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Sverre Planke - One of the best experts on this subject based on the ideXlab platform.
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a diverted submarine channel of early cretaceous age revealed by high resolution seismic data sw barents sea
Marine and Petroleum Geology, 2018Co-Authors: Romain Corseri, Thea Sveva Faleide, Jan Inge Faleide, Ivar Midtkandal, Christopher Saebo Serck, Mikal Trulsvik, Sverre PlankeAbstract:Abstract Mud-rich prograding sediment lobes make for most of the Barremian – Albian stratigraphic record in the SW Barents Sea. Submarine canyons and channels potentially represent key components of sediment transport from shelf to basin floor but Geological evidences are lacking. We present high-resolution seismic data and scrutinize an elongated, ∼150-km long bright seismic amplitude and resistive anomaly located alongslope of a NW-sourced Barremian delta in the SW Barents Sea. Seismic interpretation is performed on a comprehensive database comprising 3D/2D high-resolution P-Cable and conventional seismic data, tied to three exploration wells to provide age-control on key horizons. Our results highlight that the elongated geophysical anomaly originates from a soft layer deposited over a harder, erosional surface. The erosive morphology displays three narrow, V-shaped incisions to the NE of the Hoop area which develop into a single, ∼6 km-wide, U-shaped channel towards the transition to the Fingerdjupet Subbasin. The Geological Feature is named Ceres and interpreted as a submarine channel carved in Aptian, a period of marked sea level rise and sediment starvation in the Hoop area. An evolutionary model of a diverted submarine channel is proposed where a flooded delta lobe acted as a topographic barrier, funneling bottom currents and thereby carving an alongslope, possibly contouritic channel. This is the first documented case of a submarine channel pathway – delta lobe interaction on the Norwegian continental shelf. To account for the geophysical expression of Ceres, two competing explanations are discussed: (1) hydrocarbon-bearing sands, and (2) organic-rich source rock. Both scenarios have important implications for petroleum prospectivity: a faulted stratigraphic trap holding large volumes of hydrocarbons or alternatively the channel-controlled distribution of mature Aptian source rock in the SW Barents Sea.
Romain Corseri - One of the best experts on this subject based on the ideXlab platform.
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a diverted submarine channel of early cretaceous age revealed by high resolution seismic data sw barents sea
Marine and Petroleum Geology, 2018Co-Authors: Romain Corseri, Thea Sveva Faleide, Jan Inge Faleide, Ivar Midtkandal, Christopher Saebo Serck, Mikal Trulsvik, Sverre PlankeAbstract:Abstract Mud-rich prograding sediment lobes make for most of the Barremian – Albian stratigraphic record in the SW Barents Sea. Submarine canyons and channels potentially represent key components of sediment transport from shelf to basin floor but Geological evidences are lacking. We present high-resolution seismic data and scrutinize an elongated, ∼150-km long bright seismic amplitude and resistive anomaly located alongslope of a NW-sourced Barremian delta in the SW Barents Sea. Seismic interpretation is performed on a comprehensive database comprising 3D/2D high-resolution P-Cable and conventional seismic data, tied to three exploration wells to provide age-control on key horizons. Our results highlight that the elongated geophysical anomaly originates from a soft layer deposited over a harder, erosional surface. The erosive morphology displays three narrow, V-shaped incisions to the NE of the Hoop area which develop into a single, ∼6 km-wide, U-shaped channel towards the transition to the Fingerdjupet Subbasin. The Geological Feature is named Ceres and interpreted as a submarine channel carved in Aptian, a period of marked sea level rise and sediment starvation in the Hoop area. An evolutionary model of a diverted submarine channel is proposed where a flooded delta lobe acted as a topographic barrier, funneling bottom currents and thereby carving an alongslope, possibly contouritic channel. This is the first documented case of a submarine channel pathway – delta lobe interaction on the Norwegian continental shelf. To account for the geophysical expression of Ceres, two competing explanations are discussed: (1) hydrocarbon-bearing sands, and (2) organic-rich source rock. Both scenarios have important implications for petroleum prospectivity: a faulted stratigraphic trap holding large volumes of hydrocarbons or alternatively the channel-controlled distribution of mature Aptian source rock in the SW Barents Sea.
