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Contribution of Multiple Magmatism to the Formation of Li‐Be‐Nb‐Ta Pegmatites: Evidence from Zircon U‐Pb Ages in the Kelumute‐Jideke Pegmatite Field, Northwestern China
Author(s) -
WANG Chunlong,
QING Kezhang,
ZHOU Qifeng,
TANG Dongmei
Publication year - 2014
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.12373_26
Subject(s) - chinese academy of sciences , beijing , china , pegmatite , mineral resource classification , zircon , geology , geochemistry , earth science , geography , library science , archaeology , computer science
Located in the central part of Altay pegmatite province, Northwestern China, the Kelumute-Jideke pegmatite field (KJPF) provides a natural lab to study the regional zonation of pegmatite and longevity of pegmatitic magmatism. Rare-metal pegmatites in the KJPF are interpreted to be genetically related to the emplacement of the Jideke two-mica granite, which is described as the parental pluton by previous studies (eg. Lv et al., 2012). Except for the Kelumute Li-Be-Nb-Ta pegmatite located inside the Jideke two-mica granite, other pegmatites with different types of mineralization distributed outward the parental pluton are as following: Azubai, Xiaojideke and Dajideke muscovite-Be, Qunkuer Be-Nb-Ta, Jiamukai LiNb-Ta and Kukalagai Li-Be-Nb-Ta pegmatite, corresponding to the regional zonation of pegmatite groups (Černý, 1991). Kelumute and Kukalagai are the only two large-scale rare metal deposits in the KJPF. The Kelumute No.112 pegmatite is 1200 m in length, varying in thickness from 3.81 m (east) to 7.31 m (west), and is 200 m deep; its rare metal reserve is the second largest after the most famous Koktokay No. 3 pegmatite in the Altay pegmatite province. The main part of No. 112 pegmatite occurs EWtrending, which is controlled by faults of same direction. Five internal zones have been identified by mineral assemblages and textures, including quartzmicroclinealbite zone, blocky quartz-albite-microcline zone, quartzalbite-spodumene zone, albite-quartzmuscovite zone and saccharoidal albite zone. The Kukalagai No. 650 pegmatite dips westward with an angle of 60° to 78°, which is controlled by N-S trending foliation of biotitequartz schist. With a length of 1230 m and an average thickness of 9.88 m, the only internal zone in No. 650 pegmatite is quartz-spodumene-albite zone, with lepidolite aggregates and medium-coarse garnet grains developed locally. It iss worth mentioning that evidence of replacement (eg. saccharoidal albite and blocky quartz– muscovite) and reconstruction on the earlier pegmatite (nests of spodumene and massive albite in quartzspodumene-albite pegmatite) were identified during field observation in both No. 112 and No. 650 pegmatite.