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GEOPHYSICAL RESEARCH LETTERS, VOL. 31, L16703, doi:10.1029/2004GL019978, 2004

Topographic variations in chaos on Europa: Implications for diapiric formation

Paul M. Schenk

Lunar and Planetary Institute, Houston, Texas, USA


Robert T. Pappalardo

Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado, USA


Abstract

Disrupted terrain, or chaos, on Europa, might have formed through melting of a floating ice shell from a subsurface ocean [ Carr et al., 1998 ; Greenberg et al., 1999 ], or breakup by diapirs rising from the warm lower portion of the ice shell [ Head and Pappalardo, 1999 ; Collins et al., 2000 ]. Each model makes specific and testable predictions for topographic expression within chaos and relative to surrounding terrains on local and regional scales. High-resolution stereo-controlled photoclinometric topography indicates that chaos topography, including the archetypal Conamara Chaos region, is uneven and commonly higher than surrounding plains by up to 250 m. Elevated and undulating topography is more consistent with diapiric uplift of deep material in a relatively thick ice shell, rather than melt-through and refreezing of regionally or globally thin ice by a subsurface ocean. Vertical and horizontal scales of topographic doming in Conamara Chaos are consistent with a total ice shell thickness >15 km. Contact between Europa's ocean and surface may most likely be indirectly via diapirism or convection.

Received 12 March 2004; accepted 21 June 2004; published 26 August 2004.

Index Terms: 5430 Planetology: Solid Surface Planets: Interiors (8147); 5455 Planetology: Solid Surface Planets: Origin and evolution; 6218 Planetology: Solar System Objects: Jovian satellites.

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Citation: Schenk, P. M., and R. T. Pappalardo (2004), Topographic variations in chaos on Europa: Implications for diapiric formation, Geophys. Res. Lett., 31, L16703, doi:10.1029/2004GL019978.