The time-dependent strain relaxation of Algerie granite

In situ measurements of both instantaneous and time-dependent relaxation of the Algerie granite at a quarry near East Otis, Massachusetts, indicate that the orientation of instantaneous maximum expansion is 30° different from the orientation of the time-dependent maximum expansion. Based on comparison of these measurements with the regional contemporary tectonic stress and with measurements of petrofabrics of the sampled unit, it appears that the instantaneous relaxation orientation (ENE) is controlled by contemporary tectonic stress, whereas the time-dependent relaxation orientation is controlled by healed microcracks in the granite. The curves for time-dependent relaxation best fit a power-law function of time with the exponent varying between 0.211 and 0.872.