Phase composition and genesis of pyroxenic jadeite from Guatemala: insights from cathodoluminescence

Lin, Chuanlong; He, Xuemei; Lu, Zhiyun; Yao, Yuwei

doi:10.1039/d0ra01772h

Cited by 4 publications

(5 citation statements)

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“…521 cm −1 , its main peaks are at ca. 698 cm −1 and to a lesser extent, 431 cm −1 and 373 cm −1 [ 42 ]. Thus, if a relict jadeite could occur in Grt-1, the related most significant peak would be expected to occur at 698 cm −1 .…”

Section: The First Evidence For Uhp Metamorphism In the Sesia Zonementioning

confidence: 99%

First finding of continental deep subduction in the Sesia Zone of the Western Alps and implications for subduction dynamics

Chen

Zhou

et al. 2023

National Science Review

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Continental deep subduction after the closure of large oceanic basins is commonly ascribed to gravitational pull of the subducting oceanic slab. However, it is not clear how continental lithosphere adjacent to small oceanic basins was subducted to mantle depths. The Sesia Zone in the Western Alps provides an excellent target for exploration of subduction dynamics in such a tectonic setting. Here we report the first finding of coesite in a jadeite-bearing orthogneiss from the Sesia Zone, providing the first evidence for deep subduction of the continental crust to mantle depths for ultrahigh-pressure (UHP) metamorphism in this zone. Three coesite inclusions were identified by laser Raman spectroscopy in two garnet grains. Based on zircon U-Pb dating and trace element analysis, the UHP metamorphic age was constrained to be 76.0 ± 1.0 Ma. The phase equilibrium modelling yields peak metamorphic pressures of 2.8-3.3 GPa, demonstrating the continental deep subduction to mantle depths of >80 km. The subducted continental crust was a rifted hyperextended continental margin, which was converted to the passive continental margin during seafloor spreading and then deeply subducted during the oblique convergence between Adria microplate and Eurasian plate in the Late Cretaceous. Because the slab pull could only play a limited role in closing small oceanic basins for continental collision, the distal push of either continental breakup or seafloor spreading is suggested as the major driving force for the deep subduction of continental crust in the Western Alps. Therefore, deep subduction of the continental crust bordering small oceanic basins would be induced by the far-field stress of compression, whereas that bordering large oceanic basins was spontaneous due to the oceanic slab pull. This provides a new insight into the geodynamic mechanism of continental deep subduction.

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Section: The First Evidence For Uhp Metamorphism In the Sesia Zonementioning

confidence: 99%

First finding of continental deep subduction in the Sesia Zone of the Western Alps and implications for subduction dynamics

Chen

Zhou

et al. 2023

National Science Review

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“…In addition, we speculate that the limonite may also cause supergene oxidation in the lattice cracks of jadeite, resulting in a yellow color [27][28][29]. [29,30]. The contents of Na 2 O range from 7.44 to 7.91 wt.%, with an average value of 7.65 wt.%.…”

Section: Mineral Chemistrymentioning

confidence: 99%

“…The color of GN-3 and BU-3 samples is dark, and the transparency is low, indicating that Fe 3+ is low and Fe 2+ content is high; so, Fe 2+ is presumed to play a leading role in the color darkening and transparency reduction in jadeite. When Fe exists in the form of Fe 2+ in ompacite, leading to the jadeite jade presenting a green color with a blue-gray tone [30,31], it is comprehensively inferred that the joint action of Cr 3+ and Fe 2+ causes the blue-green jadeite jade.…”

Section: Mineral Chemistrymentioning

confidence: 99%

“…However, the distinction is quite significant, mainly because of the higher contents of Cr in sample GN-3, where Cr may be derived from hydrothermal fluids, resulting in the decrease in Na, Al and the increase in Fe, Ca components, respectively. Moreover, the presence of Ni 2+ and trace Mn 2+ will also affect the green darkening [30,31].…”

Section: Mineral Chemistrymentioning

confidence: 99%

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Color-Causing Mechanisms of Guatemala Jadeite Jade: Constraints from Spectroscopy and Chemical Compositions

