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GEOPHYSICAL RESEARCH LETTERS,
VOL. 25, NO. 23,
PAGES 4277–4280,
1998
Conamara Chaos Region, Europa: Reconstruction of Mobile Polygonal Ice Blocks
N. A. Spaun
Brown University, Department of Geological Sciences, Providence, Rhode Island
J. W. Head
Brown University, Department of Geological Sciences, Providence, Rhode Island
G. C. Collins
Brown University, Department of Geological Sciences, Providence, Rhode Island
L. M. Prockter
Brown University, Department of Geological Sciences, Providence, Rhode Island
R. T. Pappalardo
Brown University, Department of Geological Sciences, Providence, Rhode Island
Abstract
New Galileo images of Europa reveal regions of chaotic terrain in otherwise highly-lineated background plains. Examination
of Conamara Chaos shows that 59% of the region is composed of fine-textured matrix material lying at low elevations and formed
by destruction of lineated plains, while the remainder consists of 139 fragmented polygons of linear-textured background plains.
Using through-trending linear features, we reconstruct the original positions of chaos polygons and find that significant
lateral translation and rotation have occurred: 78% of the polygons have undergone horizontal translations with most moving
between 1 and 5 km, and 81% have rotated (average rotation of ∼11°). Movement of polygons appears to be inward from the chaos
margins and clockwise in the center, while polygon rotation is evenly clockwise and counterclockwise. Chaos formation in this
region thus involves destruction of over half of the pre-existing terrain, and mobilization, translation, and rotation of
the remaining polygons, implying elevated near-surface temperatures and a highly mobile substrate over lateral scales of ∼100
km.
Received 20
July
1998;
accepted 15
October
1998.
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Citation: Spaun, N. A., J. W. Head, G. C. Collins, L. M. Prockter, and R. T. Pappalardo
(1998),
Conamara Chaos Region, Europa: Reconstruction of Mobile Polygonal Ice Blocks,
Geophys. Res. Lett.,
25(23),
4277–4280.
Copyright 1998 by the American Geophysical Union.
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