%0 Journal Article %T 兴蒙造山带中段锡林浩特跃进地区石炭纪岛弧型侵入岩： 年代学、地球化学、Sr-Nd-Hf同位素特征及其地质意义<br>Geochronology, Geochemistry, Sr-Nd-Hf Isotopic Characteristics and Geological Significance of Carboniferous Yuejin Arc Intrusive Rocks of Xilinhot, Inner Mongolia %A 王树庆 %A 胡晓佳 %A 杨泽黎 %A 赵华雷 %A 张永 %A 郝爽 %A 何丽< %A br> %A Wang Shuqing %A Hu Xiaojia %A Yang Zeli %A Zhao Hualei %A Zhang Yong %A Hao Shuang %A He Li %J 地球科学(中国地质大学学报) %D 2018 %R 10.3799/dqkx.2017.510 %X 兴蒙造山带中段锡林浩特跃进地区出露一套石炭纪侵入岩，具有类似岛弧侵入岩的岩石组合(花岗闪长岩、英云闪长岩、石英闪长岩)和地球化学特征.锆石LA-MC-ICP-MS U-Pb测年结果表明，这套侵入岩形成时代为310~330 Ma，属于石炭纪中晚期.岩石地球化学分析表明，跃进侵入岩属于钠质钙碱性系列岩石；A/CNK范围为0.86~1.17，大多属于准铝－弱过铝质系列；样品均具有较高的Mg#值，范围为47.5~55.8；微量元素分析表明，跃进侵入岩具有Rb、Ba、Th、U、K等大离子亲石元素的富集，Nb、Ta、P、Ti等高场强元素的亏损；稀土总量较低(3.62×10-6~172.33×10-6，平均值为118.33×10-6)，具有轻稀土富集的配分模式,(La/Yb)N大于1，范围为2.48~9.44，重稀土分馏较弱，(Gd/Yb)N 范围为1.19~1.96，具有弱的Eu负异常(δEu值0.70~1.04).跃进侵入岩均具有亏损的Hf同位素组成，176Hf/177Hf范围为0.282651~0.282870，εHf(t)均为正值，范围为+2.0~+9.9，地壳存留模式年龄TDMC范围为829~1536Ma，集中于900~1200Ma；(87Sr/86Sr)i范围为0.7037~0.7048，(143Nd/144Nd)i范围为0.512320~0.512401，εNd(t)均为正值(+2.1~+3.6)，二阶段Nd模式年龄TDM2较集中，为新元古代(793~918 Ma).跃进侵入岩是在石炭纪活动大陆边缘的背景下，由中元古代晚期-新元古代早期的新生基性下地壳物质，在俯冲流体及岛弧基性岩浆的共同作用下部分熔融形成的，表明石炭纪中晚期兴蒙造山带中段仍然存在板块俯冲，古亚洲洋并未关闭.<br>The study of magmatism can reveal the structure and tectonic evolution of the orogeny. In this paper, we present zircon LA-MC-ICP-MS U-Pb dating, Hf-Sr-Nd isotopic compositions and whole rock geochemical data of the Carboniferous Arc intrusive rocks from Yuejin region of Xilinhot, central part of the Xingmeng Orogenic Belt. The rock suit consists of three major rock types, i.e., granodiorite, tonalite and quartz-diorite, with zircon U-Pb ages ranging from 310±1 to 330±1Ma. Geochemically, these rocks show moderate SiO2，high and variable Na2O, Al2O3, and CaO contents, but low K2O, FeOt and MgO contents.The Na2O/K2O ratios are all higher than 1(1.05-2.68, average of 1.95), while these rocks are of Calc-Alkaline series. The A/CNK ratios range from 0.86 to 1.17, indicating most of samples are meta to weak per-aluminous series. The Mg# are moderately high, from 47.5-55.8. The trace elemental data of these rocks display enrichment of LILEs, such as Rb, Ba, Th, U, K, but depletion of HFSE, i.e., Nb, Ta, P and Ti. The total REE contents are low (3.62×10-6-172.33×10-6, average of 118.33×10-6) with moderate fractionation between LREE and HREE ((La/Yb)N range from 2.48-9.44), while weak negative Eu abnormity are observed(δEu range from 0.70 to 1.04). The in-situ zircon Hf isotopic analysis show depleted compositions with 176Hf/177Hf ratios varying from 0.282723 to 0.282863, εHf(t) values from +2 to +9.9 and Hf two stage model ages(TDMC) from 829 to 1536Ma(concentrating from 900 to 1200Ma). The whole rock Sr-Nd isotopic analysis of (87Sr/86Sr)i range from 0.7037 to 0.7048，(143Nd/144Nd)i range from 0.512320 to 0.512401,with positive εNd(t) (+2.1 to +3.6), indicating depleted source, and the Nd two stage model ages(TDM2) are of Neoproterozoic(793-91Ma). The rock suit, whole rock geochemistry, Hf-Sr-Nd isotopic %K 石炭纪 %K 岛弧型侵入岩 %K 活动大陆边缘 %K 兴蒙造山带 %K 大洋俯冲 %K 新生地壳< %K br> %K Carboniferous %K arc intrusive rocks %K active continental margin %K Xingmeng orogeny %K subduction %K juvenile crust %U http://www.earth-science.net/WebPage/Article.aspx?id=3770