SPHERULE LAYERS—RECORDS OF ANCIENT IMPACTS
SPHERULE LAYERS—RECORDS OF ANCIENT IMPACTS
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DOI：
10.1146/annurev.earth.32.101802.120458
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发表时间：
2004-04
影响因子：
14.9
通讯作者：
B. Simonson;B. Glass
中科院分区：
文献类型：
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作者：
B. Simonson;B. Glass
▪ Abstract A large extraterrestrial object striking Earth at cosmic velocity melts and vaporizes silicate materials, which can condense into highly spheroidal, sand-size particles that get deposited hundreds to thousands of kilometers from the point of impact. These particles, known as impact spherules, have been detected in great abundance in a relatively small number of thin, discrete layers ranging in age from less than a million years to 3.47 billion years. Unaltered impact spherules consist entirely of glass (microtektites) or a combination of glass and crystals grown in flight (microkrystites). Impact spherule layers form very rapidly and can be very extensive, even global in extent [e.g., the Cretaceous-Tertiary (K/T) boundary layer], so they form excellent time-stratigraphic markers. Because they are always found in a stratigraphic context, spherule layers are probably superior to terrestrial craters and related structures for assessing the environmental and biotic effects of large impacts. A reco...
