In the Footsteps of Warren B. Hamilton: New Ideas in Earth Science
CONTAINS OPEN ACCESS
This unusual book, published to honor the late iconoclast and geologist extraordinaire Warren Bell Hamilton, comprises a diverse, cross-disciplinary collection of bold new ideas in Earth and planetary science. Some chapters audaciously point out all-too-obvious deficits in prevailing theories. Other ideas are embryonic and in need of testing and still others are downright outrageous. Some are doubtless right and others likely wrong. See if you can tell which is which. See if your students can tell which is which. This unique book is a rich resource for researchers at all levels looking for interesting, unusual, and off-beat ideas to investigate or set as student projects.
How spin down and radioactive decay drive rocky planet evolution
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Published:May 03, 2022
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CiteCitation
Robert E. Criss*, Anne M. Hofmeister, 2022. "How spin down and radioactive decay drive rocky planet evolution", In the Footsteps of Warren B. Hamilton: New Ideas in Earth Science, Gillian R. Foulger, Lawrence C. Hamilton, Donna M. Jurdy, Carol A. Stein, Keith A. Howard, Seth Stein
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ABSTRACT
Most differences in the gross surface morphologies, tectonic styles, overall geologic histories, and atmospheres of the rocky bodies in the solar system can be explained by contributions and dissipation of gravitational and radiogenic energy over geologic time. These two energy sources are large and measurable and can be extrapolated back in time. Accretion was likely cold, and directly converted gravitational potential energy into axial spin, a prominent feature of planets that is otherwise unexplained. Impact heating was mostly limited to planetary surfaces in the final stages of accretion. Frictional dissipation of spin contributed sufficient energy to ignite the primordial Sun and heated Earth and Venus by nearly as much as has the radioactive decay of K, U, and Th over geologic time. Energy inputs have been continuously offset by loss of heat to the surroundings. The magnitudes of most important energy contributions depend on the planet radius R and also on the distance r to the Sun. Quantitative, albeit approximate, relationships show that the net specific energy (kJ/kg) contributed to the rocky bodies over geologic time goes as: Earth ~ Venus >> Mars ~ Mercury ~ Moon >> asteroids. Net energy inputs increased the average internal temperatures of Earth and Venus by ~3000 K but heated asteroids by only a few hundred kelvins.