(U-Th)/He Dating of Phosphates: Apatite, Monazite, and Xenotime
John N. Aleinikoff, a Karen Lund, a C. Mark Fanning b a U. The Belt—Purcell Supergroup, northern Idaho, western Montana, and southern British Columbia, is a thick succession of Mesoproterozoic sedimentary rocks with an age range of about — Ma. Stratigraphic layers within several sedimentary units were sampled to apply the new technique of U—Pb dating of xenotime that sometimes forms as rims on detrital zircon during burial diagenesis; xenotime also can form epitaxial overgrowths on zircon during hydrothermal and metamorphic events. Additionally, all samples that yielded xenotime were also processed for detrital zircon to provide maximum age constraints for the time of deposition and information about provenances; the sample of Prichard Formation yielded monazite that was also analyzed.
In situ UPb dating of xenotime by laser ablation ( LA )-ICP-MS
Xenotime is a rare-earth phosphate mineral , the major component of which is yttrium orthophosphate Y P O 4. It forms a solid solution series with chernovite- Y Y As O 4 and therefore may contain trace impurities of arsenic , as well as silicon dioxide and calcium. The rare-earth elements dysprosium , erbium , terbium and ytterbium , as well as metal elements such as thorium and uranium all replacing yttrium are the expressive secondary components of xenotime. Due to uranium and thorium impurities, some xenotime specimens may be weakly to strongly radioactive.
Lithiophyllite , monazite and purpurite are sometimes grouped with xenotime in the informal “anhydrous phosphates” group. Xenotime is used chiefly as a source of yttrium and heavy lanthanide metals dysprosium, ytterbium, erbium and gadolinium.
Xenotime is an ideal mineral for U-Th-Pb isotopic dating because of its relatively high U and Th contents, but typically low concentration of common Pb. These characteristics, and the fact that it is widespread throughout various types of rocks, suggest that the U-Th-Pb dating of xenotime has broad applications. To evaluate the reliability of our method, a xenotime standard, BS-1, was analyzed and calibrated against another xenotime standard, MG We also analyzed xenotimes in leucogranites from South Tibet and granites from Xihuashan in southern China, and obtained accurate and precise ages.
The matrix-effect resulted in either under-correction or over-correction of fractionation, and thus led to inaccurate ages. Download to read the full article text. Paragenesis and U-Pb systematics of baddeleyite ZrO 2. Chem Geol, , 95— Precambrian Res, , —
Canadian Journal of Earth Sciences
Agard, P. Jolivet, and B. DOI : Allaz, B. Selleck, M. Williams, and M.
ºC for xenotime-bearing samples. Extensive dating by Cameca SX microprobe yielded a range of ages: the. majority of data cluster around — Ma.
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Clicking on the donut icon will load a page at altmetric. Find more information on the Altmetric Attention Score and how the score is calculated. The U—Pb geochronologic analysis of accessory minerals has played an important role in Earth and solar system science in constraining the ages of a wide variety of rocks and minerals. Currently, the significant matrix effects observed between different accessory minerals and the lack of high-quality standards for many minerals of interest are the major limitations of its geochronological applications.
In this study, we investigated the effects of the addition of oxygen, nitrogen, and water vapor before and after the ablation cell on the accuracy of the U—Pb dating of different minerals e. We found that the addition of water vapor, unlike that of oxygen and nitrogen, before the ablation cell can significantly suppress the matrix effects on U—Pb dating. This can be attributed to the suppression of elemental fractionation in both the laser ablation and ICP ionization processes by the presence of water vapor.
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SHRIMP U-Pb geochronology of authigenic xenotime and its potential for dating sedimentary basins
Farley, Kenneth A. Reviews in Mineralogy and Geochemistry. ISBN Full text is not posted in this repository. Consult Related URLs below. For example, apatite usually has a few tens of ppm of both U and Th, while monazite and xenotime usually have hundreds of ppm to weight percent levels of these elements.
1 State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing , China; 2 Graduate.
Official websites use. Share sensitive information only on official, secure websites. The Belt—Purcell Supergroup, northern Idaho, western Montana, and southern British Columbia, is a thick succession of Mesoproterozoic sedimentary rocks with an age range of about — Ma. Stratigraphic layers within several sedimentary units were sampled to apply the new technique of U—Pb dating of xenotime that sometimes forms as rims on detrital zircon during burial diagenesis; xenotime also can form epitaxial overgrowths on zircon during hydrothermal and metamorphic events.
Additionally, all samples that yielded xenotime were also processed for detrital zircon to provide maximum age constraints for the time of deposition and information about provenances; the sample of Prichard Formation yielded monazite that was also analyzed. We interpret the Prichard xenotime as diagenetic in origin. Monazite from the Prichard Formation, originally thought to be detrital, yielded Cretaceous metamorphic ages.
Xenotime from the McNamara and Garnet Range Formations and Pilcher Quartzite formed at about — Ma, several hundred million years after deposition, and probably also experienced Early Cretaceous growth. These xenotime overgrowths are interpreted as metamorphic—diagenetic in origin i. Several xenotime grains are older detrital grains of igneous derivation.
A previous study on the Revett Formation at the Spar Lake Ag—Cu deposit provides data for xenotime overgrowths in several ore zones formed by hydrothermal processes; herein, those results are compared with data from newly analyzed diagenetic, metamorphic, and magmatic xenotime overgrowths. The origin of a xenotime overgrowth is reflected in its rareearth element REE pattern. Detrital i. Because these characteristics seem to be process related, they may be useful for interpretation of xenotime of unknown origin.
Diagenetic xenotime dating to constrain the initial depositional time of the Yan-Liao Rift
Earth phosphate, as to constrain the in siliciclastic. U—Pb dating of heavy rare earth phosphate minerals grew. Dating of u—pb and xenotime in studying the major shareholders. U—Pb dating sites, namibia: dating sites, allanite and pennine. Analyses of unusually low lree: dating ‘bulk’ phosphates apatite monazite samples from a simple.
Among the up-to-date pieces of equipment there are three solid-source mass as zircon, monazite, baddeleyite, titanite, rutile, apatite, allanite, xenotime and.
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SHRIMP Uranium-Lead Dating of Diagenetic Xenotime in Siliciclastic Sedimentary Rocks
Data Portal List. Spatio-Temporal Dataset Search. Data Portal Monitor. Dataset Information. Title The age of the Telfer Au-Cu deposit and its relationship with granite emplacement, Paterson Province, Western Australia Description Dating of granites from the Telfer Region of the Paterson Province shows that felsic magmatism took place between ca.
Stratigraphic layers within several sedimentary units were sampled to apply the new technique of U–Pb dating of xenotime that sometimes.
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