Iron-cemented sediment on lower continental slope off Cape Hatteras

The textural, mineralogical, compositional and paleontological characteristics of an iron-cemented allochthonous sediment slab recovered from a zone of slumping between water depths of 2,100 and 2,350 m on the lower continental slope off Cape Hatteras are summarized. Results support interpretation of the sediment slab as the oxidized equivalent of pyrite-cemented Pleistocene to Recent sediment, an uncommon form of lithification in deep sea sediments. We propose that exposure of such slumped sediment slabs to seawater has produced an alteration sequence from pyrite-cement to iron oxide-cement. These observations extend the range of pyrite-cemented sediment initially reported from water depths between 4,770 and 4,950 m on the lower continental rise off Cape Hatteras.     

Blennies and Endolithic Bivalves: Differential Utilization of Shelter in Adriatic Blenniidae (Pisces: Teleostei)

Abstract. The utilization of empty holes of endolithic bivalves (Gttsirocluwnu dubui by Bknnius chdmcitinus , and Litliophaga lithophaga by all other species) as shelters by egg-guarding males of nine species of Adriatic Blenniidae is compared. A wide spectrum of entrance sizes to these "standardized" shelters is used with the most frequent utilization ranging between 1(H) and 275 mm^: (11.2–18.8mm mean entrance diameters). As a trend within and between species, larger fish utilize holes with disproportionately wider entrances. There arc significant differences between species in the means of "fit" of the heads within the entrances: the heads of B. dulmaibuts, B. canaeve, B. adrialicus , and B. zvonimiri "fit" tightly into their entrances whereas the two large species, B.puvo and B. tentacularis , which only facultatively use holes of boring mussels for breeding, arc found in holes with "oversized" entrances. In most species mean shelter depth approximates mean body length. Species which tightly "fit" their entrances tend to stay longer when disturbed mechanically or chemically compared to those with only a loose "fit". The ecological and evolutionary significance of these patterns is discussed.     

Marine resource development in Belize

Marine resource development has increased its importance for most of the world's coastal nations. This is especially true for developing coastal states that are now looking to the sea to help provide new sources of food and income. Belize is an example of such a developing state with certain features that make it particularly interesting for study.     

A pendulum inclinometer for use with small deep-submersibles

The authors developed a pendulum inclinometer suitable for use with small deep-submersibles or surface craft. The instrument uses a relatively short heavy pendulum and a viscous damping system for minimizing the effects of unwanted oscillatory motion. The pendulum relative motion is transmitted to the dial pointer through a flexible cord. The mechanism is designed so that the inclinometer gives a direct reading of the tangent of the angle of inclination. Adjustments are provided for levelling the instrument and for setting the dial to zero. Upper and lower clamping devices protect the pendulum suspension from damage during transit. The inclinometer has been used successfully in recent inclining experiments for the small research submarine Alvin.     

Constructing a 3D structural block diagram of the Central Basin in Marmara Sea by means of bathymetric and seismic data

In this study we made a comparative interpretation of multibeam bathymetric and seismic reflection data with different resolutions and penetration properties collected in the Central Basin of the Marmara Sea. Our main objectives were (i) to investigate and compare the active tectonic deformation observed on the sea bottom and within the uppermost sedimentary layers to that of the deep-seated deformation within the limits of resolution and penetration of the available geophysical data and (ii) to build a three-dimensional (3D) block diagram of the active tectonic and buried features by means of a sliced mapping technique. In this approach, we produced slice maps of the active and buried structural features at selected depths and then combined them to form a 3D structural block diagram. Motivation for our work was to produce a 3D structural diagram to derive a more detailed image of the structural features in the Central Basin where there is no available 3D seismic data. The observations from the bathymetry and seismic data and developed 3D diagram support the presence of a through-going strike-slip fault that forms a rotational depression zone against a right-stepping strike-slip faulting causing a pull-apart basin in the Central Depression zone.     

Editorial: Naming of undersea features

Editorial: Naming of undersea features     

Observations of the Temperature and Humidity Structure Parameter Over Heterogeneous Terrain by Airborne Measurements During the LITFASS-2003 Campaign

We used numerical simulations to investigate the general relationship between urban morphology and the intensity of wind gusts in built-up areas at the pedestrian level. The simulated urban boundary layer developed over a 19.2 km (length) \(\times \) 4.8 km (width) \(\times \) 1.0 km (height) simulation domain, with 2-m resolution in all directions, to explicitly resolve the detailed shapes of buildings and the flow at the pedestrian level. This complex computation was accomplished using the lattice Boltzmann method and by implementing a large-eddy simulation model. To generalize the results, a new parameter that expresses the intensity of gusts (the gust index, \({\tilde{U}}_{ max})\) was defined as the local maximum wind speed divided by the freestream velocity. In addition, this parameter was decomposed into the mean wind-speed ratio, \({\tilde{U}} \) and turbulent gust ratio, \({\tilde{U}}^{{\prime }}\) to evaluate the qualities of gusts. These parameters were useful for quantitatively comparing the gust intensities within urban canopies at different locations or even among different experiments. In addition, the entire horizontal domain was subdivided into homogeneous square patches, in which both the simulated gust parameters and the morphological characteristics of building geometries were averaged. This procedure masked the detailed structure of individual buildings but retained the bulk characteristics of the urban morphology. At the pedestrian level, the gust index decreased with increasing building cover. Compared to \({\tilde{U}} \), the quantity \({\tilde{U}}^{{\prime }}\) notably contributed to the index throughout the range of plan area index \((\lambda _p)\) values. The dependences of all normalized wind-speed ratios transiently changed at \(\lambda _p =~0.28\). In cases where \(\lambda _p < 0.28, {\tilde{U}} \) decreased with increasing \(\lambda _p \), although \({\tilde{U}}^{{\prime }}\) was almost constant. In cases where \(\lambda _p > 0.28, {\tilde{U}}\) was almost constant and \({\tilde{U}}^{{\prime }}\) decreased with increasing \(\lambda _p \). This was explained by the change in flow regimes within the building canyon. At a higher elevation above the canopy layer, \(\lambda _p \) becomes less relevant to normalized wind-speed ratios, and instead the aerodynamic roughness length became important.     

Automation and evaluation of graduated dot maps

Dot mapping is a traditional method for visualizing quantitative data, but current automated dot mapping techniques are limited. The most common automated method places dots pseudo-randomly within enumeration areas, which can result in overlapping dots and very dense dot clusters for areas with large values. These issues affect users’ ability to estimate values. Graduated dot maps use dots with different sizes that represent different values. With graduated dot maps the number of dots on a map is smaller, reducing the likelihood of overlapping dots. This research introduces an automated method of generating graduated dot maps that arranges dots with blue-noise patterns to avoid overlap and uses clustering algorithms to replace densely packed dots with those of larger sizes. A user study comparing graduated dot maps, pseudo-random dot maps, blue-noise dot maps and proportional circle maps with almost 300 participants was conducted. Results indicate that map users can more accurately extract values from graduated dot maps than from the other map types. This is likely due to the smaller number of dots per enumeration area in graduated dot maps. Map users also appear to prefer graduated dot maps over other map types.     

The search and investigation of faint blue star-like objects in the small GRB error boxes

A central part of the GRB 790613 field is investigated, which contains about 1/3 of the area of 99% confidence of the GRB localization. Up to V 25 no blue optical counterparts were found. This can be interpreted as the absence in the field of single compact objects of the neutron star type as a possible potential source of -burst, up to a distance of 30 pc.