Handbook of Archaeological Sciences
Handbook of Archaeological Sciences
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考古科学手册
DOI：
10.1002/9781119592112.ch8
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Smith V
中科院分区：
文献类型：
--
作者：
Smith V
爆炸性的火山喷发产生热气体和淬火的熔融岩石，这些岩石在岩浆离开喷口时被气体膨胀而破碎。这些碎片被称为火山碎屑。火山灰层由火山玻璃、晶体和石质物质组成。由于火山灰分散在广阔的区域，并形成地质瞬时层，这些火山灰层对年代学特别有用-如果使用放射性方法确定喷发日期，则提供地点和年龄之间的相对年代学。利用火山玻璃碎片的成分，可以将不同地点之间的火山灰层与保存在其源火山的特定喷发沉积物联系起来。对于一个特定的喷发存款，无论距离喷口多远，其主要和微量元素玻璃成分都保持不变，它们构成火山灰的化学指纹。火山沉积物的年代测定可以使用许多常用的放射性测年方法。
Explosive volcanic eruptions generate plumes of hot gas and quenched molten rock that has been fragmented by the expansion of gas as the magma exits the vent. These fragments are calledpyroclasts. The tephra layers are comprised of volcanic glass, crystals, and lithic material. Given that tephra is dispersed over wide areas and forms a geologically instantaneous layer, these tephra layers can be particularly useful for chronology – providing a relative chronology between sites and age if the eruption has been dated using radiometric methods. Correlating volcanic ash layers between sites and to specific eruption deposits preserved at their source volcanoes can be achieved using the composition of the volcanic glass shards. The major and trace element glass compositions remain the same for a specific eruption deposit irrespective of the distance from the vent, and they constitute the chemical fingerprint of the tephra. Volcanic deposits can be dated using many commonly employed radiometric dating methods.