LA-ICP-MS zircon U-Pb dating, geochemistry and tectonic implications of the Neoproterozoic Xiaoxigong granite at Dunhuang block, northeastern Tarim, NW China

• Published in: Geosciences journal (Seoul, Korea) Vol. 19; no. 4; pp. 697 - 708
• Main Authors: Zhu, Jiang, Lv, Xinbiao, Peng, Sanguo
• Format: Journal Article
• Language: English
• Published: Seoul The Geological Society of Korea 01.12.2015; Springer Nature B.V; 한국지질과학협의회
• Subjects: Age; Blocking; Earth and Environmental Science; Earth Sciences; Enrichment; Geochemistry; Granite; Plate tectonics; Radioactive age determination; Rocks; Signatures; Stone; Zircon; 지질학; China; Xiaoxigong; A-type granite; geochemistry; zircon U-Pb-Hf isotopes; northeast Tarim
• ISSN: 1226-4806; 1598-7477
• DOI: 10.1007/s12303-015-0010-9

We present new zircon U-Pb ages, Hf isotopes, and whole-rock geochemistry of the Xiaoxigong granite pluton in the Dunhuang block, northeastern Tarim Craton. LA-ICPMS zircon U-Pb dating yields a weighted mean 206 Pb/ 238 U age of 841.3 ± 8.1 Ma (MSWD = 4.4), interpreted as the emplacement age of the Xiaoxigong granite. Zircons have εHf(t) values ranging from +4.53 to +8.63 and TDM2 model ages from 1.16 to 1.38 Ga. Geochemical characteristics show that the granite belongs to the shoshonite series and has weakly peraluminous-metaluminous features. It is enriched in Si, K, Na, Rb, Th and REE, and has elevated Ga/Al ratios and high (Zr + Nb + Ce + Y) abundance, and is depleted in Mg, Ca, Mn, Ba, Sr, P and Ti. The REE composition shows significant negative Eu anomalies (Eu/Eu* = 0.18–0.31) and low (La/Yb) N (4.54–7.33). It is typical aluminous A-type granite. The geochemical and Hf isotopic signatures suggest that the Neoproterozoic Xiaoxigong granite was generated by partial melting of crustal rocks during the the post-orogenic period.