Dark SAR imaging stuff;  (besides the obvious dark center of that upper reservoir and that of several other potential round containments).

This is certainly getting weird. That unusually darker matter surrounding much of the "GUTH Venus" territory is now becoming so much harder to explain, as so much of it is not black but nearly so.

Having a clear observational understanding of SAR 8-bit imaging is not exactly rocket science. Being that light or bright areas are those representing hard/reflective surfaces of 90+%, mid gray tones are somewhat 50% that amount and those darker to black pixels are simply offering little or no SAR imaging detection, such as most fluids and soft matter might simulate (exactly like the center of that upper reservoir and quite like the SE valley indicates as black). Obviously a deep enough hole or sharp enough depressions will also provide such as a darker and even as black indication, such as those tunnel entrances and the top opening of that volcanic vent consideration situated just South of town, these will certainly indicate as something black. However, the remaining territory surrounding all that Venus style of supposed lava flows, rock and whatever artificial structural issues seems somewhat unlikely as that being comprised of any sufficient number of holes or of such a crafted terrain that could produce so much dark matter uniformity.

Downhill or downstream from that rather significant volcanic vent issue, seems to indicate no such charistics of depositing sufficiently porous volcanic like debris which might otherwise tend to absorb SAR imiging signals, yet the surrounding overall area is simply chuck full of that dark stuff (at least until you lose a bit of altitude, then, under quite similar terrain issues, it simply goes away).

As supposedly purely natural elements go (speaking of SAR imaging thereof);  first of all, this area is obviously quite elevated (perhaps 6+km), quite mountainous and thereby ruggedly representing all sorts of relatively steep terrain considerations but, then also hosting several relatively or nearly flat or essentially somewhat level considerations mixed in. All of this dark matter consideration (occupying those lower mountain sides and/or foothill zones as well as other nearly flat or essentially lessor slope areas) is therefore somewhat equally surrounded and/or occupied by an expected mixture of obvious hard as rock (bright) matter and then variations of gray tones (thereby of varying reflective densities and/or of radar energy absorbing qualities).

Remembering that this highly qualified planetary image was gathered at a super perspective of 43º and, then every pixel was comprised of at least an average of 4 looks, from an NSA spy imaging technology (at the very least "extraordinary" worthy) that offers no lens distortions nor refractions nor that which requires any illumination factor and, thereby eliminating the optical illusions and subsequent "shadow, shade and even camouflage factors". Then also, because of the "4 looks" per pixel, there are no significant noise/error issues and, even if any of this were related to radar signal echoes or subsequent signal reflection distortions, there would first have to be sufficient evidence of whatever the original or primary target was which created such and, there simply is none of that, at least as anything related to the bulk of this "dark matter" consideration.

Where there should be hard as rock surfaces (such as with the main and secondary channel banks, artificial constructions, those rock quarries, that suspension bridge and obviously of those lava flows and vertically tectonic protruding rocks and/or mountains) there is hard surface detection and, there is certainly no problem with any of that.

Where there should be erosion and perhaps subsequent rock-like sluffings, once again no apparent problem, as I've identified similar occurrences of mixed gray-tones associated with likely areas of erosion and/or tectonic activity as essentially just about everywhere I've looked on Venus. Erosion and tectonics (what little I understand of such) is apparently being upheld to the highest standards by which our fine educational institutions (including pro-NASA types) have to offer and, I totally concur.

I however can't seem to help noticing that so much of this oddly convenient darker matter seems to be so purely associated with the very elevated nature of this site and, not otherwise with regard to so many other supposedly similar as well as elevated sites. This elevated location issue is where I happen to know it's somewhat nighttime cooler and then obviously somewhat more likely as to potentially receiving seasonal/nighttime moisture and/or irrigation from just those primary 50 million cubic meters worth of capacity reservoirs (there is at least another 50 million cubic meters worth as associated with other containment issues).

I guess, I've been wondering all along; why all of that reservoir capacity?

Obviously my medication is wearing off again, so, until I get my prescription refilled, perhaps you and others can help to refine just what all of that dark matter is all about. Obviously by intentionally compensating upon either the raw or subsequently enlarged image contrast and/or by limiting the basic depth of contrast or if you must dodge away (just like filtering away those pesky stars in our Apollo missions, since they were all in the wrong places anyway), this entire "dark matter" issue will obviously resolve itself.