Terrain Types and LocalScale Stratigraphy of Grooved Terrain on Ganymede
نویسنده
چکیده
Grooved terrain is subdivided on the basis of pervasive morphology into (!) groove lanes elongate parallel groove bands, (2) grooved polygons polygonal domains ofparallel grooves, (3) reticulate rrain polygonal domains of orthogonal grooves, and (4) complex grooved terrain polygons with several complexly cross-cutting groove sets. Detailed geologic mapping ofselect areas, employing previously established conventions for determining relative age relations, reveals a general three-stage sequence of grooved terrain emplacement: first, dissection of the lithosphere by throughgoing grooves, and pervasive d formation of intervening blocks; econd, extensive flooding and continued deformation of the intervening blocks; third, repeated superposition of groove lanes concentrated at sites of initial throughgoing grooves. This sequence is corroborated by crater-density measurements. Dominant orientations of groove sets are parallel to relict zones of weakness that probably were reactivated during rooved terrain formation. Groove lane morphology and development consistent wi h that predicted for passive rifts suggests a major ole of global expansion in grooved terrain formation.
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