Lead diffusion in apatite and zircon using ion implantation and Rutherford Backscattering techniques

Cherniak, D. J.; Lanford, W. A.; Ryerson, Frederick J.

doi:10.1016/0016-7037(91)90137-t

Cited by 438 publications

(262 citation statements)

References 42 publications

Supporting

Mentioning

247

Contrasting

Unclassified

Order By: Relevance

“…The closure temperate of Pb diffusion in apatite is~350-500°C (Cherniak et al, 1991;Schoene and Bowring, 2007). The U-Pb apatite ages in this study (2188 ± 47 Ma for sample L1429 and 2258 ± 71 Ma for sample L1439) are broadly consistent with published ages from mineral systems with similar closure temperatures, such as K-Ar in hornblende.…”

supporting

confidence: 86%

See 1 more Smart Citation

Peak to post-peak thermal history of the Saglek Block of Labrador: A multiphase and multi-instrumental approach to geochronology

et al. 2018

View full text Add to dashboard Cite

A B S T R A C TThe Saglek Block of coastal Labrador forms the western margin of the North Atlantic Craton, where Archean gneisses and granulites have been reworked during the Paleoproterozoic. Previous work has established that the block is a composite of Eoarchean to Mesoarchean protoliths metamorphosed to upper amphibolite and granulite facies at around 2.8-2.7 Ga. New in-situ microbeam dating of accessory minerals in granoblastic gneisses reveals a complex peak to post-peak thermal history. Zircon growth at ca. 3.7-3.6 Ga provides the age of formation of the tonalitic protoliths to the gneisses. Further zircon growth in syn-tectonic granitic gneiss and monazite growth in a variety of orthogneisses confirm peak metamorphic conditions at ca. 2.7 Ga, but also reveal high-temperature conditions at ca. 2.6 Ga and 2.5 Ga. The former is interpreted as the waning stages of the 2.7 Ga granulite event, whereas the latter is associated with a younger phase of granitic magmatism. In addition, apatite ages of ca. 2.2 Ga may represent either cooling associated with the 2.5 Ga event or a previously unrecognized greenschist-facies metamorphism event that predates the Torngat Orogeny.

show abstract

supporting

confidence: 86%

“…Considering that the closure temperature for Pb diffusion in apatite (350-500°C; Cherniak et al, 1991) is lower than peak conditions for the formation of the host gneiss, the age could be interpreted as cooling subsequent to high-grade metamorphism at ca. 2.5 Ga.…”

Section: Sample L1429 Nulliak Islandmentioning

confidence: 99%

Peak to post-peak thermal history of the Saglek Block of Labrador: A multiphase and multi-instrumental approach to geochronology

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Radiogenic-Pb loss has been shown in some apatite systems to be solely, or at least dominantly, a function of thermally activated diffusion (Blackburn et al, 2011), a key requirement to use the mineral in thermochronometry modelling. In a situation of thermally activated volume diffusion it would be expected to observe distinct grain size populations that correspond to grain age populations; for example, a larger grain size population would correspond to an older age component, whereas a smaller grain size component may relate to a younger age component given Pb-in-apatite diffusion and spherical geometry characteristics (Cherniak, 2005;Cherniak et al, 1991). The histograms of grain age all indicate bimodal distributions whereas the grain size distributions are multimodal.…”

Section: Apatite Grain Size and Apparent Agementioning

confidence: 99%

“…The Pb diffusion closure temperature for apatite has been investigated by several workers (Cherniak, 2010;Cherniak et al, 1991;Krogstad and Walker, 1994) and Pb closure temperatures of around c.600°C for large 100-200 mm apatite grains have been suggested (Krogstad and Walker, 1994). However other studies, comparing dates from different isotopic systems, have implied a somewhat lower closure temperature of c. 400-500°C for apatite that may more generally apply (Chamberlain and Bowring, 2001).…”

Section: Radiogenic-pb Loss and New Apatite Growthmentioning

confidence: 99%

Apatite: a U-Pb thermochronometer or geochronometer?

