[X] My Assistant

[ngunn]

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!

[ngunn]

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.

[titanicrivers]

[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.