Origin of Monte Rosa whiteschist from in-situ tourmaline and quartz oxygen isotope analysis by SIMS using new tourmaline reference materials

2019 ◽  
Vol 104 (10) ◽  
pp. 1503-1520 ◽  
Author(s):  
Katharina Marger ◽  
Cindy Luisier ◽  
Lukas P. Baumgartner ◽  
Benita Putlitz ◽  
Barbara L. Dutrow ◽  
...  
Keyword(s):  
High Pressure ◽  
Oxygen Isotope ◽  
Reference Materials ◽  
Secondary Ion Mass Spectrometry ◽  
Isotope Composition ◽  
Isotope Analysis ◽  
Oxygen Isotope Composition ◽  
The Matrix ◽  
Monte Rosa

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.

scholarly journals Beryl Reference Materials for In Situ Oxygen Isotope Determination

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1322
Author(s):  
Xiaoxiao Ling ◽  
Qiuli Li ◽  
Lianjun Feng ◽  
Di Zhang ◽  
Yu Liu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Oxygen Isotope ◽  
Reference Materials ◽  
Secondary Ion Mass Spectrometry ◽  
Isotope Analysis ◽  
High Sensitivity ◽  
Isotope Ratio Mass Spectrometry ◽  
Isotopic Analysis ◽  
Good Tool

The mineral beryl (Be3Al2(SiO3)6) has the most abundant phase with industrial value for extracting a critical metal—beryllium. Due to multi-stage, fluid-induced growth, individual beryl grains may yield complex geochemical records, revealing variations in the oxygen isotopes of the fluids from which they crystallize. Secondary ion mass spectrometry (SIMS) with high sensitivity and high spatial resolution represents a good tool for in situ isotopic analysis. SIMS oxygen analyses require matrix-matched reference materials to calibrate instrumental mass fractionations during measurement. In this work, the oxygen isotope homogeneities of six beryl samples with different compositions (BS1, BS2, BS3, BS4, BS5, and BS6) were documented by SIMS. These samples’ recommended oxygen isotope compositions were characterized by laser fluorination isotope ratio mass spectrometry (IRMS). This study suggests that there is no matrix effect related to composition variation in beryl SIMS oxygen isotope analysis. The recommended δ18O values of the four reference materials, BS1, BS2, BS4, and BS5, were 15.01 ± 0.34‰ (2 standard deviations, 2 SD), 7.53 ± 0.16‰ (2 SD), 2.38 ± 0.14‰ (2 SD), and 10.72 ± 0.44‰ (2 SD), respectively. Therefore, BS1, BS2, BS4, and BS5 are recommended as suitable reference materials for in situ mineral beryl oxygen isotope microanalysis.

scholarly journals Potential Reference Materials for Hematite Oxygen Isotope Analysis

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 987
Author(s):  
Lianjun Feng ◽  
Hongwei Li ◽  
Tiejun Li
Keyword(s):  
Oxygen Isotope ◽  
Iron Oxides ◽  
Oxygen Isotopes ◽  
Reference Materials ◽  
Isotope Composition ◽  
Isotope Analysis ◽  
Isotope Ratios ◽  
Bulk Rock ◽  
Accurate Analysis ◽  
Oxygen Isotope Ratios

Hematite is a potential mineral for reconstructing the oxygen isotope composition and paleotemperature of paleowater. A highly accurate analysis of oxygen isotopes is essential. However, relative to other oxygenated minerals, we lack hematite reference materials that allow for internationally comparable analyses between different laboratories. To address this issue, we attempted to perform bulk rock oxygen isotope analysis on five hematite reference materials (GBW07223a, GBW07825, YSBC28740-95, YSBC28756-2008, Harvard 92649). Meanwhile, the oxygen isotope ratios of iron oxides (GBW07223a, GBW07825, YSBC28740-95, YSBC28756-2008) were obtained by mass balance involving other oxygen-bearing minerals such as quartz and silicates. In addition, the oxygen isotope ratios of iron oxides in an oolitic hematite (ca. 1.65 billion years ago) are consistent with the results of previous analyses of this class of minerals.

