Formation of the Late Permian Panzhihua plutonic-hypabyssal-volcanic igneous complex: Implications for the genesis of Fe-Ti oxide deposits and A-type granites of SW China

J. G. Shellnutt*, B. M. Jahn

*此作品的通信作者

研究成果: 雜誌貢獻期刊論文同行評審

101 引文 斯高帕斯(Scopus)

摘要

The Late Permian (260 Ma) Emeishan large igneous province of SW China contains numerous magmatic Fe-Ti oxide deposits. The Fe-Ti oxide deposits occur in the lower parts of evolved layered gabbroic intrusions which are spatially and temporally associated with A-type granitic rocks. The 260 Ma Panzhihua layered gabbroic intrusion hosts one of the largest magmatic Fe-Ti oxide deposits in China and is coeval with a peralkaline A-type granitic pluton. The granite has intruded the overlying Emeishan flood basalts and fed at least one dyke which erupted onto the surface producing columnar jointed trachytes. The presence of syenodiorite between the layered gabbro and granite is evidence for compositional evolution from mafic to intermediate to felsic rocks. The syenodiorites have intermediate to felsic composition with SiO2 = 61 to 65 wt.%, MgO = 0.27 to 0.6 wt.% and CaO = 1.0 to 2.5 wt.% as compared to the granite SiO2 = 65 to 72 wt.%, MgO = 0.1 to 0.4 wt.%, CaO = < 1.0 wt.%. Primitive-mantle-normalized incompatible element plots show corresponding reciprocal patterns between the mafic and felsic rocks. The chondrite-normalized REE patterns show Eu anomalies changing from > 1(Eu/Eu* = 1.1 to 2.6) in the gabbroic intrusion, to < 1 in the syenodiorite (Eu/Eu* = 0.75 to 0.83), granites and trachytes (Eu/Eu* = 0.55-0.87). Previously published εNd(T) values from clinopyroxenes (εNd(T) = + 1.1 to + 3.2) of the gabbroic intrusion match the whole-rock values of the syenodiorite (εNd(T) = + 2.1 to + 2.5), granite and trachyte (εNd(T) = + 2.2 to + 2.9), suggesting that all rock types originated from the same mantle source. MELTS and trace element modeling confirm that all rock types can be generated by fractional crystallization of high-Ti Emeishan basalt. The jump in SiO2 from the gabbro to the syenodiorite is attributed to the en masse crystallization of the Fe-Ti oxides. The geological and geochemical data indicate that fractional crystallization of a common parental magma produced the layered gabbroic intrusion and Fe-Ti oxide deposit, the syenodiorite, granites and trachyte of the Panzhihua region, which thus form a genetically related plutonic-hypabyssal-volcanic complex. Other granite-gabbro complexes in the region likely formed in a similar manner.

原文英語
頁(從 - 到)509-519
頁數11
期刊Earth and Planetary Science Letters
289
發行號3-4
DOIs
出版狀態已發佈 - 2010 一月 31
對外發佈

ASJC Scopus subject areas

  • 地球物理
  • 地球化學與岩石學
  • 地球與行星科學(雜項)
  • 空間與行星科學

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