Norman H Sleep - One of the best experts on this subject based on the ideXlab platform.
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shallow sedimentary rock as a fragile Geological Feature effects of clay content and hydrology on frictional strength
Bulletin of the Seismological Society of America, 2016Co-Authors: Norman H SleepAbstract:Strong long‐period (∼3 s) seismic waves impose dynamic strains on the shallow subsurface. The dynamic strain is the dynamic velocity divided by the phase velocity of the waves. The dynamic stress is the strain times the shear modulus. A testable hypothesis is that the shear modulus of the rock self‐organizes so that the rock barely fails in friction with typical imposed dynamic strains. The predicted value of stiffness divided by depth is then independent of depth for constant rock density and constant coefficient of friction with the water table at the surface. Predicted stiffness divided depth deviates from constancy for finite‐water‐table depth. Prior laboratory studies indicate that the coefficient of friction is lower in clay‐rich rocks than in clay‐free rocks. These effects provide appraisal of the concept in which hydrology and lithology are constrained. Four boreholes near Parkfield, California, qualitatively exhibit the predicted effects. There is some indication of the predicted effect of water‐table depth within accumulating sediments penetrated by borehole McGlincy (MGCY) in the Santa Clara Valley of California, but the effect of clay is not well resolved, due to a dearth of clay‐rich beds.
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ambient tectonic stress as fragile Geological Feature
Geochemistry Geophysics Geosystems, 2014Co-Authors: Norman H SleepAbstract:Strong seismic waves produce frictional failure within shallow pervasively cracked rocks. Distributed failure preferentially relaxes ambient tectonic stresses, providing a fragility measure of past strong shaking. Relaxation of the regional fault-normal compression appears to have occurred within granite from 768 m down to ∼1000–1600 m depth at the Pilot Hole near Parkfield, California. Subsequent movements on the main fault have imposed strike-slip stress within the relaxed region. Peak ground velocities of ∼2 m s−1 are inferred for infrequent (few 1000 yr recurrence) past earthquakes from stress relaxation within the granite and from the variation of S wave velocity with depth in the overlying sandstone. Conversely, frequent strong shaking in slowly deforming regions relaxes shallow ambient tectonic stress. This situation is expected beneath Whittier Narrows, where strong Love waves from numerous San Andreas events repeatedly produced nonlinear behavior.
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seismically damaged regolith as self organized fragile Geological Feature
Geochemistry Geophysics Geosystems, 2011Co-Authors: Norman H SleepAbstract:[1] The S-wave velocity in the shallow subsurface within seismically active regions self-organizes so that typical strong dynamic shear stresses marginally exceed the Coulomb elastic limit. The dynamic velocity from major strike-slip faults yields simple dimensional relations. The near-field velocity pulse is essentially a Love wave. The dynamic shear strain is the ratio of the measured particle velocity over the deep S-wave velocity. The shallow dynamic shear stress is this quantity times the local shear modulus. The dynamic shear traction on fault parallel vertical planes is finite at the free surface. Coulomb failure occurs on favorably oriented fractures and internally in intact rock. I obtain the equilibrium shear modulus by starting a sequence of earthquakes with intact stiff rock extending all the way to the surface. The imposed dynamic shear strain in stiff rock causes Coulomb failure at shallow depths and leaves cracks in it wake. Cracked rock is more compliant than the original intact rock. Cracked rock is also weaker in friction, but shear modulus changes have a larger effect. Each subsequent event causes additional shallow cracking until the rock becomes compliant enough that it just reaches Coulomb failure over a shallow depth range of tens to hundreds of meters. Further events maintain the material at the shear modulus as a function where it just fails. The formalism provided in the paper yields reasonable representation of the S-wave velocity in exhumed sediments near Cajon Pass and the San Fernando Valley of California. A general conclusion is that shallow rocks in seismically active areas just become nonlinear during typical shaking. This process causes transient changes in S-wave velocity, but not strong nonlinear attenuation of seismic waves. Wave amplitudes significantly larger than typical ones would strongly attenuate and strongly damage the rock.
Mikal Trulsvik - One of the best experts on this subject based on the ideXlab platform.
