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首页> 外文期刊>The Journal of Geology: a semi-quarterly magazine of geology and related sciences >Nature and Thermal State of the Lithosphere beneath the Western Margin of the Yangtze Block in South China during the Neoproterozoic
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Nature and Thermal State of the Lithosphere beneath the Western Margin of the Yangtze Block in South China during the Neoproterozoic

机译：在南方南部南部的西部边缘下的岩石圈的自然与热状态在南方南部的新典型古代

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The western margin of the Yangtze Block is characterized by numerous felsic intrusions and many mafic-ultramafic plutons that record the lithospheric thermal state of South China during the Neoproterozoic. Numerous ～800 Ma mafic dikes, intruded into the Neoproterozoic Dengxiangying Group, consist of fine- to medium-grained diabase and have variable SiO_(2) (42.80–57.20 wt%), MgO (5.16–13.15 wt%), and total alkalis (0.05–4.41 wt%). They show light rare earth element–enriched patterns with negative to slightly positive Eu anomalies ( Eu / Eu * = 0.67 – 1.09 ) and display enrichment of Pb and depletion of Nb, Ta, and Sr in the primitive mantle–normalized trace-element diagram. Rocks from the Dengxiangying mafic dikes have variable initial ~(87)Sr/~(86)Sr ratios (0.652431–0.730039) but relatively constant εNd values (?2.5 to +2.6) and Pb isotope ratios ( Pb 206 / Pb 204 = 17.53 – 17.88 , Pb 207 / Pb 204 = 15.60 – 15.63 , Pb 208 / Pb 204 = 37.66 – 38.38 ). These geochemical features suggest that the mafic dikes were derived from a lithospheric mantle enriched by slab-derived materials. PRIMELT3 modeling for the Neoproterozoic mafic rocks in the western margin of the Yangtze Block reveals that their primary magmas were in equilibrium with harzburgite and spinel peridotite with potential temperatures of 1377°–1498°C. They have high primary magmatic water contents (1900–72,000 ppm) that are similar to those of other arc basalts. These lines of evidences confirm that the Neoproterozoic mafic and ultramafic rocks were formed in an active continental setting.
机译：长江块的西方边缘的特点是许多肠外入侵和许多麦克风 - 超空间型芦苇，记录南华州内科科古代南方的岩石般的热状态。许多〜800 ma MAFIC堤防，侵入了Neoproterozoico dengxunying组，包括细至中粒蛋白质，具有可变的SiO_（2）（42.80-57.20wt％），MgO（5.16-13.15wt％）和总碱（0.05-4.41wt％）。它们显示光稀土元素富含富含Eu欧盟异常（EU / Eu * = 0.67 - 1.09）的富含稀有的富含物质的图案，并在原始地幔标准化的微量元素图中显示Nb，Ta和Sr的富集的富集和枯竭。来自邓县镁铁堤的岩石具有可变初始〜（87）Sr /〜（86）SR比率（0.652431-0.730039），但相对恒定的εnd值（？2.5至+2.6）和Pb同位素比率（Pb 206 / Pb 204 = 17.53 - 17.88，PB 207 / PB 204 = 15.60 - 15.63，PB 208 / PB 204 = 37.66 - 38.38）。这些地球化学特征表明，MAFIC Dikes衍生自富含板衍生材料的岩石罩。扬子街区西部边缘的新典型墓地岩石的Primelt3建模揭示了他们的主要岩浆与哈尔茨伯利钛矿和尖晶石恒星的平衡，潜在的温度为1377°-1498℃。它们具有高原发性岩浆水含量（1900-72,000ppm），类似于其他弧形沼气。这些证据界面证实，在主动的大陆环境中形成了NeoProotrozoic Mafic和Ultramfic岩石。

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