Stanley Hart

Stanley Hart is an American geochemist renowned for defining the distinct chemical differences between the Earth's mantle reservoirs. His pioneering research utilized isotope analysis to identify specific mantle components like HIMU and EM.

In Hart's geochemical models, HIMU stands for high U/Pb ratios, while EM stands for Enriched Mantle. These terms describe the distinct chemical signatures found in volcanic rocks that originate from different deep-earth reservoirs.

Since humans cannot directly access the deep mantle, Hart studied it by analyzing the isotope ratios of oceanic basalts. These volcanic rocks form from magma rising from the mantle, effectively acting as chemical samples of the deep earth.

Hart spent a highly influential portion of his scientific career conducting mantle research at the Massachusetts Institute of Technology (MIT). His laboratory work there helped revolutionize the modern understanding of mantle geochemistry.