The time of origin of the geodynamo has important implications for the thermal evolution of the planetary interior and the habitability of early Earth. It has been proposed that detrital zircon grains from Jack Hills, Western Australia, provide evidence for an active geodynamo as early as 4.2 billion years (Ga) ago. However, our combined paleomagnetic, geochemical, and mineralogical studies on Jack Hills zircons indicate that most have poor magnetic recording properties and secondary magnetization carriers that postdate the formation of the zircons. Therefore, the existence of the geodynamo before 3.5 Ga ago remains unknown.

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重新评估哈德族-欧亚政体发电机的证据

地震动的起源时间对行星内部的热演化和早期地球的可居住性具有重要意义。有人提出，来自西澳大利亚州杰克希尔斯的碎屑锆石可为42亿年前的伽达摩提供活跃的证据。但是，我们在Jack Hills锆石上进行的古磁，地球化学和矿物学研究相结合，表明大多数锆石的磁记录性能较差，而次级磁化载流子要晚于锆石的形成。因此，在3.5 Ga之前的大地发电机的存在仍然是未知的。