| 杨海星.大兴安岭中南段罕山林场地区玛尼吐组安山岩年代学、地球化学特征及其地质意义[J].地质与勘探,2019,55(5):1223-1240 |
| 大兴安岭中南段罕山林场地区玛尼吐组安山岩年代学、地球化学特征及其地质意义 |
| Geochronolagy and geochemistry of the andesites from the Manitu Formation in the Hanshanlinchang area, central-southern Daxinganling Mountains and their geological implications |
| 投稿时间：2018-05-18 修订日期：2019-01-02 |
| DOI：10.12134/j.dzykt.2019.05.010 |
| 中文关键词: 玛尼吐组 安山岩 锆石U-Pb年龄 岩石地球化学 地质意义 罕山林场地区 大兴安岭中南段 |
| 英文关键词: Manitu Formation, volcanic rocks, zircon U-Pb dating, petrogeochemical, geological implication |
| 基金项目:中国地质调查项目（编号:DD20160048-11、DD20160048-15、DD20160048）资助。 |
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| 中文摘要: |
| 玛尼吐组是在大兴安岭地区的重要地层单元. 本文对大兴安岭中南段罕山林场地区玛尼吐组火山岩进行LA-ICP MS 锆石U-Pb 定年和岩石地球化学分析。LA-ICP MS锆石U-Pb定年结果显示，四件安山岩样品分别形成于144.0±2.8Ma、144.6±2.1Ma、148.0±2.0Ma及151.4±2.6Ma，说明研究区玛尼吐组安山岩时代归属晚侏罗世。从岩石地球化学特征看，玛尼吐组安山岩与中国安山岩相比，下列成分的含量偏高：SiO2(50.4%~62.38%)、TiO2(0.92%~1.74%)、Al2O3(14.2%~18.34%)、CaO(4.84%~9.39%)、Na2O(2.68%~4.97%);含量相当的成分是：Fe2O3(2.91%~7.83%)、K2O(1.48%~3.27%)、P2O5(0.08%~0.52%；而下列成分的含量偏低：FeO(0.74%~4.67%)、MnO(0.04%~0.16%)、MgO(0.92%~5.06%)；因此它是一套准铝质高钾钙碱性系列安山岩。稀土总量（ΣREE）较低，介于95.88×10-6~186.76×10-6之间，轻、重稀土分异明显（LREE/HREE=5.24~9.75，(La/Yb)N=4.84~13.21）；具轻微负铕异常（δEu=0.78~1.11）。微量元素富集大离子亲石元素（Rb、Ba、K、Pb、Sr）和LREE，亏损高场强元素（Nb、Ta、Ti、P）和HREE。火山岩浆来源于俯冲流体交代的地幔楔部分熔融；形成于大陆边缘弧，与太平洋板块俯冲后的陆内伸展作用相关。 |
| 英文摘要: |
| The Manitu Formation is an important stratigraphic unit in the Daxinganling Mountains. This paper presents LA-ICPMS ziron U-Pb dating and geochemical analysis to the andesites from the Manitu Formation in the Hanshanlinchang area, central-southern Daxinganling Mountains. Dating results of four samples show ages of 144.0±2.8Ma, 144.6±2.1Ma, 148.0±2.0 Ma and 151.4±2.6Ma, respectively, indicating that Manitu Formation andesites formed in Late Jurassic. In geochemistry, compared with the general Chinese andesites, the following compositions of Manitu andisides have higher contents: SiO2 (50.4%~62.38%), TiO2(0.92%~1.74%, Al2O3 (14.2%~18.34%), CaO(4.84%~9.39%), Na2O (2.68%~4.97%); the compositions with identical contents include Fe2O3 (2.91%~7.83%), K2O(1.48%~3.27%), and P2O5(0.08%~0.52%), while FeO(0.74%~4.67%), MnO(0.04%~0.16%) and MgO(0.92%~5.06%) are relatively low ; so they should be a suite of metaluminous high potassium calc-alkaline andesites. Meanwhile, they have low total amount of rare earth elements (ΣREE=95.88×10-6~186.76×10-6); obviously fractionated LREE from HREE(LREE/HREE=5.24~9.75, (La/Yb)N=4.84~13.21) and negative Eu anomalies（δEu=0.78~1.11）. Besides, these andesites are enriched in LILE (Rb, Ba, K, Pb, Sr) and LREE, while depleted in HFSE (Nb, Ta, Ti, P) and HREE. Considering the tectonic setting of the Daxinganling Mountains, we suggest that these volcanic rocks have originated from the magma in a partially melting mantle wedge of a subduction zone with fluid replacement, which formed at a continental marginal arc, associated with intracontinental extension after the Pacific underthrusting. |
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