scholarly journals Columbite-Tantalite Group Mineral U-Pb Geochronology of Chaqiabeishan Li-Rich Granitic Pegmatites in the Quanji Massif, NW China: Implications for the Genesis and Emplacement Ages of Pegmatites

2021 ◽  
Vol 8 ◽  
Author(s):  
Tong Pan ◽  
Qing-Feng Ding ◽  
Xuan Zhou ◽  
Shan-Ping Li ◽  
Jie Han ◽  
...  
Keyword(s):  
Trace Element ◽  
Statistical Significance ◽  
Oscillatory Zoning ◽  
Evolutionary Trend ◽  
Granitic Pegmatites ◽  
Icp Ms ◽  
Trace Element Contents ◽  
Element Contents

The Chaqiabeishan area is characterized by small Li-rich granitic pegmatites in the Quanji Massif (QM), northwest China. In this study, the columbite-tantalite group minerals (CGMs) from a typical Li-rich pegmatite dike were analyzed for major element contents using an EMPA (electron microprobe analyzer), for trace element contents using LA-ICP-MS (laser ablation-inductively coupled plasma mass spectrometry), and for ages using LA-ICP-MS U-Pb dating, respectively. The CGMs from the sample can be divided into two types, i.e., magmatic Type 1 and metasomatic Type 2. Although these two types of CGMs do not exhibit distinct major and trace element variations from core to rim within an individual grain, the Ta# values, Mn# values, and some trace element contents (such as Zr, Hf, W, and Sr) of Type 1 CGMs are distinct from those of Type 2 CGMs. The overall compositional changes from Type 1 CGMs to Type 2 CGMs are consistent with the typical evolutionary trend described for many lithium-cesium-tantalum (LCT) pegmatites and the complex spodumene trend described by Černý and Ercit (Bull. Mineral., 1989, 108, 499–532). The Type 2 CGMs have formed later and must be a metasomatic product of Type 1 CGMs. Eighteen Type 1 CGMs yielded a weighted mean 206Pb/238U age of 240.6 ± 1.5 Ma. The slight oscillatory zoning and/or sector zoning suggest that the dated Type 1 columbites have a magmatic origin. Thus, the crystallization ages of Type 1 columbites represent the emplacement ages of Li-rich pegmatites. One of the Type 2 CGMs yielded a 206Pb/238U age of 211.0 ± 4.7 Ma, which is hardly interpreted to be an age representing the later hydrothermal metasomatism, because one dataset has no apparent statistical significance. Therefore, our dating results can only indicate that the Li-rich pegmatite-forming melts were emplaced at approximately 240.6 Ma. Based on these results and previous studies of the 240–254 Ma granitoids in the QM, we conclude that the 240.6 Ma Li-rich granitic pegmatites, as well as 240–254 Ma granitoids in the QM, were both emplaced during the southward subduction of the Zongwulong Ocean Plate in the Late Permian to Middle Triassic.

Insights into chemical mobility in titanite driven by low-temperature crystal-plastic deformation

2021 ◽  
Author(s):  
Nicholas Udy ◽  
Michael Stearns
Keyword(s):  
Plastic Deformation ◽  
High Temperature ◽  
Low Temperature ◽  
Crystal Lattice ◽  
Trace Element ◽  
Fault Zone ◽  
Temperature Deformation ◽  
Icp Ms ◽  
Trace Element Contents ◽  
Element Contents

<p>The U-Pb system in titanite has been shown to be reset during a variety of high-temperature processes including high-temperature deformation, but post-deformation modification and recovery of crystal-lattice strain have so far made U-Pb equilibration mechanism from deformed titanites equivocal. Microstructures, including mechanical twinning and subgrain rotation recrystallization are more likely to be preserved at low-temperatures, but the systematics of chemical equilibration have not been established for these conditions. This study identifies progressive crystallographic misorientation and deformation twins in titanite porphyroclasts from the Wasatch Fault Zone, Utah, USA. The microstructures, mapped using electron backscatter diffraction (EBSD), developed at ~11 km depth during 300–400 ºC crystal-plastic deformation within the ductile fault zone. These microstructural maps were used to guide laser ablation-split stream ICP-MS analysis: U-Pb isotopes measured in tandem with major and trace element contents. Despite the low temperature, U-Pb and trace element contents in titanite equilibrated, at least partially, during deformation. Both major and trace elements in titanite also likely partitioned with a fluid and in response to the (re)crystallization of other mineral phases in the fault zone. Chemical zoning and crystal lattice recovery suggestive of fluid-aided recrystallization are absent, and the main mechanism for this resetting may instead be an enhancement of element mobility along microstructure dislocations. These processes are interpreted to record complex open-system behavior of titanite caused by crystal-plastic deformation during the initiation of the WFZ. This presentation will summarize the comparative analysis of microstructure by EBSD and titanite chemistry by LASS-ICP-MS, and how it bears on the understanding of elemental mobility in titanite during low-temperature crystal-plastic deformation.</p>

