High-temperature creep of olivine single crystals, 1, mechanical results for buffered samples

Experimental deformation of olivine single crystals at mantle pressures and temperatures

“…We only reported in Figure 4 the data we obtained at T=1673 K, for which stress values are better constrained (see Table 1 and Section 2) and are comparable to σ values reported by Bai et al (1991). Error rectangles around high-P experimental points reported in Figure 4 were calculated taking into account our experimental uncertainties on P, T, and ε , as reported in Table 1.…”

“…In order to obtain a-sample and c-sample complete rheological laws, we compared our data with those obtained at room pressure by Bai et al (1991). These authors show plots of logB 10 B ( ε ) versus P/RT, respectively for a-samples and c-samples.…”

“…These authors show plots of logB 10 B ( ε ) versus P/RT, respectively for a-samples and c-samples. In Figure 4, high-P data points are from the present study (numbers correspond the "#" column in Table 1), while room-P data (P~0) are calculated using our experimental T-σ-fOB 2 B values in the rheological laws proposed by Bai et al (1991). These authors identified several mechanisms responsible for olivine dislocation creep, depending on the activated slip system(s) (i.e., the compression direction) and experimental T-σ-fOB 2 B conditions.…”

“…They summarized their extensive data set with constitutive equations proper to each investigated compression direction, which combine contributions of two or three mechanisms operating sequentially or concurrently (see their Table 4). Since no data are available on the effect of P on the creep mechanisms identified by Bai et al (1991), M a n u s c r i p t we assumed for further calculation that all mechanisms related to a given slip systemi.e., either [100](010) or [001](010) in the case of a-samples or c-samples -shared the same dependence on P, i.e., have the same activation volumes V* in the corresponding rheological laws. This single V* translates into a single V* in the general constitutive equations including the P dependence (such as Equation (3)), and can be deduced from ln( ε ) versus (-P/RT ) plots.…”

“…Olivine LPO depend on the dominant dislocation slip systems activated during deformation (e.g., Karato (1987), and Kaminski and Ribe (2001)). Olivine slip system relative activities have thus been extensively studied, although mostly at relatively low hydrostatic pressure (P < 3 GPa) because of experimental limitations (Raleigh, 1968;Carter and Avé Lallemant, 1970;Phakey et al 1972;Kohlstedt and Goetze, 1974;Poirier, 1975;Kohlstedt et al, 1976Kohlstedt et al, , 1980Durham et al, , 1979Gueguen, 1979;Jaoul et al, 1979;Darot and Gueguen, 1981;Gueguen and Darot, 1982;Mackwell and Kohlstedt, 1985;Ricoult and Kohlstedt, 1985;Bai et al, 1991;Kohlstedt, 1992a, 1992b;Jin et al, 1994). At P < 3 GPa, mantle temperature (T > 1173 K), moderate differential stress and in dry condition, olivine [100] (010) Yet, recent deformation experiments carried out at high pressure on forsterite (Fo100) crystals (Couvy et al, 2004;Raterron et al, 2007), as well as theoretical studies based on first-principle calculations (Durinck et al, 2005;Durinck et al, 2007), show that olivine c-slip may dominate deformation in the P and T ranges of the deep upper A c c e p t e d M a n u s c r i p t 3 mantle.…”