The Experts below are selected from a list of 99 Experts worldwide ranked by ideXlab platform
Russell B. Wynn - One of the best experts on this subject based on the ideXlab platform.
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Application of the principles of seismic geomorphology to continental-slope and base-of-slope systems: case studies from seafloor and near-seafloor analogues
SEPM Special Publication No. 99, 2012Co-Authors: Bradford E Prather, Mark E Deptuck, Berend Van Hoorn, David Mohrig, Russell B. WynnAbstract:The present-day continental slope offshore Brunei Darussalam (NW Borneo) displays several networks of submarine channels possessing planform attributes similar to those observed in better-studied river systems. We use shallow 3D seismic data to study one tributary network in detail. This network is located directly downslope from the shelf-edge Champion Delta and encompasses an area approximately 8 km by 24 km in the strike and dip directions. The channels in this network initiate 1–2 km down dip of the shelf edge and are not directly linked to a terrestrial river system. Mapping of shallow seismic horizons reveals that the tributary channel network is an aggradational feature constructed on top of a relatively smooth slide plane associated with a large mass-failure event. This observation highlights differences between network construction in submarine settings compared to terrestrial settings where tributary networks are net erosional features. The smooth slide plane provides us with the simplest possible initial condition for studying the deposit architecture of an aggradational submarine-channel network. An Isopach Map between the seafloor and the slide plane is used to unravel sedimentation trends, particularly relative rates of levee and overbank sedimentation as a function of channel relief, lateral distance from the nearest channel centerline, and distance from the shelf edge. We observe an anti-correlation between channel relief and deposit thickness, which suggests that the degree to which currents are confined within channels exerts a first-order control on local deposition rates. We also find that over 80% of the deposit volume associated with the aggradational network is within levees. Observations suggest that this channel network was constructed from turbidity currents that initiated at the shelf edge as sheet flows prior to transitioning down slope into weakly confined flows through the construction of aggradational channels. Thicknesses of channel-forming turbidity currents are estimated using the distance between channel heads and the ratio of channel to overbank deposit thickness. These two methods yield estimates for flow thicknesses that are between 1.1 and 3 times the mean relief of channels in the network.
Ralph B. Cantrell - One of the best experts on this subject based on the ideXlab platform.
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Davis Sand Lens, Hardin Field, Liberty County, Texas
2020Co-Authors: S. Russel Casey, Ralph B. CantrellAbstract:The Davis sand lens of the Hardin field is in the Eponides yeguaensis zone of the Yegua (upper Eocene) formation. The sand was first recognized as a separate sand in the Woodley Petroleum Company's Emma Davis well No. 1 where it was encountered from 7,511 to 7,525 feet below the surface. Two gas and distillate wells and one oil well are now producing from the sand. The bar is a separate and sealed reservoir. An Isopach Map of the interval containing the Davis lens shows a marked thickening within the area where the best development of the Davis sand is found. It discloses that the bar has a long axis of approximately 11,000 feet, an average width of approximately 1,250 feet and a total area of practically 320 acres. The contours of the Isopach Map are lines of sedimentation from which the section to be penetrated may be postulated in advance of the drill. The Davis "zone," wherein the lens is found, is composed of alternating sand, sandy shale, and shale and is arenaceous in character, indicating lagoonal or tidal-flat deposition. The Davis sand is composed of 98 per cent quartz; it is medium-grained in texture, whereas the typical Yegua sands are fine-grained. The Davis lens was laid down as a barrier beach or off-shore bar by a retreating Yegua sea.
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Davis Sand Lens, Hardin Field, Liberty County, Texas: ABSTRACT
AAPG Bulletin, 2020Co-Authors: S. Russell Casey, Ralph B. CantrellAbstract:The Davis sand lens of the Hardin field is a buried off-shore barrier (bar). It is in the upper Saline Bayou member of the Yegua (upper Eocene) formation. The sand was first recognized as a separate sand in the Woodley Petroleum Company's Emma Davis well No. 1; the sand was encountered at a depth of 7,511 to 7,525 feet. Two wells are now producing gas and distillate from this sand, and one well is producing 36° oil. It is a separate and closed reservoir. An Isopach Map of the interval containing the Davis lens shows a marked thickening within the area where the best development of the Davis sand is found. It discloses that the bar along its long axis is approximately 9,400 feet in length, and the width varies from approximately 300 feet to 1,200 feet. The total area covered by the lens is approximately 250 acres. The contours of the Isopach Map are lines of sedimentation from which the section to be penetrated may be postulated in advance of the drill. The Davis "zone," wherein the lens is found, is composed of alternating sand, sandy shale and shale, and is arenaceous in character indicating lagoonal or tidal-flat deposition. The main sand is a medium-grained quartz sand, containing few other minerals, as compared to the finer-grained, more mineralized sands of the Yegua formation. The lens was laid down as a barrier beach or off-shore bar by a retreating Yegua sea. End_of_Article - Last_Page 930------------
Jorge Rey Salgado - One of the best experts on this subject based on the ideXlab platform.
