Jilin Zircon – A New Natural Reference Material for Microbeam U-Pb Geochronology and Hf-O Isotopic Analysis

Author(s):  
Tao Luo ◽  
Qiuli Li ◽  
Xiaoxiao Ling ◽  
Yang Li ◽  
Chuan Yang ◽  
...  

Zircon U-Pb geochronology and Hf-O isotope composition can provide important information on geological events. The matrix-matched reference material is routinely used to yield accurate and precise zircon U-Pb ages and...

2016 ◽  
Vol 31 (4) ◽  
pp. 948-960 ◽  
Author(s):  
Yuichiro Nagai ◽  
Tetsuya Yokoyama

We developed a new, highly precise, and accurate Mo isotope analysis by thermal ionization mass spectrometry in negative ionization mode (N-TIMS) by determining the in situ O isotope composition for each measurement and using the data to correct for the O isotope interferences.


Minerals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 94
Author(s):  
Xiaoxue Tong ◽  
Kaarel Mänd ◽  
Yuhao Li ◽  
Lianchang Zhang ◽  
Zidong Peng ◽  
...  

Banded iron formations (BIFs) are enigmatic chemical sedimentary rocks that chronicle the geochemical and microbial cycling of iron and carbon in the Precambrian. However, the formation pathways of Fe carbonate, namely siderite, remain disputed. Here, we provide photomicrographs, Fe, C and O isotope of siderite, and organic C isotope of the whole rock from the ~2.52 Ga Dagushan BIF in the Anshan area, China, to discuss the origin of siderite. There are small magnetite grains that occur as inclusions within siderite, suggesting a diagenetic origin of the siderite. Moreover, the siderites have a wide range of iron isotope compositions (δ56FeSd) from −0.180‰ to +0.463‰, and a relatively negative C isotope composition (δ13CSd = −6.20‰ to −1.57‰). These results are compatible with the reduction of an Fe(III)-oxyhydroxide precursor to dissolved Fe(II) through microbial dissimilatory iron reduction (DIR) during early diagenesis. Partial reduction of the precursor and possible mixing with seawater Fe(II) could explain the presence of siderite with negative δ56Fe, while sustained reaction of residual Fe(III)-oxyhydroxide could have produced siderite with positive δ56Fe values. Bicarbonate derived from both DIR and seawater may have provided a C source for siderite formation. Our results suggest that microbial respiration played an important role in the formation of siderite in the late Archean Dagushan BIF.


2021 ◽  
Vol 25 (2) ◽  
pp. 98-109
Author(s):  
P. A. Otopkova ◽  
◽  
A. M. Potapov ◽  
A. I. Suchkov ◽  
A. D. Bulanov ◽  
...  

In order to study the isotopic effects in semiconductor materials, single crystals of high chemical and isotopic purity are required. The reliability of the obtained data on the magnitude and the direction of isotopic shifts depends on the accuracy of determining the concentration of all stable isotopes. In the isotopic analysis of enriched “silicon-28” with a high degree of enrichment (> 99.99%), it is necessary to determine the impurities of 29Si and 30Si isotopes at the level of 10-3 ¸ 10-5 at. %. At this concentration level, these isotopes can be considered as impurities. It is difficult to achieve high measurement accuracy with simultaneous registration of the main and “impurity” isotopes in such a wide range of concentrations. The registration of analytical signals of silicon isotopes must be carried out in the solutions with different matrix concentrations. The use of the solutions with the high concentration of the matrix element requires the introduction of corrections for matrix noise and the drift of the instrument sensitivity during the measurement. It is possible to reduce the influence of the irreversible non-spectral interference and sensitivity drift by using the method of internal standardization. The inconsistency of the literature data on the selection criteria for the internal standard required studying the behavior of the signals of the “candidates for the internal standard” for the ELEMENT 2 single-collector high-resolution inductively coupled plasma mass spectrometer on the matrix element concentration and the nature of the solvent, as well as on the solution nebulizing time. Accounting for the irreversible non-spectral matrix noise and instrumental drift in isotopic analysis of enriched “silicon-28” and initial 28SiF4 by inductively coupled plasma mass spectrometry had allowed us to reduce by 3-5 times the random component and by more than an order of magnitude the systematic component of the measurement error in comparison with the external standard method. This made it possible to carry out, with sufficient accuracy, the operational control of the isotopic composition of enriched “silicon-28”, both in the form of silicon tetrafluoride and polycrystalline silicon obtained from it, using a single serial device in the range of isotopic concentrations 0.0001–99.999%.


