The occurrence of pervasive chemical remanent magnetizations in sedimentary basins:implications for dating burial diagenetic events

摘要

Paleomagnetic results from Jurassic sediment on Skye,Scotland, are consistent with the hypothesis that authigenic magnetite and an associated chemical remanent magnetization (CRM) can form during the conversion of smectite to illite. Sediment in north Skye, where smectite is abundant and the clays ar unaltered, contain a weak and unstable magnetization. The same age sediment in south Skye, where the clays have been altered to illite by hydrothermal heating, contian a multi-component CRM residing in magnetite and/or pyrrhotite. The CRM was acquired in the early Tertiary, which is consistent with the timing of the hydrothermal activity that caused the alteration.