The nearly longitudinal large scale streaks east of Tsegihi have been interpreted as either parallel mountain chains or as surface deposits of some kind superimposed on the topography. As I write this we are sandwiched between two significant events in the exploration of these features, the unfortunate loss of the T60 SAR data and the hoped-for T61 VIMS imaging. Below are a few tentative thoughts that I hope may prompt some discussion.

One look at the map of Titan and it’s clear that this area looks odd. The system of parallel stripes intersects the more typical surface markings formed by the frayed southern margin of the Senkyo sand sea at an angle of about 60 degrees. Furthermore those markings, formed by an active dune system, look fresher and more distinct than the strange longitudinal stripes. This leads to suggestion one:

1/ The stripes are older surface markings exposed by the net removal of newer sediments, palimpsests from an earlier era. In support of this idea I note that the area is in the lee of Tsegihi which presently functions as an effective barrier to sand transport. Farther north where the eastward flow of sand continues relatively unimpeded into Senkyo the longitudinal stripes are not seen. Suggestion one could be tested by examining the interdune spaces in the thinner parts of Senkyo to see if continuations of the stripes can be followed beneath the modern sands.
Why might albedo markings laid down in an earlier era be so differently oriented? This leads (though far from inevitably) to suggestion two:

2/ The stripes formed when their orientation with respect to Titan’s equator was very different from now.

From an earlier forum discussion it emerged that there was no clear evidence either for or against large scale reorientations of Titan’s crust in the past. Could it be that we have been looking at part of that evidence all this time? Of course a lot more would be required to make a serious case, so it's not too late for a bit of speculation. Total refutation is always welcome!

Like ngunn I would speculate that the longitudinal streaks east of Tsegihi are partly modified portions of an older crust. I would take a broader view (as VIMS did in PIA 09033) and wonder if the streaks are related the crustal disruption caused by a giant impact. That circular structure containing Elba facula has the appearance of an old impact basin. T23 SAR covered much of the southeastern portion of this structure and the western part of the longitudinal streaks (although not the central 'mountain chain' that the lost T60 SAR covered). Looking at T23 up close shows a cracked appearance to portions of the brighter units on the western edge of the swath and a possible tectonic fault on the south eastern end of the swath. Both these crustal disruptions have a radial longitudinal orientation pointing away from the basin structure. The graphic shows the previous VIMS overview, the T23 swath location and a close up with what appears to be some tectonic crustal changes.

Click to view attachment

Nice compsite image there, and an interesting suggeston.

If I'm looking at the correct circular feature, though, that would be one enormous impact scar. That sets me wondering what is the biggest impact you can have on a world with a floating ice crust without melting the whole crust? At some point big impacts must be self-erasing. There is the question of age as well. Such a large feature would normally be inferred to be very ancient whereas the scarcity of somewhat smaller impact features on Titan suggests a younger age for the crust we see today.

Also I'm not sure that the stripes are aligned right to suggest association with an Elba-centered impact. At least at their southern 'VIMS mountains' end they seem to be converging southward, so if they are impact related maybe the 'smoking gun' crater is buried under the south polar sediments.

[quote name='ngunn' date='Sep 4 2009, 05:41 AM' post='145692']

'If I'm looking at the correct circular feature, though, that would be one enormous impact scar. There is the question of age as well. Also I'm not sure that the stripes are aligned right to suggest association with an Elba-centered impact.'

All good points nigel ! However looking a bit more (see below image) at this basin-like structure with ISS VIMS and SAR together there appears to be evidence of crater wall breaching, some flat bottom deposits and perhaps some crustal slips or tectonic ridge structures nearer to the longitudinal streaks. Some bright lines in the VIMS image are resolved into focal points of SAR brightness suggesting the streaks are in part due to the lower resolution of VIMS. All in all a fascinating area to fathom. Perhaps the additional data from T61 will help resolve the issue.

Click to view attachment

Titanicrivers What is that sar radar you have in your first ani gif?

Strange I have never seen that.

Its the second sar strip in the 1st animation.

That cool SAR swath is from T23 !! In both animations (post #2 and #4 above) I am using Part 2 of of the T23 SAR. At the end of post #2 I show part of the same strip up close to emphasize what may be faulting and breaching drainage channels. The animation in post #4 is a more accurate mapping of T23 SAR Part 2 overlying VIMS and ISS imagery of the area. Several of the SAR swaths (including T23 SAR) were highlighted in Planetary Photojournal in part only. You can get the full swaths from Perry's compilation found here:
http://pirlwww.lpl.arizona.edu/~perry/RADAR/

Oh! I see now.

Love your work.

Thanks D. (Would that all work could be so pleasant !)

The paper https://www.sciencemag.org/cgi/content/full/324/5929/921 you mentioned in post #5 of the Non-targeted flyby of Sept. 22, 2009 topic may have some relevance in this discussion. The paper shows an interesting ellipsoidal Titan shape elevation map (although the paper downplays correlation of the 4th harmonic regional Titan ellipsoidal shapes/elevation map and surface features other than the poles and Xanadu), which portrays a relatively higher surface plot in the region south of SENKYO where VIMS data suggests elevated terrain. (see below image).
Click to view attachment

Interesting comparisons both, but whereas the other 'rivers' one seems to offer direct support to the flow hypothesis in that case, I don't immediately see a useful connection here with the VIMS data and the steeper localised slopes thought to be causing topographic shading.

Of course if my more outlandish idea about the stripes being palaeo-equatorial streaks has any plausibility at all then it would make sense to look at the elevation map afresh with the possibility of differently located poles in mind. Is there another, former, rotation axis about which the form of Titan's crust still preserves a significant degree of symmetry? I don't know if the elevation data are complete enough yet, but if and when they are, that question would become a purely mathematical one that I would very much like to see addressed.