Hydrothermal alteration and mineral chemistry of the giant Baiyanghe Be-U deposit in Xinjiang, northwest China: Implications for its mineralization

Genesis of the volcanic-related Be-U-Mo Baiyanghe deposit, West Junggar (NW China), constrained by mineralogical, trace element and U-Pb isotope signatures of the primary U mineralisation

“…Furthermore, Li et al (2015) proposed that the ore-forming solutions originated from the mixing of magmatic and meteoric fluids based on O and H isotopic signatures of hydrothermal muscovite. However, whereas the dark purple fluorite (fluorite (2) in Li et al, 2015;Zhang et al, 2019) co-precipitated with the principal Be mineral (bertrandite, (Be 4 Si 2 O 7 (OH) 2 )), the textural relations between pitchblende and the other hydrothermal minerals described by Yi et al (2016) and Zhang et al (2019) do not allow for clear determination of paragenetic succession. Finally, the timing between the Be and primary U mineralisation is still under debate.…”

“…The Baiyanghe Be-U-Mo deposit is located in the late Paleozoic Xuemisitan-Kulankazi island arc at the northwest margin of the Junggar plate, in northwest China (Fig. 1A; Li et al, 2015;Zhang et al, 2019). Although the U mineralisation was first discovered in the Baiyanghe deposit (> 2000t U at 0.05-0.2% U; IAEA, 2016), it actually represents the largest beryllium deposit (2.2 M tons of ore with grades ranging from 0.2% to 1.4%) in Asia (Wang et al, 2012;Li et al, 2015).…”

“…The Be-U-Mo mineralisation in the Baiyanghe deposit is predominantly hosted in late Devonian felsic volcanic rocks of the Tarbagatay Group and in the late Carboniferous Yangzhuang granite porphyry (Fayek and Shabaga, 2011;Li et al, 2015;Shabaga et al, 2013;Zhang et al, 2019). Zou (2006) first compared this deposit with the Spor Mountain volcanic-tuff related Be-U deposit in the U.S.A that constitutes the world's most important resource of Be (Lindsey et al, 1973;Lindsey, 1977;Foley et al, 2012;Lederer et al, 2016), and suggested that the Baiyanghe Be-U-Mo deposit formed during the hydrothermal activity that post-dated the emplacement of the Yangzhuang granite porphyry (Fig.…”

“…While Shabaga et al (2013) and Fayek and Shabaga (2011) characterised the Devonian rhyolite as the main host rock and source of U and Be for the Baiyanghe deposit, other studies (e.g. Li et al, 2015;Mao et al, 2014;Zhang et al, 2019Zhang et al, , 2020 proposed the Yangzhuang granite porphyry as the predominant host rock and source of metals for the mineralisation. Moreover, the multiple generations of fluorite observed in the deposit (Li et al, 2015;Yi et al, 2016;Zhang et al, 2019) as well as the detailed petrographic and geochemical study on the alteration minerals presented in , were taken as major lines of evidence to support a hydrothermal-related metallogenic model characterising multi-stage Be-U mineralisation in the Baiyanghe deposit.…”

“…Most recent works (e.g. Xu et al, 2017;Zhang et al, 2019) also proposed that the primary U mineralisation was closely related to the multiple stages of mafic dyke intrusions emplaced during the early Permian-late Triassic post-orogenic event in West Junggar.…”