On April 11th 2015, UI SC APPG invited a guest speaker from Pertamina to present a short course entitled Sequence Stratigraphy. Rochmad is a geologists who specialized in sequence stratigraphy and had an intense research in the field. Sequence stratigraphy is a study which relates facies with framework of chronostratigraphy. Lithology, sedimentation process, and age are the main point in sequence stratigraphy. Core plugs, whole core, well logs, seismic, and borehole data needed for stratigraphy analysis. The workflow of sequence stratigraphy analysis is shown in the diagram below:


Relative sea level is controlled by the interplay of tectonics, subsidence, compaction and eustacy takes control in the sedimentation process.
In sedimentation process there are systems called System Tract Analysis:
• FSST (Falling Stage System Tract)
• LST (Low Stand System Tract)
• TST (Transgressive System Tract)
• HST (High Stand System Tract)
Stratigraphy analysis helps geoscientists to classify the formation of the sediments. Every single System Tract resulted the different sediments. High Stand System Tract means sea level rise at the time. This will impact the sediments. The characteristics of sediments from HST are Coarsening upward, aggradation to progradation sets, funnel log motif, and Shale dominated. Low Stand System Tract is the opposite of HST which result blocky log motif, aggradational parasequence sets, and Sand dominated. Falling Stage System Tract (FSST) will result Coarsening upward sediments, and bell log motif. Transgressive System Tract (TST) will result retrogradational parasequence sets, finning upward sediments, and bell log motif.

The speaker finished presenting after two and a half hours continued with discussion sessions. Discussion session took one hour and ended at 4.30.


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