Deep Sea Research (1953)最新文献

During the voyage of the Soviet Marine Antarctic Expedition on the Ob in 1955–1957, much new bottom sediment material was obtained in the Indian Ocean sector of the Antarctic and the southern Indian Ocean. The first cores as long as 16 m in this general area were taken, as well was many more up to 4 to 5 m long. Although detailed studies have not yet been completed, it is nevertheless possible to make a preliminary report on the development and properties of the main types of sediments and the rate of sedimentation at present in this part of the Antarctic. There are also some data on the thickness of ‘iceberg’ and diatom sediments.

The Melanesian Border Plateau covers an area 1000 by 200 miles along the north-eastern edge of Melanesia, facing the Central Pacific Basin, with an average depth of 1500 fm (2700 m). It trends E-W, but is broken up into a series of narrow ridges and troughs en échelon trending NW-SE, each approximately 250 miles long and 100 miles from ridge crest to crest. The troughs rarely exceed 2200 fm (4000 m) in depth. Some are closed basins and others open out in a funnel shape, sloping gradually down into the Central Pacific Basin (2700 fm or 5000 m). Although the Border Plateau is bounded by the ‘Andesite Line’ there is an anomalous absence of any belt of deep trenches on the Basin margin. The échelon ridges of the Plateau are mostly less than 1000 fm (1800 m) deep. They are capped by a few small volcanic islands and a large number of slightly submerged (10–15 fm or 18–27 m) atolls of dead, ‘drowned’ corals. Alexa Bank is a characteristic example. The cause of coral death is a mystery; vulcanism and foul upwelling are possible explanations.

The colonization of the abyssal zone by animals has extended over a very long geological time. The recent deep-sea fauna contains species which immigrated into the abyssal zone at different periods.

It is impossible to agree with Bruun that owing to a sharp decrease of the temperature of bottom waters during the late Tertiary the ancient deep-water fauna died out and that the abyssal zone was repopulated by young Quaternary forms. Since the determinations of paleotemperatures on which this concept is based were obtained by using shallow-water rather than deep-water Foraminifera such a conclusion seems questionable. It is further contradicted by the existence in the abyssal zone of many undoubtedly ancient elements (2 species of Neopilina, Spirula, Pogonophora etc.) and by the absence of a true deep-water fauna in deep basins, which were formed during the Quaternary (Japan, Mediterranean and Red seas).

The computations of Menzies and Imbrie, which led these authors to the concept of a relatively young deep-water fauna are likewise far from convincing. The groups selected for analysis are not characteristic of the deep-sea fauna; they include only about 11 per cent of the species recorded from depths exceeding 3000 m. The dominant groups of the deep-water fauna, rich both in number of species and in biomass, are not preserved in fossil condition and were not taken into account by Menzies and Imbrie.

An analysis of the systematic position and pattern of vertical distribution of many important groups of deep sea animals permits us to distinguish among them ancient and young settlers of great depths. Approximate counts show that the percentage of primitive archaic forms in the abyssal fauna is far higher than in the fauna of the shelf, thus providing evidence of the greater antiquity of the abyssal fauna.

A number of free instrument vehicles have been designed and tested. These are simple, reliable, inexpensive devices that transport recording instruments or sampling equipment to the deep-sea bottom, or to intermediate depth, and return them to the surface. Vehicles are provided with radar reflectors and other location devices. In the first tests the vehicles bore fish traps and were successfully operated to 2,000 fathoms. Other instruments designed to make use of the free vehicle's unique capabilities are under development.

Two sets of drogues were placed approximately normal to the usual flow and followed for one and three days respectively. The first set, which extended thirty miles offshore, drifted south-eastward. The second set, which extended from thirty to seventy miles offshore, also moved south-eastward but with considerable variation in speed and direction along the line. In the latter set two rapidly moving streams appeared with a body of slower water between.

Tabular masses, largely phillipsite coated with manganese oxide, are abundant on the floor of the eastern Pacific. They appear to be remnants of layers of volcanic ash derived in large part from volcanoes within the basin. Some of the ash may correlate with the Worzel ash off Central and South America.

Various types of deep-sea winches have been used aboard oceanographic vessels. Their design has been limited to use of electrically powered drums and winding engines utilizing rather elaborate speed regulation and braking devices, and of diesel-driven winches utilizing multi-ratio geared transmissions for hauling and the engine itself for braking. These winches have been able to lower cable at rates of 50–80 fathoms (100–150 m) per minute and to hoist at rates of 25–40 fathoms (50–75 m) per minute.

The recently redesigned heavy trawl winch being used aboard the R.V. Vema of the Lamont Geological Observatory (Columbia University) is described herein. During the lowering operation a Parkersburg Hydrotarder is used for braking. It provides a varying positive braking action functioning as a water brake which converts the mechanical energy into heat. For raising, a diesel engine drives the winch through a torque converter. This permits full utilization of the developed power of the engine, a method of exerting a fixed tension when pulling the apparatus out of the bottom, and eliminates the necessity of shifting gears and engine lugging (running over-loaded at slow speed) as with geared transmissions. With the new equipment, cable lowering speeds of 120 fathoms (220 m) per minute and raising cable speeds of 50–70 fathoms (100–130 m) per minute are possible.

By summing the absorbency of phytoplankton pigments with that of pure water, the absorption of the blue portion of the spectrum is markedly increased. As the concentration of phytoplankton pigments increases, the diminution of blue light gradually shifts the wave length of maximum transmission toward the green. At the concentration of phytoplankton pigments normally found in the open ocean, the red chlorophyll band has little influence on water colour.

Inadequancies in present methods for detection of absorption bands in natural waters is attributed to wide band widths of filters used in submarine photometers. Poor spectral curves applicable to colour analysis in particulate systems are obtained by conventional spectrophotometric techniques because a large portion of the scattered light never reaches the photo-detector. Improvements for spectral analysis are suggested.