| 柴北缘大柴旦滩间山花岗斑岩体锆石U-Pb年代学、地球化学及Hf同位素 |
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| 引用本文： | 张延军,孙丰月,许成瀚,禹禄.柴北缘大柴旦滩间山花岗斑岩体锆石U-Pb年代学、地球化学及Hf同位素[J].地球科学,2016,41(11):1830-1844. |
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| 作者姓名： | 张延军 孙丰月 许成瀚 禹禄 |
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| 作者单位： | 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调查项目12120114080801国家自然科学基金项目41272093 |
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| 摘 要： | 为了研究柴北缘大柴旦地区在华力西期构造演化特征，对大柴旦地区滩间山花岗斑岩进行了锆石U-Pb年代学、岩石地球化学以及Hf同位素的研究.花岗斑岩中锆石LA-ICP-MS U-Pb定年结果表明，该岩体形成于晚泥盆世(356.0±2.8 Ma，MSWD=0.53).地球化学分析显示花岗斑岩属于中钾钙碱性-钙碱性系列，A/CNK值为0.97~1.10，属弱过铝质，为I型花岗岩，富集大离子亲石元素(如K、Ba、Rb)和轻稀土元素(LREE)以及Th、U，相对亏损高场强元素(如Ta、Nb、Ti、P).岩石的εHf(t)值和二阶段模式年龄(TDM2)分别介于±5.43~±8.38和1 017~1 284 Ma之间.上述特征表明，滩间山花岗斑岩的原始岩浆源于中元古代新增生陆壳的部分熔融.综合区域地质演化背景，认为滩间山花岗斑岩形成于柴达木地块与南祁连地块碰撞后伸展构造环境.
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| 关 键 词： | 锆石U-Pb年龄 锆石Hf同位素 滩间山 地球化学 年代学 |
| 收稿时间： | 2016-04-25 |
Geochronology,Geochemistry and Zircon Hf Isotopes of the Tanjianshan Granite Porphyry Intrusion in Dachaidan Area of the North Margin of Qaidam Basin,NW China |
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| Abstract: | In order to research the Variscan tectonic evolution features of Dachaidan region in North Qaidam, this paper presents LA-ICP-MS zircon U-Pb dating, geochemical and Hf isotopic data of the granite porphyry from Tanjianshan intrusion in Dachaidan region, with the aim of constraining its formation time, petrogenesis and the regional tectonic setting. The LA-ICP-MS U-Pb dating results of zircons from the granite porphyry indicate that the intrusion formed in the Late Devonian Epoch (356.0±2.8 Ma, MSWD=0.53). Geochemically, these rocks fall into the calc-alkaline to middle-K calc-alkaline series, with an A/CNK ratio of 0.97-1.10, which are weakly peraluminous granites, being of the characteristics of I type granitoids, enriched in LILE(such as K, Ba, Rb), LREE, Th and U, relatively depleted in HFSE (such as Ta, Nb, Ti, P). The εHf(t) values of the granite porphyry vary from ±5.43 to ±8.38, and two-stage model ages (TDM2) range from 1 017 to 1 284 Ma. These characteristics suggest that the primary magma was derived from the remelting of juvenile crustal materials in Mesoproterozoic. In context of its regional geological background, we conclude the granite porphyry from Tanjianshan intrusion were formed extensional tectonic setting after the collision between Qaidam block and Qilian block. |
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