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Regeneration of ancient impact-scars affect regional geology worldwide
  • John M. Saul
John M. Saul
Independent researcher

Corresponding Author:[email protected]

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The entire Earth was bombarded c.4100-3800 Ma, establishing initial conditions for all later regional geology. Deep impact-fractures have been regenerated upward from the brittle-ductile boundary by the action of convection, outgassing, circulating fluids, the twice-daily earth-tide, and earthquakes throughout all subsequent time. In consequence, many such fractures have never entirely healed or been eliminated. The two-dimensional map-outlines and circular curvature of numerous three-dimensional “craterform” scars can be readily seen, once the observer has been alerted to the possibility of their existence. Many other Hadean/EoArchean impact-scars are covered over, as is the case at present, at any given time. These impact features have been regenerated “cold” from below and are fundamentally different from astroblemes, as presently defined, whose rocks were directly subjected to the high temperatures and pressures that accompany hypervelocity extra-terrestrial impacts. Melt rock filled the largest impact sites and produced cratons, with overflow producing platforms. In later times, craton rims buckled during collisions, producing orogens. Crater rims originally entered the Earth at near-vertical angles but after sufficient net erosion following Snowball Earth episodes, deeply exposed rim-zones entered the Earth at lower angles, thereby facilitating deep subduction. Renewed activation of earliest Precambrian fractures from below is a recurrent geological phenomenon. The largest scar, approximately 5350 kilometers in diameter, encompasses Asia and has Novaya Zemlya as part of an outer rim. Our vision has greatly improved since 1788 when James Hutton could find “no vestige of a beginning".
13 Dec 2022Submitted to ESS Open Archive
13 Dec 2022Published in ESS Open Archive