Half of the chemical elements heavier than iron are produced by the rapid neutron capture process (r-process). The sites and yields of this process are disputed, with candidates including some types of supernovae (SNe) and mergers of neutron stars. We search for two isotopic signatures in a sample of Pacific Ocean crust—iron-60 (⁶⁰Fe) (half-life, 2.6 million years), which is predominantly produced in massive stars and ejected in supernova explosions, and plutonium-244 (²⁴⁴Pu) (half-life, 80.6 million years), which is produced solely in r-process events. We detect two distinct influxes of ⁶⁰Fe to Earth in the last 10 million years and accompanying lower quantities of ²⁴⁴Pu. The ²⁴⁴Pu/⁶⁰Fe influx ratios are similar for both events. The ²⁴⁴Pu influx is lower than expected if SNe dominate r-process nucleosynthesis, which implies some contribution from other sources.

比铁重一半的化学元素是通过快速中子捕获过程（r过程）产生的。此过程的地点和产量存在争议，候选对象包括某些类型的超新星（SNe）和中子星合并。我们在一个太平洋地壳样品中搜索了两个同位素特征-铁60（⁶⁰ Fe）（半衰期为260万年），它主要是在大质量恒星中产生并在超新星爆炸中喷出，而p 244（²⁴⁴ Pu）（半衰期为8060万年），仅在r进程事件中产生。在过去的一千万年中，我们发现有两种不同的⁶⁰ Fe涌入地球，而伴有²⁴⁴ Pu的少量涌入。在²⁴⁴蒲/ ⁶⁰两种事件的铁流入率相似。在²⁴⁴浦涌入下，如果超新星主宰r-过程核合成，这意味着从其他渠道一定的贡献低于预期。