Diagenetic magnetites within sedimentary cover strata over oil or gas field are present primarily as spherical crystal aggregates that usually carry stable chemical remanent magnetization (CRM).

• 含油气区沉积盖层中分布的成岩磁铁矿具有典型球粒状的特有矿物形貌标志,它们携带了较为稳定的化学剩磁(CRM)。