40Ar-39Ar 曼森撞击结构的年代测定:一个白纪-三级纪边界火山口候选者
Science (New York, N.Y.)
|June 30, 1989
概括
甲-第三纪 (K-T) 边界粘土石矿物学表明大陆波撞击. 爱荷华州的曼森撞击结构与K-T边界撞击证据一致,可追溯到6570万年前.
科学领域:
- 地质地质地质地质地质地
- 冲击石坑的形成
- 古生物学的古生物学
背景情况:
- 甲-第三纪 (K-T) 边界标志着一个重要的大规模灭绝事件.
- 在K-T边界粘土岩石中,受冲击的矿物质和石质粒暗示了大规模的外星撞击.
- 这些颗粒的全球分布和度为撞击地点提供了线索.
研究的目的:
- 为了调查在K-T边界粘土石中发现的冲击矿物和石质粒的起源.
- 评估曼森撞击结构作为K-T边界撞击事件的潜在地点.
- 通过放射测量方法精确地测定曼森撞击结构的年代.
主要方法:
- 在全球范围内对K-T边界粘土石的冲击矿物和石质粒矿物学的分析.
- 对冲粒度和大小的地理评估.
- 阿贡-40-阿贡-39年龄谱测定曼森撞击结构中冲击微克林的年代.
主要成果:
- 冲击粒的矿物质与大陆玻利德撞击相一致.
- 最高度和最大尺寸的冲击粒在北美西部发现.
- 曼森撞击结构的阿贡-40-阿贡-39约会微线产生了65.7 +/- 1.0百万年前的年龄.
结论:
- 曼森撞击结构是K-T边界撞击事件的强有力的候选者.
- 撞击事件发生在大约6570万年前,与K-T边界相吻合.
- 这些发现支持大规模的外星撞击是导致K-T大灭绝的原因.
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