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首页> 外文学位 >Impact crater particulates: Microscopic meteoritic material surrounding meteorite craters.
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Impact crater particulates: Microscopic meteoritic material surrounding meteorite craters.

机译：撞击陨石坑颗粒：陨石陨石坑周围的微观陨石物质。

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摘要

The influx of extraterrestrial matter onto the Earth is a ongoing process. Every year 40,000 metric tons of extraterrestrial matter is accreted by the Earth (Love 1993). A small fraction of this material arrives at Earth as objects large enough to survive the passage through atmosphere. Some of this material is completely melted as it passes through the atmosphere and arrives at the surface of the Earth as cosmic spherules. Cosmic spherules formed from metallic cosmic material undergoes changes in its elemental abundance as it passes through the atmosphere. The oxidation of the spherules results in the concentration of more refractory elements like Ni and Co into the metallic phase. Cosmic spherules are also formed by the passage of large meteorites through the atmosphere and their resulting impact onto the Earth.; I found that the cosmic spherules from a wide variety of sources show a very similar trend in the elemental abundance patterns of their metallic phases. This trend is most obvious in the spherules recovered from the deep-sea and the spherules imbedded in impactite glass recovered from iron meteorite impact crater sites. The metallic spherules recovered from the soil surrounding impact craters do not show the high degree of elemental fractionation found in the deep-sea and impactite spherules. The composition of these spherules indicate that they are a mixture of meteoritic and target material.; Metallic spherules are not the only meteoritic material to be found in the soil surrounding meteorite craters. I found that small fragments of the parent meteorite are an ubiquitous component of the soil surrounding the Odessa and Dalgaranga meteorite craters. These fragments occurred as small (most less than 400 {dollar}mu{dollar}m in size) heavily weathered fragments of meteoritic metal. The total calculated mass of these fragments is an order of magnitude larger than the mass of ponderable meteorites recovered from the site but 1 to 2 orders of magnitude smaller than the estimated mass of the impactor. I have also found that similar meteoritic fragments are also found in the soil of the Henbury, Veevers, and Kaali meteorite craters.
机译：外星物质涌入地球是一个持续的过程。每年，地球会增加40,000公吨的外星物质（Love 1993）。这种物质的一小部分到达地球时，其大小足以经大气层幸存下来。这种材料中的一些在穿过大气层时完全熔化，并以宇宙小球的形式到达地球表面。由金属宇宙材料形成的宇宙球在穿过大气时会发生元素丰度的变化。球的氧化导致更多的难熔元素如Ni和Co集中到金属相中。宇宙小球也是由大型陨石穿过大气层以及它们对地球的撞击而形成的。我发现来自各种来源的宇宙球在其金属相的元素丰度图中显示出非常相似的趋势。这种趋势在从深海中回收的球体和从陨石铁撞击坑口回收的嵌在撞击玻璃中的球体中最为明显。从撞击坑周围的土壤中回收的金属小球未显示出在深海和撞击石小球中发现的高度元素分级。这些小球的组成表明它们是陨石和目标物质的混合物。金属球不是在陨石坑周围土壤中发现的唯一陨石材料。我发现母陨石的小碎片是敖德萨和达尔加兰加陨石坑周围土壤的普遍成分。这些碎片以小（风化金属陨石碎片）的大小（最大小于400 {μm} m）出现。这些碎片的总计算质量比从该地点回收的可疑陨石的质量大一个数量级，但比撞击器的估计质量小1-2个数量级。我还发现，在亨伯里，韦弗斯和卡阿里陨石坑的土壤中也发现了类似的陨石碎片。

著录项

  • 作者

    Smith, Toby Russell.;

  • 作者单位

    University of Washington.;

  • 授予单位 University of Washington.;
  • 学科 Physics Astronomy and Astrophysics.; Geology.; Geochemistry.
  • 学位 Ph.D.
  • 年度 1995
  • 页码 261 p.
  • 总页数 261
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 天文学;地质学;地质学;
  • 关键词

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