Kiel University

Monazite is a light rare earth element LREE -bearing phosphate mineral. Crystals typically contain distinct chemical domains, each of which represent successive growth thru geologic history. Electron microprobe analysis can characterize the geometry and U-Th- total Pb age for each domain. This kind of data allow the growth of monazite to be related to geologic events affecting the host rock. Monazite is common in pelitic and psammitic metamorphic rocks at greenschist facies and above where it is often recognized as inclusions in porphyroblasts but may also be in direct connection with the matrix. Locating monazite grains can be done on standard geological thin sections via x-ray compositional mapping. Figure 7A reveals a cerium x-ray map on a quartzite sample from the Cheyenne belt. Peaks in cerium content may correlate to large monazite grains. Figure 8 shows compositional zonation on selected grains identified in figure 7.

Sulphate incorporation in monazite lattice and dating the cycle of sulphur in metamorphic belts

The sample, an osumilite-bearing ultra-high-temperature granulite from Rogaland, Norway, is characterized by complexly patchy zoned monazite crystals. Three chemical domains are distinguished as 1 a sulphate-rich core 0. This study illustrates that it is possible to discriminate different generations of monazite based on their S contents.

Abstract. Monazite laser ablation–split-stream inductively coupled plasma–mass spectrometry (LASS) was used to date monazite in situ in.

Petrology and Geodynamics. Neoproterozoic reworking of the Ubendian Belt crust: Implication for an orogenic cycle between the Tanzania Craton and Bangweulu Block during the assembly of Gondwana. Precambrian Research. Available online 6 December Journal of African Earth Sciences, The Braunschweig Meteorite — a recent L6 chondrite fall in Germany. Chemie der Erde – Geochemistry. Bial, J. Timing and conditions of regional metamorphism and crustal shearing in the granulite facies basement of south Namibia: Implications for the crustal evolution of the Namaqualand metamorphic basement in the Mesoproterozoic.

Journal of African Earth Sciences, — Granulite-facies metamorphic events in the northwestern Ubendian Belt of Tanzania: Implications for the Neoarchean to Paleoproterozoic crustal evolution. Precambrian Research, 31— The long-term high-temperature history of the central Namaqua Metamorphic Complex: Evidence for a Mesoproterozoic continental back-arc in southern Africa.

Coupling of in-situ Sm-Nd systematics and U-Pb dating of monazite and allanite

Dating xenotime. May also offer opportunities for life? U-Pb dates are enriched in studying the xenotime—garnet relationships provide. Apr 25, andhra pradesh. Precambrian research —

Monazite is a common accessory mineral occurring in a wide variety of rock types (sedimentary, metamorphic and magmatic), therefore allowing the dating of.

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Monazite geochronology (EPMA)

Economic Geology ; 3 : — The Jiaodong gold province, the largest gold producer in China, formed in a setting dominated by a m. This study presents new high precision in situ sensitive high-resolution ion microprobe SHRIMP U-Th-Pb and laser ablation-inductively coupled plasma-mass spectrometry LA-ICP-MS U-Pb ages for hydrothermal monazite from the largest of the Jiaodong gold deposits, which were previously dated as indicating ore formation over a few tens of millions of years when applying sericite Ar-Ar, zircon U-Pb, and less robust analytical techniques.

Our U-Pb dating on monazite from the Jiaojia and Linglong deposits in western Jiaodong yielded consistent ages at ca. In eastern Jiaodong, the much smaller resource may have formed about 5 m.

Monazite may therefore reveal the presence of S in anatectic melts from high-​grade terrains at a specific point in time and date S mobilization.

Jercinovic University of Massachusetts. Assumption: No non-radiogenic lead in monazite or at least very little. If you can precisely measure U, Th, and Pb in ppm , you can solve this equation iteratively for lead to obtain an age. Map thin section with the microprobe Ce, Fe, Y to find all monazite crystals. See an abstract of Williams et al. This sample is currently used at UMass to test analytical precision. This sample is a sillimanite nodule-quartz-muscovite schist.

The outcrop it was taken from is part of a screen of supracrustal rocks intruded by the1.

Monazite geochronology

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The hydrothermal monazite grains contain very low U, relatively low Th, and moderate Nd and La contents. SHRIMP U-Th-Pb dating of these.

This limitation precludes the analysis of both micrometre-scale discrete monazite grains and fine textures within monazite crystals that are commonly found in geological specimens. JavaScript is disabled for your browser. Some features of this site may not work without it. Nanoscale Isotopic Dating of Monazite. Access Status In process. Authors Fougerouse, Denis. Kirkland, Chris.

Electron Microprobe Dating of Monazite

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Monazite was analyzed via in-situ EMPA on the Ultrachron microprobe at the University of A combination of monazite and zircon dating techniques from each.

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. As a consequence, these phosphates can be dated using several fundamentally different isotopic techniques. Elsewhere in this volume Harrison et al.

Dating of minerals using radiogenic He was first explored shortly after the discovery of radioactivity Strutt and was investigated extensively in the s and s, mostly on very U- and Th-rich minerals such as zircon and titanite Hurley , ; Damon and Kulp , Damon and Green Apatite He dating was first investigated by Zeitler et al. Further studies both in the laboratory Lippolt et al. Monazite and xenotime have only recently come under scrutiny for He geochronology e.

Strefa Historii

Symposium on Geol. Resources of Madagascar – A good example of the usefulness of the in-situ dating method. Madagascar displays a huge portion of the lower crust and its study is fundamental for the understanding of the evolution of this part of the crust. Unfortunately, our knowledge of this domain is limited.

applicable to subgrain dating of monazite, zircon, polycrase-euxenite, xenotime and allanite. Various studies using the CHIME method have been successful in.

Hacker, M. Racek, R. Holder, A. Kylander-Clark, K. Schulmann, P. Monazite laser ablation—split-stream inductively coupled plasma—mass spectrometry LASS was used to date monazite in situ in Barrovian-type micaschists of the Moravian zone in the Thaya window, Bohemian Massif. Heterogeneously developed retrograde shear zones S 3 are marked by widespread chloritization, but minor chlorite is present in the studied samples.

(U-Th)/He Dating of Phosphates: Apatite, Monazite, and Xenotime

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The Application of Laser-Ablation Split-Stream ICP Petrochronology