Results 291 to 300 of about 31,311 (333)

Strontium Isotopes in Deep-Sea Sediments

Science, 1966
Recent deep-sea sediments, leached of carbonate, have Sr 87 : Sr 86 ratios ranging from 0.7044 to 0.7394. Strontium in the detrital sediment has not equilibrated isotopically with seawater strontium. Amounts of strontium-bearing authigenic material in the clay-mineral assemblage are not great
E. Julius Dasch, F. Allan Hills, Karl K. Turekian   +2 more
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Strontium isotope stratigraphy

Palaeogeography, Palaeoclimatology, Palaeoecology, 1986
The 87Sr/86Sr ratio of sea water has changed significantly with time in response to the input of varying proportions of Sr derived from continental crust and upper mantle sources, as moderated and buffered by carbonate recycling. Because of these fluctuations, the marine Sr isotope record can be used for stratigraphic correlation and absolute dating ...
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Isotopes of Strontium: Properties and Applications

2019
The chapter gives an overview of properties and application of stable and radioactive isotopes of strontium. Natural strontium consists of the following four stable isotopes: 84Sr (0.56%), 86Sr (9.86%), 87Sr (7.00%), and 88Sr (82.58%). Among them, 87Sr is a radiogenic isotope being the decay product of the long-lived natural beta-emitting isotope 87Rb;
A. V. Voronina, Vladimir S. Semenishchev
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Radiochemical separation of strontium by isotopic exchange

Talanta, 1967
Isotopic exchange has been used for the rapid separation of minute quantities of radio-strontium. A number of variables such as agitation time, concentration of strontium in both phases, mode of preparation and aging of the precipitates, were studied and optimized.
M S Shahdo, S M Hasany, I H Qureshi
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Ground-state properties of strontium isotopes

Physical Review C, 1995
We present systematic constrained Hartree-Fock calculations of ground-state properties of even strontium isotopes ({ital A}=76--100) with the Skyrme interaction. Approximate projection of angular momentum is done after variation by explicit inclusion of the rotational energy {minus}{l_angle}{ital {cflx j}}{sup 2}{sub {ital x}}{r_angle}/J.
Andrzej Baran, Walter Höhenberger
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Permian strontium isotope stratigraphy

Geological Society, London, Special Publications, 2016
Abstract The secular evolution of the Permian seawater 87 Sr/ 86 Sr ratios carries information about global tectonic processes, palaeoclimate and palaeoenvironments, such as occurred during the Early Permian deglaciation, the formation of Pangaea and the Permian–Triassic (P–Tr) mass
Korte, C, Ullmann, CV
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Paleogeographic forcing of the strontium isotopic cycle in the Neoproterozoic

Gondwana Research, 2017
Abstract The period spanning from 825 to 540 Ma is characterized by major changes in the surficial Earth system. This extraordinary interval starts with the breakup of the Rodinia supercontinent and eruption of a series of large igneous provinces and ends with the assembly of Gondwana, giving rise to the Pan-African orogenies.
Goddéris, Yves, Le Hir, Guillaume, Macouin, Mélina, Donnadieu, Yannick, Hubert-Théou, Lucie, Dera, Guillaume, Aretz, Markus, Fluteau, Frédéric, Li, Z.X., Halverson, Galen   +9 more
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Isotopic Composition of Strontium in Carbonatites

Nature, 1962
THE origin of carbonatites has attracted increasing interest in recent years. The problem can be said to hinge on whether or not sedimentary carbonate rocks are involved in the formation of carbonatite. Since in general the strontium-87/strontium-86 ratios of sedimentary carbonate rocks1 differ from those of mafic igneous rocks2 we felt that a study of
J. L. Powell, J. L. Powell, P. M. Hurley, H. W. Fairbairn   +3 more
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Isotope exchange of strontium and molybdate ions in strontium polymolybdates

Journal of Radioanalytical and Nuclear Chemistry, 2002
The heterogeneous isotopic exchange reactions in strontium polymolybdates of Sr2+ and MoO42- ions in the strontium nitrate and sodium molybdate solutions have been studied using 90Sr and 99Mo as tracers. Electrometric methods have been used to study the compositions of strontium molybdates obtained by adding strontium chloride to a progressively ...
N. Bodur, Gülten Atun
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The Origin of Strontium and the Strontium Isotope Budget of the River Nile

Isotopes in Environmental and Health Studies, 1997
Abstract The river Nile has been used as an example to study the evolution of the Sr content and the Sr isotope ratios in rivers in dependence on rock types of the catchment areas, the mixing of the waters from tributaries, the levelling out in a reservoir and evaporation losses.
Farid Abou El Nour, G. Haase, H. Gerstenberger   +2 more
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