Indochinite (Pleistocene, 783-803 ka; Australasian Tektite Strewn Field, Guangdong, China) 1 : 無料・フリー素材/写真
Indochinite (Pleistocene, 783-803 ka; Australasian Tektite Strewn Field, Guangdong, China) 1 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Indochinite tektite from the Pleistocene of China. (5.2 centimeters across at its widest)Large and small impacts have affected Earth since its formation 4.55 billion years ago. Compared with the intensely pitted and cratered Moon, Earth has relatively few preserved impact craters, because they have been destroyed by water erosion, glacial erosion, and plate tectonics. Impact events are accompanied by significant heating, which results in melting of much of the ejected pulverized bedrock. The melted material cools quickly and falls back to Earth in the form of tektites - impact splash glasses. Tektites are principally composed of amorphous silica (SiO2). Broken surfaces show a conchoidal fracture. Tektites from different impact events are given different names.Indochinites are black-colored, moderately common tektites from southeastern Asia that typically are subspherical to teardrop-shaped to dumbbell-shaped. They are found throughout the Australasian Tektite Strewn Field (a.k.a. Indochinite Tektite Strewn Field). This strewn field is huge - it's estimated to cover 10 to 20% of Earth's surface. Indochinites have been found from Madagascar to Antarctica to Tasmania to South China. Samples from different geographic areas are often given different names (e.g., australites, thailandites, malaysianites, philippinites, billitonites, vietnamites), but they were all apparently formed by the same event. The site of the impact crater has long been a mystery, but has now been identified as likely buried by basaltic lava flows in Laos, southeastern Asia (Sieh et al., 2019). The age of indochinites has been reported to be about 783 to 803 ka.Locality: unrecorded/undisclosed site in Guangdong Province, South China--------------------------------Reference cited:Sieh et al. (2019) - Australasian impact crater buried under the Bolaven Volcanic Field, southern Laos. Proceedings of the National Academy of Sciences 117: 1346-1353. |
| 撮影日 | 2014-07-31 15:30:50 |
| 撮影者 | James St. John |
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