Further Characterization of the RW-1 Monazite: A New Working Reference Material for Oxygen and Neodymium Isotopic Microanalysis

Abstract

The oxygen (O) and neodymium (Nd) isotopic composition of monazite provides an ideal tracer of metamorphism and hydrothermal activity. Calibration of the matrix effect and monitoring of the external precision of monazite O–Nd isotopes with microbeam techniques, such as secondary ion mass spectrometry (SIMS) and laser ablation-multicollector-inductively coupled plasma-mass spectrometry (LA-MC-ICPMS), require well-characterized natural monazite standards for precise microbeam measurements. However, the limited number of standards available is impeding the application of monazite O–Nd isotopes. Here, we report on the RW-1 monazite as a potential new working reference material for microbeam analysis of O–Nd isotopes. Microbeam measurements by electron probe microanalysis (EPMA), SIMS, and LA-MC-ICPMS at 10–24 µm scales have confirmed that it is homogeneous in both elemental and O–Nd isotopic compositions. SIMS measurements yield δ18O values consistent, within errors, with those obtained by laser fluorination techniques. Precise analyses of Nd isotope by thermal ionization mass spectrometry (TIMS) are consistent with mean results of LA-MC-ICPMS analyses. We recommend δ18O = 6.30‰ ± 0.16‰ (2SD) and 143Nd/144Nd = 0.512282 ± 0.000011 (2SD) as being the reference values for the RW-1 monazite.

Insights into Polyphase Phanerozoic Tectonic Events in SE China: Integrated Isotopic Microanalysis of Detrital Zircon and Monazite

“…The RW-1 standard was analysed as an unknown to determine the accuracy of the compositiondependent IMF. Seventeen measurements of RW-1 during this study yielded a mean δ 18 O = 6:33‰ ± 0:49‰ (2 SD), which is consistent with the recommended value of 6:30‰ ± 0:16‰ (2 SD; [76]).…”

“…As monazite could have crystallized during the magmatic, metamorphic, and hydrothermal events, specific geochemical characteristics are used to determine the origin(s) of the monazite (e.g., [85]). In general, hydrothermal monazite has lower Th contents and Th/Ce ratios than igneous and metamorphic monazite (Figure 8(a); [76,86]). Igneous monazite falls in the centre of the Si/Ce-Ca/Ce-Y/LREE diagram, while metamorphic monazite is scattered in the low Si/Ce and low Y/LREE fields (Figure 8(b); [76]).…”

“…In general, hydrothermal monazite has lower Th contents and Th/Ce ratios than igneous and metamorphic monazite (Figure 8(a); [76,86]). Igneous monazite falls in the centre of the Si/Ce-Ca/Ce-Y/LREE diagram, while metamorphic monazite is scattered in the low Si/Ce and low Y/LREE fields (Figure 8(b); [76]). Nearly all the 235 Ma monazite grains from the Yangjiang Cambrian metasandstone show geochemical features of metamorphic origins (Figure 8).…”

The emperor's new glass: The introduction of Carolingian wood ash glass in North Sea trade

“…The REE and HFSE in the Ribe wood ash glasses are controlled by the presence and volume of heavy minerals in the glassmaking sands as illustrated by the Nd/Lu ratio versus Hf (Figure 6a). The presence of monazite ((Ce,La,Th)PO 4 ) is the most likely mineral to explain the highly fractionated LREE and HREE patterns observed in the WA‐1 samples (Figures 3, 4, 6a; Wedepohl & Simon, 2010; Wu et al, 2019 among others). Note that apatite can produce HREE fractionated patterns, but only leading to Nd/Lu ratios up to about 300 and so cannot explain the highest observed values (Figure 6a).…”

Mineralogy, geochemistry and monazite U-Th-Pb geochronology of the Hakimpur banded iron formation deposit, Bangladesh: a petrogenetic study

“…granulite facies) (Kucha 1980). Thus, monazite [2REE(PO 4 )], cheralite [Ca,Th(PO 4 ) 2 ] and huttonite [2Th(SiO 4 )] form the three end members of a ternary system (Wu et al 2019). The average end-member compositions of the studied monazites comprise of 87.39 % monazite, 7.18 % huttonite and 5.44 % cheralite (Table IV), which are classified as monazite (Pyle et al 2001).…”