The Experts below are selected from a list of 162 Experts worldwide ranked by ideXlab platform
R. A. Portaro - One of the best experts on this subject based on the ideXlab platform.
-
a morphometric analysis of the Submarine volcanic Ridge south east of pico island azores
Journal of Volcanology and Geothermal Research, 2006Co-Authors: R. C. Stretch, N.c. Mitchell, R. A. PortaroAbstract:A region of crustal extension, the Azores Plateau contains excellent examples of Submarine volcanic edifices constructed over a wide range of ocean depths along the Pico Ridge. Using bathymetric data and Towed Ocean Bottom Instrument (TOBI) side-scan sonar imagery, we measured the dimensions (diameter, height, slopes), shape, and texture of these volcanic edifices to further understanding of the geometric development of a Submarine Ridge. Our analysis and interpretation of the measurement and texture data suggest the following: (1) the various edifice types do not correlate with depth ranges, suggesting that ambient water pressure is not a controlling factor in configuration of the edifice formed; (2) the cones have a mean diameter of 948 m, height of 152 m, and slope of 15.6°, and are peaked rather than displaying flat-topped summits; and (3) while hummocky-textured cones also occur, smooth-textured cones predominate. The cones seem to develop preferentially outwards, then upwards, with only a weak correlation between diameter and height, suggesting that the cone population does not evolve self-similarly. Although smooth and hummocky cone populations are not statistically different in mean slope angle and eruption depth, the hummocky cones have a significantly greater mean diameter than the smooth cones. We suggest that hummocky-textured cones (probably involving eruption of pillow lavas) are formed after voluminous smooth textured flows. Nearest-neighbour analysis suggests that Submarine cones are distributed randomly whereas subaerial cones are not. We interpret this finding to suggest subaerial cones being masked by over-covering flows, which tend to flow further than Submarine lava flows. Furthermore, the spatial distribution of cones away from the Ridge centre is not easily explained by a magma supply fed via lava tubes from central eruptions, because of a lack of consistent pathway down gradient. Fissure vents seem to be important in determining construction of the Ridge and result in linear arrangements of edifices and cone elongation, consistent with the regional tectonic trend of this part of the Azores Plateau. Cones form as each feeding dyke intrusion cools and the eruption becomes localized along point-source vents along the fissure. The Ridge seems to be predominantly formed from fissure eruptions along the Ridge axis, with subordinate transport of lava down its flanks.
-
A morphometric analysis of the Submarine volcanic Ridge south-east of Pico Island, Azores
Journal of Volcanology and Geothermal Research, 2006Co-Authors: R. C. Stretch, N.c. Mitchell, R. A. PortaroAbstract:A region of crustal extension, the Azores Plateau contains excellent examples of Submarine volcanic edifices constructed over a wide range of ocean depths along the Pico Ridge. Using bathymetric data and Towed Ocean Bottom Instrument (TOBI) side-scan sonar imagery, we measured the dimensions (diameter, height, slopes), shape, and texture of these volcanic edifices to further understanding of the geometric development of a Submarine Ridge. Our analysis and interpretation of the measurement and texture data suggest the following: (1) the various edifice types do not correlate with depth ranges, suggesting that ambient water pressure is not a controlling factor in configuration of the edifice formed; (2) the cones have a mean diameter of 948 m, height of 152 m, and slope of 15.6°, and are peaked rather than displaying flat-topped summits; and (3) while hummocky-textured cones also occur, smooth-textured cones predominate. The cones seem to develop preferentially outwards, then upwards, with only a weak correlation between diameter and height, suggesting that the cone population does not evolve self-similarly. Although smooth and hummocky cone populations are not statistically different in mean slope angle and eruption depth, the hummocky cones have a significantly greater mean diameter than the smooth cones. We suggest that hummocky-textured cones (probably involving eruption of pillow lavas) are formed after voluminous smooth textured flows. Nearest-neighbour analysis suggests that Submarine cones are distributed randomly whereas subaerial cones are not. We interpret this finding to suggest subaerial cones being masked by over-covering flows, which tend to flow further than Submarine lava flows. Furthermore, the spatial distribution of cones away from the Ridge centre is not easily explained by a magma supply fed via lava tubes from central eruptions, because of a lack of consistent pathway down gradient. Fissure vents seem to be important in determining construction of the Ridge and result in linear arrangements of edifices and cone elongation, consistent with the regional tectonic trend of this part of the Azores Plateau. Cones form as each feeding dyke intrusion cools and the eruption becomes localized along point-source vents along the fissure. The Ridge seems to be predominantly formed from fissure eruptions along the Ridge axis, with subordinate transport of lava down its flanks. © 2006 Elsevier B.V. All rights reserved.