2020 ◽  
Vol 63 (11) ◽  
pp. 1780-1790
Author(s):  
Qindi Wei ◽  
Hao Wang ◽  
Yueheng Yang ◽  
Jinhui Yang ◽  
Chao Huang ◽  
...  
Keyword(s):  

2019 ◽  
Vol 34 (3) ◽  
pp. 561-569
Author(s):  
Axel K. Schmitt ◽  
Ming-Chang Liu ◽  
Issaku E. Kohl

High-spatial resolution O-isotope analysis of nephrite by SIMS allows rapid identification of provenance with applications in geology, archaeometry, and gemmology.


2019 ◽  
Vol 104 (10) ◽  
pp. 1503-1520 ◽  
Author(s):  
Katharina Marger ◽  
Cindy Luisier ◽  
Lukas P. Baumgartner ◽  
Benita Putlitz ◽  
Barbara L. Dutrow ◽  
...  

Abstract A series of tourmaline reference materials are developed for in situ oxygen isotope analysis by secondary ion mass spectrometry (SIMS), which allow study of the tourmaline compositions found in most igneous and metamorphic rocks. The new reference material was applied to measure oxygen isotope composition of tourmaline from metagranite, meta-leucogranite, and whiteschist from the Monte Rosa nappe (Western Alps). The protolith and genesis of whiteschist are highly debated in the literature. Whiteschists occur as 10 to 50 m tube-like bodies within the Permian Monte Rosa granite. They consist of chloritoid, talc, phengite, and quartz, with local kyanite, garnet, tourmaline, and carbonates. Whiteschist tourmaline is characterized by an igneous core and a dravitic overgrowth (XMg > 0.9). The core reveals similar chemical composition and zonation as meta-leucogranitic tourmaline (XMg = 0.25, δ18O = 11.3–11.5‰), proving their common origin. Dravitic overgrowths in whiteschists have lower oxygen isotope compositions (8.9–9.5‰). Tourmaline in metagranite is an intermediate schorl-dravite with XMg of 0.50. Oxygen isotope data reveal homogeneous composition for metagranite and meta-leucogranite tourmalines of 10.4–11.3‰ and 11.0–11.9‰, respectively. Quartz inclusions in both meta-igneous rocks show the same oxygen isotopic composition as the quartz in the matrix (13.6–13.9‰). In whiteschist the oxygen isotope composition of quartz included in tourmaline cores lost their igneous signature, having the same values as quartz in the matrix (11.4–11.7‰). A network of small fractures filled with dravitic tourmaline can be observed in the igneous core and suggested to serve as a connection between included quartz and matrix, and lead to recrystallization of the inclusion. In contrast, the igneous core of the whiteschist tourmaline fully retained its magmatic oxygen isotope signature, indicating oxygen diffusion is extremely slow in tourmaline. Tourmaline included in high-pressure chloritoid shows the characteristic dravitic overgrowth, demonstrating that chloritoid grew after the metasomatism responsible for the whiteschist formation, but continued to grow during the Alpine metamorphism. Our data on tourmaline and quartz show that tourmaline-bearing white-schists originated from the related meta-leucogranites, which were locally altered by late magmatic hydrothermal fluids prior to Alpine high-pressure metamorphism.


Author(s):  
L. Angiolini ◽  
D. P. F. Darbyshire ◽  
M. H. Stephenson ◽  
M. J. Leng ◽  
T. S. Brewer ◽  
...  

ABSTRACTThe Lower Permian of the Haushi basin, Interior Oman (Al Khlata Formation to Saiwan Formation/lower Gharif member) records climate change from glaciation, through marine sedimentation in the Haushi sea, to subtropical desert. To investigate the palaeoclimatic evolution of the Haushi Sea we used O, C, and Sr isotopes from 31 brachiopod shells of eight species collected bed by bed within the type-section of the Saiwan Formation. We assessed diagenesis by scanning electron microscopy of ultrastructure, cathodoluminescence, and geochemistry, and rejected fifteen shells not meeting specific preservation criteria. Spiriferids and spiriferinids show better preservation of the fibrous secondary layer than do orthotetids and productids and are therefore more suitable for isotopic analysis. δ18O of −3·7 to −3·1℅ from brachiopods at the base of the Saiwan Formation are probably related to glacial meltwater. Above this, an increase in δ18O may indicate ice accumulation elsewhere in Gondwana or more probably that the Haushi sea was an evaporating embayment of the Neotethys Ocean. δ13C varies little and is within the range of published data: its trend towards heavier values is consistent with increasing aridity and oligotrophy. Saiwan Sr isotope signatures are less radiogenic than those of the Sakmarian LOWESS seawater curve, which is based on extrapolation between few data points. In the scenario of evaporation in a restricted Haushi basin, the variation in Sr isotope composition may reflect a fluvial component.


