The Influence of Elevated Temperature on Time-Dependent Compaction Creep in Bleursville Sandstone

The inelastic compaction of sandstone in the upper crust typically occurs at depths where temperatures range from approximately (Formula presented.) to (Formula presented.). Previous experimental studies have shown that even this modest temperature increase can reduce the yield stress required to initiate inelastic compaction, and can also enhance time-dependent deformation within the brittle regime. However, the influence of these realistic crustal temperatures on sandstone compaction over longer time scales has not yet been systematically explored. We performed triaxial creep experiments on Bleursville sandstone at an effective pressure of 100 MPa and at temperatures of either room temperature, (Formula presented.), or (Formula presented.). Our results show that the differential stress required to initiate creep is up to 20 MPa lower at (Formula presented.) than at room temperature. In addition, at any given differential stress, axial creep strain rates were more than an order of magnitude higher at (Formula presented.).We also find that the typical decrease in strain rate with increasing axial strain was less pronounced at higher temperatures. This indicates that the stress sensitivity of the creep rate is reduced as temperature increases. Finally, we extrapolated our experimentally derived creep laws for Bleursville sandstone and combined them with theoretical estimates of pressure-solution rates at lower stresses and strain rates. This shows that time-dependent deformation at room temperature is dominated by subcritical cracking across all conditions examined. In contrast, at (Formula presented.), Bleursville sandstone may begin to deform by pressure solution once strain rates fall below approximately (Formula presented.) (Formula presented.).