Zircon U-Pb Ages and Hf Isotopes of Neoproterozoic Meta-Igneous Rocks in the Liansandao Area, Northern Sulu Orogen, Eastern China, and the Tectonic Implications

• Published in: Journal of earth science (Wuhan, China) China), 2019-12, Vol.30 (6), p.1230-1242
• Main Authors: Song, Zhaojun, Liu, Huimin, Meng, Fanxue, Yuan, Xingyu, Feng, Qiao, Zhou, Dingwu, Romaní, Juan Ramon Vidal, Yan, Hongbo
• Format: Article
• Language: English
• Subjects: Area; Biogeosciences; Continental crust; Crystallization; Earth and Environmental Science; Earth Sciences; Fault zones; Faults; Geochemistry; Geochronometry; Geology; Geotechnical Engineering & Applied Earth Sciences; Heterogeneity; Igneous rocks; Isotopes; Lava; Lead; Lead isotopes; Magma; Mantle; Metamorphism and Orogenic Belts—Response from Micro- to Macro-Scale; Ocean circulation; Orogeny; Petrogenesis; Radiometric dating; Sediment samples; Tectonics; Upwelling; Zircon
• ISSN: 1674-487X; 1867-111X
• DOI: 10.1007/s12583-019-1252-7

The Sulu Orogen preserves the Neoproterozoic tectonic-magmatic events, corresponding to the breaking up of the Rodinia supercontinent. The ages and petrogenesis of meta-igneous rocks in the Liansandao area in the northern Sulu Orogen are not well-constrained. This study reports zircon U-Pb ages and Hf isotopes of these rocks from the Liansandao area. Three meta-igneous rock samples give similar weighted mean 206Pb/238U ages of 744±11, 767±12, and 762±15 Ma, respectively, indicating the Neoproterozoic crystallization ages. These rocks formed coevally with the Wulian and Yangkou intrusions that located along the Yantai-Qingdao-Wulian fault zone. The Neoproterozoic ages indicate that the meta-igneous rocks from the Liansandao area have affinity to the Yangtze Block. The three samples have ε Hf(t) Hf( t ) values of -7.2–-10.5, -6.0–-17.5, and -6.8–-12.0, respectively. These negative ε Hf ( t ) values indicate a primarily crustal source. However, the widely various ε Hf ( t ) values that are higher than the continental crust, suggesting magma mixing between mantle-derived materials and the continental crust or source heterogeneity. Combined with the Hf model ages and geochemical characteristics, the monzodiorite (sample LSD-2) is most likely to be mantle-derived magma then interacted with ancient continental crust, and the granitic protolith (samples LSD-1 and LSD-3) in the Liansandao area might derive from the re-melting of a Paleoproterozoic continental crust at ~750 Ma, resulting from the upwelling and underplating of mantle-derived magma formed in an extensional setting due to the break- up of the Rodinia supercontinent.