地质学报2017，Vol.91Issue(5)：1007-1021,15.
南秦岭随州地区正长花岗岩锆石SHRIMP U-Pb年代学与地球化学特征
Zircon SHRIMP U-Pb Age and Geochemical Characteristics of Syenogranite in the Suizhou Area, South Qinling
摘要
Abstract
Located in the north of Suizhou,syenogranite occurs in diabase as vein-like,and strikes NW-SE direction.SHRIMP U-Pb dating yields a weighted mean 206Pb/238U age of 648.8±1.9 Ma (MSWD=0.86) for the zircons from syenogranite,indicating that syenogranite belongs to Neoproterozoic.Lithochemical analysis shows that syenogranite is slightly metaluminous and belongs to the high-K calc-alkaline series.The syenogranite is characterized by high SiO2 (70.67％ ～75.75 ％),high alkali (K2O+ Na2O=7.28 ％ ～8.53％),high FeOT/MgO (FeOT/MgO=26.37～35.50),low CaO (0.60％～1.53％) and MgO (0.07％～0.12％) contents.Chondrite-normalized REE patterns of the syenogranite are characterized by weakly HREE depletion with Eu anomalies (δEu=0.33～0.56).The values of 1000Ga/Al and Zr+Nb+Ce+Y range from 2.60 to 3.41 and from 552.48)× 10-6 to 648.87)× 10-6,respectively.The spider diagram of the trace elements shows the enrichment of large-ion lithophile elements (Rb,K,Th,etc),relative enrichment of high field strength elements (Zr,Hf,Nb,Ta),relative depletion of Sr,P and Ti.All these features above suggest that syenogranite belongs to Al-type granite.Combined with the regional tectonic evolution,it can be concluded that syenogranite formed in a regional extensional setting.During the Neoproterozoic,the tectonic regime in the Qinling-Tongbai-Dabie area changed from compression to extension,under which the upwelling magma resulted in the formation of the Al-type syenogranite.关键词
随州/Al型花岗岩/地球化学/SHRIMP U-Pb测年/新元古代Key words
Suizhou/Al-type syenogranite/geochemistry/zircon SHRIMP U-Pb dating/Neoproterozoic引用本文复制引用
王东升,王宗起,武昱东,王刚,张玉涛..南秦岭随州地区正长花岗岩锆石SHRIMP U-Pb年代学与地球化学特征[J].地质学报,2017,91(5):1007-1021,15.基金项目
本文为国家自然科学基金项目(编号41402180)和国土资源部中国地质调查局项目(编号12120113069000)资助成果. （编号41402180）
