Astrogeology, the Key to Global Tectonics

Philip J. Cannon
Exploration, Planetary Data, Tecumseh, OK

Astrogeology has given us an unprecedented view of the Solar System. A view that stresses the importance of impact cratering and gravity tides as major geologic processes. Several examples of planetary bodies indicate that the major tectonic processes in the Solar System are gravity tide driven.

The effects of gravity tides are adequately demonstrated on some of the planets and their moons. Io the inner moon of Jupiter is covered with volcanoes from pole to pole. The differential effects of gravity tide stresses between Jupiter and the three other large moons, Europa, Ganymede and Callisto, distort the mass of Io every few hours, releasing enough heat to generate volcanoes on this low density satellite which is about the same size as the Earth’s moon.

Modern remote sensing data indicates that fractures and faults are zones of weakness propagated through 4 to 5 kilometers of overlying sediments by the stresses of daily gravity tides. Twice each day, our Moon squeezes the Earth with a tidal bulge. Differential movement across the face or plane of a major fracture causes fatigue of the materials above the fracture. Zones of fatigue appear at the present surface as subtle physical discontinuities and minor chemical differences. These can be detected and enhanced with modern remote sensing techniques that are sensitive to these minor physical and chemical differences.

In relation to geologic history, a million years is a small amount of time. However, in a million years the different sides of a fracture have been moved past each other 730 million times, almost three fourths of a billion, by the gravity tides.

The Earth’s tectonic features can be adequately explained with gravity tide forces. Convection cells cannot be used, convincingly, to explain the tectonic features on Earth or other planetary bodies. Gravity tides are a real, documented force.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas