Zircon SHRIMP geochronology of the Xinkailing-Kele complex in the northwestern Lesser Xing’an Range, and its geological implications
Zircon SHRIMP geochronology of the Xinkailing-Kele complex in the northwestern Lesser Xing’an Range, and its geological implications
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DOI：
10.1360/03wd0316
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发表时间：
2004
影响因子：
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通讯作者：
L. Miao;W. Fan;Fuqin Zhang;Dunyi Liu;P. Jian;G. Shi;Hua Tao;Yuruo Shi
中科院分区：
文献类型：
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作者：
L. Miao;W. Fan;Fuqin Zhang;Dunyi Liu;P. Jian;G. Shi;Hua Tao;Yuruo Shi
Xinkailing-Kele综合体位于Xing'an-Mongolian造山带（XMOB）的东部，以前被认为是前寒武纪的变质岩石，主要根据其相对的高态级别。该络合物主要由变质岩（Kele复合物），构造岩体（“ Xinkailing oft”）和花岗岩（Xininkailing Granitoid复合物）组成。 - 晶状体片段的斑块斑块的原石年龄为337±7 mA（2σ），变质年龄为216±3 mA（Iσ）（2）“ Xininkailing群体” 292±6 Ma（2σ），指示片岩的长英质火山岩在晚期形成的片岩； （2σ），这些结果表明，Xinkailing-Kele复合物不是前寒武纪的变质岩石，而所谓的前寒武纪“ nenjiang块”实际上不是与区域地质数据相结合的。可能与三叠纪时间的碰撞构造有关，其变质年龄为216±3 Ma。 。
Located in the eastern portion of the Xing’an-Mongolian Orogenic Belt (XMOB), the Xinkailing-Kele complex has previously been considered to be Precambrian metamorphic rocks, mainly according to its relatively high metamorphic grade. Our filed observation, however, revealed that the complex is composed mainly of metamorphic rocks (Kele complex), tectono-schists (“Xinkailing Group”), and granitoids (Xinkailing granitic complex). Dating on these rocks using advanced SHRIMP zircon U-Pb technique indicates that: (1) Biotite-plagioclase gneiss from the Kele complex has a protolith age of 337±7 Ma (2σ) and a metamorphic age of 216±3 Ma (Iσ); (2) the tectono-schist of the “Xinkailing Group” gave a magmatic age of 292±6 Ma (2σ), indicative of felsic volcanic protolith of the schist formed in Late Paleozoic time; and (3) the Menluhedingzi and Lengchuan granites of the Xinkailing granitic complex were emplaced at 167±4 (2σ) and 164±4 Ma (2σ), respectively. These results suggest that the Xinkailing-Kele complex is not Precambrian metamorphic rocks and the so-called Precambrian “Nenjiang Block” does essentially not exist. In combination with regional geological data, we propose that the Kele metamorphic complex is likely related to a collisional tectonism that took place in Triassic time, as indicted by its metamorphic age of 216±3 Ma. The Xinkailing granitic complex was emplaced along the collisional zone during Mid-Jurassic time, likely in a post-orogenic or anorogenic setting.