The age of the Earth

摘要: Forty years ago, Patterson in his pioneering work on lead isotopes defined the age of Earth and meteorites with 4.55 Ga. We reconsider question its relation to meteorites, similar Patterson's approach, we use isotope systematics. UPb investigations three meteoritic objects which early thermal and/or chemical events generated large U/Pb fractionations are outlined this article: refractory inclusions Allende meteorite, phosphates ordinary chondrites basaltic achondrites. All these samples contain highly radiogenic compositions (206Pb/204Pb > 150) therefore their 207Pb206Pb is almost independent isotopic composition associated measured 204Pb within precision a few million years. The PbPb ages most range from 4.568 4.565 Ga, secondary equilibrated vary 4.563 4.504 achondrites show between 4.558 4.53 Ga. These determinations indicate precise time constraints for classical scenario concerning formation first planetary solar system. Formation occurs at 4566+2/−1 Ma. Accretion chondritic bodies occurred maximum 3 Ma later. Eight after inclusions, magmatic activity, including partial melting, magma segregation, eruption bodies. During next 200 processing, shock perturbation, heating takes place. The meaning an “age Earth” evaluated major processes, end accretion, core formation, atmosphere extraction. A value found based IXe systematics; about 0.1 Ga younger than that primitive meteorites. terrestrial interpreted as mean segregation outgassing, respectively. Within framework, corresponds accretion differentiation.