R. C. Stretch - One of the best experts on this subject based on the ideXlab platform.
-
a morphometric analysis of the Submarine volcanic Ridge south east of pico island azores
Journal of Volcanology and Geothermal Research, 2006Co-Authors: R. C. Stretch, N.c. Mitchell, R. A. PortaroAbstract:A region of crustal extension, the Azores Plateau contains excellent examples of Submarine volcanic edifices constructed over a wide range of ocean depths along the Pico Ridge. Using bathymetric data and Towed Ocean Bottom Instrument (TOBI) side-scan sonar imagery, we measured the dimensions (diameter, height, slopes), shape, and texture of these volcanic edifices to further understanding of the geometric development of a Submarine Ridge. Our analysis and interpretation of the measurement and texture data suggest the following: (1) the various edifice types do not correlate with depth ranges, suggesting that ambient water pressure is not a controlling factor in configuration of the edifice formed; (2) the cones have a mean diameter of 948 m, height of 152 m, and slope of 15.6°, and are peaked rather than displaying flat-topped summits; and (3) while hummocky-textured cones also occur, smooth-textured cones predominate. The cones seem to develop preferentially outwards, then upwards, with only a weak correlation between diameter and height, suggesting that the cone population does not evolve self-similarly. Although smooth and hummocky cone populations are not statistically different in mean slope angle and eruption depth, the hummocky cones have a significantly greater mean diameter than the smooth cones. We suggest that hummocky-textured cones (probably involving eruption of pillow lavas) are formed after voluminous smooth textured flows. Nearest-neighbour analysis suggests that Submarine cones are distributed randomly whereas subaerial cones are not. We interpret this finding to suggest subaerial cones being masked by over-covering flows, which tend to flow further than Submarine lava flows. Furthermore, the spatial distribution of cones away from the Ridge centre is not easily explained by a magma supply fed via lava tubes from central eruptions, because of a lack of consistent pathway down gradient. Fissure vents seem to be important in determining construction of the Ridge and result in linear arrangements of edifices and cone elongation, consistent with the regional tectonic trend of this part of the Azores Plateau. Cones form as each feeding dyke intrusion cools and the eruption becomes localized along point-source vents along the fissure. The Ridge seems to be predominantly formed from fissure eruptions along the Ridge axis, with subordinate transport of lava down its flanks.
-
A morphometric analysis of the Submarine volcanic Ridge south-east of Pico Island, Azores
Journal of Volcanology and Geothermal Research, 2006Co-Authors: R. C. Stretch, N.c. Mitchell, R. A. PortaroAbstract:A region of crustal extension, the Azores Plateau contains excellent examples of Submarine volcanic edifices constructed over a wide range of ocean depths along the Pico Ridge. Using bathymetric data and Towed Ocean Bottom Instrument (TOBI) side-scan sonar imagery, we measured the dimensions (diameter, height, slopes), shape, and texture of these volcanic edifices to further understanding of the geometric development of a Submarine Ridge. Our analysis and interpretation of the measurement and texture data suggest the following: (1) the various edifice types do not correlate with depth ranges, suggesting that ambient water pressure is not a controlling factor in configuration of the edifice formed; (2) the cones have a mean diameter of 948 m, height of 152 m, and slope of 15.6°, and are peaked rather than displaying flat-topped summits; and (3) while hummocky-textured cones also occur, smooth-textured cones predominate. The cones seem to develop preferentially outwards, then upwards, with only a weak correlation between diameter and height, suggesting that the cone population does not evolve self-similarly. Although smooth and hummocky cone populations are not statistically different in mean slope angle and eruption depth, the hummocky cones have a significantly greater mean diameter than the smooth cones. We suggest that hummocky-textured cones (probably involving eruption of pillow lavas) are formed after voluminous smooth textured flows. Nearest-neighbour analysis suggests that Submarine cones are distributed randomly whereas subaerial cones are not. We interpret this finding to suggest subaerial cones being masked by over-covering flows, which tend to flow further than Submarine lava flows. Furthermore, the spatial distribution of cones away from the Ridge centre is not easily explained by a magma supply fed via lava tubes from central eruptions, because of a lack of consistent pathway down gradient. Fissure vents seem to be important in determining construction of the Ridge and result in linear arrangements of edifices and cone elongation, consistent with the regional tectonic trend of this part of the Azores Plateau. Cones form as each feeding dyke intrusion cools and the eruption becomes localized along point-source vents along the fissure. The Ridge seems to be predominantly formed from fissure eruptions along the Ridge axis, with subordinate transport of lava down its flanks. © 2006 Elsevier B.V. All rights reserved.
