【作者】 王挽琼；

【导师】 刘正宏； 徐仲元；

【作者基本信息】 吉林大学 ， 构造地质学， 2014， 博士

【摘要】 内蒙古中部温都尔庙—集宁地区位于索伦缝合带南侧，横跨了华北克拉通北部和兴蒙造山带南缘，是研究古亚洲洋和兴蒙造山带演化的重要地区。研究区自南往北发育三条近东西向断裂：乌兰哈达断裂、徐尼乌苏断裂和温都尔庙断裂，将区内划分为华北前寒武纪克拉通、中新元古代大陆边缘裂谷带、白乃庙岛弧岩带和温都尔庙俯冲-增生杂岩带四个构造单元。在对区内晚古生代火成岩进行了详细的野外地质调查、岩相学研究的基础上，利用锆石LA-ICP-MS U-Pb和锆石SHRIMP U-Pb定年技术，确定了火成岩的侵位时代，建立了区内岩浆作用的年代学框架；利用岩石组合、岩相学、地球化学特征讨论了火成岩的岩浆源区性质及其形成的构造环境。通过火成岩岩石组合的时空展布特征，并结合相邻地区晚古生代火成岩等资料，最终探讨了研究区晚古生代的构造演化历史。1.泥盆纪伸展环境顶志留统西别河组海相磨拉石建造标志着早古生代沟-弧-盆体系和白乃庙岛弧与华北克拉通北缘碰撞结束。泥盆纪岩浆活动以正长岩、二长闪长岩和正长花岗岩为代表，侵位于华北克拉通北部察哈尔右翼后旗一带，正长岩中碱性暗色矿物霓石、霓辉石、钠铁闪石发育。岩石属准铝质岩浆系列，岩浆源区为岩石圈地幔和下地壳碱性玄武质岩浆，形成于白乃庙岛弧与华北克拉通北缘碰撞拼贴后的伸展环境。正长岩锆石LA-ICP-MS U-Pb定年结果为410.9±1.2Ma，结合前人报道的区内二长闪长岩侵位时代（381.5±4.1Ma）和包头北部-集宁-张家口-赤峰一带泥盆纪火成岩资料，表明410.9~363Ma时期，侵入岩岩石组合为正长岩、二长岩、A2型花岗岩，火山岩主要为流纹质凝灰岩，华北板块北缘中西段处于伸展环境。2.石炭纪—早二叠世晚期大陆边缘弧环境早石炭世岩浆侵入作用以二长花岗岩为代表，侵位于华北克拉通北部察哈尔右翼后旗一带，前人报道其形成于342.5±4.9Ma，属准铝质-弱过铝质岩浆系列、高分异I型高钾钙碱性花岗岩，富K，稀土总量中等，轻重稀土分馏明显，富集大离子亲石元素（Cs、Rb、Ba和K），亏损高场强元素（Nb、Ta、P和Ti），岩浆源区为岩石圈地幔；火山作用以查干诺尔安山岩、英安岩和流纹岩为代表，安山岩锆石SHRIMP U-Pb年龄为333±4Ma，出露在朱日和镇东部，岩浆系列具低钾拉斑系列向低钾钙碱性系列过渡的特征，稀土总量中等，富集大离子亲石元素U，亏损高场强元素（Nb、Ta和Ti），岩浆源区为岩石圈地幔。早二叠世早期岩浆活动以角闪辉长岩为代表，斜长石类型为倍长石、拉长石、中长石和更长石，单斜辉石多发育在角闪石内部，体现了鲍文反应序列的特征。岩石属钙碱性系列，稀土总量中等，轻稀土分馏较强，富含大离子亲石元素（Cs、Ba和Sr），亏损高场强元素（Nb、Ta、Zr、Hf、Ti和P），岩浆源区为岩石圈地幔，于297.2±1.7Ma（锆石LA-ICP-MS U-Pb）主要在华北克拉通北部侵位。晚期火山作用以额里图组安山岩、流纹岩、晶屑凝灰岩为主要代表，岩浆系列属钙碱性—高钾钙碱性—钾玄岩系列，稀土总量整体较高，轻重稀土分馏明显，大离子亲石元素富集（Th和U），亏损高场强元素（Nb、Ta和Ti），岩浆源区为下地壳，于277.59±0.43Ma、275.28±0.96Ma，在乌兰哈达断裂以北岩浆喷发沉积。石炭纪—早二叠世晚期，侵入岩岩石类型为二长花岗岩和角闪辉长岩，火山岩岩石组合为安山岩、英安岩、晶屑凝灰岩和流纹岩；岩浆系列以钙碱性为主，普遍稀土总量中等至较高，富集大离子亲石元素，亏损高场强元素（Nb、Ta和Ti）；侵入岩主要分布在华北克拉通北部察哈尔右翼后旗一带，火山岩分布在中新元古代大陆边缘裂谷带和白乃庙岛弧岩带内，表明该时期研究区处于大陆边缘弧环境。3.早二叠世末期—中二叠世早期大陆边缘弧向同碰撞环境转换未发育火山岩，侵入岩岩石组合为石英闪长岩+花岗闪长岩+黑云母二长花岗岩，锆石LA-ICP-MS U-Pb年龄为272.8~268.7Ma，发育大量暗色微粒包体。岩石均为高钾钙碱性岩浆系列，稀土总量高，轻重稀土分馏明显，Eu负异常显著，富集大离子亲石元素（Cs、Rb、Ba、K、Th和U），亏损高场强元素（Nb、Ta和Ti），岩浆源区为中上地壳。石英闪长岩形成于大陆边缘弧环境；花岗闪长岩形成于大陆边缘弧向同碰撞转换环境；黑云母二长花岗岩相对更富硅、铝、钠、钾和轻稀土总量，低Y、Yb和重稀土总量，形成于同碰撞环境，标志着古亚洲洋消亡不晚于黑云母二长花岗岩的侵位时代。同碰撞过程中，在早古生代弧陆拼贴带附近形成了近东西向逆冲推覆构造。4.中二叠世中期后碰撞环境中二叠世中期岩浆活动以二长花岗岩、正长花岗岩和碱长花岗岩（铝质A2型花岗岩）为代表，锆石LA-ICP-MS U-Pb年龄为267.2~265.1Ma，主要呈大型岩基产出，发育晶洞构造，属钾质-高钾质岩石，强过铝质岩石为主，属钙碱性-高钾钙碱性-钾玄岩岩浆系列，具有由钙碱性岩浆向碱性岩浆演化的趋势，岩浆源区以壳源为主，混有少量幔源物质，形成于后碰撞伸展环境。更多还原

【Abstract】 Ondor Sum-Jining is an important area to research the Paleo-Asian Ocean andthe evolution of Xingmeng Orogenic Belt. It across the North China Craton (NCC)and the southern edge of Xingmeng Orogenic Belt, specifically it locates in the southof Solon Suture Zone in the central Inner Monglia. In study area, there are threeeast-west trending Faults including Ulanhada Fault, Xuniwusu Fault and Ondor SumFault. These faults divide the