scholarly journals Textures and Chemical Compositions of Magnetite from Iron Oxide Copper-Gold (IOCG) and Kiruna-Type Iron Oxide-Apatite (IOA) Deposits and Their Implications for Ore Genesis and Magnetite Classification Schemes

2019 ◽  
Vol 114 (5) ◽  
pp. 953-979 ◽  
Author(s):  
Xiao-Wen Huang ◽  
Georges Beaudoin
Keyword(s):  
High Temperature ◽  
Iron Oxide ◽  
Trace Element ◽  
Oxygen Fugacity ◽  
Oscillatory Zoning ◽  
Chemical Compositions ◽  
Fluid Composition ◽  
Copper Gold

Abstract Textural and compositional data of magnetite from Igarapé Bahia, Alemao, Sossego, Salobo, and Candelaria iron oxide copper-gold (IOCG) and El Romeral Kiruna-type iron oxide-apatite (IOA) deposits show that some magnetite grains display oscillatory zoning or have been reequilibrated by oxy-exsolution, coupled dissolution and reprecipitation (CDR) reactions, and/or recrystallization. Textures formed via CDR are most widespread in the studied samples. The original oscillatory zoning was likely derived from the crystal growth during fluctuating fluid compositions rather than from variation in temperature and oxygen fugacity. The oxy-exsolution of ilmenite in magnetite is attributed to increasing oxygen fugacity and decreasing temperature with alteration and mineralization, resulting in product magnetite with lower Ti and higher V contents. Recrystallization of some magnetite grains is commonly due to high-temperature annealing that retained primary compositions. Two different types of CDR processes are defined according to textures and chemical compositions of different generations of magnetite. The first generation of magnetite (Mag-1) is an inclusion-rich and trace element-rich core, which was replaced by an inclusion-poor and trace element-poor rim (Mag-2). The third generation of magnetite (Mag-3), inclusion poor but trace element rich, occurs as veins replacing Mag-2 along fractures or grain margins. Type 1 CDR process transforming Mag-1 to Mag-2 is more extensive and is similar to processes reported in skarn deposits, whereas type 2 CDR process is local, transforming Mag-2 to Mag-3. During type 1 CDR process, minor and trace elements Si, K, Ca, Mg, Al, and Mn in magnetite are excluded, and Fe contents increase to various extents, in contrast to type 2 CDR process, which is characterized by increased contents of Si, K, Ca, Mg, Al, and Mn. Type 1 CDR process is possibly induced by the changing fluid composition and/or decreasing temperature during progressive alteration and ore formation, whereas type 2 CDR process can be interpreted as post-ore replacement due to a new pulse of magmatic-hydrothermal fluids. The identification of magnetite core (Mag-1) with igneous origin and rim (Mag-2) with magmatic-hydrothermal origin in the Sossego IOCG and El Romeral IOA deposits supports a fluid changing from magmatic to magmatic-hydrothermal during IOCG and IOA formation and indicates a genetic link between these two deposit types. The large data set here further demonstrates that magnetite is susceptible to textural and compositional reequilibration during high-temperature magmatic and magmatic-hydrothermal processes. Reequilibrated magnetite, particularly that formed by CDR processes, has a chemical composition that can be different from that of primary magnetite. Modified magnetite, therefore, cannot be used to discriminate its primary origin or to interpret its provenance in overburden sediments. Therefore, in situ chemical analysis of magnetite combined with textural characterization is necessary to understand the origin of magnetite in IOCG and IOA deposits.

scholarly journals Quantification of trace element contents in frozen fluid inclusions by UV-fs-LA-ICP-MS analysis

2014 ◽  
Vol 29 (6) ◽  
pp. 1034-1041 ◽  
Author(s):  
Moritz Albrecht ◽  
Insa Theresa Derrey ◽  
Ingo Horn ◽  
Stephan Schuth ◽  
Stefan Weyer
Keyword(s):  
Trace Element ◽  
Fluid Inclusions ◽  
Ms Analysis ◽  
Icp Ms ◽  
Trace Element Contents ◽  
Element Contents

