![]() (See Template:PD-USGov, NASA copyright policy page or JPL Image Use Policy. NASA copyright policy states that "NASA material is not protected by copyright unless noted". This file is in the public domain in the United States because it was solely created by NASA. ![]() 1 Tesserae often represent the oldest material at any given location and are among the most tectonically deformed terrains on Venus's surface. Mission Arbitration in tessera Venus General Bug Report Guidelines - Please Read. Licensing Public domain Public domain false false A tessera (plural tesserae) is a region of heavily deformed terrain on Venus, characterized by two or more intersecting tectonic elements, high topography, and subsequent high radar backscatter. Tessera on Venus (Defense) Dark Sector missions on Venus or Ceres. Maxwell is made up of parallel ridges 2- to 7-km (1.2- to 4.2 miles) apart and is interpreted to have formed by compressional tectonics. The western edge of Maxwell shown in this image rises sharply, 5.0 km (3.0 miles), above the adjacent plains in Lakshmi Planum. Located along the right hand part of the image is Maxwell Montes, the highest mountain on the planet, rising to an elevation of 11.5 km (7 miles) and is part of a series of mountain belts surrounding Lakshmi Planum. These features, 60- to 120-km (36- to 72- miles) long and 10- to 40- km (6- to 24- miles) wide are interpreted as graben. A series of linear parallel troughs are located along the southern edge of the image. Additional blocks of tessera are located along the left hand edge of the image. The layered and deformed structures could be oceanic sediments. The abrupt termination of dark plains against this feature indicates that it has been partially covered by lava. Tessera terrain in Ovda Regio on Venus (a radar image obtained with Magellan spacecraft). Located near the center of the image is a feature previously mapped as tessera made up of intersecting 1- to 2-km (0.6 to 1.2 miles) wide graven. The plains of Lakshmi are made up of radar-dark, homogeneous, smooth lava flows. ![]() Lakshmi Planum, surrounded by highlands, the most important being Maxwell Montes to the East. Ishtar Terra, centered on 65° N latitude and 0° E longitude includes a high plateau. This Magellan full resolution radar image is centered at 65 degrees north latitude, zero degrees east longitude, along the eastern edge of Lakshmi Planum and the western edge of Maxwell Montes. Based on full-resolution Magellan radar images, the detailed structural analysis of central Ishtar Terra (Venus) provides new insight to the understanding of the Venusian tectonics. On the basis of both theoretical and observational considerations, this contribution will suggest that coupling the formation of tessera ribbons to the emplacement of dyke swarms relatively late in the structural development of tessera terrains may provide a resolution for the apparent inconsistencies in those published models.English: Venus - Lakshmi Planum and Maxwell Montes They are based on what amount to assumptions regarding (i) the secular evolution of crustal thickness, (ii) crustal mechanical homogeneity and isotropy, (iii) the mechanics of ribbon formation, and (iv) the relative timing of ribbons in the structural geological sequence of tessera terrains. Many of the models are complex, and appear to be both internally contradictory and inconsistent with well-established geological principles. Endogenic and exogenic models have been developed over the past 25 years to explain the development of extensive, pervasive, high aspect ratio troughs and graben-like structures (“ribbons”) and short- to long-wavelength folds in tessera terrains, commonly associated with crustal plateaus on Venus.
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