...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Siderophile-rich inclusions from the Morokweng impact melt sheet, South Africa: possible fragments of a chondritic meteorite
【24h】

Siderophile-rich inclusions from the Morokweng impact melt sheet, South Africa: possible fragments of a chondritic meteorite

机译：南非Morokweng冲击熔岩中富含亲铁质的包裹体：软骨陨石的可能碎片

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

An 870 m thick (diameter ～30 km) melt sheet associated with the Morokweng impact structure, South Africa, contains Cr-rich silicate inclusions (up to 30 mm in diameter) as well as disseminated Ni-rich sulphides and oxides that commonly occur in mutual intergrowths. Although the silicate inclusions are highly altered, the mineral chemistry and petrographic evidence, along with broadly chondritic Re-Os systematics and platinum-group element (PGE) signatures, all support the view that the silicate inclusions represent relict fragments of an impactor with compositions similar to ordinary chondrites. The Ni-rich sulphides and oxides are significantly enriched (up to 35* chondrites) in PGE, Ni and Cr. Although the bulk PGE signature of the melt sheet is chondritic, the sulphides and oxides display mm and sub-mm scale fractionation of PGE into different inclusion components. A model is presented whereby pieces of the projectile react with the relatively more oxidising impact melt into which they fell, resulting in oxidation and fractionation of the metal-silicate fragments to form the inclusion assemblages. This may be the first reported occurrence of a large melt sheet (300 km~3) contaminated by swarms of discrete pebble-sized fragments of asteroid material. The high proportion of meteorite fragments in the Morokweng melt sheet suggests either that the structure was formed by a relatively low velocity (<18 km/s) impact event, or that the angle of impact was optimum for retaining maximum amounts of meteoritic material within the crater.
机译：与南非Morokweng冲击结构有关的一块870 m厚（直径〜30 km）的熔片包含富铬的硅酸盐夹杂物（直径最大为30 mm）以及弥散分布的富镍的硫化物和氧化物。共同的共生。尽管硅酸盐夹杂物发生了很大的变化，但矿物化学和岩石学证据以及广泛的软骨组织Re-Os系统学特征和铂族元素（PGE）签名均支持以下观点：硅酸盐夹杂物代表冲击器的残渣碎片，其成分相似普通的球粒陨石。富镍的硫化物和氧化物在PGE，Ni和Cr中明显富集（最多35 *球粒晶）。尽管熔体片的大部分PGE签名是软骨状的，但硫化物和氧化物显示出PGE的毫米级和亚毫米级分馏成不同的夹杂物成分。提出了一种模型，其中射弹碎片与它们掉入其中的相对更多的氧化冲击熔体反应，从而导致金属硅酸盐碎片的氧化和分馏，从而形成夹杂物组合。这可能是首次报道的大熔体片（300 km〜3）的发生，被大片离散的卵石大小的小行星材料碎片污染。 Morokweng熔体片中高比例的陨石碎片表明，该结构是由相对较低的速度（<18 km / s）的撞击事件形成的，或者撞击角度是最佳的，以在其中保留最大量的陨石物质。火山口。

著录项

相似文献

  • 外文文献
  • 中文文献
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号