The ferrimagentic mineral is mainly detrital in origin, but in the magnetic enhanced sediments at site Shidongkou occur some spherical magnetic particles derived from anthropogenic sources.

• 除了碎屑成因磁铁矿外，在磁性最强的石洞口沉积物中还出现了球状磁性颗粒，与化石燃料（如煤）高温燃烧过程中生成的球状磁铁矿相似，主要系人类活动的产物。