Based on sediment‐dispersed extraterrestrial spinel grains in the Bottaccione limestone section in Italy, we reconstructed the micrometeorite flux to Earth during the early Paleocene. From a total of 843 kg of limestone, 86 extraterrestrial spinel grains (12 grains > 63 μm, and 74 in the 32–63 μm fraction) have been recovered. Our results indicate that the micrometeorite flux was not elevated during the early Paleocene. Ordinary chondrites dominated over achondritic meteorites similar to the recent flux, but H chondrites dominated over L and LL chondrites (69%, 22%, and 9%, respectively). This H‐chondrite dominance is similar to that recorded within an enigmatic ³He anomaly (70, 27, and 3%) in the Turonian, but different from just before this ³He anomaly and in the early Cretaceous, where ratios are similar to the recent flux (~45%, 45%, and 10%). The K‐Ar isotopic ages of recently fallen H chondrites indicate a small impact event on the H‐chondrite parent body ~50 to 100 Ma ago. We tentatively suggest that this event is recorded by the Turonian ³He anomaly, resulting in an H‐chondrite dominance up to the Paleocene. Our sample spanning the 20 cm above the Cretaceous–Paleogene (K–Pg) boundary did not yield any spinel grains related to the K–Pg boundary impactor.

中文翻译：

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在意大利Bottaccione地区（翁布里亚亚平宁山脉）重建的最早古近纪期间，微陨石通向地球

根据意大利Bottaccione石灰岩剖面中沉积物分散的地球外尖晶石晶粒，我们重建了古新世早期到地球的微陨石通量。从总共843千克的石灰石中，回收了86个地球外尖晶石晶粒（12个> 63μm的晶粒，以及74个32-63μm的晶粒）。我们的结果表明，在古新世早期，微陨石通量并未升高。与最近的通量相似，普通的球粒陨石在软骨质陨石上占主导地位，但是在L和LL球粒陨石上，H球粒陨石占优势（分别为69％，22％和9％）。H球粒陨石的优势与Turonian的³ He神秘现象（70％，27％和3％）中记录的相似，但与之前³他异常且在白垩纪早期，其比率与最近的通量相似（〜45％，45％和10％）。最近坠落的H球粒陨石的K-Ar同位素年龄表明在大约50到100 Ma之前对H-球粒陨石母体的影响很小。我们初步认为，该事件是由Turonian ³ He异常记录的，导致直到古新世的H球粒体占主导地位。我们的样品跨越白垩纪-古生界（K-Pg）边界20厘米，没有产生任何与K-Pg边界冲击器有关的尖晶石晶粒。