Quartz rheology constrained from constant-load experiments: Consequences for the strength of the continental crust

The mechanical properties of quartz are fundamental to control the plastic behaviour continental crust. Our understanding rheology is still limited in following respects: i) large variability flow law parameters earlier literature (stress exponent n = 4 ≤ 2 and activation energy Q 120 242 kJ/mol), ii) difficulty identify rate-limiting deformation mechanism, if several mechanisms operating simultaneously. These two issues connected cannot be resolved separately. present study has carried out constant-load experiments constrain quartz. A new generation hydraulically-driven Griggs-type apparatus been employed, resulting reproducible data, even at very low strain rates (10−8 to10−9 s−1; so far, closest natural ones). Furthermore, Q-value constant load can estimated without prior knowledge value. (= 2) values 110 kJ/mol) fairly low. We calculated an A-value 1.56 × 10−9 /MPa/sec. Microstructural analysis suggests that bulk sample our achieved by crystal plasticity, i.e., dislocation glide with minor recovery sub-grain rotation, accompanied grain boundary migration. Micro-cracking helps nucleate grains. It inferred incompatibilities induced accommodated processes, including dissolution-precipitation creep sliding. processes responsible for n-value lower than expected (n≥ 3). consistently estimate (especially stresses) excellent agreement documented case studies predicts a rapid drop strength quartz-bearing rocks crust below depth ∼10 km or temperature ∼300 °C higher.