Outcrops remind us of the risks of applying a layer-cake approach to correlating well data. Turbidite lobes pinching out, channels abruptly transitioning to floodplain deposits or carbonate platforms only developing on local highs, all of these phenomena can often be observed in outcrops on a relatively small scale. Well data alone don’t always allow identification of these rapid transitions, which may lead to sands being over-correlated.
This photo clearly demonstrates that even on a smaller scale, direct correlation of strata can sometimes be tricky. Shown here are so-called flame structures in soft-sediment deformed turbidites overlying bioturbated mudstones, disrupting connectivity on a small scale that would not be picked up by well logs, let alone seismic data. The flame structures form part of a deepwater lobe of the Cretaceous Point Loma Formation of California,
Flame structures
