Formation of lenticulae on Europa by saucer-shaped sills

• Published in: Icarus (New York, N.Y. 1962) Vol. 286; pp. 261 - 269
• Main Authors: Manga, Michael, Michaut, Chloé
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.04.2017; Elsevier
• Subjects: Astrophysics; Chaos; Domes; Earth and Planetary Astrophysics; Elastic flexure; Intrusions; Sciences of the Universe; Sills; Chaos; Intrusions; Domes; Elastic flexure; Sills
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2016.10.009

•Saucer shaped sills may create pits, domes, spots and small chaos on Europa.•Sills are predicted to be 1–5 km below Europa's surface.•Liquid water is predicted to exist presently under pits, and some domes and small chaos. Europa's surface contains numerous quasi-elliptical features called pits, domes, spots and small chaos. We propose that these features, collectively referred to as lenticulae, are the surface expression of saucer-shaped sills of liquid water in Europa's ice shell. In particular, the inclined sheets of water that surround a horizontal inner sill limit the lateral extent of intrusion, setting the lateral dimension of lenticulae. Furthermore, the inclined sheets disrupt the ice above the intrusion allowing the inner sill to thicken to produce the observed relief of lenticulae and to fracture the crust to form small chaos. Scaling relationships between sill depth and lateral extent imply that the hypothesized intrusions are, or were, 1–5 km below the surface. Liquid water is predicted to exist presently under pits and for a finite time under chaos and domes.