study area into four tectonic units of which are thePrecambrian NCC, Mesoproterozoic-Neoproterozoic Rifted Continental Margin,Bainaimiao Island Arc Rock Belt and Ondor Sum Subduction-Accretionary ComplexBelt. Based on the detailed geological survey and petrographic study, then with thezircon LA-ICP-MS U-Pb and zircon SHRIMP U-Pb dating can confirmed theemplacement age of igneous and also established the chronology framework ofregional magmatism; the rock assemblages, petrographic and geochemicalcharacteristics were used to discuss the igneous magma source and their tectonicsetting. Finally, combined the distribution feature of the igneous rocks andinformation of Late Paleozoic igneous in adjacent areas to explore the Late Palezozoictectonic evolution history of the study area. 1. D·evonian extension settingMarine molasse of Upper Silurian Xibiehe Formation marked the end ofPaleozoic trench-arc-basin system in the northern margin of the North China Plate andthe collision between Bainaimiao Island Arc and the NCC. The Devonian igneousrocks mainly composed of the syenite, monzonite-diorite and syenite granite, theyemplaced in Chahayouhouqi area in the northern NCC. The major alkaline darkminerals in the syenite are aegirine, aegirine-augite and arfvedsonite. The igneousrocks are metaluminous and its magma source was alkaline-basaltic magma fromelithosphere mantle and of lower earth crust. According to zircon LA-ICP-MS U-Pb dating result of410.9±1.2Ma, the previously reported381.5±4.1Ma ofmonzonite-diorite in the study area and Devonian igneous rocks in the Baotou-Jining-Zhangjiakou-Chifeng area, these datas indicate that the middle-western part of thenorthern North China Plate is extension setting and the combination of intrusive rocksare syenite, monzonite and A2-type granite, the volcanic rock mainly is rhyotaxitictuff.2. Ca·rboniferous-Early Permian an active continental margin arc settingThe Early Carboniferous magmatism is represented by monzonite granites, whichemplaced at342.5±4.9Ma reproted in the previous study. They are metaluminous-weakly peraluminous magma series, highly fractionated I-type and high K calc-alkaline granite. The volcanism is represented by andesite with the zircon SHRIMPU-Pb age333±4Ma. The volcanic rock is named Chagannuoer volcanic rock that ismainly composed of andesite, dacite and rhyolite.The Early Permian magmatism is represented by hornblende gabbro and have thefeatrues of the Bowen Reflect Series that the plagioklases typies are oligoclase,andesine, labradorite and bytownite, some amphibole aroud clinopyroxene. The