Something odd is cooking in the center of Earth. heat from the core has sustained the geomagnetic field for 3.5 billion years, but standard calculations show the core should have long ago lost its primordial warmth. For three decades, V. Rama Murthy, a geochemist at the University of Minnesota, has argued that radioactive potassium at Earth's center keeps things toasty. The idea remains controversial (see Discover, August 2002), but now he says he has evidence to back it up.
Murthy and his colleagues combined potassium-rich silicate material, similar to the composition of the mantle, with iron and iron sulfide, thought to make up the bulk of the core. At corelike temperatures and pressures, potassium from this "mantle" entered and blended with the "core" material. The result indicates that large amounts of radioactive potassium could have migrated to the center when Earth formed. The decay of that potassium storehouse could account ...
