A Curious Aspects of Topography of Mars: Impact volcanism?

Generated by the Mars Orbiter Laser Altimeter (MOLA), an instrument aboard NASA's Mars Global Surveyor, the  high-resolution map represents 27 million elevation measurements gathered in 1998 and 1999. The data serves as a basic reference book for Mars scientists , and  inspires a variety of insights about the planet's geologic history.

The data were assembled into a global grid with each point spaced 60 kilometers apart at the equator, and less elsewhere. Each elevation point is known with an accuracy of 13 meters in general, with large areas of the  flat northern hemisphere known to better than two meters. The full range of topography on Mars is about 30 kilometers
 

The Curious Aspects of the Topography of Mars

Lowlands-highlands

The one well-known curious aspect of the topographic map is  the striking difference  between the planet's low, smooth Northern Hemisphere and the heavily cratered  Southern Hemisphere, which sits, on average, about three to  five kilometers higher than the north. One clue is that the boundary between the terrains is roughly  circular. See fig. 1

One questionable explanation is that a giant impact hit  the north early in the history of the planet, thereby lowering it. But as one can see from the fig. 2 of crustal structure, the terrain continues to
slope beyond the lowland-highland boundary:

Additional analysis of the topography and gravity indicates that the northern lowlands was likely a zone of high heat flow early in Martian history, relecting vigorous convection of the Martian interior[1].
This rapid heat loss could have released gases  trapped within the planet to the atmosphere and underground ice or water to thesurface, helping to produce an ocean in the Northern Hemisphere. If this process was axial symmetrical so one can find the place of the old poles from the fig 1. : 65 North and 170 West. The old equator :

The Mars with magnetism inscriptions in the same position :


 

Impact Volcanism

Hellas  Basin - Alba Patera

The massive Hellas impact basin in the Southern Hemisphere is another striking feature of the map. (Nearly nine kilometers deep and 2,100 kilometers acros  the basin is surrounded by a ring of material that rises about two kilometers above the surroundings and stretches out to 4,000 kilometers from the basin center.)

But what impressed me the most is the fact, that there is another striking feature of Mars on the exact opposite point of the Mars globe: The crater of Alba Patera. (The Alba Patera a 6 km high volcano with a territory of 1200x1600 km).
 

The Point of Cataclysm

The Isidis Planitia's counter point (the "Point of Cataclysm") is a very interesting place: It is on the Tharsis bulge, which is unique in the solar system and rises to 10 km above the "Marsian see level".  The Point of Cataclysm is in the center of a system of tectonic features that covers the entire western hemisphere.  It is at the beginning of Valles Marineris and near to the top of the bulge in Noctis Labyrinthus which were formed when the crust was pulled apart in extension, radiating out from a center. Everything is here the largest in the solar system and appears to have reulted from adjustment in the outer layer of the planet caused by impact tectonics:
 

Argyre impact basin- Elysium Mons

The Elysium mons is 1000-1200 km far from the counter point. Why this difference? Or where supposed the Argyre impact basin to be? See the figure.

On the next figure one can see  three place of rotation . All three rotation clockwise and has the same value:29 degrees plus/minus 2 degrees. The rotation of Lunae Planum and Valles Marineris is evident from the pictures. The third constructed in the following way: We hawe to place, the Argyre basin, and a point where it shuld be. If this difference is coused by rotation so the  centre of rotation should be on the normal bisector of the line between these two points. What is very interesting, the "point of cataclysm" will be on the bisector. So I took the point of cataclysm as centre of rotation. So reconstructing the events: the  Argyre impact came  first and with it the Elysium volcanos om the other side and secondly the Isidis impact made to rotate the Argyre basin around a its counter-point as centre with ~29 degree.

Conclusions

The longevity and vigor of internal geologic activity of terrestrial planets correlates roughly with size. (This is understandable, considering that most geologic and tectonic processes are driven by the heat engine of a planet.)
As the Mars is a one-plate planet, where nothing goes down, there will be nothing to drive the volcanism. So where did those violent tectonic events come from? Mars is just large enough to became active with the help of giant impacts, but not so active that all records of its early history be destroyed. My hypothesis is that the huge impacts are the causes of  volcanism and cataclysmic movement of huge part of crust. Time to time the planetary billiard revived the volcanism of an inactive Mars and the events connected to it.  And the explosive volcanic eruptions and cataclysmic movement of crust , fueled colossal floods that carved some of the gorges and gouges found on the Red Planet.
This idea came to me seenig the picture PIA02035 (Maps of the Mars Topography, site  photojournal.jpl.nasa.gov) in Apr. of 2000 and induced me to send a message to the discussion web site of CNN [2]. Afterwards I developed the program "PlanetScape" to study Mars and other planets.
PlanetScape was used to generate all but two figures.

In the Tharsis region the tectonic events include clockwise rotation of the Lunea Planum, Valles Marineris and  Argyre Planitia.

In the end I should like to say, that it is the most unfortunate thing that no topogrphic data for the Moon, though  it would be not too expensiv to put a laser altimeter arond the Moon

By Marton ZSENEI
 

[1] Zuber, M.T., S.C. Solomon, R.J. Phillips, D.E. Smith, G.L. Tyler,
    O. Aharonson, G. Balmino, W.B. Banerdt, J.W. Head,
    C.L. Johnson, F.G. Lemoine, P.J. McGovern, G.A. Neumann, D.D. Rowlands,
    S. Zhong,
    Internal structure and early thermal evolution of Mars from Mars Global
    Surveyor topography and gravity, Science, 287, 1788-1793, 2000.

[2] Marton ZSENEI - Sunday, 04/23/00, 8:14:28am (#1979 of 1980)
    Discussion web-site "Destination Mars"