Mars Borealis Basin
We were discussing the Lightning Scarred Planet Mars recently here at . Today I read Mike Fischer's ideas about the largest basins on the Moon and Mars at . He references a number of papers that discuss formation of the Mars northern basin, Borealis, suggesting a large glancing impact was the cause. Charles, I think you're the only one who considers many impacts to involve thermonuclear explosion. If that's true, would your model then require much modification of those analyses? For example, a quote there from one of the referenced papers says: ""Simulation results show that "depending on impact angle, 50-70% of the melt stays inside the excavated boundary, 25-30% is deposited outside the boundary, and the remainder is ejected from the planet."3"" Do you think the CFDLs may tend to minimize how much material would leave the planet?
This article "A Vast Oceanus Borealis May have Once Covered 1/3 of Mars" at apparently shows an image of the Borealis basin as if it were covered with an ocean here: . The significance of the image for this discussion is the shape, i.e. elliptical, but with a side branch, like the letter "Y". It looks like the peninsula region between the two arms is the volcanic shield that holds 4 large volcanoes on a highland. Imagining a grazing impact causing the Y shape, I suppose the impacter would have carved out the leg of the Y first, and finished with the arms, but the area between the arms would have been somewhat removed too, but may have partly fallen back down and/or vulcanism may have produced flood basalt with the volcanoes poking through it at the end of the event. Any thoughts about that and whether the asteroids and comets could have come from that impact? Fischer implies that he thinks Phobos and Deimos came from it. The latter article with the ocean image has some speculation that many of the large boulders, probably including the "Face on Mars", came from underwater landslides like what have occurred in Earth's oceans.
By the way, the second biggest crater on Mars, seen in the lower part of this image in dark blue, or purple, at looks to me like an object impacted at a steep angle, so that it buried itself deep inside Mars and left a deep basin, deeper than Borealis. Does that seem plausible? And would that have contributed to flood basalt and vulcanism in the shield area?