Graphitization in Paleoproterozoic granulites from the Taihua Complex, North China Craton: Constraints from laser Raman spectroscopy, carbon isotopes and geochronology

Zhang, Cun; He, Xiao-Fang; Sun, Laixi; Santosh, M.; Chi, Jie; Yu, Xiang; Li, Zengsheng; Meng, Yan

doi:10.1016/j.lithos.2023.107266

Cited by 2 publications

(4 citation statements)

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“…Generally, the WJ-type nephrite jade from Xinjiang was formed through the skarn-type metasomatism of intermediate-felsic granitic rocks and Precambrian dolomite marble [2,5,6,8]. Our recent work proposes that the formation mechanism model of WJ-type nephrite jade was formed through metamorphism/metasomatism during continent-continent collision [29]. The original carbon-bearing material may have been deposited in the carbonate rocks and subsequently subducted.…”

Section: Implication For Graphite Growth and Nephrite Jade Formationmentioning

confidence: 96%

“…However, the graphite Raman geothermometers used do not work for the carbon spectrum without the D band, indicating that the formation temperature was above the upper limit. In this study, the metamorphic temperatures of graphite inclusions of black nephrite jade are estimated using the quantitative parameter of area ratio (R2), which is defined as D1/(G + D1 + D2) (R2), while the D2 peak area is generally negligible [10,11,23,28,29]. The decomposition peak in the first order region of graphite Raman spectrum show that the R2 varies by 0.28-0.59 with an average value of about 0.41, except for partial QHL-4 samples that exceeded its working limit.…”

Section: Formation Temperatures Of Graphite Inclusionsmentioning

confidence: 99%

“…The decomposition peak in the first order region of graphite Raman spectrum show that the R2 varies by 0.28-0.59 with an average value of about 0.41, except for partial QHL-4 samples that exceeded its working limit. The graphite inclusions formation temperatures were calculated by Equations ( 1) and (2), based on Beyssac et al [10,11] and Aoya et al [29], respectively. T(°C) = −445 × R2 + 641 (330 < T < 650), R2 = 0.96 ± 50 °C…”

Section: Formation Temperatures Of Graphite Inclusionsmentioning

confidence: 99%

“…The sample QHL-4 shows a high degree of crystallization with similar properties to fluid-precipitated graphite, which may represent peak metamorphism. [10,11,29]. Note: D1 I1 : intensity of D1, G I2 : intensity of G, D1 A1 : peak area of D1, G A1 : peak area of G, Full width at half maximum (FWHM), R2 area ratio of graphite spectrums were obtained using the Peakfit software Origin 9.0. n. d. = not discernible S. E. = Standard Error.…”

Section: T(mentioning

confidence: 99%

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Constraints on Crystallinity of Graphite Inclusions in Nephrite Jade from Xinjiang, Northwest China: Implications for Nephrite Jade Formation Temperatures

Zheng,

Chen,

Zhang

et al. 2023

Minerals

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Graphite usually occurs in mineral/rock associations in the form of solid inclusions and plays an important role in tracing regional metamorphic degree, ore-forming temperature, fluid evolution, as well as the deep carbon cycle of the Earth. In this study, we investigate the placer black nephrite jade where the co-occurrence of abundant graphite inclusions and jade remains extraordinary. By employing petrographic, mineral-chemical, and Raman spectroscopic methods, we characterize the textures and crystallinity of graphite inclusions that exist in nephrite jade. EPMA and petrological data indicate that the main constituents of black jade are tremolite and graphite, with minor phases of diopside, calcite, dolomite, epidote, and apatite. Micro-Raman spectroscopic thermometry of carbonaceous material shows that most of the formation temperatures of graphite inclusions are between 378 and 556 °C, and only a few temperatures may be above 650 °C, indicating that graphite inclusions were formed at medium- to high-temperature metamorphic facies. The petrologic and spectral investigations of graphite inclusions in these nephrite jade samples show major metamorphic signatures with mixed features associated with fluid precipitation. Our results allow us to propose that primary nephrite jade was formed under multi-stage tectonic evolution conditions, and regional temperatures were predominately driven by the late continent–continent collision, while the ore-controlling temperatures of nephrite jade formation were found in a medium- to high-temperature environment.

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