2020 ◽  
Author(s):  
Malin Andersson ◽  
Valentin Troll ◽  
Martin Whitehouse ◽  
Frances Deegan ◽  
Karin Högdahl ◽  
...  

<p>Sweden is responsible for over 90% of the iron ore production in the European Union, the bulk of which originates from the Kiruna-Malmberget region in northern Sweden, the type locality for Kiruna-type apatite-iron oxide ores. Despite thorough investigations of these long known deposits, their origin is still debated. Currently, two main formation theories are discussed: formation by orthomagmatic processes (Nyström & Henriquez 1994; Troll et al. 2019), versus hydrothermal processes (Hitzman et al. 1992; Smith et al. 2013).</p><p>Secondary ion mass spectrometry (SIMS) analysis allows gathering of more detailed information regarding intra-crystal variations, such as core to rim growth zonations, than bulk analysis do. Measurements of δ<sup>56</sup>Fe and δ<sup>18</sup>O in Kiruna-type magnetites by SIMS would therefore aid in the determination of their main formation process. However, there are conflicting studies regarding crystallographic orientation effects of δ<sup>56</sup>Fe and δ<sup>18</sup>O in magnetite, and while some authors found that the isotope ratios varied depending on how the crystal was oriented (e.g. Huberty et al. 2010), others found no such effects (e.g. Marin-Carbonne et al. 2011). This research project thus aims to further examine any effects of crystal orientation on Fe and O isotope signatures and identify a suitable magnetite reference material for SIMS analysis. To enable comparison between isotope ratios and crystal orientations, the sample orientations will therefore be determined by electron backscatter diffraction (EBSD) prior to SIMS analysis. SIMS analysis require reference material mounted next to the sample for continuous corrections during analysis. Different magnetite samples will now be tested for usage as reference materials. If a homogeneous reference material is found, future studies can utilise it for further investigations of the formation of Kiruna-type magnetite, as well as any other research concerning δ<sup>56</sup>Fe or δ<sup>18</sup>O in magnetite.</p><p>Hitzman, M.W., Oreskes, N., & Einaudi, M.T. (1992). Geological characteristics and tectonic setting of proterozoic iron oxide (Cu-U-Au-REE) deposits. Precambrian Research. Precambrian Metallogeny Related to Plate Tectonics, vol. 58 (1), pp. 241–287. DOI:10.1016/0301-9268(92)90121-4.</p><p>Huberty, J.M., Kita, N.T., Kozdon, R., Heck, P.R., Fournelle, J.H., Spicuzza, M.J., Xu, H., & Valley, J. W. (2010). Crystal orientation effects in 18O for magnetite and hematite by SIMS. Chemical Geology, vol. 276 (3), pp. 269–283. DOI:10.1016/j.chemgeo.2010.06.012.</p><p>Marin-Carbonne, J., Rollion-Bard, C., & Luais, B. (2011). In-situ measurements of iron isotopes by SIMS: MC-ICP-MS intercalibration and application to a magnetite crystal from the Gunflint chert. Chemical Geology, vol. 285 (1), pp. 50–61. DOI:10.1016/j.chemgeo.2011.02.019.</p><p>Nyström, J.O. & Henriquez, F. (1994). Magmatic features of iron ores of the Kiruna type in Chile and Sweden; ore textures and magnetite geochemistry. Economic Geology, vol. 89(4), pp. 820–839. DOI:10.2113/gsecongeo.89.4.820.</p><p>Smith, M.P., Gleeson, S.A., & Yardley, B.W.D. (2013). Hydrothermal fluid evolution and metal transport in the Kiruna District, Sweden: Contrasting metal behaviour in aqueous and aqueous–carbonic brines. Geochimica et Cosmochimica Acta, vol. 102, pp. 89–112. DOI:10.1016/j.gca.2012.10.015.</p><p>Troll, V.R., Weis, F.A., Jonsson, E., Andersson, U.B., Majidi, S.A., Högdahl, K., Harris, C., Millet, M.-A., Chinnasamy, S.S., Kooijman, E., &Nilsson, K.P. (2019). Global Fe–O isotope correlation reveals magmatic origin of Kiruna-type apatite-iron-oxide ores. Nature Communications, vol. 10(1), pp. 1712. DOI:10.1038/s41467-019-09244-4.</p>


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