MapTool version 2 : user’s manual

MapTool is an interactive computer program for the display of common marine geophysical data. At present, the program displays isolines, color-filled contours, navigation tracklines, and navigated scalar values in a variety of styles. A variety of map projections are supported. This document describes the basic requirements for running the MapTool program, for creating various displays, and generating hard copy output. The supported data file formats are described. All of the options, displays, menus, and windows are documented.Funding was provided by the Office of Naval Research under Grant N00014-90-J-1621

Brazil Basin Tracer Release Experiment

The purpose of the Brazil Basin Tracer Release Experiment is to measure diapycnal (across isopycnal) mixing and epipycnal (along-isopycnal) mixing and stirring in the deep ocean. This cruise is the fourth in the overall experiment. In the first cruise in early 1996, 110 kg of sulfur hexafluoride (SF6) were released on an isopycnal surface near 4000 meters depth in the eastern part of the basin on the flanks of the Mid-Atlantic Ridge (MAR). The location of the release was near 21.7 S, 18.4 W. The release site was over a zonal valley that leads to the MAR and is about 5000 m deep. The isopycnal surface of the release was defined as the surface on which the potential density anomaly, referenced to 4000 dbar pressure, was 45.9408 kg/m3. The release streaks and results of initial sampling in 1996 are described in Polzin et al. [1997]

R. v. Powley: Building a Foundation for the Constitutional Recognition of Métis Aboriginal Rights

In R. v. Powley, the Supreme Court has provided a firm foundation upon which to build a Métis section 35 Aboriginal rights jurisprudence. This paper outlines the essential elements of the decision, emphasizing the fact that the Powley test modifies the Van der Peet approach to Aboriginal rights in one crucial respect: Instead of the Aboriginal community having to come into existence at or near the point of European contact, the Métis community may come into existence at a later date but before effective European control. The paper discusses other approaches to Métis aboriginal rights that were raised before the Court but were not discussed in its decision. The paper also canvasses aspects of the decision that are likely to generate future litigation, especially the identification of and membership in historic Métis communities. It concludes by noting that the decision should be seen as a sound first step in an ongoing process of defining Métis Aboriginal rights

NECOR SEA BEAM DATA COLLECTION AND PROCESSING DEVELOPMENT.

Sea Beam multibeam seafloor mapping systems were introduced to the oceanographic community little more than a decade ago. These systems have profoundly changed the way many oceanographic surveys are conducted as well as the quality of the final results. Several characteristics of these systems have made these changes possible. This paper details the capabilities which have been developed for NECOR data acquisition and processing of Sea Beam multibeam bathymetric data and associated navigation and geophysical data

Development and evolution of detachment faulting along 50 km of the Mid-Atlantic Ridge near 16.5°N

A multifaceted study of the slow spreading Mid-Atlantic Ridge (MAR) at 16.5°N provides new insights into detachment faulting and its evolution through time. The survey included regional multibeam bathymetry mapping, high-resolution mapping using AUV Sentry, seafloor imaging using the TowCam system, and an extensive rock-dredging program. At different times, detachment faulting was active along ∼50 km of the western flank of the study area, and may have dominated spreading on that flank for the last 5 Ma. Detachment morphologies vary and include a classic corrugated massif, noncorrugated massifs, and back-tilted ridges marking detachment breakaways. High-resolution Sentry data reveal a new detachment morphology; a low-angle, irregular surface in the regional bathymetry is shown to be a finely corrugated detachment surface (corrugation wavelength of only tens of meters and relief of just a few meters). Multiscale corrugations are observed 2–3 km from the detachment breakaway suggesting that they formed in the brittle layer, perhaps by anastomosing faults. The thin wedge of hanging wall lavas that covers a low-angle (6°) detachment footwall near its termination are intensely faulted and fissured; this deformation may be enhanced by the low angle of the emerging footwall. Active detachment faulting currently is limited to the western side of the rift valley. Nonetheless, detachment fault morphologies also are present over a large portion of the eastern flank on crust >2 Ma, indicating that within the last 5 Ma parts of the ridge axis have experienced periods of two-sided detachment faulting