The half-life of87Rb measured as difference between the isotopes87Rb and85Rb

Neumann, W.; Huster, E.

doi:10.1007/bf01677443

Cited by 42 publications

(10 citation statements)

References 22 publications

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“…Rb-Sr ages were calculated using the least square regression technique of York (1969); errors are reported on the 2σ level. A decay constant of λRb 1.42 × 10 -11 /a -1 (Neumann & Huster, 1974) was used for age calculations. The analytical results and apparent ages are reported in Tables 3, 4 and 5.…”

Section: Methodsmentioning

confidence: 99%

Rb–Sr isotope studies on Tinos Island (Cyclades, Greece): additional time constraints for metamorphism, extent of infiltration-controlled overprinting and deformational activity

Bröcker¹,

1998

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This study presents new Rb-Sr age data concerning the metamorphic evolution of the AtticCycladic Crystalline Belt which represents a complex polymetamorphic terrane within the Alpidic orogenic belt of the Hellenides. Two major groups of tectonic units can be distinguished. Metamorphism in parts of the upper units is commonly considered as a Cretaceous event. In contrast, the group of lower units experienced Tertiary high-pressure metamorphism which was followed by a medium-pressure overprint. We focus on the island of Tinos where a representative spectrum of the rock units found in the Cyclades is exposed in three tectonic units: the Upper Unit, the Intermediate Unit and the Basal Unit. The complete range of tectono-metamorphic and magmatic events affecting the Attic-Cycladic Crystalline Belt is documented by numerous petrological and tectonic studies. Phyllites and phyllonites from the ophiolitic Upper Unit yielded Rb-Sr apparent ages (phengite-whole-rock) between c. 92 and 21 Ma. The older age differs from the Cretaceous dates reported for upper unit rocks elsewhere in the Cyclades. It is suggested that the sequence studied belongs to the Jurassic ophiolites of the Hellenides rather than to Cretaceous occurrences. The spread to younger ages is related to non-pervasive rejuvenation and resetting of the Rb-Sr system during tectonic juxtaposition of the Upper Unit over the Intermediate Unit. The youngest age obtained so far for a sample from the Upper Unit (21 Ma) is believed to approximate the timing of tectonic juxtaposition which probably occurred during a regional greenschist-facies episode producing a pervasive overprint in the structurally lower tectonic unit. The major phyllite/meta-gabbro/serpentinite sequence of the Upper Unit is interpreted as an emplacement-related ductile shear zone which experienced reworking under brittle conditions. In the Intermediate Unit, a gradient in Rb-Sr ages from top (c. 40 Ma) to the bottom (c. 22 Ma) was recognized, which is interpreted to represent greater effects of fluid infiltration and overprinting in the lower parts of this unit, possibly controlled by variable intensity of deformation which might be related to tectonic juxtaposition onto the Basal Unit. We suggest that synmetamorphic stacking of all three tectonic units took place during an Oligocene-Miocene greenschist event. Extensional deformation continued after tectonic stacking and after intrusion of the main granite, as is indicated by a Rb-Sr whole-rock isochron (15.1 ± 0.6 Ma) for a ductilely deformed garnet-bearing leucogranite from the marginal parts of the main undeformed pluton. Application of the Rb-Sr dating technique provided no unequivocal evidence that previously published Eocene K-Ar and 40 Ar-39 Ar dates for high-pressure phengites from the lower units are significantly contaminated with excess argon.

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Section: Methodsmentioning

confidence: 99%

Rb–Sr isotope studies on Tinos Island (Cyclades, Greece): additional time constraints for metamorphism, extent of infiltration-controlled overprinting and deformational activity

Bröcker¹,

1998

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“…Strontium has four stable isotopes: 84 Sr (0.56%), 86 Sr (9.86%), 87 Sr (7.0%), and 88 Sr (82.58%). The relative abundances of 84 Sr, 86 Sr, and 88 Sr are invariant, but 87 Sr is produced by beta decay from 87 Rb, which decays with a half-life of 4.88 Â 10 10 years (Neumann and Huster, 1974). The relative abundance of 87 Sr, expressed as the ratio of 87 Sr to 86 Sr or 87 Sr/ 86 Sr, varies according to both the original Rb/Sr ratio and the age of the sample (Faure and Mensing, 2005).…”

Section: Strontium Isotopes and The Study Of Human Mobilitymentioning

confidence: 99%

Megaliths and mobility in south-western Sweden. Investigating relationships between a local society and its neighbours using strontium isotopes

