{{short description|Set of fractures in the northern Tharsis region of Mars}} {{Infobox feature on celestial object |name = Ceraunius Fossae |image = [[File:MOLA colorized image of Ceraunius Fossae region.jpg|280px]] |caption = [[Mars Orbital Laser Altimeter|MOLA]] colorized image of the Ceraunius Fossae region. The fractured terrain consists of two large patches of north-south trending faults surrounded by lava flows. The [[Alba Mons]] volcano is the large, circular feature at top. |location = [[Tharsis quadrangle]] |coordinates = {{coord|29.2|N|251|E|globe:mars_type:landmark|display=inline,title}} |coordinates_footnotes = <ref name=GPN1>Gazetteer of Planetary Nomenclature. https://planetarynames.wr.usgs.gov/Feature/1105</ref> |discoverer = [[Mariner 9]] |type = Fracture system }} The '''Ceraunius Fossae''' are a set of fractures in the northern [[Tharsis]] region of [[Mars]]. They lie directly south of the large [[volcano]] [[Alba Mons]] and consist of numerous parallel [[fault (geology)|fault]]s and tension cracks that deform the ancient highland crust.<ref name=Carr06p87>Carr, M.H. (2006). ''The Surface of Mars;'' Cambridge University Press: Cambridge, UK, p. 87. {{ISBN|978-0-521-87201-0}}.</ref> In places, younger [[lava flow]]s cover the fractured terrain, dividing it into several large patches or islands.<ref name=Raitala88>Raitala, J. (1988). Composite Graben Tectonics of Alba Patera on Mars. ''Earth, Moon, and Planets,'' '''42''', 277–291.</ref> They are found in the [[Tharsis quadrangle]].
The faults are mainly narrow, north–south oriented [[graben]]. Graben (the name is both singular and plural) are long, narrow troughs bound by two inward-facing normal [[fault (geology)|faults]] that enclose a downfaulted block of crust. The graben in the Ceraunius Fossae are commonly several kilometers wide, between 100 and slightly over 1000 m deep,<ref>JMARS MOLA Gridded Dataset. University of Arizona. http://jmars.asu.edu/</ref> and very closely spaced, giving the terrain a rugged ridge and groove [[topography]].<ref name=Banerdt92>Banerdt, W.B.; Golombek, M.P.; Tanaka, K.L. (1992). Stress and Tectonics on Mars in ''Mars,'' H.H. Kieffer ''et al.,'' Eds.; University of Arizona Press: Tucson, AZ, pp. 248–297.</ref> Many of the graben are hundreds of kilometers long<ref name=Tanaka90>Tanaka, K.L. (1990). Tectonic history of the Alba Patera–Ceraunius Fossae Region of Mars. ''Lunar. Planet. Sci. Conf.,'' '''20''', 515–523. http://articles.adsabs.harvard.edu//full/1990LPSC...20..515T/0000515.000.html.</ref> and have walls with complex scalloped segments.<ref name=Carr06p87 /> Some contain [[Crater chain|pit crater chains]] (catenae) at their bottoms, suggesting the presence of deep-seated tension cracks into which surface material has drained.<ref name=Raitala88 /><ref name=Banerdt92 />
==Name== The term Ceraunius is from an [[Classical albedo features on Mars|albedo feature]] at lat. 19.78°N, long. 267°E. It was named by Greek Astronomer [[E. M. Antoniadi]] in 1930 for the [[Ceraunian Mountains]] on the coast of [[Epirus (region)|Epirus]], [[Greece]]<ref name=GPN2>Gazetteer of Planetary Nomenclature. https://planetarynames.wr.usgs.gov/Feature/1103.</ref> (now southwestern [[Albania]]). [[wikt:fossa|Fossa]] (pl. ''fossae'') is [[Latin]] for ditch and is a [[descriptor term]] used in [[planetary geology]] for a long, narrow depression or trench.<ref name=Russel92>Russell, J.F.; Snyder, C.W.; Kieffer, H.H. (1992). Origin and Use of Martian Nomenclature in ''Mars,'' H.H. Kieffer ''et al.,'' Eds.; University of Arizona Press: Tucson, AZ, p. 1311.</ref> The [[International Astronomical Union]] (IAU) formally adopted the term Ceraunius Fossae in 1973.<ref name=GPN1 /> The name Ceraunius Fossae is plural and translates into "the Ceraunian trenches". [[File:Alba Patera - topography map.png|thumb|left|240px|Location and regional [[topography]] of [[Alba Mons]] and the Ceraunius Fossae. The Ceraunius rise is the narrow orange area extending southward from Alba Mons like a handle ([[Mars Orbital Laser Altimeter|MOLA]]).]]
