scholarly journals Strengths and limitations of in situ U-Pb titanite petrochronology in polymetamorphic rocks: An example from western Maine, USA.

2021 ◽  
Author(s):  
Jesse Walters ◽  
Alicia Cruz-Uribe ◽  
Won Joon Song ◽  
Christopher Gerbi ◽  
Kimberley Biela
Keyword(s):  
Single Spot ◽  
Inductively Coupled ◽  
Inductively Coupled Mass Spectrometry ◽  
South Central ◽  
Eu Anomaly ◽  
Fluid Infiltration ◽  
Icp Ms ◽  
Thermal Maximum ◽  
Textural Data

Titanite is a potentially powerful U-Pb petrochronometer that may record metamorphism, metasomatism, and deformation. Titanite may also incorporate significant inherited Pb, the correction for which may introduce inaccuracies and result in geologically ambiguous U-Pb dates. Here we present laser ablation inductively coupled mass spectrometry (LA-ICP-MS)-derived titanite U-Pb dates and trace element concentrations for two banded calc-silicate gneisses from south-central Maine, USA (SSP18-1A & -1B). Single spot common Pb-corrected dates range from 400 to 280 Ma with 12–20 Ma propagated 2SE. Titanite in sample SSP18-1B exhibit regular core-to-rim variations in texture, composition, and date. We identify four titanite populations: 1) 399 ± 5 Ma (95 % CL) low Y + HREE cores and mottled grains, 2) 372 ± 7 Ma high Y + REE mantles and cores, 3) 342 ± 6 Ma cores with high Y + REE and no Eu anomaly, and 4) 295 ± 6 Ma LREE-depleted rims. We interpret the increase in titanite Y + HREE between ca. 400 and ca. 372 Ma to constrain the timing of diopside fracturing and recrystallization and amphibole breakdown. Apparent Zr-in-titanite temperatures (803 ± 36 °C at 0.5 ± 0.2 GPa) and increased XDi suggest a thermal maximum at ca. 372 Ma. Population 3 domains dated to ca. 342 Ma exhibit no Eu anomaly and are observed only in compositional bands dominated by diopside (> 80 vol %), suggesting limited equilibrium between titanite and plagioclase. Finally, low LREE and high U/Th in Population 4 titanite date the formation of hydrous phases, such as allanite, during high XH2O fluid infiltration at ca. 295 Ma. In contrast to the well-defined date-composition-texture relationships observed for titanite from SSP18-1B, titanite grains from sample SSP18-1A exhibit complex zoning patterns and little correlation between texture, composition, and date. We hypothesize that the incorporation of variable amounts of radiogenic Pb from dissolved titanite into recrystallized domains resulted in mixed ages spanning 380–330 Ma. Although titanite may reliably record multiple phases of metamorphism, these data highlight the importance of considering U-Pb data along with chemical and textural data to screen for inherited radiogenic Pb.

Southampton, Canada’s third pallasite

2013 ◽  
Vol 50 (1) ◽  
pp. 26-31 ◽  
Author(s):  
Stephen A. Kissin ◽  
Neil D. MacRae ◽  
Reid R. Keays
Keyword(s):  
Inductively Coupled Plasma ◽  
Main Group ◽  
Metal Phase ◽  
Triaxial Ellipsoid ◽  
Exterior Surface ◽  
Inductively Coupled ◽  
South Central ◽  
Oxidized Iron ◽  
Icp Ms ◽  
Plasma Mass Spectrometry

A. 3.58 kg pallasite meteorite was found in April 2001, near the mouth of the Saugeen River on Lake Huron (44°30.385′N, 81°22.330′W) by Carl Young of London, Ontario. The specimen is in the form of an irregular triaxial ellipsoid approximately 6.8 cm × 13.4 cm × 18.1 cm. Olivine crystals are visible on the smooth exterior surface which has a thin rind of oxidized iron. The sectioned interior contains olivine crystals with a considerable range in sizes up to approximately 2.5 cm diameter. Larger crystals have angular outlines and some are fractured, although corners and small grains are rounded. Apart from the kamacite and taenite of the metal phase, only small amounts of schreibersite and troilite are present. Analysis of the metal phase by instrumental neutron activation analysis (INAA) yielded Ni 97.4 mg/g, Ga 17.2 μg/g, Ge 77.8 μg/g, Ir 0.137 μg/g, and Au 2.12 μg/g. These values lie within the defined ranges for main group pallasites, except that Ge is ca. 20% higher. Analysis by inductively coupled plasma – mass spectrometry (ICP–MS) yielded Ir 0.0755 μg/g and Au 0.937 μg/g, differences attributed to difference in the mass and heterogeneity of the material analyzed. Olivines were found to have a mean composition of fayalite (Fa) 12.30, within the range of compositions for main group pallasites. Although the Hopewell Mounds of south-central Ohio contain fragments of the Brenham (Kansas) pallasite that were transported there by pre-contact people and are in the same region as the Southampton meteorite find, the apparent glacial transport of the newly found pallasite together with its compositional and textural differences indicate that it is a unique meteorite and the third pallasite found in Canada. The pallasite is named after the community of Southampton in which it was found.

