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首页> 外文期刊>Acta Geologica Sinica >Geochronology and Geochemical Characteristics of the Early Mesozoic Tangquan Pluton in Southwestern Fujian and Its Tectonic Implications
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Geochronology and Geochemical Characteristics of the Early Mesozoic Tangquan Pluton in Southwestern Fujian and Its Tectonic Implications

机译：闽西南地区早中生代汤泉岩体的年代学，地球化学特征及其构造意义

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摘要

The Tangquan granodioritic pluton in Datian County, southwestern Fujian, China, which extends in a NE direction with an exposed area of about 130 km~2, used to be considered a product of Early Cretaceous magmatism. The present study suggests for the first time that the pluton was formed in the Early Jurassic by using multiple methods for isotopic dating, which give zircon U-Pb ages of 186.8 Ma and 179.0 Ma, Rb-Sr isochron age of 162.02+-4.5 Ma, and biotite ~(40)Ar/~(39)Ar plateau age of 158.1+-0.7 Ma. The cooling rate for the pluton was relatively low (4.76℃/Ma) during the early stage (183―162 Ma) because of the compressional environment. It was emplaced in a higher cooling rate (50℃/Ma) in an extensional environment during the later stage (162―158 Ma). The granodiorites are metaluminous-peraluminous, relatively enriched in Na_2O and depleted in K_2O, and characteristic of I-type granites of crust-mantle mixed sources. They are moderately enriched in Rb, Th, Hf and LREE, and depleted in Ti, Nb, Ta and Sr, and have geochemical features of cal-alkaline rocks of an island arc or active continental margin. Their (~(87)Sr/~(86)Sr)_i ratio varies from 0.70769 to 0.70822, ε_(Nd)(t) from ―9.68 to ―10.07 and T_(DM) from 1.52 to 1.55 Ga. They were formed by mixing of mantle-derived mafic magma with the granitic magma resulting from partial melting of crust-derived materials in an upwelling of the asthenospheric mantle in South China during the Early Mesozoic.
机译：福建西南大田县的汤泉花岗二叠纪岩体向东北方向延伸，裸露面积约130 km〜2，曾被认为是早白垩世岩浆作用的产物。本研究首次表明，通过多种同位素测年方法在侏罗纪早期形成了质子，锆石的U-Pb年龄为186.8 Ma和179.0 Ma，Rb-Sr等时年龄为162.02 + -4.5 Ma ，黑云母〜（40）Ar /〜（39）Ar高原年龄158.1 + -0.7 Ma。由于受压缩环境的影响，在早期（183〜162 Ma），冷却子的冷却速率较低（4.76℃/ Ma）。在后期（162〜158 Ma），将其置于较高的冷却速度（50℃/ Ma）中。花岗闪长岩为金属-高铝质，相对富集Na_2O，贫乏K_2O，具有壳幔混合源的I型花岗岩特征。它们富含Rb，Th，Hf和LREE，贫有Ti，Nb，Ta和Sr，具有岛弧或活动大陆边缘的钙碱性岩石的地球化学特征。它们的（〜（87）Sr /〜（86）Sr）_i比值从0.70769变到0.70822，ε_（Nd）（t）从9.68变到-10.07，T_（DM）从1.52变到1.55 Ga。早中生代华南软流圈地幔上升中，地幔源性物质部分熔融导致地幔源性镁铁质岩浆与花岗岩岩浆混合。

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