Conamara Chaos Region, Europa: Reconstruction of mobile polygonal ice blocks

Spaun, N. A.; Head, J. W.; Collins, G. C.; Prockter, L. M.; Pappalardo, R.

doi:10.1029/1998gl900176

Cited by 90 publications

(110 citation statements)

References 4 publications

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“…[140] Riley et al [2000] and [Spaun et al [1999[Spaun et al [ , 2001] provide size histograms of chaos/lenticulae on Europa. However, Spaun uses a set of equally sized bins, while Riley's bin widths increase geometrically.…”

Section: Discussionmentioning

confidence: 99%

“…This flow might drive ice-raft motion. O'Brien et al [2002] demonstrated that this flow was too slow to counteract melt-through of the ice layer, but perhaps it could transport ice rafts laterally a few km, accounting for the motion observed by Spaun et al [1998]. We are presently investigating this possibility.…”

Section: Viscous Deformationmentioning

confidence: 99%

“…They note that, given a steady supply of heat, a hydrothermal plume periodically sheds warm baroclinic eddies into its surroundings, and speculate that the ''satellite lenticulae'' found near chaos regions may be formed as the warm eddies heat the overlying ice. Finally, they note that ice rafts in Conamara Chaos appear to have drifted in a clockwise direction during chaos formation [Spaun et al, 1998]. They note that this is the expected direction of current flow at the top of a hydrothermal plume at the Chaos's location, and suggest that the blocks were transported by the current.…”

Section: Hydrothermal Plumes On Europamentioning

confidence: 99%

“…The blocks are translated and rotated from their original orientations [Spaun et al, 1998]. The scene is reminiscent of tabular Antarctic icebergs locked in a matrix of sea ice, but the true formation process remains one of the major outstanding questions in the study of Europa [Greeley et al, 2003].…”

Section: Introductionmentioning

confidence: 99%

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Hydrothermal plume dynamics on Europa: Implications for chaos formation

et al. 2004

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[1] Hydrothermal plumes may be responsible for transmitting radiogenic or tidally generated heat from Europa's rocky interior through a liquid ocean to the base of its ice shell. This process has been implicated in the formation of chaos regions and lenticulae by melting or exciting convection in the ice layer. In contrast to earlier work, we argue that Europa's ocean should be treated as an unstratified fluid. We have adapted and expanded upon existing work describing buoyant plumes in a rotating, unstratified environment. We discuss the scaling laws governing the flow and geometry of plumes on Europa and perform a laboratory experiment to obtain scaling constants and to visualize plume behavior in a Europa-like parameter regime. We predict that hydrothermal plumes on Europa are of a lateral scale (at least 25-50 km) comparable to large chaos regions; they are too broad to be responsible for the formation of individual lenticulae. Plume heat fluxes (0.1-10 W/m 2 ) are too weak to allow complete melt-through of the ice layer. Current speeds in the plume (3-8 mm/s) are much slower than indicated by previous studies. The observed movement of ice blocks in the Conamara Chaos region is unlikely to be driven by such weak flow.

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Section: Discussionmentioning

confidence: 99%

Section: Viscous Deformationmentioning

confidence: 99%

Section: Hydrothermal Plumes On Europamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydrothermal plume dynamics on Europa: Implications for chaos formation

et al. 2004

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“…Spaun et al, 1998] originated with a single major melt-through event, the tangential velocity u in the cyclonically rotating ice-water matrix of the plume is approximated by the relation tt2/r + fu -#drl/dr = 0, …”

Section: Currents In Conamara Chaosmentioning

confidence: 99%

Evidence for a weakly stratified Europan ocean sustained by seafloor heat flux

Thomson¹,

Delaney²

2001

J. Geophys. Res.

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Abstract. We interpret chaos-type features on the surface of Europa as melt-through structures formed by rotationally confined, steady and/or episodic oceanic plumes that rise to the base of the ice shell from magmatically heated regions of the seafloor. Smaller lenticular features in the vicinity of chaos-type regions might be formed by baroclinically unstable vortices that spin off the main convective plume or by persistent heating from localized hydrothermal venting sites. The ocean is assumed to be weakly stratified because of turbulent convection generated by heating from below and cooling from above.

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Domes, pits, and small chaos on Europa produced by water sills

2014

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Key Points:• The spreading of water sills is limited by ice fracturing • Deep sills can thicken significantly in contrast to shallow sills • Pits, domes, and small chaos morphology can result from subsequent sill evolution Abstract Pits, domes, and small chaos on Europa's surface are quasi-circular features a few to a few tens of kilometers in diameter. We examine if injection of water sills into Europa's ice shell and their subsequent evolution can induce successive surface deformations similar to the morphologies of these features. We study the dynamics of water spreading within the elastic part of the ice shell and show that the mechanical properties of ice exert a strong control on the lateral extent of the sill. At shallow depths, water makes room for itself by lifting the overlying ice layer and water weight promotes lateral spreading of the sill. In contrast, a deep sill bends the underlying elastic layer and its weight does not affect its spreading. In that case, the sill lateral extent is limited by the fracture toughness of ice and the sill can thicken substantially. After emplacement, cooling of the sill warms the surrounding ice and thins the overlying elastic ice layer. As a result, preexisting stresses in the elastic part of the ice shell increase locally to the point that they may disrupt the ice above the sill (small chaos). Disruption of the surface also allows for partial isostatic compensation of water weight, leading to a topographic depression at the surface (pit), of the order of ∼10 2 m. Complete water solidification finally causes expansion of the initial sill volume and results in an uplifted topography (dome) of ∼10 2 m.

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Conamara Chaos Region, Europa: Reconstruction of mobile polygonal ice blocks

Cited by 90 publications

References 4 publications

Hydrothermal plume dynamics on Europa: Implications for chaos formation

Hydrothermal plume dynamics on Europa: Implications for chaos formation

Evidence for a weakly stratified Europan ocean sustained by seafloor heat flux

Domes, pits, and small chaos on Europa produced by water sills

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