Sample records for australites
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International Nuclear Information System (INIS)
Davis, J.
1981-01-01
Clues as to the possible origin of tektites are found by studying the chemical composition, sites where they are found, and shapes. An important chemical fact of tektites is that they are extremel dry. Tektites lie in four major areas and in three isolated regions. They are distributed as if they fell from the skies. By studying the flanged shapes of the australites, it was concluded that their shape was due to a fast, hot trip through the atmosphere. Tektites show no cosmic ray tracks which implies their space exposure time was short. This rules out the possibility that they are a form of meteorite with these clues in mind, four theories on their possible origin are discussed in this paper. The theories are: (1) terrestial impact by meteorite or comet; (2) lunar impact; (3) terrestial volcanoes; and (4) lunar volcanoes. This article rules out the first three theories for reasons which are given and leans toward the fourth theory as the most probable of the four
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OKeefe, J. A.
1960-01-01
Tektites are probably extraterrestrial, rather than the result of heating some terrestrial materials, because they are a chemically homogeneous group with definite peculiarities (high silica, excess of alkaline earths over alkalis, excess of potash over soda, absence of water), and because some of them (the australites) appear to have undergone ablation in flight through the atmosphere. Since comparatively slow heating is required to explain the liquefaction of the tektite material, it is suggested that the tektites arrived along orbits which were nearly parallel to the surface of the earth, and which resulted from the decay of the orbit of a natural satellite. The great meteor procession of February 9, 1913, is an example of such an object. Comparison with the reentry phenomena of the artificial satellite 1957 Beta suggests that the 1913 shower consisted of a single large stone weighing about 400 kilograms, and a few dozen smaller bodies weighing about 40 grams each, formed by ablation from the larger body. It is shown that under the observed conditions considerable liquid flow would be expected in the stone, which would be heated to about 2100 K. Objects falling from such a shower near the perigee point of the orbit would have a considerable distribution along the orbit as a result of slight variations in height or drag coefficient. The distribution in longitude would be made wider by the turning of the earth under the orbit during the time of fall. The ultimate source of the body which produces a tektite shower is probably the moon, which appears, by virtue of its polarization and the phase distribution of the returned light, to contain high-silica materials. It is suggested that the Igast object alleged to have fallen in 1855 is in fact genuine and represents an unmelted portion of the lunar crust.
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Age of the Australasian Tektite Strewn Field
Izokh, E. P.
1993-07-01
to be the most appropriate process of the tektite formation and launching [7]. The frequent shift of the K-Ar ages relative to the fission-track ages of tektites can be explained by the presence of an extra argon inherited from some older crystalline inclusions foreign to the tektite glass. These inclusions are most common to the Muong Nong-type layered tektites and to flanges of the button-shape australites, and can be considered as an extraterrestrial environmental dust peppering. References: [1] Storzer and Wagner (1980) Meteoritics, 15, 372. [2] Fleischer et al. (1969) EPSL, 7, 51-52. [3] Storzer and Muller-Sonhius (1986) Meteoritics, 21, 518-519. [4] Kashkarov et al. (1986) Meteoritika, 45, 105-170. [5] Izokh (1991) Soviet Geol. and Geophys., 32, 1-10. [6] Tollman and Tollmann (1992) Mitt. Osterr. Geol. Ges., 84. [7] Izokh and Le duc An (1983) Meteoritika, 42, 158-169.