Zircon trace element and isotopic (Sr, Nd, Hf, Pb) effects of assimilation-fractional crystallization of pegmatite magma: A case study of the Guangshigou biotite pegmatites from the North Qinling Orogen, central China

Yuan, Feng; Liu, Jiajun; Carranza, Emmanuel John M.; Zhang, Shuai; Zhai, Degao; Liu, Gang; Wang, Gongwen; Zhang, Hongyuan; Sha, Yazhou; Yang, Shangsong

doi:10.1016/j.lithos.2017.12.022

Cited by 20 publications

(17 citation statements)

References 116 publications

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“…The uranium minerals display euhedral-subhedral cubic crystal forms for uraninite (up to 300 µm in size), but an aggregate of nodular grains and veinlets for coffinite ( Figure 2). Uraninite grains are intimated intergrown or textually associated with biotite aggregates (Figure 2a The individual uraniferous pegmatites exhibit mineralogical zonation, which can be subdivided into rim, internal, and quartz core zones (see the details in [5]). Based on field and petrographic observations, there paragenetic stages are present ( Figure 3): (1) the stage I (represented by the rim zone), the stage II (represented by the internal zone), and the stage III (represented by the quartz core zone).…”

Section: Occurrence Of Uraninite and Coffinitementioning

confidence: 99%

“…Previous studies of geological characteristics, Sr-Nd-Hf-Pb isotopes, bulk-rock, and mineral chemistry have been conducted for the biotite pegmatites in the Shangdan uraniferous province (e.g., [5,21,22,39]). However, there is still controversy about the timing of U mineralization.…”

Section: Timing Of the Uraninite (U) Mineralizationmentioning

confidence: 99%

“…For instance, LA-ICP-MS zircon U-Pb dating gave weighted mean 206 Pb/ 238 U ages of 414-417 Ma [59], 414-415 Ma (unpub. data), and 413-415 Ma [22] for the Chenjiazhuang, Xiaohuacha, and Guangshigou biotite pegmatites, respectively; Liu [60] and Feng et al [39] conducted biotite K-Ar dating of the Chenjiazhuang and Guangshigou biotite pegmatites, and obtained isotopic ages of 329.8-426.1 Ma and 400 Ma, respectively; Yuan et al [5] and Xu and Du [45] reported a pyrite Pb-Pb isochron age of 413 ± 22 Ma and two whole rock Rb-Sr isochron ages of 378 and 386 Ma for the Guangshigou biotite pegmatite. The available ages are often inconsistent with each other, which may be caused by the large age uncertainty for some analyses, excess argon, or fluid-assisted resetting of the K-Ar and Rb-Sr chronometers [61,62], resulting in uncertainties of interpretation.…”

Section: Timing Of the Uraninite (U) Mineralizationmentioning

confidence: 99%

“…There is an increased demand for U resources, referred to as strategic metal resources and clean energy, with development of nuclear reactors for electric power generation [1]. Renewed interest in biotite pegmatites has arisen due to their economic U endowment [2][3][4][5]. The most important U hosts in pegmatite-type U deposits are uraninite and coffinite, common minerals containing reduced U 4+ found in nature [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Geochronology and Geochemistry of Uraninite and Coffinite: Insights into Ore-Forming Process in the Pegmatite-Hosted Uraniferous Province, North Qinling, Central China

et al. 2019

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The biotite pegmatites in the Shangdan domain of the North Qinling orogenic belt contain economic concentrations of U, constituting a low-grade, large-tonnage pegmatite-hosted uraniferous province. Uraninite is predominant and ubiquitous ore mineral and coffinite is common alteration mineral after initial deposit formation. A comprehensive survey of the uraninite and coffinite assemblage of the Chenjiazhuang, Xiaohuacha, and Guangshigou biotite pegmatites in this uraniferous province reveal the primary magmatic U mineralization and its response during subsequent hydrothermal events. Integrating the ID-TIMS (Isotope Dilution Thermal Ionization Mass Spectrometry) 206 Pb/ 238 U ages and U-Th-Pb chemical ages for the uraninites with those reported from previous studies suggests that the timing of U mineralization in the uraniferous province was constrained at 407-415 Ma, confirming an Early Devonian magmatic ore-forming event. Based on microtextural relationships and compositional variation, three generations of uranium minerals can be identified: uaninite-A (high Th-low U-variable Y group), uranite-B (low Th-high U, Y group), and coffinite (high Si, Ca-low U, Pb group). Petrographic and microanalytical observations support a three-stage evolution model of uranium minerals from primary to subsequent generations as follows: (1) during the Early Devonian (stage 1), U derived from the hydrous silicate melt was mainly concentrated in primary magmatic uaninite-A by high-T (450-607 • C) precipitation; (2) during the Late Devonian (stage 2), U was mobilized and dissolved from pre-existing uraninite-A by U-bearing fluids and in situ reprecipitated as uraninite-B under reduced conditions. The in situ transformation of primary uraninite-A to second uraninite-B represent a local medium-T (250-450 • C) hydrothermal U-event; and (3) during the later low-T (100-140 • C) hydrothermal alteration (stage 3), U was remobilized and derived from the dissolution of pre-existing uraninite by CO 2 -and SiO 2 -rich fluids and interacted with reducing agent (e.g., pyrite) leading to reprecipitation of coffinite. This process represents a regional and extensive low-T hydrothermal U-event. In view of this, U minerals evolved from magmatic uraninite-A though fluid-induced recrystallized uraninite-B to coffinite, revealing three episodes of U circulation in the magmatic-hydrothermal system.

