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Impact basin relaxation as a probe for the thermal history of Pluto
Author(s) -
Kamata Shunichi,
Nimmo Francis
Publication year - 2014
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
eISSN - 2169-9100
pISSN - 2169-9097
DOI - 10.1002/2014je004679
Subject(s) - structural basin , pluto , geology , relaxation (psychology) , tectonics , geophysics , ridge , radiogenic nuclide , thermal , geomorphology , astrobiology , paleontology , mantle (geology) , physics , meteorology , psychology , social psychology
We investigate viscoelastic impact basin relaxation on Pluto for a variety of thermal evolution scenarios encompassing both convective and conductive ice shells. Basins smaller than 200 km in diameter do not relax appreciably, while relaxation fractions can be up to ∼60% for large impact basins. The main control on basin relaxation is the amount of radiogenic heat produced in the rocky core; our results are insensitive to the formation time of the basin, the ice reference viscosity adopted, and the presence/absence of a subsurface ocean. Other volatiles, such as CO 2 or NH 3 , if present in the ice shell in sufficient quantities could increase the predicted relaxation fraction of basins. Relaxation causes extensional stresses interior to the basin; the orientation of the resulting tectonic features is controlled by the effective elastic thickness beneath the basin. Future observations of the relaxation states and tectonics of impact basins are therefore likely to provide a key constraint on Pluto's thermal history.