Elysium Rise and valleys

Origin of name:
Home of the blessed on western edge of world.

A név eredete:
Homerus csábítóan szép képét rajzolja, szerinte van egy hely a földnek nyugati szélén, az Oceanuson innen, ahol az emberek minden fáradság és baj nélkül, zavartalan boldogságban élnek. Nincs ott hóvihar, se téli zimankó, se zápor, csak a langyos Zephyrus fuvallat által az Oceanus felől, hogy az embereket lehűtse.
Görögösen Elüszion. A mennyország görög mitológiai megfelelője: Tartarosz a gyötrelmes bűnhődés, Elüszion a boldog lelkek hona.

Geologic description and interpretation:
Elysium Planitia and the Cerberus plains… are argued to be the youngest volcanic plains unit of Mars. [1] Lava flows associated with Elysium Mons extend several hundred kilometers into the northern lowland plains (Utopia Planitia).[2].

Elysium valleys: Hrad Vallis is a long sinuous valley. Flanking both sides of the source region is a lobate deposit. Previous studies have suggested the formation of the Hrad Vallis source region was the result of explosive magma–ice interaction and that the lobate deposit is a mudflow.[3]

Granicus Valles: the water that eroded the channels burst from pits and grooves partway up the flank of Elysium. As the volcano grew, it pressurized the slopes, forcing meltwater out of the ground through faults that radiate like spokes of a wheel. Molten rock forcing its way into the faults could have widened them, releasing water. Molten rock could also increase the outflow by melting large quantities of ground ice. However it occurred, the water undermined the surface before flowing away. The flows must have contained a mixture of water and volcanic debris, making what researchers call a mudflow, or lahar. Four separate episodes of flooding and channel carving took place. The third of these stages dominates the scene because it cut the deepest. The water responsible for the fourth stage of channel cutting did not come from the volcano's flanks. Instead, it burst out of the ground along the joints and fractures in the basin floor material which form a kind of rectilinear grid. This fourth stage of channeling created small-scale, linear channels that dissect the larger, often streamlined pieces of ground. But as with the channels on the volcano's flanks, when the water escaped from the subsurface, it undermined the ground and caused it to collapse, a process geologists call sapping. If the Utopia basin once held a large body of water, it was most likely frozen over. [4] Hebrus Valles consist of linear fracture segments connected by braided channels and may have formed through expulsed pressurized ground-fluid[5]. The Hebrus Valles and Hephaestus Fossae were formed by either solution, subsurface erosion (piping) or faulting. The Hebrus Vallis system changes from a continuous surface channel upstream (with streamlined islands) to discontinuous lines of depressions downstream), formed by a combination of surface and subsurface flow.[6]

Geológiai leírás és magyarázat:
Az Elysium Planitiát és a Cerberus síkságjait tartják a Mars legfiatalabb vulkáni egységeinek. Az Elysium Monsszal összefüggésben lévő lávafolyások több szát km-re terjednek az északi síkságokon (Utopia Planitia)
Az Elysium körüli völgyek közül a Hrad Vallis egy hosszan meanderező völgy. Forrásvidéke egykori robbanásos magma-jég kölcsönhatás nyomán alakult ki, s ekkor keletkeztek a sárfolyásnak tartott lebenyes üledékek.
A Granicus Valles keletkezése us az Elysiumhoz kötődik. Ahogy a vulkán növekedett, nyomás alá kerültek a lejtői, az olvadékvizeket a felszínre nyomva a vulkánt küllőként körülölelő tektonikus repedéseken keresztül. A megolvadt kőzet is hozzájárulhatott az áradásokhoz, nagy mennyiségű talajjeget felolvasztván. A víz a felszínt aláásta, mielőtt elfolyt volna. A folyások víz és vulkáni törmelék keverékéből álltak, sárfolyást vagy lahart alkotván.

[1] THEMIS website 2006: Feature Image: Fire and Water in Granicus Valles http://themis.asu.edu/features/granicusvalles

[2] Skinner, James A. Jr and Kenneth L. Tanaka 2007: Evidence for and implications of sedimentary diapirism and mud volcanism in the southern Utopia highland–lowland boundary plain, Mars Icarus

Volume 186, Issue 1, January 2007, Pages 41-59 http://dx.doi.org/10.1016/j.icarus.2006.08.013

[3] Bourke, Mary C. Les Bleamaster, Dan Berman, Michael Manga, Paul Williams: Pseudokarst on Mars: the evolution of the Hephaestus Fossae and Hebrus Vallis Systems, Utopia Basin. Project summary online. http://www.psi.edu/staff/bourkeprojects/PseudokarstOnMars.htm