Remarks on the Iapetus’ bulge and ridge

Leszek Czechowski,Jacek Leliwa-Kopystynski

doi:10.5047/eps.2012.12.008

Leszek Czechowski, Jacek Leliwa-Kopystynski

Open Access

https://doi.org/10.5047/eps.2012.12.008

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Abstract

Iapetus is a medium sized icy satellite of Saturn. It has two spectacular features: the equatorial ridge (ER) and the abnormally large flattening. The flattening is usually explained in terms of large non-hydrostatic fossil equatorial bulge (EB) supported by a thick lithosphere. Here we show, building on the principle of isostasy, that EB and ER could be a result of low density roots underlying the lithosphere below the equator. The low density matter formed the layer over the core of the satellite. Such situation was unstable. The instability led to origin of axially symmetric plumes that formed equatorial bulge and equatorial ridge. So, we explain both: EB and ER in the frame of one hypothesis.

Highlights

Iapetus is a medium-sized icy satellite (MIS) of Saturn with two spectacular features: the geologically old equatorial ridge (ER) rising above the equatorial bulge (EB)— Fig. 1
The flattening is usually explained in terms of large non-hydrostatic fossil equatorial bulge (EB) supported by a thick lithosphere
The interiors of MIS behave like viscous liquid in geological time scale, the gravity and the centrifugal force give them a hydrostatic shape, i.e. an oblate ellipsoid with flattening depending on period of rotation Tr

Summary

Introduction

Iapetus is a medium-sized icy satellite (MIS) of Saturn with two spectacular features: the geologically old equatorial ridge (ER) rising above the equatorial bulge (EB)— Fig. 1. We show, building on the principle of isostasy, that EB and ER could be a result of low density roots underlying the lithosphere below the equator. The low density matter formed the layer over the core of the satellite.

Results

Conclusion