The Chicxulub asteroid that ended the Cretaceous Era ∼66.05 million years ago caused a prolonged time of global darkness – the impact winter – leading to mass extinctions. Elements from the asteroid, including the platinum group elements (PGEs) osmium, iridium and platinum are known from the globally distributed boundary clay but their carrier elements have so far been unknown. We identify, for the first time in detail, the presence of these PGEs within Chicxulub impact spherules and importantly, we identify their carrier elements. We show through synchrotron Nano-XRF how these PGEs occur in nanostructures as un-ordered cube- and/or needle-like crystals co-localizing with both siderophile and chalcophile elements including Co, Ni, Cu, Zn, and Pb, derived from the asteroid. These crystals are set within a matrix of iron-rich calcium and silica glass revealing the mix of vaporized target rock and the asteroid. The results provide insights into the combination of elements present in the spherules, indicating formation of new minerals. We argue that the nano-shards of unreactive elements such as platinum, iridium and copper acted as nuclei for aerosol formation and potentially contributed to a prolonged impact winter with darkness and cooling leading to a profound and long-term climate change.

中文翻译：

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在 Chicxulub 小行星撞击球体中发现的铱和其他铂族元素纳米颗粒 – 对撞击冬季和深刻气候变化的影响


大约 6605 万年前结束白垩纪的 Chicxulub 小行星导致了全球长时间的黑暗——撞击冬季——导致大规模灭绝。来自这颗小行星的元素，包括铂族元素 （PGE） 锇、铱和铂，都是从全球分布的边界粘土中已知的，但迄今为止它们的载体元素尚不清楚。我们首次详细地确定了 Chicxulub 撞击球体中存在的这些 PGE，重要的是，我们确定了它们的载体元素。我们通过同步加速器纳米 XRF 展示了这些 PGE 如何在纳米结构中以无序的立方体和/或针状晶体的形式出现，与来自小行星的嗜铁和亲辉元素（包括 Co、Ni、Cu、Zn 和 Pb）共定位。这些晶体位于富含铁的钙和硅玻璃基质中，揭示了汽化目标岩石和小行星的混合物。结果提供了对小球中存在的元素组合的见解，表明新矿物的形成。我们认为，铂、铱和铜等非反应性元素的纳米碎片充当了气溶胶形成的核，并可能导致冬季的漫长影响，黑暗和冷却导致深刻而长期的气候变化。