Boreholes, orebodies, and heat refraction : Implications for heat flow density studies and paleoclimatic reconstructions
Abstract
Although thermal conductivity in crustal rocks does not vary much, there may be . Because exceptions near some ore deposits boreholes that areused in heat flow density studies as well as in paleoclimatic reconstructions are generally drilled for mineral exploration, it is worth understanding the effects of heat refraction at depth, near these thermal conductors.At the surface, the constant temperature condition tends to smooth refraction effects related to narrow conductive bodies, whereas at depth, wherethis condition has less effect, lateral heat transfer could significantly distort the temperature field. When several boreholes are used to estimate the heat flow values, there the chances of a biased determination are small. On the other hand, when a single borehole is used, the heat flow estimate might be in error. Synthetic examples of thermal refraction show that perturbations can be recorded away from the conductor. Perturbations are shown to be higher above the inclined sides of the orebody. Examples of inversion of ground surface temperature history from synthetic temperature profiles disturbed by a thermal conductor show that heat refraction effects can also lead to apparent warming or cooling signatures depending on the position of the borehole.
Domains
Applied geology
Origin : Files produced by the author(s)