Kirkland

Yakymchuk

Szilas

et al. 2018

Lithos

127

View full text Add to dashboard Cite

Apatite is an accessory mineral that is frequently found in both igneous and clastic sedimentary rocks. It is conventionally considered to be characterized by a closure temperature range between 375 and 600°C and hence has been employed to address mid-temperature thermochronology questions relevant to the reconstruction of thermal events in the middle to lower crust. However, questions remain as to whether apatite faithfully records thermally-activated volume diffusion profiles, or rather is influenced by recrystallization and new growth processes. We present a case study of two apatite samples from the Akia Terrane in Greenland that help chart some of the post magmatic history of this region. Apatite in a tonalitic gneiss has distinct U-enriched rims and its U-Pb apparent ages correlate with Mn chemistry, with a high Mn group yielding an age of c. 2813 Ma. The U-Pb and trace element chemistry and morphology support an interpretation in which these apatite crystals are originally igneous and record cooling after metamorphism, with subsequent generation of discrete new rims. Epidote observed in the sample implies a b600°C fluid infiltration event associated with apatite rims. The second sample, from a granitic leucosome, contains apparently homogeneous apatite, however U-Pb analyses define two distinct discordia arrays with different common Pb components. An older, c. 2490 Ma, component is associated with elevated Sr, whereas a younger, c. 1800 Ma, component has lower Sr concentration. A depth profile reveals an older core with progressively younger ages towards a compositionally discrete late Paleoproterozoic rim. The chemical and age profiles do not directly correspond, implying different diffusion rates between trace elements and U and Pb. The variation in core ages is interpreted to reflect radiogenic-Pb loss from a metamorphic population during new rim growth. The younger, c. 1800 Ma U-Pb age is interpreted to date new apatite growth from a compositionally distinct reservoir driven by tectonothermal and fluid activity, consistent with regional mica Ar-Ar ages. Results from these two samples show that recrystallization, dissolution and regrowth processes likely formed the younger rim overgrowths, and at temperatures below those often considered to be closure temperatures for Pb diffusion in apatite. The results from these samples imply many apatite grains may not record simple thermally activated Pb diffusion profiles and cautions against inversion of apatite U-Pb data to thermal histories without detailed knowledge of the grain growth/alteration processes.

show abstract

“…U-Pb-Pb phosphate ages: the closure temperature is given by Cherniak et al (1991). Phosphate U-Pb-Pb age data are from Table 6.…”

mentioning

confidence: 99%

Thermal evolution and sintering of chondritic planetesimals

Gail

Henke

Trieloff

2015

A&A

View full text Add to dashboard Cite

Context. Reconstruction of the thermal history of individual meteorites which can be assigned to the same parent body allows us to derive general characteristics of the parent body, such as its size and formation time, which hold important clues on the planetary formation process. This requires us to construct a detailed model of the heating of such a body by short lived radioactives, in particular by 26 Al, and its cooling by heat conduction, which may then be compared to the reconstructed cooling histories of the meteorites. Aims. The heat conductivity of the material from which planetesimals are composed depends critically on the porosity of the chondritic material. This changes during the process of compaction (also called sintering) of the material at elevated temperatures and pressures. Therefore, compaction of an initially granular material is a key process determining the thermal history of the parent bodies of meteorites. The most realistic modelling of sintering of chondritic material is required. Methods. The modelling of the compaction process is improved by applying concepts originally developed for the modelling of hot isostatic pressing in metallurgical processes, and by collecting data available from geosciences for the materials of interest. It is extended to a binary mixture of granular components of very different diameters -matrix and chondrules -as observed in chondrites.Results. By comparison with some published data on sintering experiments it is shown that the algorithm to follow the decrease of porosity of granular material during progressive sintering allows a sufficiently accurate modelling of the compaction of silicate material. The dependence of the compaction process on the nature of the precursor material, either matrix-dominated or chondruledominated, is discussed. It is shown that the characteristic temperature at which sintering occurs is different for matrix or chondruledominated precursor material. We apply the new method for calculating compaction to the evolution of the parent body of the H chondrites and determine an improved optimised set of model parameters for this body.

show abstract

Lead diffusion in apatite and zircon using ion implantation and Rutherford Backscattering techniques

Cited by 438 publications

References 42 publications

Peak to post-peak thermal history of the Saglek Block of Labrador: A multiphase and multi-instrumental approach to geochronology

Peak to post-peak thermal history of the Saglek Block of Labrador: A multiphase and multi-instrumental approach to geochronology

Apatite: a U-Pb thermochronometer or geochronometer?

Thermal evolution and sintering of chondritic planetesimals

Contact Info

Product

Resources

About