吉林省闫家街—宋家街石英钠长斑岩岩石地球化学特征及其构造意义
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摘要
闫家街—宋家街石英钠长斑岩体位于华北板块北缘东段。岩体富硅、钾、钠,高铝,低镁、磷,铝指数A/CNK为0.91~1.21,分异指数为82.02~91.94,属高分异I型花岗岩类。LR/HR=6.44~8.31,La N/Yb N=5.03~10.92,配分曲线呈不对称右倾形,具有Eu的负异常(δEu=0.40~0.68);与原始地幔相比,富集大离子亲石元素(LILEs,如Rb、Ba),亏损高场强元素(HFSEs,如Nb、Ta、P和Ti),显示火山弧岩浆岩特征;样品在花岗岩构造环境判别图解中均落入火山弧范围内。结合区域研究资料,表明其可能为一种活动大陆边缘弧环境。
Yanjiajie-Songjiajie quartz albitophyres situated in the eastern section of northern margin of the north china plate. This rock mass is rich in Si, K, Na, especially in Al, and poor in Mg, P, the aluminum index A/CNK is 0.91~1.21, and the differentiation index is 82.02 ~91.94, belongs to highly fractionated I-type granites. LR/HR=6.44~8.31, La N/Yb N=5.03~10.92, the distribution curve is asymmetrically rightward with negative Eu anomaly(Eu=0.40~ 0.68). Compared with the original mantle, the enrichment of large ionic(LILEs, such as Rb, Ba) and loss of high field strength elements(HFSEs, such as Nb, Ta, P and Ti) shows the characteristics of volcanic arc magmatic rocks. The samples fall into the range of volcanic arc in the granite tectonic environment discrimination diagram. Combined with regional research data, it is shown that it may be an active continental edge arc environment.
Yanjiajie-Songjiajie quartz albitophyres situated in the eastern section of northern margin of the north china plate. This rock mass is rich in Si, K, Na, especially in Al, and poor in Mg, P, the aluminum index A/CNK is 0.91~1.21, and the differentiation index is 82.02 ~91.94, belongs to highly fractionated I-type granites. LR/HR=6.44~8.31, La N/Yb N=5.03~10.92, the distribution curve is asymmetrically rightward with negative Eu anomaly(Eu=0.40~ 0.68). Compared with the original mantle, the enrichment of large ionic(LILEs, such as Rb, Ba) and loss of high field strength elements(HFSEs, such as Nb, Ta, P and Ti) shows the characteristics of volcanic arc magmatic rocks. The samples fall into the range of volcanic arc in the granite tectonic environment discrimination diagram. Combined with regional research data, it is shown that it may be an active continental edge arc environment.
引文
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[2]Batchlor R B,Bowden P.Petrogenetic Interpretation of Granitiod Rock Series Using Multicationic Parameters[J].Chemical Geology,1985,48:43-55.
[3]Boynton W V.Geochemistry of the rare-earth elements:Meteorite studies.In:Henderson[J].Rare Earth Element Geochemistry,Amsterdam:Elservier,1984,63-114.
[4]陈静,孙丰月,潘彤,等.黑龙江霍吉河钼矿成矿地质特征及花岗闪长岩年代学、地球化学特征[J].吉林大学学报(地球科学版),2012,42(S1):207-215.
[5]邓晋福,刘翠,冯艳芳,等.高镁安山岩/闪长岩类(HMA)和镁安山岩/闪长岩类(MA):与洋俯冲作用相关的两类典型的火成岩类[J].中国地质,2010,37(4):1 112-1 118.