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Numerical modeling of an impact-induced hydrothermal system at the Sudbury crater

Summary: Numerical modeling of an impact-induced hydrothermal system
at the Sudbury crater
Oleg Abramov and David A. Kring
Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA
Received 11 November 2003; revised 11 May 2004; accepted 17 June 2004; published 20 October 2004.
[1] Large impact events, like the one that formed the Sudbury crater in Ontario, Canada,
at 1.85 Ga, significantly increase the temperature of target rocks. The heat sources
generated by such an impact event can drive the circulation of groundwater, establishing a
hydrothermal system. We report on the results of numerical modeling of postimpact
cooling with and without the presence of water at the Sudbury crater. A hydrothermal
system is initiated in the annular trough between the peak ring and final crater rim, perhaps
venting through faults that bound blocks of the crust in the modification zone of the crater.
Although circulation through the overlying breccias may occur in the center of the crater,
the central melt sheet is initially impermeable to circulating fluids. By $105
years the
central melt sheet crystallizes and partially cools, allowing fluids to flow through it. Host
rock permeability is the main factor affecting fluid circulation and lifetimes of
hydrothermal systems. High permeabilities lead to a rapid system cooling, while lower
permeabilities allow a steady transport of hot fluids to the surface, resulting in high surface
temperatures for longer periods of time than cooling by conduction alone. The simulations


Source: Abramov, Oleg - Lunar and Planetary Institute


Collections: Geosciences; Physics