CAJ | 학술논문

用SHRIMP锆石U-Pb测年法获得滇西北衙地区炭窑石英正长斑岩的年龄TY-1为31.5 Ma±1.1Ma,TY-3为31.34Ma±0.73Ma,证明该斑岩形成于新生代.北衙富碱斑岩具有富碱、高钾的特点,总体属于钾玄岩系列的岩石.岩石富轻稀土和Rb、Ba等大离子亲石元素而亏损Nd、Ta等高场强元素.岩石的∑LREE/∑HREE比值和(La/Yb)_N比值高,Eu异常不明显.综合北衙地区富碱侵入岩的常量、微量、稀土元素和同位素地球化学特征发现.富碱斑岩具有许多与埃达克岩(adakite)相似的岩石地球化学特征,但又与Defant等定义的典型埃迭克岩有明显的差别,而与中国可可西里钾质埃迭克岩更为接近.通过对北衙地区富碱斑岩的Sr、Nd、Pb同位素的系统研究发现,富碱斑岩的源区具有EMⅡ富集地幔的地球化学特征.
용SHRIMP고석U-Pb측년법획득전서북아지구탄요석영정장반암적년령TY-1위31.5 Ma±1.1Ma,TY-3위31.34Ma±0.73Ma,증명해반암형성우신생대.북아부감반암구유부감、고갑적특점,총체속우갑현암계렬적암석.암석부경희토화Rb、Ba등대리자친석원소이우손Nd、Ta등고장강원소.암석적∑LREE/∑HREE비치화(La/Yb)_N비치고,Eu이상불명현.종합북아지구부감침입암적상량、미량、희토원소화동위소지구화학특정발현.부감반암구유허다여애체극암(adakite)상사적암석지구화학특정,단우여Defant등정의적전형애질극암유명현적차별,이여중국가가서리갑질애질극암경위접근.통과대북아지구부감반암적Sr、Nd、Pb동위소적계통연구발현,부감반암적원구구유EMⅡ부집지만적지구화학특정.
In this paper SHRIMP U-Pb ages,TY-1 (31.5±1.1Ma)、TY-3 (31.34±0.73 Ma) of Tanyao quartz syenite porphyries in Beiya are published for the first time, which suggest that the intrusions are formed in Cenozoic. The results show that alkali-rich porphyries in Beiya are characterized by enrichment in alkaline and potassium. They are high in LREE and LILE (such as Rb、Ba etc.), with depletion of HFSE(such as Nd、Ta etc.), high Σ LREE/Σ HREE and (La/Yb)_N ratios, and lack of apparent Eu anomalies. Based on the characteristics of major elements, trace elements, REE, and isotope geochemistry of alkali-rich intrusion in Beiya area, we've concluded that they have many similar petrological and geochemical characteristics to adakites, but are quite different from those of typical features of adakite defined by Defant and Drummond (1990), which are more close to those adakites in Hoh Xil Area. Systematical studies on Sr、Nd、Pb isotopic characteristics in this paper found out that the source region of the alkali-rich porphyries have the typical geochemical characteristics of EM II enriched mantle.