doi:10.2204/iodp.pr.308.2005
Figure F46. A. Site U1324. Temperature gradient = ~18°C/km (red), overpressure ratio (
*) = ~0.6, overpressure = blue. B. Site U1322. Temperature gradient = ~26°C/km (red), overpressure ratio (*) = ~0.6, overpressure = blue. C. Conceptual model of flow in Ursa Basin. The constant overpressure gradient at both sites implies that flow is driven upward at approximately the same rate in both locations within the mudrock above the Blue Unit. However, because Site U1324 is considerably deeper than Site U1322, the pressures at the top of the Blue Unit must be greater at Site U1324 (~3.1 MPA) than at Site U1322 (~1.3 MPa). We infer that the Blue Unit is composed of multiple hydraulically isolated sand bodies. Flow is transported laterally from Site U1324 to U1322 only within the deepest sand body because the overlying sand bodies have been truncated by the Ursa channel-levee system. To the right of the levee, flow is upward through both sands and shales. The elevated temperature gradient at Site U1322 may record the lateral flow within the Blue Unit.
