DRIVING FORCE OF EARTH'S TECTONIC RESURFACING
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The shape of the earth’s gravity field as it is measured by satellite orbital dynamics is compared to a calculated field derived form a modeled ellipsoid of rotation, presumed distribution of material to depth in the solid earth, and major inequalities in crustal relief. The resultant variations from predicted orbital path are interpreted as high and low earth’s gravity field strength. The color-coded isobars of this estimated gravity field form the basis of the image presented here. Blues and purples indicate areas where gravity is weaker than modeled and the satellites orbit varies upward as it passes over. RED/Yellows imply stronger gravity. Faded green and faded yellow zones represent the zero isobars, where prediction and measurement coincide. This colored image is overlaid on a black and white image of the earth, which highlights the surface features, such as ridges, trenches, and continental slopes. Noticeably, the position of the active ridge systems falls on or near the zero isobar of the gravity map. Also, and importantly most trenches delineate the same zone of high gravity field strength. The low gravity well centered beneath the tip of India is the main anomaly. Using this point to center the globe, all tectonic features and apparent motions become sensible. By analyzing the relationships between the present gravity field and tectonic features, and apparent continental motions, an understanding of the impulses and forces, which drive or resist continental motions, may be gathered.
The consistent relationship between the zero gravity isobars and the active ridgelines must be explained. The few locations where this correspondence is broken are also noteworthy. What does it mean that ridge extrusions occur where gravity is modeled accurately? That is the calculated ellipsoid of rotation correctly corresponds to the apparent earth’s surface. Yet these are very active lines, changing rapidly in the geologic timescale. Is it the activity, which makes them match the ellipsoid? Is it restoration of the ellipsoid, which is forcing the activity?
Central to all crustal and tectonic features, jostled between the Malaysian trench and the Indian ocean ridge, pierced by the Ninety east and Himalayan faults, and crowned by the most severe crustal relief on the planet; is the unnamed low gravity anomaly south of India. (K crater). What could have caused such a concentration of volatiles ? i.e. low density equals weak gravity.. Current theory suggests that India has floated through this gravity low. Has the history of Earth’s gravity been documented by tectonic development of the crust? Is the K crater gravity low the driving force for tectonics?
William Kersey
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