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Abstract

The contribution to the earth’s surface of certain amounts of cosmic material including meteorites, fine particulate meteoritic substances and cosmic dust was first postulated and recognized long ago. However, it was only the beginning of space exploration by rockets and satellites that provided the opportunity for more accurate qualitative and quantitative estimations of the cosmic sediment source.

So far, no large meteorite fragments on the ocean bottom have been found. The bulk of cosmic material are black magnetic iron spherules (cryoconite) and glassy tektites, which were only recently discovered in sediments.

Magnetic spherules are formed during melting and scattering of meteorites as they pass through the dense atmospheric layers. They are found both at the surface of large meteorites and near meteor craters. Meteoric dust which settled during the fall of the Sikhota-Alin meteorite had the form of spherules 200 to 1 µ in diameter (Kirova, 1961). Similar spherules were collected near Meteor Crater in Arizona (Zaslow and Kellog, 1961).

Iron meteorites constitute only 6 to 7 percent of the total number of the meteorites studied. Most meteorites are stone and iron-stone meteorites, or chondrites. No fine particulate matter of corresponding mineralogy has been found in oceanic sediments.

The extraterrestrial origin of cryoconite from Greenland ice was first suggested in 1870. At the same time the challenger expedition found a certain amount of such magnetic balls in the deep sea sediments it collected (Murray and Renard, 1891). These materials, disregarded for almost 100 years, have aroused

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