Mark D Kurz - One of the best experts on this subject based on the ideXlab platform.
-
Genovesa Submarine Ridge: A manifestation of plume‐Ridge interaction in the northern Galápagos Islands
Geochemistry Geophysics Geosystems, 2003Co-Authors: K S Harpp, Daniel J Fornari, Dennis Geist, Mark D KurzAbstract:[1] Despite its circular coastline and calderas, Genovesa Island, located between the central Galapagos Platform and the Galapagos Spreading Center, is crosscut by both eruptive and noneruptive fissures trending NE-SW. The 075° bearing of the fissures parallels that of Genovesa Ridge, a 55 km long volcanic rift zone that is the most prominent Submarine rift in the Galapagos and constitutes the majority of the volume of the Genovesa magmatic complex. Genovesa Ridge was the focus of detailed multibeam and side-scan sonar surveys during the Revelle/Drift04 cruise in 2001. The Ridge consists of three left stepping en echelon segments; the abundances of lava flows, volcanic terraces, and eruptive cones are all consistent with constructive volcanic processes. The nonlinear arrangement of eruptive vents and the Ridge's en echelon structure indicate that it did not form over a single dike. Major and trace element compositions of Genovesa Ridge glasses are modeled by fractional crystallization along the same liquid line of descent as the island lavas, but some of the glasses exhibit higher Mg # than material sampled from the island. Most of the Submarine and the subaerial lavas have accumulated plagioclase. Incompatible trace element abundances of dredged Genovesa Ridge rocks are lower than the island's lavas, but ratios of the elements are similar in the two settings, which suggests that the island and Ridge lavas are derived from nearly identical mantle sources. Glass inclusions in plagioclase phenocrysts from the Ridge are compositionally diverse, with both higher and lower MgO than the matrix glass, indicative of homogenization at shallow levels. The structural and geochemical observations are best reconciled if Genovesa Ridge did not form in response to injection of magma laterally from a hot spot-supplied central volcano, like Kilauea's Puna Ridge. Instead, Genovesa Ridge and its western extension are the result of passive upwelling directed by far-field tectonic stresses that are generated by tension across the 91°W transform. The proximity of the plume causes magmatism in the extensional zones where it would not ordinarily occur.
-
genovesa Submarine Ridge a manifestation of plume Ridge interaction in the northern galapagos islands
Geochemistry Geophysics Geosystems, 2003Co-Authors: K S Harpp, Daniel J Fornari, Dennis Geist, Mark D KurzAbstract:[1] Despite its circular coastline and calderas, Genovesa Island, located between the central Galapagos Platform and the Galapagos Spreading Center, is crosscut by both eruptive and noneruptive fissures trending NE-SW. The 075° bearing of the fissures parallels that of Genovesa Ridge, a 55 km long volcanic rift zone that is the most prominent Submarine rift in the Galapagos and constitutes the majority of the volume of the Genovesa magmatic complex. Genovesa Ridge was the focus of detailed multibeam and side-scan sonar surveys during the Revelle/Drift04 cruise in 2001. The Ridge consists of three left stepping en echelon segments; the abundances of lava flows, volcanic terraces, and eruptive cones are all consistent with constructive volcanic processes. The nonlinear arrangement of eruptive vents and the Ridge's en echelon structure indicate that it did not form over a single dike. Major and trace element compositions of Genovesa Ridge glasses are modeled by fractional crystallization along the same liquid line of descent as the island lavas, but some of the glasses exhibit higher Mg # than material sampled from the island. Most of the Submarine and the subaerial lavas have accumulated plagioclase. Incompatible trace element abundances of dredged Genovesa Ridge rocks are lower than the island's lavas, but ratios of the elements are similar in the two settings, which suggests that the island and Ridge lavas are derived from nearly identical mantle sources. Glass inclusions in plagioclase phenocrysts from the Ridge are compositionally diverse, with both higher and lower MgO than the matrix glass, indicative of homogenization at shallow levels. The structural and geochemical observations are best reconciled if Genovesa Ridge did not form in response to injection of magma laterally from a hot spot-supplied central volcano, like Kilauea's Puna Ridge. Instead, Genovesa Ridge and its western extension are the result of passive upwelling directed by far-field tectonic stresses that are generated by tension across the 91°W transform. The proximity of the plume causes magmatism in the extensional zones where it would not ordinarily occur.
