| タイトル | Large Aerial Bursts: An Important Class of Terrestrial Accretionary Events |
| 著者（英） | Wasson, John T. |
| 著者所属（英） | California Univ. |
| 発行日 | 2003-01-01 |
| 言語 | eng |
| 内容記述 | Large aerial bursts similar to the 1908 Tunguska bolide but much larger in magnitude have surely been responsible for many catastrophic events in the history of the Earth. Because aer- ial bursts produce shallow (or even negligible) craters, their existence is difficult to document in the geological record. Even aerial bursts as small as Tunguska deposit enough energy to melt -1 mm of dry soil. Silica-rich glass formed in such melts has the potential to survive in the soil for many Ma, thus a potential indicator of large aerial bursts is glass that was formed as thick regions within silicate melt sheets. The layered tektites from Southeast Asia and the Libyan desert glass may have formed by a combination of sedimentation and downslope flow of silicate melt heated by radiation from large aerial bursts. The alternative, formation of lay- ered tektites as crater ejecta, cannot account for observations such as uniformly high l0Be con- tents, the orientation of the magnetic remanence field, and the absence of splash-form (e.g., teardrop or dumbbell) tektites in regions where layered tektites are common. The largest as- teroids or comets make craters no matter what their strength. Recent reviews suggest that, for events in the energy range up to 1019-1020 J (about two orders of magnitude larger than the Meteor Crater impact), aerial bursts are more likely than cratering events, and the layered tek- tites of Southeast Asia imply the existence of aerial bursts one to two orders of magnitude larger still. |
| NASA分類 | Geosciences (General) |
| 権利 | Copyright |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/333007 |
|
