Apatite U-Pb Dating and Composition Constraints for Magmatic–Hydrothermal Evolution in the Giant Renli Nb-Ta Deposit, South China

Abstract

Apatite is a nearly ubiquitous accessory phase in igneous rocks that crystallizes during the entire magma evolution process and has great implications for geochronology and petrogenesis. Previous studies suggested that Nb-Ta mineralization in the giant Renli deposit was genetically related to Late Jurassic two-mica monzogranite or Early Cretaceous muscovite monzogranite. Moreover, the magmatic–hydrothermal evolution of these two stages is poorly understood. In our study, we confirm that the muscovite monzogranite, biotite monzogranite, and two-mica monzogranite are all spatially associated with Nb-Ta pegmatites. We present new apatite U-Pb ages to constrain the timing of Nb-Ta mineralization and related magmatism. The results show that apatite from the two-mica pegmatite yield a lower intercept age of 130 ± 2 Ma (2σ), and apatite grains from two two-mica pegmatite samples yield a lower intercept age of 135 ± 8 Ma (2σ) and 134 ± 3 Ma (2σ), respectively. Apatite and whole-rock geochemistry suggest the oxidation degree of the Nb-Ta mineralization increases from north (RL-6) to south (RL-16) in the giant Renli deposit. This study demonstrates that a combination of apatite composition and U-Pb ages can be used to constrain the magmatic–hydrothermal evolution of granite and pegmatite-type Nb-Ta deposits.

Petrogenesis of Shihuiyao Rare-Metal Granites in the Southern Great Xing’an Range, NE China

“…The Shihuiyao granites display enrichment in Rb, Li and K, and depletion in Ba, Sr, P, Ti, Mg and Ca, suggesting a continental crust origin [46]. They have high SiO 2 contents (73.66-77.08 wt%) and Mg # values (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14), consistent with crust-derived melts [47]. Low Ti/Zr (1.14-2.77) and Ti/Y (5.95-21.52) ratios are also similar to the crustal values (<20 and <200, respectively) [48].…”

“…In recent years, vigorous explorations have been carried out with the aim of discovering new rare-element mineral deposits in China. Previous research in South China has proposed a linkage between highly evolved granites and rare-element mineralization (e.g., Renli Nb-Ta, Shizhuyuan W-Sn and Jiepailing Sn-Be-F deposits in Hunan Province [1][2][3][4]; Yichun Ta-Nb and Xihuashan W-Be-REE deposits in Jiangxi Province [5,6]). Highly evolved raremetal-bearing granites are small bodies, but they are major suppliers of several "critical" rare metals (e.g., Li, Be, Rb, W, Sn, Nb, Ta).…”

Compositional Variations in Apatite and Petrogenetic Significance: Examples from Peraluminous Granites and Related Pegmatites and Hydrothermal Veins from the Central Iberian Zone (Spain and Portugal)

“…A good number of studies have concluded that apatite is a key mineral in magmatichydrothermal systems to record their crystallization history and to reflect the melt composition and oxidation conditions [2,4,[6][7][8]10,11,15,17,21,124,132,153]. Moreover, compositional variations of apatite may help to determine the economic potential and fertility index in different ore deposit environments, including granitoids (e.g., [7,10,134]); pegmatites, (e.g., [10,16,49,154,155]); carbonatites (e.g., [10,23]); skarns (e.g., [11]); Sn, W and Mo deposits (e.g., [6,11]); Cu-porphyry [156,157]; and Au-epithermal deposits [26] among others.…”