在奇克苏鲁布撞击结构深处的热碳酸盐
Pim Kaskes1,2, Marta Marchegiano1,3, Marion Peral1,4
1Research Unit: Archaeology, Environmental Changes and Geo-Chemistry (AMGC), Vrije Universiteit Brussel, 1050 Brussels, Belgium.
PNAS nexus
|January 12, 2024
概括
碳酸盐凝聚同位素温度测量揭示了奇克苏鲁布撞击结构内的高温,挑战了白纪-古世灭绝事件期间二氧化碳释放的模型.
科学领域:
- 地质化学 地质化学
- 同位素地球化学 同位素地球化学
- 行星科学 行星科学
背景情况:
- 超高速冲击产生短暂的热状态,使热力学条件分析具有挑战性.
- 奇克苏鲁布撞击结构提供了一个独特的自然实验室,用于研究撞击过程及其影响.
研究的目的:
- 用碳酸盐凝聚同位素温度计重建奇克苏鲁布火山口撞击岩层的绝对温度.
- 调查奇克苏鲁布撞击结构中的热史和过程.
- 评估撞击产生的二氧化碳释放对白纪 - 古世大灭绝的气候影响.
主要方法:
- 稳定同位素分析 (δ18O, δ13C) 和聚类同位素分析 (Δ47) 在含碳酸盐的冲击岩石,冲击融化岩石和目标石质上.
- 使用四个钻芯穿过Chixulub结构的截面.
- 应用凝聚同位素温度计 (T(Δ47)) 来确定形成温度.
主要成果:
- 聚集的同位素温度 (T ((Δ47)) 始终高于白纪晚期的海面温度,除了特定的古世石灰岩和低融度石.
- 丰富融的撞击突破产生了111 ± 10°C的T (Δ47),表明喷射期间的热处理.
- 低温和冲击融化岩石的温度为327±33°C,与脱碳和反反应过程有关.
结论:
- 在奇克苏鲁布撞击结构中记录了高温,特别是在融丰富的单元和撞击融化岩石中.
- 观察到的脱碳和反反应过程表明,撞击后存在复杂的热和化学相互作用.
- 这些发现表明,当前的数值模型可能高估了来自奇克苏鲁布撞击的二氧化碳释放,这对理解白纪-古世大灭绝事件有意义.
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