Cathodoluminescence (CL) behaviour and crystal chemistry of apatite from rare-metal deposits

2002 ◽  
Vol 66 (1) ◽  
pp. 151-172 ◽  
Author(s):  
U. Kempe ◽  
J. Götze
Keyword(s):  
Rare Earth ◽  
Trace Element ◽  
Crystal Chemistry ◽  
Rare Earth Element ◽  
Earth Element ◽  
Rare Metal ◽  
Oscillatory Zoning ◽  
Luminescence Spectroscopy

AbstractApatite samples from rare-metal mineralization were investigated by a combination of cathodoluminescence (CL) microscopy and spectroscopy, microchemical analysis and trace element analysis. Internal structures revealed by CL can be related to variations in the crystal chemistry and may sometimes reflect changes in the composition of the mineralizing fluids.Apatite from mineralization related to alkaline rocks and carbonatites (Type 1) typically exhibits relatively homogeneous blue and lilac/violet CL colours due to activation by trace quantities of rare earth element ions (Ce3+, Eu2+, Sm3+, Dy3+ and Nd3+). These results correlate with determined trace element abundances, which show strong light rare earth element (LREE) enrichment for this type of apatite. However, a simple quantitative correlation between emission intensities of REE3+/2+ and analysed element concentrations was not found.Apatite from P-rich altered granites, greisens, pegmatites and veins from Sn-W deposits (Type 2) shows strong Mn2+-activated yellow-greenish CL, partially with distinct oscillatory zoning. Variations in the intensity of the Mn2+-activated CL emission can be related either to varying Mn/Fe ratios (quenching of Mn activated CL by Fe) or to self-quenching effects in zones with high Mn contents (>2.0 wt.%). The REE distribution patterns of apatite reflect the specific geological position of each sample and may serve as a “tracer” for the REE behaviour within the ore system. Although the REE contents are sometimes as high as several hundred parts per million, the spectral CL measurements do not exhibit typical REE emission lines because of dominance of the Mn emission. In these samples, REE-activated luminescence is only detectable by time-resolved laser-induced luminescence spectroscopy.Both types of apatite (Type 1 in the core and Type 2 in the rim) were found in single crystals from the Be deposit Ermakovka (Transbaikalia). This finding proves the existence of two stages of mineralization within this deposit.

Trace Element Contents in Thyroid Cancer Investigated by Instrumental Neutron Activation Analysis

2018 ◽  
Vol 1 (1) ◽  
pp. 1-13
Keyword(s):  
Thyroid Cancer ◽  
Neutron Activation Analysis ◽  
Instrumental Neutron Activation Analysis ◽  
Activation Analysis ◽  
Neutron Activation ◽  
Trace Element ◽  
Thyroid Tissue ◽  
Tissue Levels ◽  
Trace Element Contents ◽  
Element Contents

Background: Thyroid cancer is an internationally important health problem. The aim of this exploratory study was to evaluate whether significant changes in the thyroid tissue levels of Ag, Co, Cr, Fe, Hg, Rb, Sb, Sc, Se, and Zn exist in the malignantly transformed thyroid. Methods: Thyroid tissue levels of ten trace elements were prospectively evaluated in 41 patients with thyroid malignant tumors and 105 healthy inhabitants. Measurements were performed using non-destructive instrumental neutron activation analysis with high resolution spectrometry of long-lived radionuclides. Tissue samples were divided into two portions. One was used for morphological study while the other was intended for trace element analysis. Results: It was found that contents of Ag, Co, Cr, Hg, and Rb were significantly higher (approximately 12.8, 1.4, 1.6, 19.6, and 1.7 times, respectively) in cancerous tissues than in normal tissues. Conclusions: There are considerable changes in trace element contents in the malignantly transformed tissue of thyroid.

LA-ICP-MS U Pb columbite ages and trace-element signature from rare-element granitic pegmatites of the Pampean Pegmatite Province, Argentina

Lithos ◽  
2021 ◽  
Vol 386-387 ◽  
pp. 106001
Author(s):  
Miguel Ángel Galliski ◽  
Albrecht von Quadt ◽  
María Florencia Márquez-Zavalía
Keyword(s):  
Trace Element ◽  
Rare Element ◽  
Granitic Pegmatites ◽  
Icp Ms ◽  
Trace Element Signature
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