Laser ablation inductively coupled plasma mass spectrometry for multi-elemental determination in dried blood spots

2017 ◽  
Vol 32 (8) ◽  
pp. 1500-1507 ◽  
Author(s):  
Jorge Moreda-Piñeiro ◽  
Alicia Cantarero-Roldán ◽  
Antonio Moreda-Piñeiro ◽  
José Ángel Cocho ◽  
Pilar Bermejo-Barrera
Keyword(s):  
Mass Spectrometry ◽  
Laser Ablation ◽  
Inductively Coupled Plasma ◽  
Dried Blood Spots ◽  
Element Determination ◽  
Inductively Coupled ◽  
Inductively Coupled Mass Spectrometry ◽  
Icp Ms ◽  
Elemental Determination ◽  
Plasma Mass Spectrometry

An approach by laser ablation (LA) coupled with inductively coupled mass spectrometry (ICP-MS) for multi-element determination in whole blood is described.

Dating polymetamorphism using titanite: Linking trace elements, textures, and ages

2021 ◽  
Author(s):  
Jesse Walters ◽  
Alicia Cruz-Uribe ◽  
Won Joon Song ◽  
Joshua Stone ◽  
Hanna Brooks ◽  
...  
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Bulk Composition ◽  
Granulite Facies ◽  
Compositional Variation ◽  
Excimer Laser Ablation ◽  
Eu Anomaly ◽  
Fluid Infiltration ◽  
Icp Ms ◽  
The University

<p>Here we present titanite U-Pb dates from two banded calc silicate gneisses (SSP18-1A and 1B) from western Maine. Mineral textures and compositions display multiple phases of metamorphism. The peak lower granulite facies assemblage is Di + Kfs + Pl + Ttn, with little to no calcite present. Late Czo + Tr replaces Di + Pl, suggesting an influx of X<sub>H2O</sub> > 0.90 fluids. Nearby metapelites show the transition from sillimanite-bearing to muscovite-bearing assemblages, indicating that fluid infiltration may be widespread. Compositional maps of clinopyroxene in SSP18-1B show fracturing and rehealing of early Fe-rich diopside with late Mg-rich diopside. Both samples exhibit overprinting of An-rich plagioclase by increasingly Ab-rich plagioclase. Titanite grains in both samples exhibit BSE textures and compositional variation consistent with multiple phases of growth and dissolution-reprecipitation reactions.</p><p>Titanite trace element and U-Pb data were collected by LA-ICP-MS at the University of Maine using an ESI NWR193<sup>UC</sup> excimer laser ablation system coupled to an Agilent 8900 ICP-MS. Single spot ages range from 280 to 400 Ma with 12-20 Ma propagated 2SE. Four composition-date domains are identified in SSP18-1B: A. 400 ± 8 Ma (dark BSE cores), B. 372 ± 4 Ma (bright BSE cores), C. 342 ± 6 Ma (bright BSE cores, no Eu anomaly), and D. 302 ± 3 Ma (dark BSE rims, low LREE). Titanite Fe and Y concentrations increase with decreasing date, whereas Sr concentrations decrease. In clinopyroxene, Fe and Y decrease between high Fe-diopside and late Mg-diopside, placing the fracturing and rehealing events between 400 and 372 Ma. Strontium concentrations in titanite decrease between subsequent generations of plagioclase, diopside, and titanite, suggesting a continual fractionation of Sr from the reactive bulk composition. Low LREE in ca. 300 Ma titanite domains in both samples are consistent with the formation of texturally late allanite and clinozoisite, thus constraining the timing of the high X<sub>H2O</sub> fluid infiltration event. Zr-in-titanite temperatures for rims in the quartz-bearing SSP18-1B give a weighted mean T of 764 °C at 4.5 GPa, consistent with the muscovite-absent sillimanite-bearing assemblage in garnet cores from metapelite samples. However, the 100-150 °C lower Grt-Bt temperatures for metapelites are not consistent with peak metamorphic phase equilibria. Our data demonstrate the utility of linking titanite textures and trace element concentrations with those of other minerals to reveal past metamorphic and deformational events. Additionally, we show that titanite may reliably preserve U and Pb isotopic ratios, trace elements, and textures over subsequent high-T metamorphic events.</p>

High-resolution LA-ICP-MS trace-element mapping of magmatic biotite: A new approach for studying syn- to post-magmatic evolution