Sjögren

Price²,

Ahlström³

2009

Journal of Anthropological Archaeology

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“…Regression lines are calculated using the least-square-cubic method of York (1969). A decay constant for 87 Rb of 1.42 10 -11 a -1 (Neumann and Huster 1974) was used for all age calculations.…”

Section: Rb-srmentioning

confidence: 99%

Metapegmatites in the western Bohemian massif: ages of crystallisation and metamorphic overprint, as constrained by UPb zircon, monazite, garnet, columbite and RbSr muscovite data

Glodny

Grauert

Fiala

et al. 1998

Geologische Rundschau

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Granitic metapegmatites of two crystalline units of the western Bohemian massif, the Zone of Erbendorf-Vohenstrauss in Germany (ZEV), and the Zone of Teplá-Domažlice in the Czech Republic (ZTD) have been dated by means of U-Pb and Rb-Sr methods. Ages interpreted to reflect emplacement and crystallisation of the pegmatites were found consistently to be approximately 480 Ma, as constrained by U-Pb analyses of primary magmatic zircon, monazite, garnet and columbite, and by Rb-Sr analyses of large pegmatitic muscovites. Later Devonian amphibolite-facies metamorphism caused ductile shearing of the pegmatites, leading to partial recrystallisation of pegmatitic material. A metamorphic, fine-grained generation of muscovite yielded consistent Rb-Sr ages of 371-376 Ma for both the ZEV and the ZTD, interpreted as dating the end of deformational activity. The Rb-Sr system of the large pegmatitic muscovites turned out to remain closed up to metamorphic temperatures of >600°C. Deformation at elevated temperatures is identified as the dominant mechanism for opening of the Rb-Sr system of primary muscovites: apparent ages grade towards Devonian ages as the muscovites become more deformed and fragmented. The data derived from the metapegmatites point to a similar or common tectonometamorphic evolution for the ZEV and the ZTD since the Ordovician. Furthermore, the magmatic formation of granitic pegmatites implies an upper crustal Metapegmatites in the western Bohemian massif: ages of crystallisation and metamorphic overprint, as constrained by U-Pb zircon, monazite, garnet, columbite and Rb-Sr muscovite data Key words Bohemian massif ⋅ Metapegmatites ⋅ Geochronology ⋅ U-Pb ⋅ Rb-Sr ⋅ Granitic pegmatites ⋅ ZEV ⋅ KTB and their host rocks are semiconcordant due to common deformation, which has been stated before for some ZEV occurrences (Fischer 1968). The fact that metapegmatites are restricted to the medium-pressure metamorphic units, and unmetamorphosed pegmatites to the Moldanubian, im-plies that the two types of pegmatites are related to different events in host units of contrasting tectonometamorphic evolution.Previous petrological and geochronological investigations have demonstrated that the basement rocks of the ZTD 125

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The half-life of87Rb measured as difference between the isotopes87Rb and85Rb

Cited by 42 publications

References 22 publications

Rb–Sr isotope studies on Tinos Island (Cyclades, Greece): additional time constraints for metamorphism, extent of infiltration-controlled overprinting and deformational activity

Rb–Sr isotope studies on Tinos Island (Cyclades, Greece): additional time constraints for metamorphism, extent of infiltration-controlled overprinting and deformational activity

Megaliths and mobility in south-western Sweden. Investigating relationships between a local society and its neighbours using strontium isotopes

Metapegmatites in the western Bohemian massif: ages of crystallisation and metamorphic overprint, as constrained by UPb zircon, monazite, garnet, columbite and RbSr muscovite data

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The half-life of87Rb measured as difference between the isotopes87Rb and85Rb

Cited by 42 publications

References 22 publications

Rb–Sr isotope studies on Tinos Island (Cyclades, Greece): additional time constraints for metamorphism, extent of infiltration-controlled overprinting and deformational activity

Rb–Sr isotope studies on Tinos Island (Cyclades, Greece): additional time constraints for metamorphism, extent of infiltration-controlled overprinting and deformational activity

Megaliths and mobility in south-western Sweden. Investigating relationships between a local society and its neighbours using strontium isotopes

Metapegmatites in the western Bohemian massif: ages of crystallisation and metamorphic overprint, as constrained by UPb zircon, monazite, garnet, columbite and RbSr muscovite data

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Metapegmatites in the western Bohemian massif: ages of crystallisation and metamorphic overprint, as constrained by UPb zircon, monazite, garnet, columbite and RbSr muscovite data