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Section: Occurrence Of Uraninite and Coffinitementioning

confidence: 99%

Section: Timing Of the Uraninite (U) Mineralizationmentioning

confidence: 99%

Section: Timing Of the Uraninite (U) Mineralizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Geochronology and Geochemistry of Uraninite and Coffinite: Insights into Ore-Forming Process in the Pegmatite-Hosted Uraniferous Province, North Qinling, Central China

et al. 2019

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“…Three large granitic pegmatite regions are distributed in the Qinling Orogenic Belt in China: the Shangnan, Baoji, and Ningshan pegmatite districts. Detailed studies have been conducted on the Shangnan pegmatite district, with the classification, internal structure, mineral assemblage, mineralization characteristics, metallogenetic epoch, and genetic relationships between granites and pegmatites having been reported [21][22][23][24][25]. In contrast, the Ningshan pegmatite district, located in South Qinling Orogen, is poorly investigated.…”

Section: Introductionmentioning

confidence: 99%

Geochemical Contrasts between Late Triassic Rb-Rich and Barren Pegmatites from Ningshan Pegmatite District, South Qinling Orogen, China: Implications for Petrogenesis and Rare Metal Exploration

et al. 2020

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The Ningshan pegmatite district in the South Qinling Orogen hosts numerous Rb-(Be) mineralized pegmatites. In this study, whole-rock geochemistry, mineral geochemistry, and zircon U–Pb isotopes of the Rb-rich and barren pegmatites were determined. The barren pegmatites consist mainly of muscovite, microcline, albite, quartz, and garnet, whereas the Rb-rich pegmatites are mainly composed of muscovite, albite, quartz, and beryl, with minor chrysoberyl, cassiterite and columbite-group mineral. The muscovite and albite are the main Rb-bearing minerals. The U–Pb zircon dating of the Rb-rich and barren pegmatites yielding an age of 212–203 Ma, which is similar to that of the neighboring two-mica monzogranites distributed in the Ningshan area. Compared with the two-mica monzogranites, geochemical features, such as the Zr/Hf, Rb/Sr and Nb/Ta ratios and trace element contents indicated that the Rb-rich and barren pegmatites derived from fractionation of the two-mica monzogranites. In combination, the current and previous results suggest that the fractionation of the two-mica monzogranites caused the generation of the affinitive residual melts that, finally, crystallized to form the pegmatites. Compared to those from the barren pegmatites, the apatite from the Rb-rich pegmatites have higher MnO (14.51–19.12 wt.%) and Cl (0.12–0.16 wt.%) contents and lower F/Cl rartios (20–29). We conclude that these differences reflect unique geochemical signatures, and the geochemical composition of the apatite can be used as exploration guidance for rare metal-rich pegmatites.

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Two episodes of REE mineralization in the Qinling Orogenic Belt, Central China: in-situ U-Th-Pb dating of bastnäsite and monazite

et al. 2019

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Zircon trace element and isotopic (Sr, Nd, Hf, Pb) effects of assimilation-fractional crystallization of pegmatite magma: A case study of the Guangshigou biotite pegmatites from the North Qinling Orogen, central China

Cited by 20 publications

References 116 publications

Geochronology and Geochemistry of Uraninite and Coffinite: Insights into Ore-Forming Process in the Pegmatite-Hosted Uraniferous Province, North Qinling, Central China

Geochronology and Geochemistry of Uraninite and Coffinite: Insights into Ore-Forming Process in the Pegmatite-Hosted Uraniferous Province, North Qinling, Central China

Geochemical Contrasts between Late Triassic Rb-Rich and Barren Pegmatites from Ningshan Pegmatite District, South Qinling Orogen, China: Implications for Petrogenesis and Rare Metal Exploration

Two episodes of REE mineralization in the Qinling Orogenic Belt, Central China: in-situ U-Th-Pb dating of bastnäsite and monazite

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