2020 ◽  
Vol 58 (3) ◽  
pp. 293-311 ◽  
Author(s):  
Zeinab Azadbakht ◽  
David R. Lentz
Keyword(s):  
New Brunswick ◽  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Fluid Phase ◽  
New Approach ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Magma Crystallization ◽  
Topaz Granite

ABSTRACT Biotite grains from 22 felsic intrusions in New Brunswick were mapped in situ using a laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS). We investigated the extent to which biotite can retain its magmatic zoning patterns and, where zoning does exist, how it can be used to elucidate early to late stage, syn-magmatic to post-crystallization processes. Although the major element and halogen contents of the examined biotite phenocrysts are homogeneous, two-thirds of the grains display trace-element zoning for Ba, Rb, and Cs. The results also indicated that zoning is better retained in larger grains (i.e., > 500 × 500 μm) with minimal alteration and mineral inclusions. An exceptionally well-zoned Li-rich siderophyllite from the Pleasant Ridge topaz granite in southwestern New Brunswick shows Ti, Ta, Sn, W, Cs, Rb, and V (without Li or Ba) zoning. Cesium values increase from 200 to 1400 ppm from core to rim. Conversely, Sn and W values decrease toward the rim (50 to 10 and 100 to 10 ppm, respectively). Tantalum and Ti values show fewer variations but drop abruptly close to the rim of the grain (100 to 20 and 2000 to 500 ppm, respectively). These observations may indicate crystallization of mineral phases with high partition coefficients for these highly incompatible elements (except Ti) (e.g., cassiterite and rutile) followed by fractionation of a fluid phase at a later stage of magma crystallization. The preservation of zoning may indicate rapid cooling post-crystallization of the parent magma.

Evaluation of 24-h urine containers for urine copper measurement by inductively coupled plasma mass spectrometry

2020 ◽  
Vol 57 (3) ◽  
pp. 246-248
Author(s):  
Anna F Robson ◽  
Philip Lockett ◽  
Lesley Tetlow ◽  
Chris Chaloner
Keyword(s):  
Mass Spectrometry ◽  
Inductively Coupled Plasma ◽  
Clinical Decision ◽  
Urine Samples ◽  
Inductively Coupled ◽  
Inductively Coupled Mass Spectrometry ◽  
Icp Ms ◽  
Plasma Mass Spectrometry ◽  
Minimal Concentration ◽  
Clinical Decision Limits

Objective To determine the necessity for acid-washed containers for 24-h urine copper analysis. Methods Copper solutions, with concentrations relevant to clinical decision limits, were prepared by spiking both assay diluent and unknown urine samples with the copper calibrator. Samples were split between plain and acid-washed 24-h urine containers, and copper analysis was performed using inductively coupled mass spectrometry (ICP-MS). Results Measurement of copper in both spiked diluent and spiked urine samples showed minimal concentration bias between acid-washed and plain 24-h urine containers. Conclusions Acid-washed containers are not required for the measurement of copper in 24-h urine samples.

scholarly journals Evaluation of a Novel Boron-Containing α-d-Mannopyranoside for BNCT

Cells ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1277 ◽  
Author(s):  
Takao Tsurubuchi ◽  
Makoto Shirakawa ◽  
Wataru Kurosawa ◽  
Kayo Matsumoto ◽  
Risa Ubagai ◽  
...  
Keyword(s):  
Normal Tissue ◽  
Cultured Cells ◽  
Tumor Model ◽  
Intracellular Distribution ◽  
Inductively Coupled ◽  
Inductively Coupled Mass Spectrometry ◽  
Icp Ms ◽  
High Concentrations

Boron neutron capture therapy (BNCT) is a unique anticancer technology that has demonstrated its efficacy in numerous phase I/II clinical trials with boronophenylalanine (BPA) and sodium borocaptate (BSH) used as 10B delivery agents. However, continuous drug administration at high concentrations is needed to maintain sufficient 10B concentration within tumors. To address the issue of 10B accumulation and retention in tumor tissue, we developed MMT1242, a novel boron-containing α-d-mannopyranoside. We evaluated the uptake, intracellular distribution, and retention of MMT1242 in cultured cells and analyzed biodistribution, tumor-to-normal tissue ratio and toxicity in vivo. Fluorescence imaging using nitrobenzoxadiazole (NBD)-labeled MMT1242 and inductively coupled mass spectrometry (ICP-MS) were performed. The effectiveness of BNCT using MMT1242 was assessed in animal irradiation studies at the Kyoto University Research Reactor. MMT1242 showed a high uptake and broad intracellular distribution in vitro, longer tumor retention compared to BSH and BPA, and adequate tumor-to-normal tissue accumulation ratio and low toxicity in vivo. A neutron irradiation study with MMT1242 in a subcutaneous murine tumor model revealed a significant tumor inhibiting effect if injected 24 h before irradiation. We therefore report that 10B-MMT1242 is a candidate for further clinical BNCT studies.

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