This article was accepted into the corpus but its outbound wikilinks were never NER-processed — typical at the deepest BFS hop or when the run's entity cap was reached. No expansion funnel to show.
| Rb–Sr dating | |
|---|---|
| Name | Rubidium–strontium dating |
| Type | Radiometric dating |
| Isotope | Rubidium-87 to Strontium-87 |
| Parent | Rubidium |
| Daughter | Strontium |
| Decay mode | Beta decay |
| Half life | ~4.88×10^10 years |
| Primary used for | Age determination of rocks and meteorites |
Rb–Sr dating is a radiometric technique that uses the beta decay of Rubidium-87 to Strontium-87 to determine the ages of minerals, rocks, and meteorites. Developed in the mid‑20th century, the method links isotope geochemistry, laboratory mass spectrometry, and field petrology to yield absolute crystallization ages, thermal histories, and provenance information. It is widely applied in studies involving the Precambrian, Paleozoic, and Hadean eons as well as investigations of lunar samples returned by the Apollo program.
The Rb–Sr system exploits the decay of the long‑lived parent nuclide Rubidium-87 to the radiogenic daughter Strontium-87, with analytical comparisons to the non‑radiogenic isotope Strontium-86. Core practitioners include laboratories at institutions such as Carnegie Institution for Science, Massachusetts Institute of Technology, Caltech, and Smithsonian Institution. Key field sites range from the Isua supracrustal belt to the Barberton Greenstone Belt and the Murray Formation (Mars) analog studies, linking cosmochemistry, tectonics, and stratigraphy in major programs supported by agencies like NASA and the National Science Foundation.
The theoretical foundation rests on radioactive decay laws developed after the work of Ernest Rutherford and formalized by physicists including Niels Bohr and Enrico Fermi. The isochron method, first popularized by scientists such as Alfred O. Nier and Clair Patterson, plots the ratio of radiogenic Strontium-87 to Strontium-86 against the ratio of Rubidium-87 to Strontium-86 for coeval samples. A linear isochron implies a closed system since formation, with slope proportional to e^(λt)−1 where λ is the decay constant determined in studies linked to laboratories at University of Cambridge, University of Chicago, and Columbia University. The intercept yields the initial Strontium isotopic composition, crucial for correlating events across provinces like the Canadian Shield and the Fennoscandian Shield.
Sample selection draws on field work in terrains studied by groups at United States Geological Survey, Geological Survey of Canada, and university departments such as University of Oxford and University of California, Berkeley. Mineral separation often targets phases like muscovite, biotite, K‑feldspar, plagioclase, and whole‑rock fractions. Chemical separation uses ion‑exchange procedures developed in part at Los Alamos National Laboratory and mass spectrometric analysis employs thermal ionization mass spectrometers and multi‑collector inductively coupled plasma mass spectrometers pioneered at Argonne National Laboratory and Scripps Institution of Oceanography. Quality control references isotopic standards maintained by International Atomic Energy Agency and interlaboratory comparison exercises coordinated with American Geophysical Union meetings.
Rb–Sr ages have constrained the timing of orogenies such as the Appalachian Mountains and the Himalayas, and have dated magmatic suites from provinces like the Deccan Traps and Siberian Traps. In sedimentary provenance studies it complements detrital zircon U–Pb work from locales such as the Williston Basin and Chengjiang deposits. Planetary applications include age determinations of lunar samples from Mare Imbrium and chondritic meteorites sampled in collections connected to Smithsonian Institution curatorial programs and missions by European Space Agency. Geochronologists integrate Rb–Sr results with thermochronology techniques applied at Lamont–Doherty Earth Observatory and basin analysis carried out with collaborators at Stanford University.
Rb–Sr dating assumes isotopic closure; disturbance by metamorphism, hydrothermal alteration, or weathering—documented in studies of the Greenland craton and Pilbara craton—can reset the system. Common issues include initial strontium heterogeneity, open‑system behavior observed in contact metamorphism near igneous intrusions like the Sierra Nevada batholith, and analytical biases arising from isobaric interferences addressed in work at Oak Ridge National Laboratory. Interpretation also depends on accurate decay constants established through experiments at institutions such as National Institute of Standards and Technology, and on correct mineral selection informed by petrologists from Princeton University and University of Michigan.
The method evolved alongside radiometric dating pioneers including Arthur Holmes and Clair Patterson, with technical advances from mass spectrometry innovators at California Institute of Technology and radiochemical techniques refined at University of California, San Diego. Key milestones include early whole‑rock isochron studies in the Canadian Shield and calibration of the decay constant through international collaborations involving Max Planck Institute for Chemistry and University of Tokyo. The technique’s application expanded during the Cold War era in programs at Lawrence Berkeley National Laboratory and later in planetary science following analyses of samples returned by the Apollo program.
Landmark results include age constraints on the formation of the Moon derived from analyses of Mare Imbrium samples, timing of Precambrian crust formation in the Canadian Shield and Yilgarn Craton, and dating of continental flood basalts in the Deccan Traps tied to mass extinction studies involving researchers from Brown University and Harvard University. Rb–Sr isochrons have been instrumental in resolving debates over the age of the Isua supracrustal rocks and in corroborating ages from U–Pb dating of accessory minerals in investigations by teams at ETH Zurich and Australian National University.
Category:Geochronology Category:Radiometric dating Category:Geochemistry