Topic
Oceanic zone
About: Oceanic zone is a research topic. Over the lifetime, 52 publications have been published within this topic receiving 1851 citations.
Papers published on a yearly basis
Papers
TL;DR: In this paper, a thermal model of the Cascadia subduction margin is used to estimate the temperature at the top of the oceanic crust at the deformation front and the transition stable sliding zone with a temperature of about 450°C.
Abstract: Constraints on the seismogenic portion of the subduction thrust zone along the Cascadia margin are provided by the thermal regime. The zone of stick-slip “locked” behavior where earthquakes can nucleate may be limited downdip by a temperature of about 350°C, and the transition stable sliding zone into which coseismic displacement can extend by a temperature of approximately 450°C. The seaward limit of the stick-slip zone may be associated with the dehydration of stable sliding clays at 100 to 150°C and dissipation of high pore pressures in the area of the deformation front. Temperatures on the thrust have been estimated by numerically modelling the thermal regimes along three profiles crossing the margin with constraints provided by surface heat flow and detailed structural information, particularly at southern Vancouver Island. The models that best fit the heat flow data have negligible shear strain heating. The Cascadia subduction margin is unusually hot as a consequence of the very young plate age and the thick insulating sediment section on the incoming plate; the temperature at the top of the oceanic crust at the deformation front is about 250°C. As a result, the modelled zone of stick-slip seismogenic behaviour is restricted to a narrow zone beneath the continental slope and outer shelf, with the transition zone extending to the inner shelf. The seismogenic zone is wider off the Olympic Peninsula compared to off southern Vancouver Island because of the much shallower thrust dip angle and the slightly older incoming plate. The profile off Oregon is found to have intermediate width zones. An important assumption, well justified only off southern Vancouver Island, is that the thrust detachment is located at the top of the downgoing oceanic crust. The same modelling technique shows that more typical subduction zones with older incoming oceanic lithosphere such as central Chile have thermally restricted seismogenic zones that are much wider, commonly extending well beneath the coast. Support for the position of the Cascadia locked zone from the thermal results is provided by a comparison of the horizontal and vertical interseismic deformation predicted by simple dislocation models with the observed rates from tide gauge and geodetic surveys on adjacent coastal regions. The general agreement indicates that any seismic “locked zone” must be located offshore where the subduction thrust fault is less than about 20 km deep and where the contact is between the oceanic crust and the accreted sedimentary wedge, not between the oceanic and continental crusts. The restriction to an offshore zone provides an important limit to the maximum magnitude and to the ground motion and seismic hazard from subduction megathrust earthquakes in southwestern British Columbia, Washington, and Oregon.
587 citations
TL;DR: In this paper, the results of fifteen Expanding Spread Profiles (ESP's), and a seismic wide angle reflection-refraction Une, performed during March-April 1986, in the Gulf of Suez and the Egyptian part of the northern Red Sea area (north of 25°N), were reported.
125 citations
TL;DR: Rapid turnover of dissolved free amino acids (DFAA) by bacterioplankton in the Gulf of Mexico was observed with techniques designed to eliminate contamination of samples with trace metals and organic compounds, and rates are faster than those in parallel samples measured by traditional techniques.
Abstract: Rapid turnover of dissolved free amino acids (DFAA) by bacterioplankton in the Gulf of Mexico was observed with techniques designed to eliminate contamination of samples with trace metals and organic compounds. The mean turnover rate of DFAA, based on incorporation of 0.5 nM additions of a mixture of amino acids, was 4.9-d-l for high productivity neritic environments and 1.3.d-’ for low productivity oceanic environments. These rates are faster than those in parallel samples measured by traditional techniques and are consistently faster than previously reported values. Data for multiple level (0.01-7 nM) additions of the mixed substrate were in accord with the Michaelis-Menten enzyme kinetics model. Kinetic parameters derived from this model (V,,,, K, + S,, and R), bacterial cell numbers, and V,,,/cell were highest at photic depths of the neritic zone, intermediate at photic depths of the oceanic zone, and lowest at aphotic depths of the oceanic zone. Estimates of secondary productivity by bacterioplankton (based on V,,,,,) on an equal water volume basis were 6.6 + 1.5% (+-SE, y1 = 5) of the light-saturated primary productivity at the maximum productivity depth. Estimated turnover time of the bacterioplankton community ranged from 2.4 d at 5 m at the highest productivity station to 130 days at 250 m at the lowest productivity
100 citations
TL;DR: In this paper, the authors used generalized dissimilarity modeling to model species assemblages in the Indian sector of the Southern Ocean by combining with Geographic Information Systems (GIS) for creating models between communities and environmental factors.
Abstract: The Southern Ocean is delimited by major frontal zones which influence pelagic life at the spatial macroscale. There is a sharp ecological segregation of pelagic fish that inhabit this ocean with some families living in the neritic zone and others in the oceanic zone. The neritic zone is dominated by fish of the Notothenioid suborder. In the oceanic zone, mesopelagic species are dominated by myctophids. Their spatial distribution is highly influenced by meso- or sub-mesoscale oceanographic features. Myctophid presence/absence records from historical surveys and from the Census of Antarctic Marine Life were used to model species assemblages in the Indian sector of the Southern Ocean by using generalized dissimilarity modeling. This statistical technique is data-driven and is used in conjunction with Geographic Information Systems for creating models between communities and environmental factors. Application of these models in large unsurveyed areas is possible and helps in delineating regions of potential similar assemblages. This will allow us to move from the bioregionalization of the Southern Ocean based on only abiotic factors and chlorophyll, to its ecoregionalization by adding species assemblages.
88 citations
TL;DR: In this article, the trophic and metabolic characteristics of mesozooplankton for the oceanic, upwelling and eddy system of the Canary Current System are reviewed.
81 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 1 |
| 2020 | 3 |
| 2019 | 1 |
| 2018 | 2 |
| 2017 | 3 |
| 2016 | 1 |