The role of extensional instability in creating Ganymede grooved terrain: Insights from Galileo high-resolution stereo imaging
نویسندگان
چکیده
Galileo stereo images covering about 1500 km 2 of Uruk Sulcus on Ganymede have revealed two scales of ridges; (1) large-scale ridges and troughs spaced -6 km apart, corresponding to the "grooves" seen in Voyager images, and (2) small-scale ridges spaced hundreds of meters apart superimposed on the large-scale ridges. We interpret the small-scale ridges to be the result of tilt-block normal faulting of the surface brittle layer, while the large-scale ridges may be due to necking of the brittle layer over a ductile substrate. The geometry of the tilt blocks revealed in Galileo images leads to a minimum estimation of 51% to 58% extensional strain in the area. The strain estimate, when incorporated into a model for the formation of grooved terrain by necking of a brittle layer undergoing extension, leads us to estimate a thermal gradient of--20 K/km and a strain rate of "'10 '14 S 'l during groove forma-
منابع مشابه
Grooved Terrain on Ganymede: First Results from Galileo High-Resolution Imaging
allowing extrapolation of the observed brightness and topographic relationships to the rest of the imaged area. Distinct High-resolution Galileo imaging has provided important geological units are apparent across the region, and ridges and insight into the origin and evolution of grooved terrain on grooves are ubiquitous within these units. The stratigraphically Ganymede. The Uruk Sulcus target...
متن کاملGlobal Expansion of Ganymede Derived from Strain Measurements in Grooved
Introduction: Grooved terrain on Ganymede records an episode of extensional tectonics and possibly cryovolcanism [1], but the cause of groove formation remains uncertain. With little evidence for surface contraction to balance out extension, various mechanisms have been proposed to increase the interior volume of Ganymede and thus cause global expansion. Global expansion may be caused by the in...
متن کاملFormation of Ganymede Grooved Terrain by Sequential Extensional Episodes: Implications of Galileo Observations for Regional Stratigraphy
High-resolution Galileo images of grooved terrain on GanGrooved terrain covers over half of Ganymede’s surface ymede have revealed details of the morphology of grooves and their stratigraphic relationships. Based on lower resolution and records a period of intense surface deformation at Voyager images, complex areas of grooved terrain in Uruk some point in the satellite’s history. Ganymede’s ne...
متن کاملEvidence for Europa-like tectonic resurfacing styles on Ganymede
[1] Very high-resolution imaging and stereo topographic data obtained during the Galileo G28 encounter with Ganymede show 1) evidence for Europa-like, crustal spreading and resurfacing to form portions of the bright terrain, and 2) bright terrain that appears smooth at Voyager resolution (and thus a strong candidate for cryovolcanism) but instead is tectonically deformed and lacks embayment rel...
متن کاملTectonic Resurfacing of Icy Satellites by Periodic Necking Instabilities: Application to Ganymede and Enceladus
Overview: Many of the icy satellites in our solar system include young, highly tectonized terrains. Two of the most prominent examples of such surfaces are Ganymede's grooved terrain and Enceladus' south polar tiger stripes, both of which appear to have ages of less than 1 Ga [1, 2]. While cryovolcanism likely has occurred and is occurring on these bodies, the lack of obvious cryovolcanic struc...
متن کامل