吉林抚松四道砬子河岩组斜长角闪岩成因

发布时间：2018-11-05 20:41

【摘要】：在吉林抚松地区出露有一套太古宙角闪岩相变质岩石,其形成时代和成因机制长期存在争议。选定其中的斜长角闪岩作为研究对象,进行了岩石学、矿物学、岩石地球化学、锆石U-Pb年代学系统研究,分析了其形成过程,探讨了同时期构造岩浆演化背景。斜长角闪岩LA-ICP-MS锆石U-Pb测年取得的岩浆型锆石年龄分别为(2 555±13)Ma、(2 528±13)Ma、(2 529±9.8)Ma,表明其形成于新太古代晚期(2.55~2.50 Ga)。主量元素平均化学成分与基性火山岩中玄武岩成分相似,Si O2含量为46.22%~59.6%,平均值为51.13%;Al2O3含量11.83%~17.59%,平均值为13.42%。稀土元素总量53.74×10-6~219.07×10-6,平均值为108.17×10-6,(La/Yb)N=2.07~8.98,平均值5.19,表明轻稀土相对富集且轻重稀土分馏较明显。微量元素中较富集K、Rb、Ba等大离子亲石元素(LILE);亏损Zr、Ti、Nd、Ta等高场强元素(HFSE)。综合岩石矿物组成及地球化学成分特征,认为吉林抚松地区斜长角闪岩属正变质岩,原岩应为玄武质火山岩,岩浆主要来源于亏损地幔,同时伴有少量古老地壳的混染再造,形成于岛弧环境,该区是华北克拉通新太古代吉—辽—冀弧陆碰撞增生造山带的北延部分。
[Abstract]:There is a set of Archean amphibolite facies metamorphic rocks exposed in Fusong area Jilin Province. The diagonal amphibolite is selected as the research object. The petrology, mineralogy, petrogeochemistry and zircon U-Pb chronology are studied systematically, the formation process is analyzed and the tectonic magma evolution background of the same period is discussed. The magmatic zircon ages obtained from the LA-ICP-MS zircon dating of the amphibolite are (2 555 卤13) Ma, (2 528 卤13) Ma, (2 529 卤9.8) Ma, respectively, indicating that they were formed in the late NeoArchaean period (2. 55) Ma, (2. 50 Ga). The average chemical composition of the principal elements is similar to that of basalt in the basic volcanic rocks. The content of Si O 2 is 46.22 and the average value is 59.6.The average value is 51.13Al 2O 3 11.83 and 17.59.The average value is 13.422. The total amount of rare earth elements is 53.74 脳 10-6 (219.07 脳 10-6), with an average value of 108.17 脳 10-6, (La/Yb) Nu 2.077 (8.98), with an average value of 5.19, which indicates that LREE is relatively enriched and the fractionation of LREE is obvious. Enrichment of large Ionic Lipophilic elements such as Ke, RB, Ba and other heavy Ions in Trace elements (LILE); depleted Zr,Ti,Nd,Ta and other High Field strength elements (HFSE). According to the characteristics of rock mineral composition and geochemical composition, it is considered that the amphibolite in Fusong area of Jilin Province is orthomorphic, the primary rock should be Black Tortoise volcanic rock, the magma is mainly derived from the depleted mantle, and is accompanied by a small amount of ancient crustal mixing and reconstructing. Formed in the island arc environment, the area is the northern extension of the NeoArchaean Archean-Liao-Hebei-Arc collision and accretive orogenic belt in the North China Craton.
【作者单位】：吉林大学地球科学学院;中国人民武装警察部队黄金第一支队;
【基金】：中国地质调查局项目“吉林抚松1∶5万开锋林场等四幅区域地质矿产调查”(12120114038401)
【分类号】：P588.125

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