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25-497: 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 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, and very closely spaced, giving the terrain a rugged ridge and groove topography . Many of

50-428: A block of land downward. Graben often occur side by side with horsts . Horst and graben structures indicate tensional forces and crustal stretching. Graben are produced from parallel normal faults, where the displacement of the hanging wall is downward, while that of the footwall is upward. The faults typically dip toward the center of the graben from both sides. Horsts are parallel blocks that remain between graben;

75-472: A half-graben strongly affects syntectonic deposition. Comparatively little sediment enters the half-graben across the main bounding fault because of footwall uplift on the drainage systems. The exception is at any major offset in the bounding fault, where a relay ramp may provide an important sediment input point. Most of the sediment will enter the half-graben down the unfaulted hanging wall side (e.g., Lake Baikal ). Ejecta blanket An ejecta blanket

100-683: 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. 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 fields have changed somewhat over time. 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

125-406: Is a depressed block of the crust of a planet or moon, bordered by parallel normal faults . Graben is a loan word from German , meaning 'ditch' or 'trench'. The first known usage of the word in the geologic context was by Eduard Suess in 1883. The plural form is either graben or grabens . A graben is a valley with a distinct escarpment on each side caused by the displacement of

150-414: Is a common feature to be seen on the martian impact craters specifically around fresh impact crater . One-third of the martian impact craters with ≥ 5 km diameter have discernible impact ejecta around. Layered ejecta blanket are plentiful on the surface of Mars as around 90% of ejecta are characterized as layered materials. Though impact cratering and resulted ejecta blanket are ubiquitous features in

175-517: Is a generally symmetrical apron of ejecta that surrounds an impact crater ; it is layered thickly at the crater's rim and thin to discontinuous at the blanket's outer edge. The impact cratering is one of the basic surface formation mechanisms of the solar system bodies (including the Earth) and the formation and emplacement of ejecta blankets are the fundamental characteristics associated with impact cratering event. The ejecta materials are considered as

200-525: Is manifested as slip on faults that are recognizable in images from orbit. Most of the tectonic features in the western hemisphere of Mars are explained by crustal deformation from the 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, magmatic intrusion , and volcanic loading (deformation due to

225-591: The Ceraunius rise. 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. The Ceraunius Fossae are tectonic features indicating 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

250-401: The bounding faults of a horst typically dip away from the center line of the horst. Single or multiple graben can produce a rift valley . In many rifts , the graben are asymmetric, with a major fault along only one of the boundaries, and these are known as half-graben. The polarity (throw direction) of the main bounding faults typically alternates along the length of the rift. The asymmetry of

275-481: The coast of Epirus , Greece (now southwestern Albania ). Fossa (pl. fossae ) is Latin for ditch and is a descriptor term used in planetary geology for a long, narrow depression or trench. The International Astronomical Union (IAU) formally adopted the term Ceraunius Fossae in 1973. The name Ceraunius Fossae is plural and translates into "the Ceraunian trenches". Most of the Ceraunius Fossae are located in

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300-442: The crater rim to the final crater rim and beyond the crater rim. Approximately half the volume of ejecta falls within 1 crater radius of the rim, or 2 radii from the center of the crater. The ejecta blanket becomes thinner with distance and increasingly discontinuous. Over 90% of the debris falls within approximately 5 radii of the center of the crater. Ejecta which falls within that area is considered proximal ejecta . Beyond 5 radii,

325-554: The discontinuous debris is considered distal ejecta . Ejecta blankets are found on the terrestrial planets (e.g., Earth, Mars, and Mercury) and satellites (e.g., Moon). Many of the ejecta blankets of Mars are characterized by fluidized flowing across the surface. In contrast, the ejecta blankets and proximal ejecta deposits of Moon and Mercury (or on airless bodies) are attributed to ballistic sedimentation. Lunar fresh impact craters preserve continuous ejecta blanket that are characterized by blocky and high albedo materials. Similar to

350-542: The extent of ejecta blanket that ranging from size and mass of impactor (meteorite, asteroid, or comet), surface temperature, gravity and atmospheric pressure of target body, the physical characteristics of target rock. The martian ejecta blankets are categorized broadly into three groups based on the observed morphology identified by spacecraft data: a. Layer ejecta pattern: the ejecta blanket seems have formed by fluidization process and composed of single or multiple partial or complete layers of sheet of materials surrounding

375-500: The fresh lunar craters, the Mercurian impact craters also form continuous ejecta deposits of blocky and high albedo materials. Radial structure of ejecta deposits are seen around the lunar impact crater and generally thins out as increase distance form the center of the crater. Presence of boulder materials are also seen in the lunar ejecta deposits. However, the diameter of boulder found in ejecta deposits are directly correlated with

400-487: The graben are hundreds of kilometers long and have walls with complex scalloped segments. Some contain pit crater chains (catenae) at their bottoms, suggesting the presence of deep-seated tension cracks into which surface material has drained. The term Ceraunius is from an 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

425-474: The impact process. These information also give an idea about the planetary environment e.g., gravity and atmospheric effects associated with the impact cratering. Studying impact ejecta is an excellent sampling environment for the future in-situ lunar exploration. Ejecta blanket may not always evenly distributed around an impact crater. Based on the structure, ejecta blanket are described as rampart, lobate, butterfly, splosh, sinuous, etc. Many factors determine

450-509: The large, sagging weight of the volcanic mass). The Ceraunius Fossae fractures are 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. A large number of extensional structures, including graben and rifts , radiate outward from the center of Tharsis. Mechanical studies indicate that

475-408: The magma exploits or opens up fractures in the subsurface, causing a crack or pit crater chain to form at the surface. 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. Graben In geology , a graben ( / ˈ ɡ r ɑː b ən / )

500-556: 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. The Ceraunius Fossae lie on a broad topographic ridge up to 1.5 km high, called

525-435: The size of impact crater diameter. The low gravity and lack of atmosphere (air less bodies) favors the formation of the impact cratering and associated ejecta black on the surface of moon and Mercury. Although a thick atmosphere and relatively higher gravity of Venus reduce the likelihood impact cratering, the higher surface temperature augments the efficiency of the impact melting and associated ejecta deposits. Ejecta blanket

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550-488: The solid bodies of the solar system, the Earth rarely preserve the signature of impact ejecta blanket due to erosion. However, to date, there are 190 identified impact craters on the surface of Earth. Ejecta blankets have a diverse morphology. Variations in ejecta blanket indicates different geological characteristics involved with the impact cratering process such as nature of target materials and kinetic energy involved with

575-433: The transported materials beyond the transient cavity formed during impact cratering regardless of the state of the target materials. A blanket of ejecta is formed during the formation of meteor impact cratering and is composed usually of the materials of that are ejected from the cratering process. Ejecta materials are deposited on the preexisting layer of target materials and therefore it form an inverted stratigraphy than

600-413: The underlying bedrock. In some cases, the excavated fragment of ejects materials can form secondary craters . The materials of ejecta blanket come from rock fragments of crater excavation, materials due to impact melting, and outside the crater. Immediately after an impact event , the falling debris forms an ejecta blanket surrounding the crater. An ejecta blanket is deposited in the interior regions of

625-449: The void, a pit crater may form. Pit craters are distinguishable from impact craters in lacking raised rims and surrounding ejecta blankets . On Mars, individual pit craters can coalesce to form crater chains (catenae) or troughs with scalloped edges. 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 dikes . The migration of

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