福建锦城187Ma花岗岩的发现: 对华南沿海早侏罗世构造演化的制约

Translated title of the contribution: Discovery of the 187Ma granite in Jincheng area, Fujian Province: constraint on Early Jurassic tectonic evolution of Southeastern China

Qian Liu*, Jin Hai Yu, Bin Su, Qin Wang, Hong Feng Tang, Hai Xu, Xiang Cui

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

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 ± IMa, which is the firstly found Early Jurassic magmatism in the coastal Fujian Province, and the Niutouwei granodiorite is 130 ± IMa, representing a stage of Late Yanshanian (Cretaceous) magmatism. The Jincheng granite is high-K calc- alkaline, and characterized by high contents of SiO2, alkali and Fe2 O2T. It is depleted in HFSE ( Nb, Ta, Ti) , and enriched in LREE and LILE, such as Ba, Sr with high Rb/Sr (1.31 ∼ 1. 93 ) ratios and low Rb/Ba ( 0. 26 ∼ 0. 29 ) , Eu/Eu * ( 0. 30 ∼ 0. 56 ) , La/Yb (5. 69 ∼ 18. 39) , Sr/Y (2.24 ∼ 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 εHf(t) values (2. 18 ∼ 4. 73 and 1.25 ∼ 4. 15 respectively) and Hf model ages ( ∼ 1.OGa) , suggesting that they originated from similar source, a Neoproterozoic juvenile crust. Coupled with previous data, this paper points out that the Jincheng granite has genetic relationship with the coeval magmatism (194 ∼ 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.

Translated title of the contributionDiscovery of the 187Ma granite in Jincheng area, Fujian Province: constraint on Early Jurassic tectonic evolution of Southeastern China
Original languageChinese
Pages (from-to)3575-3589
Number of pages15
JournalActa Petrologica Sinica
Volume27
Issue number12
Publication statusPublished - 2011
Externally publishedYes

Keywords

  • Early Jurassic granite
  • Pingtan-Dongshan metamorphic belt
  • The subduction of paleo-Pacific plate
  • Zircon U-Pb-Hf isotope analyses

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