This study presents bulk geochemical and zircon U-Pb-Hf isotopic results for the Jincheng granite and Niutouwei granodiorite in the Fuqing area, coastal Fujian Province. LA-ICP-MS zircon U-Pb dating results show that the jincheng granite has an crystallization age of 187 +/- 1Ma, which is the firstly found Early Jurassic magmatism in the coastal Fujian Province, and the Niutouwei granodiorite is 130 +/- 1Ma, representing a stage of Late Yanshanian (Cretaceous) magmatism. The Jincheng granite is high-K calc-alkaline, and characterized by high contents of SiO(2), alkali and Fe(2)O(3)(T). It is depleted in HFSE (Nb, Ta, Ti), and enriched in LREE and LILE, such as Ba, Sr with high Rb/Sr (1.31 similar to 1.93) ratios and low Rb/Ba (0.26 similar to 0. 29), Eu/Eu* (0.30 similar to 0. 56), La/Yb (5. 69 similar to 18. 39), Sr/Y (2. 24 similar to 2. 29) ratios. The Jincheng granite is typical I-type granite with the volcanic arc granitic (VAG) geochemical characteristics, and formed in the subduction-related tectonic setting. The Niutouwei granodiorite has higher Mg, Ca, Ba, Sr contents, lower SiO(2), K, Nb, Ta contents and lower Rb/Sr (0. 27), Rb/Ba (0. 09) ratios and higher Eu/Eu* (0. 98), La/Yb (16. 87), Sr/Y (19.08) ratios than the Jincheng granite. The Niutouwei granodiorite is also calc-alkaline I-type granite with the VAG geochemical characteristics similar to the Jincheng granite, and formed in the continental arc environment. The Jincheng granite and Niutouwei granodiorite have similar Hf isotopic compositions of zircons with positive epsilon(Hf)(t) values (2. 18 similar to 4. 73 and 1. 25 similar to 4. 15 respectively) and Hf model ages (similar to 1. 0Ga), suggesting that they originated from similar source, a Neoproterozoic juvenile crust. with previous data, this paper points out that the Jincheng granite has genetic relationship with the coeval magmatism (194 similar to 172Ma) in the Nanling Range, implying that the subduction of paleo-Pacific plate probably started from Early Jurassic time. Consequently, the transition from the Tethys orogenic regime to the paleo-Pacific tectonic regime in the Southeast China probably occurred before Early Jurassic, approximately from 205Ma to 190Ma.

Publication name	ACTA PETROLOGICA SINICA　Volume:27　Issue:12　Pages:3575-3589　Published:DEC 2011
Author(s)	Liu Qian; Yu JinHai; Su Bin; Wang Qin; Tang HongFeng; Xu Hai; Cui Xiang
Corresponding author	LIU Qian  thlove1314@163.com,jhyu@nju.edu.cn  Nanjing Univ, Sch Earth Sci & Engn, State Key Lab Mineral Deposits Res, Nanjing 210093, Peoples R China
Author(s) from IGCAS	TANG Hongfeng