Petrogenesis and magmatic–hydrothermal evolution time limitation of Kelumute No. 112 pegmatite in Altay, Northwestern China: Evidence from zircon UPb and Hf isotopes

摘要: Abstract Granitic pegmatites and associated rare-metal deposits, unique features in the Altay orogen, are located a key tectonic position of southern Central Asian Orogenic Belt (CAOB) document evolution Paleo-Asian Ocean. The Kelumute No. 112 pegmatite, which intruded into Jideke two-mica granites, hosts abundant (e.g., Li, Be, Nb, Ta) ore deposits ranks only second to Koktokay 3 pegmatite both size reserves. To explore time limitation magmatic, magmatic–hydrothermal hydrothermal stages magma system, setting genetic relationship between this study presents zircon U Pb Hf isotopic compositions wall rocks (two-mica granite biotite granite) as determined by LA-ICPMS LA-MC-ICPMS. weighted mean 206 Pb/ 238 ages internal textural zones including I, II, III, V VI, 238.3 ± 2.0 Ma, 233.5 ± 3.7 Ma, 188.3 ± 1.7 Ma, 218.8 ± 1.9 Ma 210.7 ± 1.6 Ma, respectively. Wall dated at 445.6 ± 4.3 Ma 455.6 ± 5.4 Ma, Zircons from have lower positive e (t) values (+ 0.03 + 2.35), with T DM model 1112–1225 Ma. show similar (− 1.41 + 4.13) (1172 1515 Ma). However, three xenocrystic zircons granites characterized larger negative eHf(t) (− 5.85 − 9.83) older (1839 2090 Ma). Thus, following conclusions can be drawn: 1) its (Jideke no relationship, indicated large gaps their formation ages. they did originate common source composed ancient crust mantle-derived materials under two different settings; 2) transition lasted for ~ 5 Ma, ~ 23 Ma ~ 22 Ma, respectively; 3) was most likely formed post-collision setting, indicating that block amalgamation collisional orogeny CAOB continued Triassic.