黑龙江南蛤拉河子地区二浪河组火山岩的锆石U-Pb年代学及地球化学特征  

Zircon U-Pb chronology and geochemical characteristics of volcanic rocks from erlanghe formation in Nanhalahezi district of Heilongjiang province

作　　者：朱敬宾 任永健[1] 杨宏图[1] 曹光远[1] 王博[1] 

机构地区：[1]中化地质矿山总局地质研究院,河北涿州072754

出　　处：《化工矿产地质》2017年第3期129-139,共11页Geology of Chemical Minerals

摘　　要：通过对南蛤拉河子二浪河组火山岩进行锆石U-Pb LA-ICP-MS测年、岩石地球化学测试,讨论其形成的时代和背景。测年结果显示,二浪河组火山岩形成于177.7±0.54Ma^183.1±0.36Ma,是早侏罗世岩浆活动的产物。火山岩的岩石组合为安山岩-英安岩-流纹岩,属于高钾钙碱性-中钾钙碱性系列。流纹岩具有富集Rb、Th、K等大离子亲石元素(LILE)、亏损Nb、Ti等高场强元素(HFSE)及P、Sr等元素的特征,岩石以Rb、U、K、Th、Zr正异常,Ba、Nb、P、Sr、Ti等负异常为特征。Rb、U、Th、Zr强烈富集,且富集程度随着岩浆的演化而加大,明显亏损Nb、P、Ti等元素,并在Nb、P、Ti三处出现向下凹陷,在K、Rb、Th、Ce、Sm(Hf)出现向上隆起,显示了大陆弧的"三弧"隆起特征。结合该时期区域构造演化史,火山岩地球化学特征揭示了二浪河组火山岩的形成与岛弧环境下的局部伸展作用有关,是在古亚洲洋板块俯冲松嫩-张广才岭地块的背景下造成的。In this paper, samples of volcanicrocks from Erlanghe formation inNanhalahezi district were analyzed for major, trace elements and zircon U-Pb dating to validate theirtectonic setting and formation ages.LA-ICP-MS U-Pb dating of magmatic zircons from Erlanghe formationyield weighted average206Pb/238U ages of 177.7 ±0.54Ma to 183.1 ± 0.36Ma, belonging to Early Jurassic magmatic.Volcanic rocks in the study area mainly consist of andesites, dacites and rhyolites, belonging to high-K to middle-K calc-alkaline series. Rhyolitesare characterized by large ion lithophile element（LILE; e. g., Rb, K）enrichment, high field-strength element（HFSE; e. g., Nb, P, Ti）depleted, positive anomaly of Rb, U, K, Th, Zr, and negative＇ anomaly of Ba, Nb, P, Ti. As the magmatic evolved, Rb, U, Th, Zr became more and more enriched. Negative anomaly of Nb, P, Ti and positive anomaly of K, Rb, Th, Ce, Sm （HI） show the geochemical characteristics of continental arc. Combined with the regional geological data and geochemical characteristics, we therefore suggestthat the volcanic rocks from Erlanghe formation were probably the products of continental arc magmatism with local extensionwhen Paleoasian oceanic plate subducted down Songnen-Zhangguancai block.

关 键 词：二浪河组 火山岩 锆石U-PB年龄 地球化学 南蛤拉河子 

分 类 号：P588.14[天文地球—岩石学] P597.3[天文地球—地质学]