Li,

Zhang,

et al. 2023

Crystals

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The jadeite jade in Guatemala exerts remarkable commercial quality, which has attracted wide attention. Guatemalan jadeite jade displays a rich variety of colors; however, the color formation of this jadeite jade has not been systematically investigated to date. In this paper, we study different colors of jade samples to trace the compositions and color-causing mechanisms through petrography, X-ray fluorescence spectroscopy (XRF), Fourier transform infrared spectroscopy (FTIR), laser Raman spectroscopy (LRS), and UV-visible absorption spectroscopy (UV-Vis), as well as electron probe microanalysis (EPMA). The results show that jadeite and omphacite are the main mineral compositions of Guatemalan jadeite jade, together with minor albite and other impurities. The color of Guatemala jadeite jade is mainly related to Cr3+, Fe2+, and Fe3+, of which a small amount of Cr3+ causes the jadeite jade to be emerald green. Moreover, 1~2% FeO contents can lead to the blue or gray color of the samples, while the Fe3+ makes the sample dark green. The green color of some Cr3+-free jadeite is caused by the electron transition between bands of Fe3+, and the green color is related to the iron content. Moreover, the chemical composition analysis shows that some metallic elements existed in Guatemalan jadeite jade, such as Ca, Ti, Al, Si, Ni, Fe, Mn, Cr, Na, Mg, and Sr, and some trace elements were lost or unevenly distributed, which may lead to the heterogeneity of the color of the samples. Our present investigation provides insights into color discrimination, quality evaluation, and identification of Guatemala jadeite jade.

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“…Because jadeite grows in a special environment with high pressure and low temperature, it is only produced in a few countries around the world [ 1 , 2 , 3 , 4 ]. At present, there is no precise location from which Qing dynasty jadeite was sourced.…”

Section: Introductionmentioning

confidence: 99%

Comparative Analysis of Guatemalan and Qing Dynasty Jadeite Elemental Signs

et al. 2023

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Different jadeites have different characteristics. In this paper, the La-ICP-MS test is used to compare and analyze the elemental characteristics of jadeite in Guatemala and the Qing dynasty. The test results show that the highest value of Guatemalan jadeite Ca can reach 2.5 apfu, while the highest value of Qing dynasty jadeite is 0.73 apfu. The highest value of Na is the same for both. The concentration distribution range and highest value of Guatemalan jadeite and Qing dynasty jadeite Mg/(Mg + Fe) are the same. Guatemalan jadeite and Qing dynasty jadeite have a very wide content of trace elements. Qing dynasty Ca/(Mg + Fe) distribution is wider. Concentrations of Guatemalan and Qing dynasty jadeite Sr/Ba, which is a marine sediment, are greater than 1. The Ba in the Qing dynasty jadeite sediments contains a large amount of clay, resulting in higher levels than the average amount in Guatemalan jadeite Ba. The standard distribution map is similar, showing a “horn” shape. The Sr distribution is uneven. Guatemalan jadeite is heavily enriched in rare earths. Eu shows positive and negative abnormalities. The total rare earth value is 8.15 ppm. Qing Dynasty jadeite shows light rare earth enrichment, and Eu is a positive anomaly. The total rare earth value is 7.07 ppm. The characteristics of the two elements are somewhat similar, but different, which does not rule out the possibility that Qing dynasty jadeite came from Guatemala.

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Phase composition and genesis of pyroxenic jadeite from Guatemala: insights from cathodoluminescence

Abstract: This paper introduces two studies that combine CL microscopy: phase investigation of green pyroxenic jadeite from Guatemala, and jadeite generations.

Cited by 4 publications

References 31 publications

First finding of continental deep subduction in the Sesia Zone of the Western Alps and implications for subduction dynamics

First finding of continental deep subduction in the Sesia Zone of the Western Alps and implications for subduction dynamics

Color-Causing Mechanisms of Guatemala Jadeite Jade: Constraints from Spectroscopy and Chemical Compositions

Comparative Analysis of Guatemalan and Qing Dynasty Jadeite Elemental Signs

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