You say: “I strongly suspect that many deltas can reach the shelf edge through normal progradation on most types of margin, and if this is the case, it is unlikely shelf-edge deltas are uniquely or even typically lowstand.”

That’s a really good point. Just for the sake of discussion, while *some* deltas could get to shelf edge during non-lowstand conditions, wouldn’t *all* deltas be at the shelf edge during lowstand conditions?

Great site – I like it. And I like your paper – I’m a big fan of questioning the lowstand model in the face of all sorts of various evidence. But do you really think the lowstand model is a good rule of thumb for passive margins? Like most elements of the sequence stratigraphic model, it lacks any substantive evidence or indeed theoretical basis, so I’m not so sure. I strongly suspect that many deltas can reach the shelf edge through normal progradation on most types of margin, and if this is the case, it is unlikely shelf-edge deltas are uniquely or even typically lowstand.

Anyway, keep up the good work with the site.

cheers, Pete

Regarding submarine canyon head morphology and processes, Charlie Paull at MBARI continues to collect information from Monterey. Seems like each time we get more information we find out something we never knew…which is really exciting.

Thanks for the great web-site, there are some spectacular things to see in the seafloor morphology (and subbottom structure, too).
Mark

See the Paull et al. (2003) paper in Geo-Marine Letters about a turbidity current that was ‘caught in the act’ in Monterey submarine canyon…if I remember they were able to make some measurements. But, I think the current lifted up their heavy equipment off the canyon floor and then redeposited it several km down-canyon!

Without looking this stuff up, I recall that estimated/measured velocities for turb currents have a huge range…some are actually not as fast as one would think (few meters/sec), while others are an order of magnitude faster.

As for duration of sediment retention in the canyon head before being flushed down-system, this is also not very well known. But, as more and more ocean observation systems are being designed and deployed (e.g., NEPTUNE system out of U of Washington), I hope we can amass more direct measurements of these processes.

Yes, the Weber et al. ’97 paper is a good one…I need to remember to revisit that.

I have seen that paper, it is very cool. Kudrass is 2nd author on Michels et al. (1998) paper from Marine Geology about cyclone-dominated sedimentation patterns on the G-B submarine delta. I can’t say that I agree with it all, but they make some very interesting arguments for their position.

You might check out the Weber et al. 1997 Geology paper titled “Active growth of the Bengal Fan during sea-level rise and highstand” as it seems fairly relevant to your paper.

I am actually working up a post about some of my current research on the Ganges-Brahmaputra Delta, hopefully I’ll get it finished soon.

You’ve probably seen the Kudrass et al. (1998) Geology paper about how storms and tides influence sediment transport into the Swatch of No Ground Canyon. Pretty cool.

As for your fluid flow rates question…do you mean for individual sediment gravity flow events? Or, whether or not there is temporary storage in the canyon head before getting down to fan?

Have you been able to work out any estimates for fluid flow rates from the head of the canyon to the fan?

Keep up the excellent posts! I like the new setup.