Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第26卷    第3期    总第204期    2016年3月

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文章编号:1004-0609(2016)-03-0636-12
辽东榛子沟铅锌矿煌斑岩锆石U-Pb年代学、地球化学特征及其地质意义
张朋1, 2,陈冬3,赵岩1,寇林林1,杨宏智1,王希今1,沙德铭1

(1. 沈阳地质矿产研究所中国地质调查局沈阳地质调查中心,沈阳 110034;
2. 吉林大学地球科学学院,长春 130061;
3. 江苏省地质调查研究院,南京 210018
)

摘 要: 阐述辽东榛子沟铅锌矿区煌斑岩岩相学、锆石U-Pb年代学、元素地球化学及Sr-Nd同位素地球化学特征。锆石LA-ICP-MS U-Pb定年结果表明煌斑岩侵位时代为(227.7±1.3) Ma,属于晚三叠世。岩石地球化学分析表明煌斑岩具有高钾(K2O/Na2O为2.34~3.64)、富碱(K2O+Na2O为4.12~4.67),富集大离子亲石元素(Rb、Ba)和轻稀土元素,亏损重稀土元素和高场强元素(Nb、Ta、Zr、Hf)特征。同位素显示高(87Sr/86Sr)i(0.71224~0.71248)低εNd(t)(-1.53~-0.43)特点。岩石地球化学和同位素特征表明,煌斑岩可能为EMⅡ型富集地幔部分熔融的产物,推测源区可能与板块俯冲带组分脱水产生的富集LILE而亏损HFSE的流体交代富集地幔有关,岩浆上升过程中未发生明显的地壳混染作用。结合区域构造演化,认为扬子克拉通向华北克拉通深俯冲过程中板片断离可能是该区煌斑岩形成的地球动力学背景。

 

关键字: 煌斑岩;年代学;地球化学;榛子沟铅锌矿

Zircon U-Pb geochronology , geochemical characteristics andits geological significance of lamprophyres inZhenzigou Pb-Zn deposit, Liaodong
ZHANG Peng1, 2, CHEN Dong3, ZHAO Yan1, KOU Lin-lin1, YANG Hong-zhi1, WANG Xi-jin1, SHA De-ming1

1. China Geological Survey, Shenyang Institute of Geology and Mineral Resources, Shenyang 110034, china;
2. College of Earth Sciences, Jilin University, Changchun 130061, China;
3. Geological Survey of Jiangsu Province, Nanjing 210018, China

Abstract:The petrographical, zircon U-Pb dating, geochemical and Sr-Nd isotopic characteristic of lamprophyres in Zhenzigou Pb-Zn deposit, Qingchengzi, Liaodong peninsula. Zircon LA-ICP-MS U-Pb dating yields an age of (227.70±1.30) Ma, the lamprophyres are the product of late Indosinian magmatism in North China Craton(NCC). Geochemically, the lamprophyres have high values of potassium (K2O/Na2O are 2.34~3.64), alkaline (K2O+Na2O are 4.12~4.67) and are enriched in large ion lithophile elements (Rb, Ba) and LREEs and depleted in the high field strength elements (Nb, Ta, Zr, Hf) and HREEs. The isotopic of lamprophyres are characterized by high (87Sr/86Sr)I (0.71224~0.71248),low εNd(t) (-1.53~-0.43). Based on the geochemistry and isotope, the lamprophyres were derived from EMⅡ which are metasomatized by the enriched in large ion lithophile elements while depleted in the high field strength elements fluid from the dehydration of the subducted plate, which was not obvious undergo contamination of crust in the process of magma rising. Combined with regional tectonic evolution, the lamprophyre is originated from slab break-off during the process of Yangtze Craton and North China Craton continental deep subduction.

 

Key words: lamprophyres; geochronology; geochemical; Zhenzigou Pb-Zn deposit

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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