I am working on a manuscript on a stratigraphic model for Marmara Sea Turkey. We (researchers from Lamont-Doherty Earth Observatory, Istanbul Technical University, Dokuz Eylül Üniversitesi, and U Cal Santa Barbara (me)) are interested in the development of the fault system and basin over especially the last 1 million years. So, I got a very rough draft together more than a month ago and realized that I needed to do more work on the age model (which is now mostly done), and that I had not read many of the important published papers at all, or had not read then in 5 or more years. So, I have been re-reading papers. I am getting older and information does not stick as well as it did 20 years ago, so I read 2 or 3 papers in a day or 2 and forgot which paper was which and what was in them just afterwards.

But, some information from my 2 or 3 formerly favorite papers, published between 2001 and 2004, is sticking. These state that the North Anatolia fault propagated west across Turkey (meaning, the fault system got longer by pushing into areas farther west over millions of years). These papers have the big basins in Marmara Sea, offshore Turkey, form as a series of "pull-apart" basins bounded by (oblique) normal faults and connected by strike-slip transfer faults, with this extensional system taking up to 2+ cm/year of plate motion. Then, in the last couple hundred thousand years, this extensional system was abandonned and a purely strike-slip system pushed its way through. Thrust-fold anticline ridges formed on one side of the new fault system as the strike-slip fault propagated westward, and then these thrusts were abandonned and are now inactive.

A really nice model, and when I just had the papers and a few digital seismic reflection profiles to look at, I thought it was correct.

Now, I have a ton of seismic reflection profiles, with much of it very high quality, high resolution data that we collected and processed in 2008 and June 2010. Now I think that almost everything in these published models is not correct. The extensional (transtensional) faults are still active. The thrust folds are likely still active. The vertical component of slip across the main North Anatolian fault has been at more or less a constant rate for at least the last 500,000 years. The southern edges of 2 major basins have been tilting at more or less a constant rate for at least the last 500,000 years. The thrust-folding on the western Ridge are on the wrong side of a fault termination for a right-lateral fault propagating to the west. There should have been extension there instead. (Propagation towards the east would work, but I instead think it is like the Western Transverse Ranges of California; pre-existing structure in an orientation favorable for thrusting, and likely vertical axis clockwise rotation.

My manuscript will be about the stratigraphic model (based on glacial period shelf-edge deltas that we imaged), but it needed a "punch line" to make it seem more significant. The constant rates of deformation near and across the main strand of the fault will be the punchline.

The punchline could have been that the sedimentary rocks have been sliding slowly into the deep basins down the steep slopes over the last 1 million years or more in places. But, a researcher in our group is writing a manuscript on these collapse features and so I decided better to not steal her thunder. We do not see such odd collapse folds and faults offshore southern California. I think the sedimentary rocks in Marmara Sea are exceptionally weak. This is likely due to all the gas in them. Maybe there are some deeper layers of gypsum or even salt to help them flow downslope, but this is speculative.

OK, too long.

Chris