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The base of the gas hydrate stability zone (GHSZ) is a critical interface, providing a first-order estimate of gas hydrate distribution. Sensitivity to thermobaric conditions makes its prediction challenging particularly in the regions with dynamic pressure-temperature regime. In Green Canyon in the northern Gulf of Mexico (Block GC955), the seismically inferred base of the GHSZ is 450 meters (1476 ft) below the seafloor, which is 400 m (1312 ft) shallower than predicted by gas hydrate stability modeling using standard temperature and pressure gradient assumptions, and an assumption of structure I (99.9% methane gas) gas hydrate. We use 3D

Channel-levee systems are responsible for constructing deep sea fans, among the largest sedimentary deposits on Earth. Levee height plays a key role in defi ning the volume and texture of the material that is deposited in the bounding levees, and thus the morphology of submarine fans. Models of channel formation and evolution generally assume that the levees aggrade in response to the cumulative overspill of turbidity fl ows, and that their height is controlled by these fl ows. In contrast, we show that levee growth in the Ursa Basin (Gulf of Mexico) is limited by the mechanical strength of the levee, not the fl ow behavior. While many studies document sidewall failures in levee systems, our poro-mechanical model is the fi rst to demonstrate that collapse of levees is a large-scale, deep-seated process driven by the interaction of levee formation and high fl uid pressure. Rapid deposition of a regional sand unit induced large fl uid overpressure in the underlying mud, which preconditioned the system for levee failure, which then fed a large volume of sediment back into the channel-levee system. Long-lived levee failures continually reintroduced previously deposited levee material back into the channel system. This implies that a large volume of sediment is continuously recycled, which has not been previously understood. Turbidite fl ow models generally assume that fl ows progressively lose their fi ne-grained component due to levee overspill as they traverse the channel. In contrast, we show a mechanism by which fi ne-grained material can re-enter the system in large quantities, and this has signifi cant and broad importance for models of channel and fan evolution. We also show that that levee failure introduces signifi cant unconformities, in contrast with the common assumption that levees offer complete and high-resolution records of climate, tectonics, and sea level.