Integration of zircon and apatite U–Pb geochronology and geochemical mapping of the Wude basalts (Emeishan large igneous province): A tool for a better understanding of the tectonothermal and geodynamic evolution of the Emeishan LIP

• Published in: Di xue qian yuan. 2021-03, Vol.12 (2), p.573-585
• Main Authors: Fu, Jia-Nan, Pirajno, Franco, Yang, Fan, Shivute, Espine, Sun, Yi-Zhan, Ai, Ning, Qiu, Kun-Feng
• Format: Article
• Language: English
• Subjects: Anomalies; Apatite; Basalt; Contamination; Early Eocene superposition; Emeishan basalt; Geochronology; Indian–Eurasian plate collision; Inductively coupled plasma mass spectrometry; Isotopes; Laser ablation; Lava; Lithogeochemistry; Lu–Hf isotope; Mapping; Mass spectrometry; Niobium; Plates (tectonics); Radiometric dating; Rocks; Superposition (mathematics); Tantalum; Volcanic eruptions; Zircon; Zircon and apatite
• ISSN: 1674-9871; 2588-9192
• DOI: 10.1016/j.gsf.2020.08.004

Radiogenic isotopic dating and Lu–Hf isotopic composition using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) of the Wude basalt in Yunnan province from the Emeishan large igneous province (ELIP) yielded timing of formation and post-eruption tectonothermal event. Holistic lithogeochemistry and elements mapping of basaltic rocks were further reevaluated to provide insights into crustal contamination and formation of the ELIP. A zircon U–Pb age of 251.3 ​± ​2.0 ​Ma of the Wude basalt recorded the youngest volcanic eruption event and was consistent with the age span of 251–263 ​Ma for the emplacement of the ELIP. Such zircons had εHf(t) values ranging from −7.3 to +2.2, identical to those of magmatic zircons from the intrusive rocks of the ELIP, suggesting that crust-mantle interaction occurred during magmatic emplacement, or crust-mantle mixing existed in the deep source region prior to deep melting. The apatite U–Pb age at 53.6 ​± ​3.4 ​Ma recorded an early Eocene magmatic superimposition of a regional tectonothermal event, corresponding to the Indian–Eurasian plate collision. Negative Nb, Ta, Ti and P anomalies of the Emeishan basalt may reflect crustal contamination. The uneven Nb/La and Th/Ta values distribution throughout the ELIP supported a mantle plume model origin. Therefore, the ELIP was formed as a result of a mantle plume which was later superimposed by a regional tectonothermal event attributed to the Indian–Eurasian plate collision during early Eocene. [Display omitted] •Wude basalt forming at 251 ​Ma recorded the termination of ELIP volcanic volcanism.•Wude basalt documented an early Eocene overprinting attributed to Indian-Eurasian plate collision.•Nb/La and Th/Ta contour maps support a mantle plume model origin.