Age,Petrogenesis and Tectonic Implications of Permian Hornblendite in Tugurige,Urad Zhongqi,Inner Mongolia
Wang Jian
Sun Fengyue
Li Bile
Wang Yingde
Li Ruihua
Abstract：Electron microprobe results,zircon U-Pb dating,Hf isotope data and geochemistry of hornblendite at Tugurige, Urad Zhongqi,Inner Mongolia are reported in the paper,which provide constraints on formation time,magma source,and tec-tonic setting of the intrusions.The dating results indicate that the hornblendite formed in the late Early Permian (273.5 ± 1.3 Ma,MSWD=0.48;274.4±4.3 Ma,MSWD=0.041),and it contains low Na2 O and K2 O,high Al2 O 3 ,TFe2 O 3 ,MgO, CaO,Mg# =46.95-63.53,M/F=0.87 - 1.72.Chondrite-normalized REE patterns show LREE enrichment.On a trace ele-ment spider diagram,large ion lithophile elements (LILEs)such as Rb,Ba and K are enriched,whereas the high field strength elements Ti,P,Th and U are relatively depleted.Electronic Probe analysis results show that hornblende belongs to calcic am-phibole and has the characteristics of mantle hornblende.TheεHf (t )values of zircons from the hornblendite vary between -0.3 and 8.5,and their Hf one-stage model ages vary from 580 to 920 Ma,implying that their magma source was derived from a de-pleted mantle and may have been added metasomatic enriched lithospheric mantle components.Combined with regional tectonic evolution,the hornblendite formed in the post-collisional extension setting,perhaps triggered by slab break-off.
Keywords：Inner MongoliaUrad Zhongqicrystal chemistrygeochronologygeochemistryHf isotope
Publication Date：2016-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：17( 792-808 )