==Location and size== Most of the Ceraunius Fossae are located in the northern [[Tharsis quadrangle]]. A portion extend northward into the southwestern part of the [[Arcadia quadrangle]] where the fossae diverge around the flanks of Alba Mons to form the Alba and [[Tantalus Fossae]] systems. The area stretches from lat. 18.9° to 38°N and from long. 247° to 255°E. The entire feature has a north–south length of 1137 km.<ref name =GPN1 /><ref name=GPN3>Gazetteer of Planetary Nomenclature. Specifics of the Gazetteer. https://planetarynames.wr.usgs.gov/Page/Specifics</ref>
The Ceraunius Fossae lie on a broad topographic ridge up to 1.5 km high,<ref name=Ivanov06>Ivanov, M. A.; Head, J.W. (2006), Alba Patera, Mars: Topography, Structure, and Evolution of a Unique Late Hesperian–Early Amazonian Shield Volcano. ''J. Geophys. Res.,'' '''111''', E09003, {{doi|10.1029/2005JE002469}}.</ref> called the Ceraunius rise.<ref name=Anderson04>Anderson, R.C. ''et al.'' (2004). Tectonic Histories Between Alba Patera and Syria Planum, Mars. ''Icarus,'' '''171''', 31–38.</ref> The ridge projects from the southern edge of Alba Mons and extends southward for a distance of over 1000 km. The southern half of the Alba Mons volcano is built over the northern extension of this ridge.<ref name=Ivanov06 />
==Geology== The Ceraunius Fossae are [[tectonic]] features indicating [[stress (mechanics)|stresses]] in the planet's [[lithosphere]]. The fractures form when the stresses exceed the [[yield strength]] of rock, resulting in deformation of surface materials. Typically, this deformation is manifested as slip on faults that are recognizable in images from orbit.<ref name=Banerdt92 /> Most of the tectonic features in the western hemisphere of Mars are explained by crustal deformation from the [[Tharsis#Location and Size|Tharsis bulge]] (a huge volcanic mass up to 7 km high that covers nearly a quarter of the planet's surface). Among the processes proposed to explain the tectonic features associated with Tharsis are domal uplifting, [[magma]]tic [[intrusion]], and volcanic loading (deformation due to the large, sagging weight of the volcanic mass).<ref name=Head07>Head, J.W. (2007). The Geology of Mars: New Insights and Outstanding Questions in ''The Geology of Mars: Evidence from Earth-Based Analogs,'' M. Chapman, Ed.; Cambridge University Press: Cambridge: UK, p. 23. {{ISBN|978-0-521-83292-2}}.</ref>
The Ceraunius Fossae fractures are [[extensional tectonics|extensional]] features produced when the crust is stretched apart. The fractures are oriented north–south, radial to an early center of volcano-tectonic activity in [[Syria Planum]], a region in southern Tharsis.<ref name=Tanaka90 /><ref>Anderson, R.C. ''et al.'' (2001). Primary Centers and Secondary Concentrations of Tectonic Activity through Time in the Western Hemisphere of Mars. ''J. Geophys. Res.,'' '''106'''(E9).</ref> A large number of extensional structures, including [[graben]] and [[rift]]s, radiate outward from the center of Tharsis. [[Mechanics|Mechanical]] studies indicate that a regional pattern of radiating graben and rifts is consistent with stresses caused by loading of the lithosphere by the enormous weight of the Tharsis bulge.<ref name=Banerdt92 /> The immense [[Valles Marineris]] is probably the best known example of a rift system that lies radial to Tharsis. Several generations of grabens with slightly different orientations are present in Ceraunius Fossae, indicating that [[stress field]]s have changed somewhat over time.<ref name=Carr06p87 /> [[File:Southern part of Ceraunius Fossae based on day THEMIS.png|thumb|Southern part of Ceraunius Fossae based on [[Thermal Emission Imaging System|THEMIS]] day-time image]] In addition to producing normal faults and graben, extensional stresses can produce dilatant fractures or tension cracks that can open up subsurface voids. When surface material slides into the void, a pit crater may form. Pit craters are distinguishable from impact craters in lacking raised rims and surrounding [[ejecta blanket]]s. On Mars, individual pit craters can coalesce to form [[crater chain]]s (catenae) or troughs with scalloped edges.<ref name=Ferrill04>Ferrill, D.A.; Wyrick, D.Y.; Morris, A.P; Sims, D.W.; Franklin, N.M. (2004). Dilational Fault Slip and Pit Chain Formation on Mars. ''GSA Today,'' '''14'''(10), 4-12.</ref><ref>Wyrick, D.Y.; Ferrill, D.A.; Sims, D.W.; Colton, S.L. (2003). Distribution, Morphology and Structural Associations of Martian Pit Crater Chains. 34th Lunar and Planetary Science Conference, Abstract #2025. http://www.lpi.usra.edu/meetings/lpsc2003/pdf/2025.pdf.</ref>
Evidence also exists that some of the graben and crater chains in the Ceraunius Fossae may have been formed by the intrusion of [[magma]], which forms large underground [[dike (geology)|dikes]]. The migration of the magma exploits or opens up fractures in the subsurface, causing a crack or pit crater chain to form at the surface.<ref>Wilson, L.; Head, J.W. (2002). Tharsis-Radial Graben Systems as the Surface Manifestation of Plume-Related Dike Intrusion Complexes: Models and Implications. ''J. Geophys. Res.,'' '''107'''(E8), 5057, {{doi|10.1029/2001JE001593}}.</ref>
Knowledge of the locations and formation mechanisms of pit craters and fossae is important for the future colonization of Mars because subsurface fractures may act as conduits or reservoirs for water and ice.<ref name=Ferrill04 />
==Photo gallery== <gallery class="center" widths="190px" heights="180px" > Image:Tharsis Quadrangle map-la.svg|Map of Tharsis quadrangle with major features indicated. The Ceraunius Fossae are in the upper right. Image:Ceraunius Valley PIA07864.jpg|Graben in the Ceraunius Fossae, as seen by [[Mars Global Surveyor]] MOC. Note dark slope streaks. Image:Ceraunius Fossae.JPG|The Ceraunius Fossae, as seen by [[HiRISE]]. Image:Ceraunius Pits.jpg|Pit crater chain in Ceraunius Catena, as seen by [[HiRISE]]. </gallery>
==See also== {{commons category|Ceraunius Fossae}} *[[Alba Mons]] *[[Fossa (geology)]] *[[HiRISE]] *[[Mars Global Surveyor]] *[[Tharsis]] *[[Volcanism on Mars]]
== References == {{reflist}}
{{Geography of Mars}} {{Portal bar|Solar System}}
[[Category:Valleys and canyons on Mars]] [[Category:Tharsis quadrangle]]