Figure 2.7



Figure 2.7A Figure 2.7B Figure 2.7C

Crustal strength as a function of depth. The brittle part is computed from the Ranalli and Yin (1990) formulation using µ= 0.75, So = 10 MPa, = 2.6 gcm-3 and =0.0 (dry) and 0.9. The ductile part is computed using equation 2.17, with rheological parameters given in the text, a strain rate of 10-16 s-1, and three geotherms: A) Minimum 90% ; B) Average; C) Maximum 90%. The rocks used are: Adirondack Granulites (AG);wet Orthopyroxenite (wO); Pikwitonei Granulite (PG); wet Websterite (wW); and wet Clinopyroxenite (wC). Rocks that do not appear in the ductile part of the diagrams have a creep strength higher than 10000 MPa. MaxS placed at 200 MPa indicates the maximum crustal stress difference discussed in the text and interpreted from Figure 2.3.