Sequence stratigraphic surfaces are defined based on shoreline position and systems tracts are defined based on shoreline trajectory; therefore, shoreline position and trajectory are in fact the key observations to be made in a sequence stratigraphic interpretation. Terms like highstand, lowstand, and falling stage should be replaced by observation-based terms like "aggradation-progradation", "progradation-aggradation" and "degradation", respectively. Finally, research remains to be done on the relations between stratal stacking and various controls, and on the formation and chronostratigraphic significance of surfaces that demarcate changes in stacking.

Join us for this 60 to 70 minute talk via Zoom on 24 September at 8:30pm (20:30) Singapore time (GMT+8)

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