I friend interpreted Gato Canyon potential field in Santa Barbara Channel as a passive roof duplex. Now that I've been reminded by the links on this thread, I suppose there are horses in passive roof duplexes. Sorry, you'll have to google again. I tend to be concerned about these types of structures because they can accommodate a lot of shortening and they may not image well on 1980s 2D seismic, and may not be able to be mapped on 2D seismic unless the grids are very dense. I used to use UNFOLD and map restoration (gratier etc.) to determine fault slip from bedding strain...and we might underestimate in areas of hard-to-image thrust structure.
Chris