Fletcher, Birger Rasmussen , Neal Mcnaughton. N2 – SHRIMP Sensitive High-Resolution Ion MicroProbe analytical procedures have been developed to enable dating of the small, early diagenetic xenotime overgrowths that commonly occur on zircons in siliciclastic sedimentary rocks. The method will be particularly useful in Precambrian terranes, where diagenetic xenotime dating could play a role equivalent to biostratigraphic dating in the Phanerozoic. In contrast, greenschist-facies metasediments of the Archaean Witwatersrand Basin, South Africa, contain both authigenic and alteration xenotime that record a complex history of growth from early diagenesis to the last major thermal event to affect the basin. Overview Fingerprint. Abstract SHRIMP Sensitive High-Resolution Ion MicroProbe analytical procedures have been developed to enable dating of the small, early diagenetic xenotime overgrowths that commonly occur on zircons in siliciclastic sedimentary rocks. Access to Document
SHRIMP U-Pb geochronology of authigenic xenotime and its potential for dating sedimentary basins
Skup 21st meeting of the International Mineralogical Association. They formed during Sveconorwegian orogeny around 1 Ga ago. The electron microprobe analysis gave a monazite- Ce composition for both monazite samples concerned, with Ce2O3 ranging from The xenotime- Y sample contains
Title: SHRIMP Uranium-Lead Dating of Diagenetic Xenotime in Siliciclastic Sedimentary Rocks. Author(s): Neal J. McNaughton, Birger Rasmussen, and Ian R.
Data points are arrayed linearly and enable us to define an isochron which passes through the origin. The chemical Th-U-total Pb isochron ages coincide well with mineral and whole-rock ages isotopically determined for the same samples. The chemical Th-U-total Pb isochron method was applied to the age determination of monazite, zircon and xenotime from the Tsubonosawa paragneiss and the host Hikami granite in the South Kitakami terrane of Northeast Japan.
The Ma event corresponds to the intrusion of the Hikami granite, and the Ma one to the intrusion of the Cretaceous Kesengawa granite. The and Ma events may correspond in age to the main metamorphic event and subsequent igneous activity in the Hida terrane, central Japan. The chemical Th-U-total Pb isochron age in terms of the precise microprobe analysis of low-level Th, U and Pb will open a new vista on the Paleozoic-Mesozoic tectonics of the Japanese Islands.
Precambrian provenance and Silurian metamorphism of the Tsubonosawa paragneiss in the South Kitakami terrane, Northeast Japan, revealed by the chemical Th-U-total Pb isochron ages of monazite, zircon and xenotime.
SHRIMP Uranium-Lead Dating of Diagenetic Xenotime in Siliciclastic Sedimentary Rocks
Farley, Kenneth A. Reviews in Mineralogy and Geochemistry. ISBN
Tatry Mountains orthogneisses Western Carpathians,. Box , 05 Bratislava, Slovak Republic;. Manuscript received September 12, ; accepted in revised form March 16, Biotite- hosted monazite is commonly overgrown by thin REE-epidote rims, in a less foliated sample it is apparently unstable and breaks down to apatite, REE-epidote and a Th-silicate huttonite?
Empirical thermometers based on Y in monazite give — Extensive dating by Cameca SX microprobe yielded a range of ages: the.
SHRIMP uranium-lead dating of diagenetic xenotime in siliciclastic sedimentary rocks
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.
U-Pb zircon-xenotime-monazite dating and Hf-isotope tracing to distinguish Cretaceous and Paleogene granitoids in the Western Rhodopes and Rila Mountain.
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, , — Precise U-Pb and Th-Pb age determination of kimberlitic perovskites by secondary ion mass spectrometry. Chem Geol, , — In situ U-Pb age determination and Nd isotopic analysis of perovskites from kimberlites in southern Africa and Somerset Island, Canada.
Lithos, , —
Helium Diffusion in Natural Xenotime
Dating xenotime. May also offer opportunities for life? U-Pb dates are enriched in studying the xenotime—garnet relationships provide. Apr 25, andhra pradesh.
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.
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(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.
SHRIMP (Sensitive High-Resolution Ion MicroProbe) analytical procedures have been developed to enable dating of the small, early diagenetic xenotime.
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.