نتایج جستجو برای: oceanic
تعداد نتایج: 14084 فیلتر نتایج به سال:
Love and Rayleigh wave phase velocities increase systematically with increasing age of oceanic lithosphere up to 150 Ma. The rates of increase differ between oceans and vary for different age intervals. Modeling of lithospheric age–phase velocity relations indicates that the high velocity seismic lid thickens and the velocities in the sub-lithospheric low velocity Ž . zone LVZ increase with age...
Flat slab subduction has been attributed to various causes including mantle wedge dynamics, overriding by the upper plate, age of the subducting plate, and subduction of anomalously thick oceanic crust. One often favored explanation for flat slabs is the subduction of buoyant features on the oceanic plate in the form of an aseismic-ridge or oceanic plateau. We show through plate tectonic recons...
[1] High-pressure assemblages of subducted oceanic crust are denser than the normal upper mantle but less dense than the uppermost lower mantle. Thus subducted oceanic crust may accumulate at the base of the upper mantle. Direct observational evidence for this hypothesis, however, remains elusive. We present an analysis of a negativepolarity shear wave converted from compressional wave at a sei...
To determine whether loggerhead turtles (Caretta caretta) nesting in southeastern USA exhibit polymorphic foraging strategies, we evaluated skin samples for stable isotopes of carbon (dC) and nitrogen (dN) from 310 loggerheads from four locations on the east coast of Florida and epibionts from 48 loggerheads. We found a dichotomy between a depleted dC cluster and an enriched dC cluster. Epibion...
The diversification of Cheirolophus in Macaronesian archipelagos constitutes a paradigmatic example of radiation on oceanic islands. Phylogenetic and molecular dating analyses indicate an extraordinarily fast process, showing one of the highest speciation rates ever found on plants from oceanic islands. Such radiation has been recently studied employing phylogeographic, population genetic and m...
Phytoplankton Distribution in Relation to Environmental Drivers on the North West European Shelf Sea
The edge of the North West European Shelf (NWES) is characterised by a steep continental slope and a northward flowing slope current. These topographic/hydrographic features separate oceanic water and shelf water masses hence potentially separate phytoplankton communities. The slope current may facilitate the advective transport of phytoplankton, with mixing at the shelf edge supporting nutrien...
BACKGROUND The Janzen-Connell model states that plant-specific natural enemies may have a disproportionately large negative effect on progeny close to maternal trees. The majority of experimental and theoretical studies addressing the Janzen-Connell model have explored how it can explain existing patterns of species diversity in tropical mainland areas. Very few studies have investigated how th...
Oceanic internal waves play an important role in fishing activities and the safety of oil drilling platforms, as well as the navy’s antisubmarine warfare (ASW) and the safety of submarines. Due to its characteristics of relatively all weather capability, Synthetic Aperture Radar (SAR) images became popular in observing the appearance of oceanic internal waves recently. The purpose of this study...
Since the transition from terrestrial to marine environments poses strong osmoregulatory and energetic challenges, temporal and spatial fluctuations in oceanic salinity might influence salt and water balance (and hence, body condition) in marine tetrapods. We assessed the effects of salinity on three species of sea snakes studied by mark-recapture in coral-reef habitats in the Neo-Caledonian La...
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