Uranium-238 decay series

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O Hara MJ (1968) The bearing of phase equilibria studies in synthetic and natural systems on the origin and evolution of basic and ultrabasic rocks. Earth Sci Rev 4 69-133 O Nions RK, McKenzie D (1993) Estimates of mantle thorium/uranium ratios from Th, U and Pb isotope abundances in basaltic melts. Phil Trans Royal Soc 342 65-77 Oversby V, Gast PW (1968) Lead isotope compositions and uranium decay series disequilibrium in reeent volcanic rocks. Earth Planet Sci Lett 5 199-206... 

Williams RW, Gill JB (1989) Effects of partial melting on the uranium decay series. Geochim Cosmochim Acta 53 1607-1619... 

Wendt Jl, Regelous M, Collerson KD, Ewart A (1997) Evidence for a contribution from two mantle plumes to island arc lavas from northern Tonga. Geology 25 611-614 Williams RW, Gill JB (1989) Effects of partial melting on the uranium decay series. Geochim Cosmochim Acta 53 1607-1619... 

Wiggins, R. (1976). Interpolation of digitized curves. Bull. Seism. Soc. Amer., 66, 2077-81. Wilkinson, J. H. (1965). The Algebraic Eigenvalue Problem. Oxford Clarendon Press. Williams, R. W. Gill, J. B. (1989). Effects of partial melting on the uranium decay series. Geochim. Cosmochim. Acta, 53, 1607-19. 

ISOTOPES There are 41 isotopes of polonium. They range from Po-188 to Po-219. All of them are radioactive with half-lives ranging from a few milliseconds to 102 years, the latter for its most stable isotope Po-209. Polonium is involved with several radioactive decay series, including the actinium series, Po-211 and Po-215 the thorium series, Po-212 and Po-216 and the uranium decay series, Po-210, Po-214, and Po-218. 

Most of the known chemistry of polonium is based on the naturally occurring radioactive isotope polonium-210, which is a natural radioactive decay by-product of the uranium decay series. Its melting point is 254°C, its boiling point is 962°C, and its density is 9.32g/cm. ... 

Uranium is the fourth metal in the actinide series. It looks much like other actinide metallic elements with a silvery luster. It is comparatively heavy, yet malleable and ductile. It reacts with air to form an oxide of uranium. It is one of the few naturally radioactive elements that is fissionable, meaning that as it absorbs more neutrons, it splits into a series of other lighter elements (lower atomic weights) through a process of alpha decay and beta emission that is known as the uranium decay series, as follows U-238—> Th-234—>Pa-234—>U-234—> Th-230 Ra-226 Rn-222 Po-218 Pb-2l4 At-218 Bi-2l4 Rn-218 Po-2l4 Ti-210—>Pb-210—>Bi-210 Ti-206—>Pb-206 (stable isotope of lead,... 

Uranium-238 has a half-life of 4.468 billion years over which time it decays into stable lead-206. This process can be used to date ancient rocks by comparing the ratio of the isotope lead-206, the last isotope in the uranium decay series, to the level of uranium-238 in the sample of rock to determine its age. This system has been used to date the oldest rocks on Earth as being about 4.5 billion years old, which is about the time of the formation of our planet. 

Radium is an intermediate member of the uranium decay series. Therefore, it is present in all uranium minerals. Its abundance in uranium is calculated to be about 0.33ppm. 

The previous four chapters deal with the fractionation of stable trace elements during partial melting. In this chapter, we study the behaviors of radioactive uranium decay series during partial melting. Since quantitative models for uranium-series disequilibria need to include additional parameters in decay constants and are thus more complicated, for simplicity, we assume that the partition coefficients remain constant during partial melting. Thus, we only present modal dynamic melting. 

Equation (5.31) can be used to model the uranium decay series (U-series) nuclides in the residual melt that is in chemical equilibrium with the solid during dynamic partial melting ... 

The half-lives of the isotopes found in the uranium decay series. 

Radionuclides in the uranium decay series serve as useful tracers of particle flux. One type of these tracers consists of a soluble parent nuclide and a particle-reactive daughter. These soluble nuclide-particle-reactive pairs include 234 j 230jjj and The half-life of the... 

Radiochemical sources and distributions uranium decay series... 

The longest lived nuclides of the uranium decay series, which are located at the early part of the series, are shown in Fig. 1. In a closed system, given sufficient time, the decay series will reach a state of secular equilibrium wherein the radioactivity (or activity ) of each member will be the same, although the actual number of atoms present may vary greatly. Activity for a given nuclide is defined by ... 

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