Crater-Centered Laccoliths on the Moon: Modeling Intrusion Depth and Magmatic Pressure at the Crater Taruntius
✍ Scribed by R.W. Wichman; P.H. Schultz
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 322 KB
- Volume
- 122
- Category
- Article
- ISSN
- 0019-1035
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✦ Synopsis
around the crater floor (Schultz 1976). Rarely, in cases of extreme crater modification (e.g., Gassendi), deformation Many floor-fractured craters on the Moon show surface deformation like that seen over terrestrial laccoliths. Consequently, can extend beyond the crater rim to form another annular terrestrial laccoliths provide one model for such crater modifitrough surrounding a narrowed, ridge-like crater rim cation. This model directly relates surface deformation to the (Schultz 1976).
growth of a shallow, crater-centered intrusion, and it estimates
This sequence of progressive crater floor uplift can be intrusion size and magma pressure. It also yields a minimum attributed to both a viscous relaxation of crater topography estimate for intrusion depth. Maximum intrusion depths cannot (e.g., Danes 1965, Hall et al. 1981) and the emplacement be directly constrained, but a range of likely intrusion depths of crater-centered intrusions (e.g., Schultz 1972Schultz , 1976, can be derived with additional assumptions. When the model Brennan 1975). However, several observations appear to is applied to the crater Taruntius, the surface record indicates favor the igneous intrusion mechanism. In particular, the an intrusion ȁ30 km across and 1900 m thick. The calculated frequency of crater-centered volcanism, the equilibration excess magma pressure is ȁ9 MPa (90 bar), and the estimated intrusion depths range from ȁ1 to ȁ5 km. If magma pressure of uplifted crater floors with nearby mare levels, and the reflects a hydrostatic magma column beneath Taruntius, these selectivity of crater modification in some regions are all values suggest a total magma column length of ȁ65 km during more consistent with igneous intrusions than with viscous crater modification.