Strongly peraluminous granites of Mesozoic in Eastern Nanling Range, southern China: Petrogenesis and implications for tectonics
Strongly peraluminous granites of Mesozoic in Eastern Nanling Range, southern China: Petrogenesis and implications for tectonics
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DOI：
10.1360/03yd0042
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发表时间：
2005-02
期刊：
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通讯作者：
T. Sun;Xinmin Zhou;Peirong Chen;Huimin Li;Hong-ying Zhou;Zhicheng Wang;W. Shen
中科院分区：
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作者：
T. Sun;Xinmin Zhou;Peirong Chen;Huimin Li;Hong-ying Zhou;Zhicheng Wang;W. Shen
南岭东段强过铝花岗岩以富含白云母、富铝黑云母、电气石、石榴石等高铝矿物而不含堇青石为特征。从岩石学、地球化学、Nd同位素、单颗粒锆石U-Pb定年等方面对它们的代表性岩体进行了研究。研究表明，这些花岗岩形成于228-225 MaBP和J2- 3159 ~ 156 MaBP两个阶段，分别属于印支期和燕山早期。εNd（t）值（−10.6-−11.1），高的A/CNK、Rb/Sr比值和tDM值（1887-1817 Ma），以及REE的四分体效应（TE 1，3=1.13-1.34）。通过与邻区花岗岩的地质、岩石学和年代学对比，认为ENR印支期SPG形成于印支运动大碰撞后20 Ma的后碰撞伸展环境（258-243 Ma BP），燕山早期SPG形成于受古太平洋构造域控制的弧后伸展背景下，两个阶段的间隔，是华南地区从特提斯构造域向太平洋构造域过渡的时期。这些SPG具有相似的地质和地球化学特征，它们都是在增厚的地壳（≤50 km）变薄、减压、导水的条件下，由早元古代变质沉积岩部分熔融形成的岩浆结晶而成。
The strongly peraluminous granites (SPGs) of Eastern Nanling Range (ENR) are a characteristic of all bearing highly aluminous minerals, such as muscovite Alrich biotite tourmaline garnet, and lack of cordierite. In respect of petrography, geochemistry, Nd isotope, and single grain zircon U-Pb dating, the representative granite bodies of them are studied. The research shows that these granites were emplaced in two stages, namely 228–225 Ma BP and J2–3 159–156 Ma BP, belonging to Indosinian and early Yanshanian periods, respectively, and they have low? εNd(t) values (−10.6-−11.1), high A/CNK, Rb/Sr ratios and tDM values (1887–1817 Ma), and REE’s tetrad effect (TE1, 3=1.13–1.34). In comparison with related geology, petrology and chronology of granites in adjacent regions, it is suggested that Indosinian SPGs of ENR formed in the circumstance of post-collisional extension 20 Ma after the major collision of Indosinian Movement (258-243 Ma BP) in Indo-China Peninsula, and early Yanshanian SPGs formed in the background of back-arc extension setting controlled by paleo-Pacific tectonic domain, and J1, the interval of two stages, is the interim from Tethyan to Pacific tectonic domains in South China. These SPGs have similar geological and geochemical characteristics, because they all crystallized from the magma of partial melting of early Proterozoic metasedimentary rocks when the thickened crust (≤50 km) became thinning, decompression, and transmitting of water.