Zircon U–Pb ages and Hf isotopic compositions from the Sin Quyen Formation: the Precambrian crustal evolution of northwest Vietnam
Zircon U–Pb ages and Hf isotopic compositions from the Sin Quyen Formation: the Precambrian crustal evolution of northwest Vietnam
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DOI：
10.1080/00206814.2011.646831
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发表时间：
2012-08
影响因子：
2.6
通讯作者：
P. T. Hieu;Fukun Chen;Levi Me;N. Thuy;W. Siebel;Tingguang Lan
中科院分区：
文献类型：
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作者：
P. T. Hieu;Fukun Chen;Levi Me;N. Thuy;W. Siebel;Tingguang Lan
越南西北部华南地块和印度支那地块之间的缝合带的位置几十年来一直存在争议。一般来说，这些区块之间的边界沿着（1）哀牢山-红河带或（2）松马带。 Sin Quyen 组位于这些区域之间，以前被认为是古元古代和中元古代层序。它包括它的起源和构造亲和力。我们采用激光烧蚀电感耦合等离子体质谱 U-Pb 测年技术分析了 Sin Quyen 组两块副片麻岩和一块混合岩中的碎屑锆石。这些锆石的U-Pb年龄显示了锆石形成的三个主要时期：∼2.7-3.0、∼2.2-2.5和∼1.8 Ga，表明Sin Quyen岩石主要源自古元古代和太古宙基底单元。由于华南基底由年龄相似的岩石组成，我们得出结论，Sin Quyen 组属于该区块。我们的新数据强化了华南地块和印度支那地块之间的缝合线位于松马地带内的观点。此外，U-Pb年龄>30亿年的锆石是迄今为止越南西北部报道的最古老的矿物，表明该地区存在中太古代地壳遗迹。
The location of the suture zone between the South China and Indochina blocks in northwest Vietnam has been under debate for decades. Generally, the boundary between these blocks has been placed along (1) the Ailaoshan–Red River zone or (2) the Song Ma zone. The Sin Quyen Formation, lying between these zones, was previously regarded as a Palaeo- and Mesoproterozoic sequence. It comprises its provenance and tectonic affinity. We analysed detrital zircons from two paragneisses and one migmatite of the Sin Quyen Formation employing laser ablation inductively coupled plasma mass spectrometry U–Pb dating techniques. U–Pb ages of these zircons show three main periods of zircon formation: ∼2.7–3.0, ∼2.2–2.5, and ∼1.8 Ga, suggesting that Sin Quyen rocks were mainly derived from Palaeoproterozoic and Archaean basement units. Inasmuch as the South China basement comprises rocks of similar ages, we conclude that the Sin Quyen Formation belongs to that block. Our new data strengthen the view that the suture between the South China and Indochina blocks is located within the Song Ma zone. In addition, zircons with U–Pb ages >3.0 thousand million years represent the oldest minerals reported in northwest Vietnam so far, indicating the existence of Mesoarchaean crustal remnants in this region.