Siderophile element concentrations in magnetic spherules from deep sea sediments revealed by instrumental neutron activation analysis

Abstract

For the purpose of deciding the extraterrestrial origin of the magnetic spherules found in deep sea sediments, the siderophile elements Co, Ni, Ir and/or Au etc., were measured by instrumental neutron activation analysis. Spherules were collected from red clay samples which were dredged from Mid Pacific Ocean. Only spherules which had smooth surfaces and relatively high specific gravities were chosen for analysis. Existence of Co, Ni and It in most spherules suggests the possibility of an extraterrestrial origin for these spherules. It is not clear whether these spherules are droplets ablated from iron meteorites entering into the Earth's atmosphere or they are cosmic iron grains themselves. X-ray diffraction analysis suggested that these spherules are the products of rapid cooling materials.