Boron and Oxygen Isotope Composition of Certified Reference Materials NIST SRM 610/612 and Reference Materials JB-2 and JR-2

2001 ◽  
Vol 25 (2-3) ◽  
pp. 405-416 ◽  
Author(s):  
Simone Kasemann ◽  
Anette Meixner ◽  
Alexander Rocholl ◽  
Torsten Vennemann ◽  
Martin Rosner ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Reference Materials ◽  
Certified Reference Materials ◽  
Isotope Composition ◽  
Oxygen Isotope Composition

Carbon-oxygen isotope analysis of fault rocks in carbonates from different orogenic cycles in the Cantabrian Zone (N Spain): similarities and differences

2021 ◽  
Author(s):  
Sergio Llana-Funez ◽  
Manuel Ignacio de Paz-Álvarez ◽  
Marco Antonio Lopez-Sanchez ◽  
Stefano M. Bernasconi ◽  
Juan Luis Alonso ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Isotope Composition ◽  
Isotope Analysis ◽  
Fault Rocks ◽  
Cantabrian Zone ◽  
Geological Processes ◽  
Carbon And Oxygen Isotope ◽  
Calcite Veins ◽  
The Matrix ◽  
Thrust Sheets

<p>The isotopic carbon and oxygen isotope composition of carbonates (δ<sup>13</sup>C and δ<sup>18</sup>O), determined by temperature and the relative abundances of stable isotopes of both elements in water at the time the carbonate is precipitated, can be modified subsequently during geological processes that involve the recrystallization of carbonate. Temperature changes mostly affect δ<sup>18</sup>O, while additional sources of carbon have a greater impact on δ<sup>13</sup>C. Amongst the various processes that may alter the original isotopic signature of carbonate rocks are deformation processes, which can lead the dissolution and reprecipitation of carbonates during deformation, or the involvement of fluids of various origin during younger tectonic events.</p><p>Here, we present the results of isotope analysis in fault rocks from two distinct faults in the Cantabrian Zone (CZ) in northern Spain. It represents the foreland fold and thrust belt of the Variscan orogen in Iberia and is characterized by numerous and large thrust sheets that were emplaced during the Carboniferous. Subsequent rifting episodes in the Mesozoic and more recently Alpine North-South convergence produced the overprinting of some of the earlier Variscan structures. In all cases, brittle processes produced often similar-looking rocks as the fracturing occurred under upper crustal conditions, relatively close to the surface. Fluids involved during deformation on both cycles are likely to differ, so to evaluate alternative tools to distinguish the different cycles of fracturing in carbonates, a stable isotope analysis on carbon and oxygen was undertaken in two well-known structures in the region: the Somiedo nappe and the Ventaniella fault.</p><p>The Somiedo nappe is one of the largest thrust sheets in the Cantabrian Zone, with an estimated offset close to 20 km. The base of the thrust sheet is characterized by well-developed cataclasites and ultracataclasites that formed on Cambrian fine-grained dolostones. It has relatively minor vein activity associated, although the dolostones have been partially recrystallized. The Ventaniella fault is a dextral strike-slip structure cutting obliquely the Cantabrian Mountains. It runs for tens of kilometres inland and has an estimated offset of approximately 5 km. The fault zone in the studied area is characterized by the fracturing and dextral offset of Carboniferous micritic limestones and, more importantly, a relatively strong vein activity that formed a distributed network of calcite veins.</p><p>Cataclasite matrix and fragments, and associated veins were sampled for isotope analysis in the two fault zones. In both cases, the matrix has a signature which is intermediate between the undeformed rock and that of the veins. The fragments have a signature which is indistinguishable from the matrix, suggesting the reworking of the fault rock. The veins have a distinct pattern in both faults, but different from each other. Those related to the Ventaniella fault are mostly hydrothermal, with limited range in δ<sup>18</sup>O and δ<sup>13</sup>C, while the veins from the base of the Somiedo nappe have a larger range of δ<sup>13</sup>C, but limited δ<sup>18</sup>O variation.</p>

Stable oxygen isotope composition of plant tissue: a review

2007 ◽  
Vol 34 (2) ◽  
pp. 83 ◽  
Author(s):  
Margaret M. Barbour
Keyword(s):  
Oxygen Isotope ◽  
Plant Tissue ◽  
Organic Molecules ◽  
Isotope Composition ◽  
Measurement Techniques ◽  
Isotope Analysis ◽  
Theoretical Models ◽  
Oxygen Isotope Composition ◽  
Stable Oxygen Isotope ◽  
Stable Oxygen

With the development of rapid measurement techniques, stable oxygen isotope analysis of plant tissue is poised to become an important tool in plant physiological, ecological, paleoclimatic and forensic studies. Recent advances in mechanistic understanding have led to the improvement of process-based models that accurately predict variability in the oxygen isotope composition of plant organic material (δ18Op). δ18Op has been shown to reflect the isotope composition of soil water, evaporative enrichment in transpiring leaves, and isotopic exchange between oxygen atoms in organic molecules and local water in the cells in which organic molecules are formed. This review presents current theoretical models describing the influences on δ18Op, using recently published experimental work to outline strengths and weaknesses in the models. The potential and realised applications of the technique are described.

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