| 辽东连山关地区新太古代花岗杂岩SHRIMP U-Pb年龄、Hf同位素组成及地质意义 |
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| 引用本文： | 杨凤超,孙景贵,宋运红,张朋,毕中伟.辽东连山关地区新太古代花岗杂岩SHRIMP U-Pb年龄、Hf同位素组成及地质意义[J].地球科学,2016,41(12):2008-2018. |
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| 作者姓名： | 杨凤超 孙景贵 宋运红 张朋 毕中伟 |
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| 作者单位： | 1.吉林大学地球科学学院，吉林长春 130061 |
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| 基金项目： | 中国地质调查局地质资源大调查项目12120113058800国家自然科学基金青年基金项目41501093 |
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| 摘 要： | 辽东本溪连山关花岗杂岩岩体的精细年代学和地球化学的研究匮乏，区域上辽东地区新太古代岩浆活动较少，研究也相对较弱.辽东本溪连山关地区处于铀矿集中区，是内生铀矿床的有利成矿地区.区内铀矿主要赋存于连山关花岗杂岩体与辽河群浪子山组或鞍山群的接触带附近，表明了岩体与铀矿化关系密切.连山关地区浅肉红色正长花岗岩SHRIMP U-Pb年龄为2 512±14 Ma，灰白色条痕状二长花岗岩SHRIMP U-Pb年龄为2 510±15 Ma，花岗杂岩侵位时代为新太古代.正长花岗岩SiO2含量为69.28%~72.70%，K2O含量为6.24%~7.12%，Na2O含量为2.77%~3.09%，Al2O3含量为13.68%~15.92%；二长花岗岩SiO2含量为65.53%~71.01%，K2O含量为2.95%~3.90%，Na2O含量为3.57%~4.23%，Al2O3含量为14.13%~14.90%；连山关花岗杂岩含白云母，A/CNK为1.09~1.16(平均1.12)，刚玉(C)为1.37~2.28，P2O5和SiO2无负相关关系，表现为高钾的S型花岗岩.稀土总量较高，轻重稀土元素之间强烈分馏，从正铕异常到负铕异常(δEu=3.55~0.36)，亏损Nb、Ta、P、Ti等高场强元素，富集Rb、Th、K等大离子亲石元素.锆石εHf(t)值为-15.19~-0.47，对应的单阶段Hf模式年龄TDM为2 826~3 400 Ma，两阶段Hf模式年龄TDMC为2 931~3 650 Ma.辽东连山关花岗杂岩可能是在高温中压条件下由中太古代和古太古代地壳物质(以变质泥岩和杂砂岩为主)发生深熔作用形成的，可能发生在后碰撞环境，指示华北克拉通各微陆块拼贴完成.
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| 关 键 词： | 辽东半岛 花岗杂岩 太古代 地质年代学 S型花岗岩 岩石学 |
| 收稿时间： | 2016-02-26 |
SHRIMP U-Pb Age,Hf Isotope Composition and Geochemical Characteristics of Neoarchean Granitic Complex in Liaodong Lianshanguan Area,NE China |
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| Abstract: | The fine chronology and geochemistry of the Lianshanguan granite complex in Benxi are scarce, and the Neoarchean magmatism in the Liaodong area is less and the study is relatively weak. The Lianshanguan area at Benxi in East Liaoning is the favorable metallogenic area for endogenous uranium deposits within uranium concentration area. Uranium deposits near the contact zone with the region mainly occur in Lianshanguan granitic complex and Langzishan Formation of Liaohe Group or Anshan Group, indicating close relationship between the rock and uranium mineralization. In Lianshanguan area, light flesh red syenogranite yields an SHRIMP U-Pb age of 2 512±14 Ma, white streak-shape monzonitic granite yields an SHRIMP U-Pb age of 2 510±15 Ma, and emplacement age of granitic complex is Neoarchean. Syenogranites show SiO2 of 69.28%-72.70%, K2O of 6.24%-7.12%, Na2O of 2.77%-3.09%, Al2O3 of 13.68%-15.92%. Monzonitic granites show SiO2 of 65.53%-71.01%, K2O of 2.95%-3.90%, Na2O of 3.57%-4.23%, Al2O3 of 14.13%-14.90%. Lianshanguan granitic complex contains muscovite and shows 1.09-1.16 (average 1.12) of A/CNK, 1.37-2.28 of corundum (C), no negative correlation between P2O5 and SiO2, so it is characterized by high potassium S-type granite. rare earth elements show higher content, strong fractional distillation between light and heavy rare earth elements, from positive to negative Eu anomaly (δEu=3.55-0.36), loss of Nb, Ta, P, Ti high field strength elements, enrichment of Rb, Th, K and other large-ion lithophile elements. The εHf(t) is -15.19 to -0.47, single-stage Hf model ages TDM are 2 826-3 400 Ma, and two-stage Hf model ages TDMC are 2 931-3 650 Ma. The Lianshanguan granitic complex in Liaodong area may be formed by deep-melting of Middle-Archean and Paleozoic crustal materials (mainly metamorphic mudstones and miscellaneous sandstones) under high-temperature and medium-pressure conditions, and may occur in the post-collision environment. It indicates that North China Craton micro-land collage was completed. |
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