现代地质
現代地質
현대지질
GEOSCIENCE-JOURNAL OF GRADUATE SCHOOL CHINA UNIVERSITY OF GEOSCIENCES
2014年
1期
16-28
,共13页
张亚峰%蔺新望%王星%郭岐明%赵端昌%吕军利%王旭
張亞峰%藺新望%王星%郭岐明%趙耑昌%呂軍利%王旭
장아봉%린신망%왕성%곽기명%조단창%려군리%왕욱
角闪黑云英云闪长岩%LA-ICP-MS锆石U-Pb定年%昆格依特岩体%大青格里河%阿尔泰%新疆
角閃黑雲英雲閃長巖%LA-ICP-MS鋯石U-Pb定年%昆格依特巖體%大青格裏河%阿爾泰%新疆
각섬흑운영운섬장암%LA-ICP-MS고석U-Pb정년%곤격의특암체%대청격리하%아이태%신강
hornblende biotite tonalite%LA-ICP-MS zircon U-Pb dating%Kungeyite pluton%Qingeli River%Al-tay%Xinjiang
昆格依特岩体出露于阿尔泰造山带南缘青河县大青格里河昆格依特一带,主要为角闪黑云英云闪长岩。LA-ICP-MS锆石U-Pb定年结果显示,锆石的206 Pb/238 U年龄加权平均值为(403.4±7.4)Ma,表明该岩体形成于早泥盆世。岩体的SiO2含量介于52.39%~71.89%之间,里特曼指数为0.68~1.53,A/CNK值为0.76~1.06,属中钾、钙碱性、准铝质-弱过铝质岩石。具有富集Cs、Rb、Th、U等大离子亲石元素和轻稀土元素,相对亏损Nb、Ta、Hf、Ti等高场强元素和重稀土元素,弱的负Eu异常(δEu=0.56~0.86)的岛弧岩浆岩特征。结合区域地质资料,认为阿尔泰造山带南缘早泥盆世昆格依特岩体形成于活动大陆边缘的陆缘弧构造环境,是古亚洲洋俯冲过程中幔源的基性岩浆底侵下地壳使之熔融,并发生了岩浆混合和分异作用的产物。
昆格依特巖體齣露于阿爾泰造山帶南緣青河縣大青格裏河昆格依特一帶,主要為角閃黑雲英雲閃長巖。LA-ICP-MS鋯石U-Pb定年結果顯示,鋯石的206 Pb/238 U年齡加權平均值為(403.4±7.4)Ma,錶明該巖體形成于早泥盆世。巖體的SiO2含量介于52.39%~71.89%之間,裏特曼指數為0.68~1.53,A/CNK值為0.76~1.06,屬中鉀、鈣堿性、準鋁質-弱過鋁質巖石。具有富集Cs、Rb、Th、U等大離子親石元素和輕稀土元素,相對虧損Nb、Ta、Hf、Ti等高場彊元素和重稀土元素,弱的負Eu異常(δEu=0.56~0.86)的島弧巖漿巖特徵。結閤區域地質資料,認為阿爾泰造山帶南緣早泥盆世昆格依特巖體形成于活動大陸邊緣的陸緣弧構造環境,是古亞洲洋俯遲過程中幔源的基性巖漿底侵下地殼使之鎔融,併髮生瞭巖漿混閤和分異作用的產物。
곤격의특암체출로우아이태조산대남연청하현대청격리하곤격의특일대,주요위각섬흑운영운섬장암。LA-ICP-MS고석U-Pb정년결과현시,고석적206 Pb/238 U년령가권평균치위(403.4±7.4)Ma,표명해암체형성우조니분세。암체적SiO2함량개우52.39%~71.89%지간,리특만지수위0.68~1.53,A/CNK치위0.76~1.06,속중갑、개감성、준려질-약과려질암석。구유부집Cs、Rb、Th、U등대리자친석원소화경희토원소,상대우손Nb、Ta、Hf、Ti등고장강원소화중희토원소,약적부Eu이상(δEu=0.56~0.86)적도호암장암특정。결합구역지질자료,인위아이태조산대남연조니분세곤격의특암체형성우활동대륙변연적륙연호구조배경,시고아주양부충과정중만원적기성암장저침하지각사지용융,병발생료암장혼합화분이작용적산물。
The Kungeyite plutons,outcropped in Qingeli River in Qinghe County of southern margin of Altay orogenic belt are mainly hornblende biotite tonalite,which were determined for LA-ICP-MS zircon U-Pb ages. The result shows that the zircon 206Pb/238U weighted average age is (403.4 ±7.4)Ma (MSWD=1.07),indi-cating the plutons were formed at Early Devonian.The SiO2 contents range from 52.39% to 71.89% and σfrom 0.68 to 1.53,A/CNK from 0.76 to 1.06,indicating that the plutons are mid-K calc-alkaline,metalumi-nous-weakly peraluminous rocks.In addition,the plutons are enrichment in LILE (Cs,Rb,Th,U )and LREE,obvious negative anomaly in HFSE (Nb,Ta,Hf,Ti),HREE and Eu (δEu =0.56 -0.86),thus resembling granitoid rocks formed in island-arc.Combined with the data of southern margin of Altay,the Kunge-yite plutons were generated by partial melting of the lower crust underplayed by mafic magma of the mantle in a continental arc setting of active continental margin,and occurred magma mixing and differentiation.