N.c. Mitchell - One of the best experts on this subject based on the ideXlab platform.
-
a morphometric analysis of the Submarine volcanic Ridge south east of pico island azores
Journal of Volcanology and Geothermal Research, 2006Co-Authors: R. C. Stretch, N.c. Mitchell, R. A. PortaroAbstract:A region of crustal extension, the Azores Plateau contains excellent examples of Submarine volcanic edifices constructed over a wide range of ocean depths along the Pico Ridge. Using bathymetric data and Towed Ocean Bottom Instrument (TOBI) side-scan sonar imagery, we measured the dimensions (diameter, height, slopes), shape, and texture of these volcanic edifices to further understanding of the geometric development of a Submarine Ridge. Our analysis and interpretation of the measurement and texture data suggest the following: (1) the various edifice types do not correlate with depth ranges, suggesting that ambient water pressure is not a controlling factor in configuration of the edifice formed; (2) the cones have a mean diameter of 948 m, height of 152 m, and slope of 15.6°, and are peaked rather than displaying flat-topped summits; and (3) while hummocky-textured cones also occur, smooth-textured cones predominate. The cones seem to develop preferentially outwards, then upwards, with only a weak correlation between diameter and height, suggesting that the cone population does not evolve self-similarly. Although smooth and hummocky cone populations are not statistically different in mean slope angle and eruption depth, the hummocky cones have a significantly greater mean diameter than the smooth cones. We suggest that hummocky-textured cones (probably involving eruption of pillow lavas) are formed after voluminous smooth textured flows. Nearest-neighbour analysis suggests that Submarine cones are distributed randomly whereas subaerial cones are not. We interpret this finding to suggest subaerial cones being masked by over-covering flows, which tend to flow further than Submarine lava flows. Furthermore, the spatial distribution of cones away from the Ridge centre is not easily explained by a magma supply fed via lava tubes from central eruptions, because of a lack of consistent pathway down gradient. Fissure vents seem to be important in determining construction of the Ridge and result in linear arrangements of edifices and cone elongation, consistent with the regional tectonic trend of this part of the Azores Plateau. Cones form as each feeding dyke intrusion cools and the eruption becomes localized along point-source vents along the fissure. The Ridge seems to be predominantly formed from fissure eruptions along the Ridge axis, with subordinate transport of lava down its flanks.
-
A morphometric analysis of the Submarine volcanic Ridge south-east of Pico Island, Azores
Journal of Volcanology and Geothermal Research, 2006Co-Authors: R. C. Stretch, N.c. Mitchell, R. A. PortaroAbstract:A region of crustal extension, the Azores Plateau contains excellent examples of Submarine volcanic edifices constructed over a wide range of ocean depths along the Pico Ridge. Using bathymetric data and Towed Ocean Bottom Instrument (TOBI) side-scan sonar imagery, we measured the dimensions (diameter, height, slopes), shape, and texture of these volcanic edifices to further understanding of the geometric development of a Submarine Ridge. Our analysis and interpretation of the measurement and texture data suggest the following: (1) the various edifice types do not correlate with depth ranges, suggesting that ambient water pressure is not a controlling factor in configuration of the edifice formed; (2) the cones have a mean diameter of 948 m, height of 152 m, and slope of 15.6°, and are peaked rather than displaying flat-topped summits; and (3) while hummocky-textured cones also occur, smooth-textured cones predominate. The cones seem to develop preferentially outwards, then upwards, with only a weak correlation between diameter and height, suggesting that the cone population does not evolve self-similarly. Although smooth and hummocky cone populations are not statistically different in mean slope angle and eruption depth, the hummocky cones have a significantly greater mean diameter than the smooth cones. We suggest that hummocky-textured cones (probably involving eruption of pillow lavas) are formed after voluminous smooth textured flows. Nearest-neighbour analysis suggests that Submarine cones are distributed randomly whereas subaerial cones are not. We interpret this finding to suggest subaerial cones being masked by over-covering flows, which tend to flow further than Submarine lava flows. Furthermore, the spatial distribution of cones away from the Ridge centre is not easily explained by a magma supply fed via lava tubes from central eruptions, because of a lack of consistent pathway down gradient. Fissure vents seem to be important in determining construction of the Ridge and result in linear arrangements of edifices and cone elongation, consistent with the regional tectonic trend of this part of the Azores Plateau. Cones form as each feeding dyke intrusion cools and the eruption becomes localized along point-source vents along the fissure. The Ridge seems to be predominantly formed from fissure eruptions along the Ridge axis, with subordinate transport of lava down its flanks. © 2006 Elsevier B.V. All rights reserved.
