ORIGINAL RESEARCH article
Front. Earth Sci.
Sec. Geochemistry
Volume 13 - 2025 | doi: 10.3389/feart.2025.1513583
Geochronology and geochemistry of mafic igneous rocks in the Zhegu area of southern Tibet
Provisionally accepted
Ming Cheng1Yuanlin Lou1Yingzi Min1Yao Tang1Xinyue Li1Ming Zhang1Xuming Hu1Tianyong Wan1Hao Zou1Kaihong Xu1
Saijun Sun2*Chao Chen3Junjie Zhang2Wei Guo1- 1Changsha Natural Resources Comprehensive Survey Center, China Geological Survey, Changsha City, China
- 2Center for Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences (CAS), Qingdao, China
- 3Kunming General Survey of Natural Resources Center, China Geological Survey, Kunming, Yunnan Province, China
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The Zhegu region, located in southern Tibet, is positioned within the central and eastern segments of the Tethys Himalayan tectonic belt. In this area, mafic igneous rocks are predominantly intrusion into Jurassic strata, occurring as vein-like bodies. This study presents zircon U-Pb age determinations and whole-rock geochemical analyses of diabase and gabbro samples from the region, aimed at elucidating their petrogenesis and geodynamic background. The zircon U-Pb ages yield crystallization ages of 130.7 ± 1.5 Ma for diabase and 131.6 ± 2.5 Ma for gabbro, both of which are consistent with the crystallization ages of ocean island basalt (OIB)-type mafic rocks in the Comei Large Igneous Province (130~136 Ma). Geochemical data reveal that these mafic rocks are characterized by elevated TiO2, FeOT, and P2O5 contents, alongside relatively low MgO content, indicative of tholeiitic affinities. They exhibit enrichment in light rare earth elements (LREEs) and high field strength elements (HFSEs) such as Nb, Hf and Y, resembling OIB signatures. These rocks show evidence of fractional crystallization without significant crustal contamination. Melting models suggest that the magmas originated from partial melting of a garnet-lherzolite mantle source. The petrogenetic characteristics of these rocks reflect interactions between the Kerguelen mantle plume and the overlying lithospheric mantle.
Keywords: zircon U-Pb age, Whole-rock geochemistry, OIB-like type mafic rocks, Kerguelen mantle plume, Southern Tibet
Received: 18 Oct 2024; Accepted: 24 Jun 2025.
Copyright: © 2025 Cheng, Lou, Min, Tang, Li, Zhang, Hu, Wan, Zou, Xu, Sun, Chen, Zhang and Guo. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Saijun Sun, Center for Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences (CAS), Qingdao, China
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