Strontium history

Farver J.R. and Giletti B.J. (1989) Oxygen and strontium diffusion in apatite and potential applications to thermal history determinations. Geochim. Cosmochim. Acta S3, 1621-1631. 

A popular method used to date rocks is the potassium-argon method. Potassium is abundant in rocks such as feldspars, hornblendes, and micas. The K-Ar method has been used to date the Earth and its geologic formations. It has also been applied to determine magnetic reversals that have taken place throughout the Earth s history. Another method used in geologic dating is the rubidium-strontium, Rb-Sr, method. Some of the oldest rocks on Earth have been dated with this method, providing evidence that the Earth is approximately 5 billion years old. The method has also been used to date moon rocks and meteorites. 

Internal 87Rb-87Sr isochrons were particularly useful in unraveling the history of the Moon and Mars. As an example, consider mare basalts from the Sea of Tranquility collected by Apollo 11. These lunar basalts consist primarily of calcium-rich (anorthitic) plagioclase and low-calcium pyroxene, along with ilmenite, crystobalite, and other minor phases. Strontium is concentrated in the calcium sites in plagioclase and is excluded from most other phases, resulting in a variation of a factor of several hundred in the strontium... 

Lowenstam H.A. (1961) Mineralogy, 180/160 ratios, and strontium and magnesium contents of recent and fossil brachiopods and their bearing on the history of the oceans. J. Geol. 69, 241-260. 

A significant step in the history of the HTSs was the discovery in 1966 of superconductivity in the oxygen-deficient perovskite SrTi03 5, containing some barium or calcium substituted for strontium. Although the Tc value was very low (0.55 K), in retrospect it can be seen as the first superconducting ceramic. In 1979 a Tc of approximately 13 K was discovered for BaPb075Bi025O3, which also has the perovskite structure. 

The importance of this history is that it meant there was a precedent for the use of lithium as a medicine. It also meant that lithium was readily available for experimentation in the pharmacies of psychiatric hospitals. Therefore when John Cade, an Australian psychiatrist, suggested that lithium might be a useful treatment in people with mania in the 1940s, it did not seem curious. Cade also experimented with use of the elements strontium and cerium in the treatment of psychiatric disorders, but they never caught on in the same way because there was no prior history of medicinal use. 

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... 

Starinsky A., Bielski M., Lazar B., Steinitz G., and Raab M. (1983b) Strontium isotope evidence on the history of oilfield brines, Mediterranean Coastal Plain, Israel. Geochim. Cosmochim. Acta 47, 687-695. 

The marine strontium isotope record is the proxy record most commonly used to constrain the geologic history of chemical weathering. However, in recent years it has been widely criticized as a proxy indicator of past silicate weathering rates. The osmium isotope record is analogous to the strontium record in many respects, and can help to constrain interpretations of the marine strontium isotope record. In this section the geochemical factors that influence the osmium and strontium isotope compositions of seawater are reviewed, and the structure of these two records of Cenozoic ocean chemistry is discussed. 

Figure 26 Strontium isotopic composition of sedimentary carbonate rocks during geologic history. Reproduced from Shields and Veizer (2002). Circles and triangles represent samples with good and poor age assignment,...

Zhu and MacDougall (1998) showed that calcium isotope composition of the shells was both species and temperamre dependent and that river water is depleted by 2%o relative to seawater. The temperature dependency of calcium isotope fractionation enables this tracer to be a potential paleotem-peramre proxy (Nagler et al., 2000). The seawater Cal" Ca secular variations are indicated by the results of De La Rocha and De Paolo (2000) for the last 160 Myr, and by the data of Zhu (1999) for the entire 3.4 Gyr of earth history. The latter indicate that, in analogy to strontium isotopes (Veizer and Compston, 1976), the Archean samples have C Ca ratios similar to the earth mantle, with the crustal-like values first appearing at the Archean/Proterozoic transition. However, in contrast to the strontium isotope trend, the calcium isotope ratios appear to dip towards mantle values also at —1.6 Gyr ago. 

White, C.D., T.D. Price, and RJ. Longstaffe. 2007. Residential histories of the human sacrifices at the Moon Pyramid evidence from oxygen and strontium isotopes. Ancient Mesoamerica 18 159-172. 

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