| 大兴安岭漠河前哨林场侵入岩年代学、岩石地球化学特征及其地质意义 |
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| 引用本文： | 陆胜,王可勇,赵焕利,相雷,刘阳,张志博.大兴安岭漠河前哨林场侵入岩年代学、岩石地球化学特征及其地质意义[J].吉林大学学报(地球科学版),2021,51(1):126-140. |
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| 作者姓名： | 陆胜 王可勇 赵焕利 相雷 刘阳 张志博 |
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| 作者单位： | 1. 黑龙江省第五地质勘查院, 哈尔滨 150090;2. 吉林大学地球科学学院, 长春 130061;3. 黑龙江省地质矿产局, 哈尔滨 150300 |
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| 基金项目： | 中国地质调查局项目（2017YFC0601304） |
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| 摘 要： | 前哨林场大地构造上位于大兴安岭北段额尔古纳地块北部的漠河前陆盆地边缘。本文研究了大兴安岭漠河前哨林场侵入岩的岩相学、年代学及岩石地球化学特征，探讨了研究区内侵入岩的形成时代、岩石成因及其构造环境。LA-ICP-MS锆石U-Pb定年结果表明，花岗岩形成于199.9~199.3 Ma、辉长岩形成于（201.8±2.6） Ma，即研究区内的花岗岩、辉长岩均形成于晚三叠世—早侏罗世。岩石地球化学研究表明：花岗岩的w（SiO2）为63.22%~70.10%，w（Al2O3）为12.43%~14.36%，里特曼指数（σ）为0.74~1.65，属高钾钙碱性系列岩石，具有较低的Mg#值（平均值为39.43），w（TFeO）为2.80%~4.41%，w（CaO）为1.47%~3.38%，轻重稀土分馏明显，富集轻稀土，亏损重稀土，δEu为0.48~0.84，富集Rb、Ta、K、La、Nd、Zr、Ti等元素，相对亏损Th、U、Sr、P、Eu等元素；辉长岩的w（SiO2）为51.42%~51.98%，w（Al2O3）为17.24%~17.73%，里特曼指数（σ）为3.00~3.53，属高钾钙碱性系列岩石，具有较高的Mg#值（平均值为51.07），w（TFeO）为9.06%~9.14%，w（CaO）为5.81%~6.69%，重稀土分馏不明显，δEu为0.86~0.98，富集Rb、Ta、Nb、Nd等元素，相对亏损Th、U、P、Eu等元素。上述岩石地球化学特征表明，花岗岩为辉长岩结晶分异的产物，原始岩浆起源于地幔，并受地壳物质的混染改造。研究区侵入岩形成于造山阶段挤压环境，是蒙古—鄂霍茨克洋俯冲碰撞的产物。
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| 关 键 词： | LA-ICP-MS锆石U-Pb定年 地球化学 侵入岩 前哨林场 大兴安岭 |
| 收稿时间： | 2019-03-27 |
Geochronology,Geochemistry and Geological Significance of Intrusive Rocks in Qianshao Forest Farm of Mohe Area,Great Xing'an Range |
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| Lu Sheng,Wang Keyong,Zhao Huanli,Xiang Lei,Liu Yang,Zhang Zhibo.Geochronology,Geochemistry and Geological Significance of Intrusive Rocks in Qianshao Forest Farm of Mohe Area,Great Xing'an Range[J].Journal of Jilin Unviersity:Earth Science Edition,2021,51(1):126-140. |
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| Authors: | Lu Sheng Wang Keyong Zhao Huanli Xiang Lei Liu Yang Zhang Zhibo |
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| Institution: | 1. The Fifth Geological Prospecting Institute of Heilongjiang Province, Harbin 150090, China;2. College of Earth Sciences, Jilin University, Changchun 130061, China;3. Bureau of Geology and Mineral Resources of Heilongjiang Province, Harbin 150300, China |
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| Abstract: | Qianshao forest farm is located at the edge of Mohe foreland basin in the northern part of Erguna block in the north of Great Xing'an Range. The authors studied the petrography, geochemistry, and geochronology of intrusive rocks in Qianshao forest farm, and discussed the formation age, petrogenesis, and tectonic environment of the intrusive rocks. The results of LA-ICP-MS zircon U-Pb dating show that the granite was formed in (199.9-199.3) Ma, gabbro was formed at (201.8±2.6) Ma, in Late Triassic-Early Jurassic. The petro-geochemical studies show that the w(SiO2) of granite is 63.22%-70.10%, w(Al2O3) is 12.43%-14.36%, and the Ritman index(σ) is 0.74-1.65, indicating that they belong to cala-alkaline series. They have low Mg# values (average 39.43), w(TFeO) is 2.80%-4.41%, and w(CaO)is 1.47%-3.38%. The REE is characterized by significant fractionation of light and heavy rare earth elements with enrichment of LREE and depletion of HERR, δEu of 0.48-0.84, enrichment of Rb, Ta, K, La, Nd, Zr, Ti, and depletion of Th, U, Sr, P, Eu. The w(SiO2) of gabbro is 51.42%-51.98%, w(Al2O3) is 17.24%-17.73%, and the Ritman index(σ) is 3.00-3.53, indicating that they belong to cala-alkaline series. They have high Mg# values (average 51.07), w(TFeO)is 9.06%-9.14%, and w(CaO) is 5.81%-6.69%, light fractionation of light and heavy rare earth elements with δEu of 0.86-0.98, enrichment of Rb, Ta, Nb, Nd, and depletion of Th, U, P, Eu. The above geochemical characteristics show that the granite was the product of crystallization differentiation of gabbro. The original magma was sourced from the mantle and subsequently contaminated by crustal materials. The intrusive rocks in the study area were formed in the compressive environment of the subduction and collision orogenic stage between the Mongolian and Okhotsk Sea. |
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| Keywords: | LA-ICP-MS zircon U-Pb dating geochemistry intrusive rock Qianshao forest farm Great Xing’an Range |
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