rockemplaced into the northern NCC at297.2±1.7Ma resulted by the zircon LA-ICP-MSU-Pb dating.The volvanism is represented by the andesite and crystal tuff in the ElituFormation and magmatic eruption at nearly277.59±0.43Ma and275.28±0.96Ma.In Carboniferous-Early Permian, the intrusive rocks are mainly distributed near inthe Chahayouhouqi in the northern NCC, volcanic rocks are distribuded in the Mesoproterozoic-Neoproterozoic Continental Margin Rift and Bainaimiao IslandArc. Intrusive rocks are composed of monzonite granite and hornblende gabbro andvocanic rocks are composed of andesite, dacite crystal tuff, rhyolite and litter basalt,belong to calc-alkaline series-high K calc-alkaline series-tephrite series, theirmagma sourced from the lithosphere mantle-lower earth crust, enrichments in largeion lithophile elements and depletions in high field-strength elements, indicatemagmatisms formed in active continental margin arc setting related to the subductionevent of the Paleo-Asian Ocean beneath the northern margin of North China Plate.3. Early-Middle Permian continental margin arc transform to the syncollisional settingThe intrusive rocks are represented by quartz-diorite, granodiorite, biotitemonzonite granite. They have a large number of magic microgranular enclaves andhave the zircon LA-ICP-MS U-Pb dating age is272.8~268.7Ma. Rocks belongto high K calc-alkaline series and have high contents of∑REE, enrichments in lightrare elements and depletions in hight rare elements, monzonite granite have highercontents of∑REE than others. Their magma derived from upper-middle crust.Quartz-diorite formed in the continental margin arc setting, granodiorite formed in thesetting that continental margin arc trasform to the syn collision, biotite monzonitegranite formed in the syn collision. Their tectonic settings indicate that the closuretime of Paleo-Asian Ocean is earlier than the formation of the biotite monzonitegranite and Xuniwusu overthrust structure formed near the arc-continental collagezone during the syn collision.4. Middle Permian post-collisional tectonic settingThe Middle Permian magmatism is represented by monzonite granite, syenitegranite and alkali feldspar granite. Rocks primarily output as a large batholith and theage is267.2~265.1Ma by zircon LA-ICP-MS U-Pb dating. They belong to stronglyperalminous rocks, calc-alkaline-high K calc-alkaline-shoshonite series and calc-alkaline to alkaline series evolutiong trend, magma mainly sourced from crustmaterial and mixed with some mantle material and emplaced in the post-collisional extentional setting.更多还原