EXTENDED ABSTRACT: Correlating Sandstones Within and Between Growth-Faulted Intraslope Subbasins; Rules and Common Correlation Pitfalls

Lowstand sandstone lithofacies (or any other facies) cannot be correlated between different systems tracts within a subbasin or between diachronous subbasins on the basis of similar wireline-log shape. Pattern correlations equate only lithogenetically similar facies, not chronostratigraphically equivalent facies. Log-facies maps are based on time-equivalent facies and not genetically similar log patterns. On-shelf highstand and transgressive sandstone facies do not correlate with off-shelf lowstand sandstone facies within the same subbasin even though they occur between the same marine-condensed sections. On-shelf and off-shelf sandstone depositional episodes were temporally unique, and the facies are diachronous. Assumptions that in different subbasins, lowstand sandstone facies that occur between the same condensed sections are chronostratigraphically equivalent may lead to serious miscorrelations. Subbasin lowstand tracts become younger basinward, even if they occur between the same condensed sections. Laterally positioned subbasins on downthrown sides of the same regional growth faults were filled contemporaneously, and their basin fills are isochronous. Sandstone facies within high continuity on-shelf highstand and transgressive systems tracts can be correlated lithostratigraphically across large areas with confidence using the condensed section envelope as proof of time-equivalence. On-shelf progradational or retrogradational units are cut by high-frequency time lines precluding absolute equivalency throughout. The lowstand sandstone facies within different subbasins must be components of the same 3rd-or higher frequency sequence before accepting time equivalence. The correct way to ensure equivalency is to verify that the marine-condensed sections at the top of the transgressive tracts within each sequence are faunally equivalent.