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a diverted submarine channel of early cretaceous age revealed by high resolution seismic data sw barents sea
Marine and Petroleum Geology, 2018Co-Authors: Romain Corseri, Thea Sveva Faleide, Jan Inge Faleide, Ivar Midtkandal, Christopher Saebo Serck, Mikal Trulsvik, Sverre PlankeAbstract:Abstract Mud-rich prograding sediment lobes make for most of the Barremian – Albian stratigraphic record in the SW Barents Sea. Submarine canyons and channels potentially represent key components of sediment transport from shelf to basin floor but Geological evidences are lacking. We present high-resolution seismic data and scrutinize an elongated, ∼150-km long bright seismic amplitude and resistive anomaly located alongslope of a NW-sourced Barremian delta in the SW Barents Sea. Seismic interpretation is performed on a comprehensive database comprising 3D/2D high-resolution P-Cable and conventional seismic data, tied to three exploration wells to provide age-control on key horizons. Our results highlight that the elongated geophysical anomaly originates from a soft layer deposited over a harder, erosional surface. The erosive morphology displays three narrow, V-shaped incisions to the NE of the Hoop area which develop into a single, ∼6 km-wide, U-shaped channel towards the transition to the Fingerdjupet Subbasin. The Geological Feature is named Ceres and interpreted as a submarine channel carved in Aptian, a period of marked sea level rise and sediment starvation in the Hoop area. An evolutionary model of a diverted submarine channel is proposed where a flooded delta lobe acted as a topographic barrier, funneling bottom currents and thereby carving an alongslope, possibly contouritic channel. This is the first documented case of a submarine channel pathway – delta lobe interaction on the Norwegian continental shelf. To account for the geophysical expression of Ceres, two competing explanations are discussed: (1) hydrocarbon-bearing sands, and (2) organic-rich source rock. Both scenarios have important implications for petroleum prospectivity: a faulted stratigraphic trap holding large volumes of hydrocarbons or alternatively the channel-controlled distribution of mature Aptian source rock in the SW Barents Sea.
Thea Sveva Faleide - One of the best experts on this subject based on the ideXlab platform.
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a diverted submarine channel of early cretaceous age revealed by high resolution seismic data sw barents sea
Marine and Petroleum Geology, 2018Co-Authors: Romain Corseri, Thea Sveva Faleide, Jan Inge Faleide, Ivar Midtkandal, Christopher Saebo Serck, Mikal Trulsvik, Sverre PlankeAbstract:Abstract Mud-rich prograding sediment lobes make for most of the Barremian – Albian stratigraphic record in the SW Barents Sea. Submarine canyons and channels potentially represent key components of sediment transport from shelf to basin floor but Geological evidences are lacking. We present high-resolution seismic data and scrutinize an elongated, ∼150-km long bright seismic amplitude and resistive anomaly located alongslope of a NW-sourced Barremian delta in the SW Barents Sea. Seismic interpretation is performed on a comprehensive database comprising 3D/2D high-resolution P-Cable and conventional seismic data, tied to three exploration wells to provide age-control on key horizons. Our results highlight that the elongated geophysical anomaly originates from a soft layer deposited over a harder, erosional surface. The erosive morphology displays three narrow, V-shaped incisions to the NE of the Hoop area which develop into a single, ∼6 km-wide, U-shaped channel towards the transition to the Fingerdjupet Subbasin. The Geological Feature is named Ceres and interpreted as a submarine channel carved in Aptian, a period of marked sea level rise and sediment starvation in the Hoop area. An evolutionary model of a diverted submarine channel is proposed where a flooded delta lobe acted as a topographic barrier, funneling bottom currents and thereby carving an alongslope, possibly contouritic channel. This is the first documented case of a submarine channel pathway – delta lobe interaction on the Norwegian continental shelf. To account for the geophysical expression of Ceres, two competing explanations are discussed: (1) hydrocarbon-bearing sands, and (2) organic-rich source rock. Both scenarios have important implications for petroleum prospectivity: a faulted stratigraphic trap holding large volumes of hydrocarbons or alternatively the channel-controlled distribution of mature Aptian source rock in the SW Barents Sea.