Open AccessGeological history of the Tyre region of Europa: A regional perspective on Europan surface features and ice thickness
Author(s) -
Kadel Steven D.,
Chuang Frank C.,
Greeley Ronald,
Moore Jeffrey M.
Publication year - 2000
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1999je001203
Subject(s) - geology , lithosphere , impact crater , massif , ridge , dome (geology) , landform , geomorphology , tectonics , geophysics , paleontology , astrobiology , physics
Galileo images of the Tyre Macula region of Europa at regional (170 m/pixel) and local (∼40 m/pixel) scales allow mapping and understanding of surface processes and landforms. Ridged plains, doublet and complex ridges, shallow pits, domes, “chaos” areas, impact structures, tilted blocks and massifs, and young fracture systems indicate a complex history of surface deformation on Europa. Regional and local morphologies of the Tyre region of Europa suggest that an impactor penetrated through several kilometers of water ice to a mobile layer below. The surface morphology was initially dominated by formation of ridged plains, followed by development of ridge bands and doublet ridges, with chaos and fracture formation dominating the latter part of the geologic history of the Tyre region. Two distinct types of chaos have been identified which, along with upwarped dome materials, appear to represent a continuum of features (domes‐platy chaos‐knobby chaos) resulting from increasing degrees of surface disruption associated with local lithospheric heating and thinning. Local and regional stratigraphic relationships, block heights, and the morphology of the Tyre impact structure suggest the presence of low‐viscosity ice or liquid water beneath a thin (several kilometers) surface ice shell at the time of the impact. The very low impact crater density on the surface of Europa suggests that this thin shell has either formed or been thoroughly resurfaced in the very recent past.