K S Harpp - One of the best experts on this subject based on the ideXlab platform.
-
Genovesa Submarine Ridge: A manifestation of plume‐Ridge interaction in the northern Galápagos Islands
Geochemistry Geophysics Geosystems, 2003Co-Authors: K S Harpp, Daniel J Fornari, Dennis Geist, Mark D KurzAbstract:[1] Despite its circular coastline and calderas, Genovesa Island, located between the central Galapagos Platform and the Galapagos Spreading Center, is crosscut by both eruptive and noneruptive fissures trending NE-SW. The 075° bearing of the fissures parallels that of Genovesa Ridge, a 55 km long volcanic rift zone that is the most prominent Submarine rift in the Galapagos and constitutes the majority of the volume of the Genovesa magmatic complex. Genovesa Ridge was the focus of detailed multibeam and side-scan sonar surveys during the Revelle/Drift04 cruise in 2001. The Ridge consists of three left stepping en echelon segments; the abundances of lava flows, volcanic terraces, and eruptive cones are all consistent with constructive volcanic processes. The nonlinear arrangement of eruptive vents and the Ridge's en echelon structure indicate that it did not form over a single dike. Major and trace element compositions of Genovesa Ridge glasses are modeled by fractional crystallization along the same liquid line of descent as the island lavas, but some of the glasses exhibit higher Mg # than material sampled from the island. Most of the Submarine and the subaerial lavas have accumulated plagioclase. Incompatible trace element abundances of dredged Genovesa Ridge rocks are lower than the island's lavas, but ratios of the elements are similar in the two settings, which suggests that the island and Ridge lavas are derived from nearly identical mantle sources. Glass inclusions in plagioclase phenocrysts from the Ridge are compositionally diverse, with both higher and lower MgO than the matrix glass, indicative of homogenization at shallow levels. The structural and geochemical observations are best reconciled if Genovesa Ridge did not form in response to injection of magma laterally from a hot spot-supplied central volcano, like Kilauea's Puna Ridge. Instead, Genovesa Ridge and its western extension are the result of passive upwelling directed by far-field tectonic stresses that are generated by tension across the 91°W transform. The proximity of the plume causes magmatism in the extensional zones where it would not ordinarily occur.
-
genovesa Submarine Ridge a manifestation of plume Ridge interaction in the northern galapagos islands
Geochemistry Geophysics Geosystems, 2003Co-Authors: K S Harpp, Daniel J Fornari, Dennis Geist, Mark D KurzAbstract:[1] Despite its circular coastline and calderas, Genovesa Island, located between the central Galapagos Platform and the Galapagos Spreading Center, is crosscut by both eruptive and noneruptive fissures trending NE-SW. The 075° bearing of the fissures parallels that of Genovesa Ridge, a 55 km long volcanic rift zone that is the most prominent Submarine rift in the Galapagos and constitutes the majority of the volume of the Genovesa magmatic complex. Genovesa Ridge was the focus of detailed multibeam and side-scan sonar surveys during the Revelle/Drift04 cruise in 2001. The Ridge consists of three left stepping en echelon segments; the abundances of lava flows, volcanic terraces, and eruptive cones are all consistent with constructive volcanic processes. The nonlinear arrangement of eruptive vents and the Ridge's en echelon structure indicate that it did not form over a single dike. Major and trace element compositions of Genovesa Ridge glasses are modeled by fractional crystallization along the same liquid line of descent as the island lavas, but some of the glasses exhibit higher Mg # than material sampled from the island. Most of the Submarine and the subaerial lavas have accumulated plagioclase. Incompatible trace element abundances of dredged Genovesa Ridge rocks are lower than the island's lavas, but ratios of the elements are similar in the two settings, which suggests that the island and Ridge lavas are derived from nearly identical mantle sources. Glass inclusions in plagioclase phenocrysts from the Ridge are compositionally diverse, with both higher and lower MgO than the matrix glass, indicative of homogenization at shallow levels. The structural and geochemical observations are best reconciled if Genovesa Ridge did not form in response to injection of magma laterally from a hot spot-supplied central volcano, like Kilauea's Puna Ridge. Instead, Genovesa Ridge and its western extension are the result of passive upwelling directed by far-field tectonic stresses that are generated by tension across the 91°W transform. The proximity of the plume causes magmatism in the extensional zones where it would not ordinarily occur.