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Distribution and thickness of sedimentary facies in the coastal dune, beach and nearshore sedimentary system at Maspalomas, Canary Islands
Geo-Marine Letters, 2013Co-Authors: Angela Fontán Bouzas, Javier Alcántara-carrió, Isabel Montoya Montes, Andrés Barranco Ojeda, Silvia Albarracín, Jorge Rey Díaz De Rada, Jorge Rey SalgadoAbstract:Numerous studies have shown that most beaches and coastal dune systems of the world are currently eroding but very few have investigated the combined sediment budgets of subaerial and nearshore submarine systems. In the case of the dune field of the Maspalomas Natural Special Reserve (in the south of Gran Canaria), the adjacent Maspalomas and El Inglés beaches and the adjacent submarine platform, the sediment budgets have been severely affected by erosion over the past few decades. The objectives of this study were to investigate the availability of sand within the modern sedimentary system, including the coastal dunes, the beaches and the submerged shelf, but also to assess local sediment sinks. An Isopach Map generated on the basis of topo-bathymetric data and seismic-reflection profiles revealed that sediment thickness varies from 0–22 m in the study area. Expanses of relatively low sediment thickness were identified in the south-western sector of the coastal dune field along Maspalomas beach, and in the nearshore region to the south of this beach. These localized sediment-deficit areas earmark Maspalomas beach as the most vulnerable shore strip threatened by erosion. The shallow seismic data also revealed that the submarine platform south of Maspalomas represents a marine terrace cut into an ancient alluvial fan, thus documenting an influence of the geomorphological heritage on the present-day morphodynamics. A side-scan sonar mosaic of this nearshore platform enabled the delimitation of areas covered by rock, boulders and gravel, vegetated sand patches and a mobile sand facies, the latter including ripple and megaripple fields. The megaripple field in a valley close to the talus of the marine terrace has been identified as a major sediment sink of the Maspalomas sedimentary system. It is fed by south-westerly storm-wave events. The sediment deficit in the coastal dune field and along Maspalomas beach can therefore only be explained by a currently faster loss of sediment to an offshore sink than can be compensated by the supply of sand from outside the system.
Bradford E Prather - One of the best experts on this subject based on the ideXlab platform.
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Application of the principles of seismic geomorphology to continental-slope and base-of-slope systems: case studies from seafloor and near-seafloor analogues
SEPM Special Publication No. 99, 2012Co-Authors: Bradford E Prather, Mark E Deptuck, Berend Van Hoorn, David Mohrig, Russell B. WynnAbstract:The present-day continental slope offshore Brunei Darussalam (NW Borneo) displays several networks of submarine channels possessing planform attributes similar to those observed in better-studied river systems. We use shallow 3D seismic data to study one tributary network in detail. This network is located directly downslope from the shelf-edge Champion Delta and encompasses an area approximately 8 km by 24 km in the strike and dip directions. The channels in this network initiate 1–2 km down dip of the shelf edge and are not directly linked to a terrestrial river system. Mapping of shallow seismic horizons reveals that the tributary channel network is an aggradational feature constructed on top of a relatively smooth slide plane associated with a large mass-failure event. This observation highlights differences between network construction in submarine settings compared to terrestrial settings where tributary networks are net erosional features. The smooth slide plane provides us with the simplest possible initial condition for studying the deposit architecture of an aggradational submarine-channel network. An Isopach Map between the seafloor and the slide plane is used to unravel sedimentation trends, particularly relative rates of levee and overbank sedimentation as a function of channel relief, lateral distance from the nearest channel centerline, and distance from the shelf edge. We observe an anti-correlation between channel relief and deposit thickness, which suggests that the degree to which currents are confined within channels exerts a first-order control on local deposition rates. We also find that over 80% of the deposit volume associated with the aggradational network is within levees. Observations suggest that this channel network was constructed from turbidity currents that initiated at the shelf edge as sheet flows prior to transitioning down slope into weakly confined flows through the construction of aggradational channels. Thicknesses of channel-forming turbidity currents are estimated using the distance between channel heads and the ratio of channel to overbank deposit thickness. These two methods yield estimates for flow thicknesses that are between 1.1 and 3 times the mean relief of channels in the network.
Angela Fontán Bouzas - One of the best experts on this subject based on the ideXlab platform.
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Distribution and thickness of sedimentary facies in the coastal dune, beach and nearshore sedimentary system at Maspalomas, Canary Islands
Geo-Marine Letters, 2013Co-Authors: Angela Fontán Bouzas, Javier Alcántara-carrió, Isabel Montoya Montes, Andrés Barranco Ojeda, Silvia Albarracín, Jorge Rey Díaz De Rada, Jorge Rey SalgadoAbstract:Numerous studies have shown that most beaches and coastal dune systems of the world are currently eroding but very few have investigated the combined sediment budgets of subaerial and nearshore submarine systems. In the case of the dune field of the Maspalomas Natural Special Reserve (in the south of Gran Canaria), the adjacent Maspalomas and El Inglés beaches and the adjacent submarine platform, the sediment budgets have been severely affected by erosion over the past few decades. The objectives of this study were to investigate the availability of sand within the modern sedimentary system, including the coastal dunes, the beaches and the submerged shelf, but also to assess local sediment sinks. An Isopach Map generated on the basis of topo-bathymetric data and seismic-reflection profiles revealed that sediment thickness varies from 0–22 m in the study area. Expanses of relatively low sediment thickness were identified in the south-western sector of the coastal dune field along Maspalomas beach, and in the nearshore region to the south of this beach. These localized sediment-deficit areas earmark Maspalomas beach as the most vulnerable shore strip threatened by erosion. The shallow seismic data also revealed that the submarine platform south of Maspalomas represents a marine terrace cut into an ancient alluvial fan, thus documenting an influence of the geomorphological heritage on the present-day morphodynamics. A side-scan sonar mosaic of this nearshore platform enabled the delimitation of areas covered by rock, boulders and gravel, vegetated sand patches and a mobile sand facies, the latter including ripple and megaripple fields. The megaripple field in a valley close to the talus of the marine terrace has been identified as a major sediment sink of the Maspalomas sedimentary system. It is fed by south-westerly storm-wave events. The sediment deficit in the coastal dune field and along Maspalomas beach can therefore only be explained by a currently faster loss of sediment to an offshore sink than can be compensated by the supply of sand from outside the system.
