Nature of the Jurassic Magnetic Quiet Zone

The nature of the Jurassic Quiet Zone (JQZ), a region of low‐amplitude oceanic magnetic anomalies, has been a long‐standing debate with implications for the history and behavior of the Earth's geomagnetic field and plate tectonics. To understand the origin of the JQZ, we studied high‐resolution sea surface magnetic anomalies from the Hawaiian magnetic lineations and correlated them with the Japanese magnetic lineations. The comparison shows the following: (i) excellent correlation of anomaly shapes from M29 to M42; (ii) remarkable similarity of anomaly amplitude envelope, which decreases back in time from M19 to M38, with a minimum at M41, then increases back in time from M42; and (iii) refined locations of pre‐M25 lineations in the Hawaiian lineation set. Based on these correlations, our study presents evidence of regionally and possibly globally coherent pre‐M29 magnetic anomalies in the JQZ and a robust extension of Hawaiian isochrons back to M42 in the Pacific crust. Key Points Refining and reidentifying M sequence anomalies Verify globally coherent Jurassic geomagnetic field behavior Expand the oldest trace of the early Pacific plate formation and evolution