Neodymium history

Unlike. 208pb/204pb or 2 pb/204pb, which depend on Th/Pb and U/Pb, respectively, 208p 5 /206p]3 reflects the Th/U ratio integrated over the history of the Earth. The existence of global correlations between neodymium, strontium, and hafnium isotope ratios and, and the absence... 

Four cratonic, ultradeep xenoliths from S. Africa and Sierra Leone have been analyzed for their strontium and neodymium isotopic compositions (Macdougall and Haggerty, 1999). The neodymium isotopic compositions of minerals from these xenoliths suggest that they were emplaced into the African lithosphere at times ranging from approximately the time of kimberlite emption to hundreds of millions of years earlier. The samples show a complex history of melt... 

Mantle evolution curves for neodymium isotopic compositions in the Earth prior to 2.7 Ga are much less well defined than for younger time periods. Many studies have elected simply to extrapolate a linear evolution from 2.7 Ga to the composition of the primitive mantle (snu = 0) at 4.56 Ga (e.g., Goldstein et al., 1984). In contrast, other studies have attempted a more precise definition of the neodymium mantle evolution curve for the Archean based on observed compositions (e.g., Bennett et al., 1993 Bowring and Housh, 1995 Vervoort and Blichert-Toft, 1999). The justification of these efforts is that Archean mantle chemistry, particularly for the long-lived isotopic systems, provides a window into the first 700 Myr of Earth s history, prior to establishment... 

Ga would be extremely important, as this would require extreme early differentiation of the Earth s mantle within the first 100-400Myr of Earth history. As shown in Figure 2, to generate SNd of - -2 to - -4 at 3.8 Ga requires ratios in the pre-3.8 Ga upper mantle similar to those in the present-day depleted mantle, yet the modem mantle records the effects of extraction of the whole of the continental cmst. Thus, neodymium isotopic compositions of the early preserved continental cmst provide strong evidence that portions of the Earth s upper mantle in the Early Archean were significantly lithophile-element-depleted requiring very early (>4.0 Ga) differentiation. 

One difficulty is that there is no stable isotope of plutonium with which to compare its abundance. To really quantify its abundance, it is necessary to consider the amount of " " Pu relative to an isotope of a similar element. The definition of similar depends on the problem to be addressed. In studies of nucleosynthesis, the similar element used is usually uranium, another actinide, which is produced in the same stellar environments. In studies of the history of specific meteorite parent bodies, the similar element is more commonly a light rare earth element (TREE) like neodymium, since the geochemical behavior of plutonium is apparently most similar to that of the LREE. We will discuss the details of the experimental technique of each approach below. 

Pr and Nd C. Auer von Welsbach (1885). First they were considered to be one element, didymium, but as Delafontaine suspected, it was not one single element. It appeared to consist of two quite similar elements. The Greek word didymos, meaning twin, from which the name didymium is derived, refers to this. Praseodymium was isolated first, with "Praseo-green referring to the green color of its salts. Then another one was isolated, which was the new one of the twin Neodymium (http // www.rsc.org/periodic-table/element/59/praseodymium history Weeks 1968)... 

The work of Moseley made clear the existence of an unknown element between neodymium and samarium. But the situation proved to be not so clear and dramatic events rapidly followed in the history of element 61. 

As just mentioned, thirteen lanthanides had been discovered but, according to the new knowledge of the atom, one was missing. In 1914, Moseley confirmed that there must be an element with atomic number 61 between neodymium and samarium. Where was that element in nature Astronomical studies indicated that it is present on the surface of star in the Andromeda galaxy. But all attempts to find it on earth failed. The search had to take quite different paths than had been common in the whole history of lanthanide discovery. 

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